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1
Zhao, Wenhui, Qian Su, Feng Han, and Wubin Wang. "Study on the Heat of Hydration and Strength Development of Cast-In-Situ Foamed Concrete." Advances in Materials Science and Engineering 2020 (April 8, 2020): 1–12. http://dx.doi.org/10.1155/2020/9061819.
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This study aims to investigate the relationship between the heat of hydration and the strength development of cast-in-situ foamed concrete. First, indoor model tests are conducted to determine the effects of the casting density and the fly ash content on the hydration heat of foamed concrete in semiadiabatic conditions. Second, compression tests are carried out to evaluate the development of the compressive strength with the curing time under standard curing conditions and temperature matched curing conditions. Third, the hydration heat development of the foamed concrete is tested in four projects. The results showed that the peak temperature, the maximum temperature change rate, and the maximum temperature difference increased with the increase in the casting density at different positions in the foamed concrete. For the same casting density of the foamed concrete, the peak temperature, the maximum temperature change rate, and the maximum temperature difference decreased with the increase in the fly ash content. For the foamed concrete without the admixture, the early strength was significantly higher under temperature matched curing conditions than under standard curing conditions, but the temperature matched curing conditions had a clear inhibitory effect on the strength of the foamed concrete. The strengths during the early stage and the later stage were both improved under temperature matched curing conditions after adding the fly ash, and the greater the fly ash content, the larger the effect. The maximum temperature increments were higher in the indoor model test than in the field tests for the same casting density. Reasonable cooling measures and the addition of fly ash decreased the maximum temperature increments and increased the corresponding casting times.
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Yang, Ming Shan, Ran Yan, Yu Hong Yan, and Yang Liu. "The Curing Behavior of Organosilicone Materials for Large-Power LED Packaging." Applied Mechanics and Materials 509 (February 2014): 15–19. http://dx.doi.org/10.4028/www.scientific.net/amm.509.15.
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The organosilicone gel material for large-power LED packaging was prepared through Si-H addition reaction of hydrogen-silicone with vinyl-silicone catalyzed by Pt coordination compound in this paper. The curing behavior was investigated by DSC method, and the curing dynamic parameters were obtained, i.e., the curing activation energy and reaction level of the system were 79.23kJ/mol and 0.8271 respectively, the initial curing temperature, maximum curing temperature and post-curing temperature were 75°C, 90°Cand 120°C, respectively, which supplied the basic data for the preparation and application of organosilicone materials for large-power LED packaging.
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Wang, Liu Bing, Hong Gao, Jian Ma, and Xu Chen. "Residual Stress Analysis in Curing Process of COG Module." Advanced Materials Research 118-120 (June 2010): 434–38. http://dx.doi.org/10.4028/www.scientific.net/amr.118-120.434.
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In this study, the bonding reliability of the COG devices was studied. A finite element analyses model was established to study the curing process of COG module. The equivalent stress of the different locations of the package structure and the change of the temperature distribution with time were studied. The heat transfer process and the conductive particle deformation process were displayed through the simulation. The results show that the curing process is the heat transformation and particle deformation process. The residual stress generated by the temperature difference between the curing temperature and the operated temperature. The results show that the maximum residual stress is in the most distorted places of the conductive particles. The maximum residual thermal stress was studied with different bump pitch (35μm 30μm 25μm and 20μm) and the size of the particles (5μm, 4μm and 3.5μm). It shows that for a certain size of the particles, the maximum residual thermal stress will decrease when the bump pitch decreases. For a certain bump pitch, the maximum residual thermal stress will decrease when the size of the particles decrease.
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Yarlagadda, Prasad K. D. V., Andre Poh, and Shu Hau Hsu. "Microwave Curing of Non-Traditional Polymer Materials Used in Manufacture of Injection Moulds." Advanced Materials Research 338 (September 2011): 214–22. http://dx.doi.org/10.4028/www.scientific.net/amr.338.214.
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Microwave heating technology is a cost-effective alternative way for heating and curing of used in polymer processing of various alternate materials. The work presented in this paper addresses the attempts made by the authors to study the glass transition temperature and curing of materials such as casting resins R2512, R2515 and laminating resin GPR 2516 in combination with two hardeners ADH 2403 and ADH 2409. The magnetron microwave generator used in this research is operating at a frequency of 2.45 GHz with a hollow rectangular waveguide. During this investigation it has been noted that microwave heated mould materials resulted with higher glass transition temperatures and better microstructure. It also noted that Microwave curing resulted in a shorter curing time to reach the maximum percentage cure. From this study it can be concluded that microwave technology can be efficiently and effectively used to cure new generation alternate polymer materials for manufacture of injection moulds in a rapid and efficient manner. Microwave curing resulted in a shorter curing time to reach the maximum percentage cure.
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Aarre, Tine, and Martin Kaasgaard. "Influence of Curing Temperature on Strength Development of Concrete." Key Engineering Materials 711 (September 2016): 118–25. http://dx.doi.org/10.4028/www.scientific.net/kem.711.118.
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With the aim to test the applicability of the commonly used maturity concept introduced by Freiesleben et al [1] to modern concrete and to investigate the impact of the curing history on the compressive strength of laboratory samples cured at elevated temperatures, four concretes with different binder compositions (a pure CEM I 42.5N, CEM I 42.5N with fly ash, CEM I 52.5N with fly ash and a CEM III/B) were cured and tested at temperatures ranging from 5 to 60 °C.To test the maturity concept, the development of the compressive strength of samples cured at temperatures ranging from 5 to 60 °C were tested at maturities ranging from 1 to 28 days.To test the impact of curing history at elevated temperatures on the compressive strength, concrete samples were cured at 60°C using two different temperature scenarios: (1) at a constant temperature of 60 °C and (2) at gradually increasing temperature from the casting temperature to the maximum temperature of 60 °C.It was found that the commonly used maturity concept is still applicable to modern concrete although the activation energy is dependent on the binder composition. Concerning the impact of curing history it was found that at 28 days of maturity, the strength of concrete cured at constant temperature of 60 °C was significantly lower than that of concrete cured at 20 °C. For the concrete exposed to gradually increasing temperature up to 60 °C, only a slight decrease in strength was observed for the pure cement concretes while the strength of the binder systems with fly ash increased.
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Wright, F. S., and D. M. Porter. "Shaded Windrow Curing for Peanuts in Virginia1." Peanut Science 24, no. 2 (1997): 78–80. http://dx.doi.org/10.3146/i0095-3679-24-2-3.
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Abstract At digging, peanut (Arachis hypogaea L.) plants were placed in shaded and conventional (inverted) windrows to determine if peanut quality could be improved. Florigiant and NC 6 cultivars were dug and placed in the two windrow types on days when freezing temperatures or frost were predicted. All peanuts were dug with a conventional digger-inverter. The shaded windrows were hand formed by placing a layer of peanuts on the inverted windrow so that the peanuts were protected from direct exposure to the sky. The peanut temperature in the conventional windrow reached the lowest temperature in the nighttime and highest temperature in the daytime and fluctuated from the lowest to highest level compared to the shaded windrow and the ambient temperature. Peanut temperatures in the conventional and shaded windrows were approximately 0C or below for a short duration during the windrow curing period. The average “maximum” peanut temperature from 12 to 5 p.m. was 3.7C higher for the conventional than the shaded windrows for all tests. From 2 to 7 a.m., the average “minimum” peanut temperature was 1.1C lower for the conventional than the shaded windrow. The peanut moisture content in the shaded windrow averaged 7.3% higher at combining than peanuts in the conventional windrow. In a test where the ambient temperature dropped below freezing for two nights following digging, the alcohol headspace meter readings were above the rejection level for freeze damage in the conventional windrow. The shaded windrow provided minimal freeze protection over the conventional windrow and shading is not recommended in the Virginia-Carolina production area.
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Zheng, Yun Wu, Li Bin Zhu, Ji You Gu, and Yan Hua Zhang. "Study on the Thermal Stability of MUF Co-Polymerization Resin." Advanced Materials Research 146-147 (October 2010): 1038–42. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.1038.
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Curing is the key to the bonding, the study indicate that: curing effect on the glue bond strength, formaldehyde emission as well as Productive Efficiency; the better curing system can ensure the Productive Efficiency in basic to decrease the FE. This paper considered the production practice, studied the curing properties of different MUF resin with TGA. The experimental result: Different curing systems, made different curing process. For A curing system, curing rate is the fastest, the degree of curing is best. Cured stability is well. While in the C curing system, Because of their poor degree of cross-linking, poly-condensation cross-linked imperfect. While, Along with the increasing of n(F):n(U1), initial decomposition temperature increased, the maximum rate of mass loss moved to higher temperature, mass loss declined, decomposition activation energy increases, aging resistance increased.
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Sun, Ximei, and Avraam I. Isayev. "Cure Kinetics Study of Unfilled and Carbon Black Filled Synthetic Isoprene Rubber." Rubber Chemistry and Technology 82, no. 2 (2009): 149–69. http://dx.doi.org/10.5254/1.3548241.
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Abstract The reversion type cure kinetic and induction time models were successfully utilized to predict the isothermal and nonisothermal evolution of the state of cure in vulcanization of the unfilled and carbon black (CB)-filled IR compounds measured by APA 2000. The rate constants for the reversion reaction and the formation of the stable and unstable crosslinks and the parameters of the induction time function with the Arrhenius temperature dependences were determined from the isothermal cure measurements. The equation was proposed to adequately describe the measured dependence of the difference between the maximum and minimum torques as a function of isothermal curing temperature. The measured induction time as a function of heating rate and step temperature variation was successfully predicted based on parameters of the isothermal induction time model. Isothermal cure modeling at each curing temperature individually or at all the curing temperatures simultaneously showed the excellent agreement with the experimental data for both curing and reversion. More severe reversion in the CB-filled IR in comparison with the unfilled IR was explained by comparing their reversion rate constants.
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Chen, Mei, Fu Quan Zhang, Yong Zhou Wang, and Mao Fang Huang. "Study on Curing Kinetics of Natural Rubber Dried by Microwave." Advanced Materials Research 807-809 (September 2013): 2809–12. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.2809.
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In this article, the curing kinetics of natural rubber (NR) dried by microwave at frequency of 2450MHz was studied using vulcameter, as well as molecular weight. Seen from the results, the molecular weight distribution of NR dried by microwave was wide, the reaction rate of NR dried by microwave at any temperatures increased with conversion degree (α) increment and passed through a maximum at the value ofαbetween 0.1 and 0.3, the peak height ofαwas increased with a shift in peak position towards a higherαvalue, which provided evidences that the curing behavior illustrated autocatalytic characteristics and depended on curing temperature.
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Wang, Qing, Xin Tu, Zhao Yang Ding, and Zhi Tong Sui. "Effect of Curing System on Mechanical Property of Slag-Based Geopolymer." Advanced Materials Research 250-253 (May 2011): 3372–76. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.3372.
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Geopolymer has been gradually attracting world attention as a potentially revolutionary material that is one of the ideal substitutes of Portland cement, and fundamental studies on geopolymer are increased rapidly because of its potential commercial applications. However, little work has been done in the field of curing system of geopolymer. In this paper, influence of curing temperature, curing time and curing humidity on the mechanical properties of slag-based geopolymer was studied by using the compressive strength as benchmark parameter. Results have shown that the early age compressive strength of geopolymer increased and the long-term compressive strength decreased at first and then increased as the curing temperature increased, 80°C was the best curing temperature. With prolonging the curing time, it was found that the compressive strength of early age of geopolymer reached the maximum ( 116.3 MPa for 1d, 97.5 MPa for 3d) as the curing time was 12h, and that of 28d geopolymer was 91.3 MPa as the curing time was 10h. It was also found that the compressive strength of geopolymer reduced evidently as the humidity increased.
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Channasanon, Somruethai, Pakkanun Kaewkong, and Siriporn Tanodekaew. "Dual-Curing Polylactide for Resorbable Bone Cement." Key Engineering Materials 798 (April 2019): 77–82. http://dx.doi.org/10.4028/www.scientific.net/kem.798.77.
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Polymeric cement based on poly (methyl methacrylate) (PMMA) has been known as a common material for fixation of prostheses with the advantages of mechanical properties. However, one of drawbacks of PMMA cement is heat produced during polymerization. The elevating temperature during polymerization resulting from exothermic polymerization of MMA can cause bone cellular necrosis. Additionally, the residual MMA monomer after polymerization is an issue regarding the biocompatibility of cement. In this study, a resorbable cement based on polylactide (PLA) has been developed. Its physical, mechanical and biological properties were investigated as an alternative biocompatible bone cement. The dual-cured polylactide cements prepared by combining spherical powder of star-shaped and linear PLA blends with triethylene glycol dimethacrylate liquid were radically polymerized by UV-VIS light and self-curing methods. Flexural strength, maximum temperature during polymerization and biocompatibility via the percentages of cell viability using MTT assay of the dual-cured polylactide were determined to meet requirements for bone cement. The best flexural strength of 108 MPa was achieved from the cement composed of 80%-wt of star-shaped PLA with molecular weight (Mw) of 10770. The preparation of cement using paste/liquid mixing, in which the powder was allowed to wet in the liquid before mixing, significantly encouraged mechanical properties compared to powder/liquid mixing due to satisfactory solubility of PLA prior to polymerization. The amount of initiator/activator was studied to fine-tune the maximum temperature during polymerization. The maximum temperature during polymerization of the PLA cement was in the range of 80-90 degree Celsius and the percentage of osteogenic cell viability immediately after cement setting was 83 indicating a non-toxic material. Therefore, this PLA cement polymerized with a dual curing mode is promising for a resorbable bone cement.
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Yin, Jicai, Yanli Teng, Xiaojun Meng, Yuanyuan Ge, and Xiuhong Zhang. "Influence of fly ash on the curing characteristics of an epoxy resin." Polymers and Polymer Composites 28, no. 8-9 (2019): 579–88. http://dx.doi.org/10.1177/0967391119894083.
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With excellent damping capacity, growing interest has been focused on polymer concrete (PC) as a novel machine tool bed material in the field of ultraprecision machining. It is widely acknowledged that the fly ash (FA) is an essential component material in reducing the curing shrinkage of PC, which can significantly affect the curing characteristic of PC. However, the effect of FA on the curing characteristic of epoxy resin is not studied in detail. In this article, the effect of FA on the curing characteristic of epoxy resin was examined by differential scanning calorimetry. Experimental results show that the peak temperature and curing rates of epoxy resin/curing agent and epoxy resin/curing agent/FA increase with the increasing heating rates, and the peak temperature and curing rates of epoxy resin/curing agent are greater than that of the epoxy resin/curing agent/FA with the same heating rates. In addition, the difference between the maximum curing rates of epoxy resin/curing agent and epoxy resin/curing agent/FA decreased with the increasing heating rates. This article can provide technical reference for curing process of PC for machine tool beds and further improve the machining accuracy.
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Abdul Rahim, Rosniza Hanim, Khairun Azizi Azizli, Zakaria Man, and Muhd Fadhil Nuruddin. "Effect of Curing Conditions on the Mechanical Properties of Fly Ash-Based Geopolymer without Sodium Silicate Solution." Applied Mechanics and Materials 699 (November 2014): 15–19. http://dx.doi.org/10.4028/www.scientific.net/amm.699.15.
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Geopolymer is associated with the alkali activation of materials rich in Si and Al, and alkali activator such as sodium hydroxide is used for the dissolution of raw material with the addition of sodium silicate solution to increase the dissolution process. However, the trend of strength development of geopolymer using sodium hydroxide alone is not well established. This paper presents an evaluation on compressive strength of fly ash–based geopolymer by varying curing time with respect to different curing temperature using sodium hydroxide as the only activator. The samples were cured at room temperature and at an elevated temperature (60°C). Further analysis on the microstructure of geopolymer products cured at 60°C was carried out using Field Emission Scanning Microscopy (FESEM). It can be observed that the compressive strength increased as the curing time increased when cured at room temperature; whereas at elevated temperature, the strength increased up to a maximum 65.28 MPa at 14 days but gradually decreased at longer curing time. Better compressive strength can be obtained when the geopolymer was cured at an elevated temperature compared to curing at room temperature.
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Ahn, Chi-Hyung, Jinbok Lee, Dong-Jin Kim, and Hyun-Oh Shin. "Development of a Novel Concrete Curing Method Using Induction Heating System." Applied Sciences 11, no. 1 (2020): 236. http://dx.doi.org/10.3390/app11010236.
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This study aimed to develop an accelerated concrete curing method based on induction heating (IH) technology. The proposed curing method provides improved heating efficiency and safety since it directly heats only the metallic forms in a non-contacting manner. It also has the advantage of being capable of heating the concrete according to a desirable heating scenario. The effects of several parameters on its performance were evaluated using a finite element method (FEM)-based thermal analysis and heating performance tests. The FEM analysis revealed the steel form to be appropriate for the IH system. The analysis also revealed that equally spaced three-turn coils yielded increased temperature uniformity in the steel form, which was verified by results of the steel form heating experiments. Furthermore, the minimum temperature generated in the form was sufficient for concrete curing. The efficiency of the use of IH for concrete curing and the effects of curing parameters were further investigated through compression tests after applications of various curing methods and by examining the temperature distributions during curing. The test results revealed early strength development even under water freezing conditions. This demonstrated the effectiveness of IH for concrete curing in cold weather. However, the efficiency decreased when the cross-sectional dimension of the specimen increased. The test results also verified that the maximum temperature and duration of induction heat curing affect the early age strength of concrete.
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Revie, I. C., M. E. Wallace, and J. F. Orr. "The Effect of PMMA Thickness on Thermal Bone Necrosis around Acetabular Sockets." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 208, no. 1 (1994): 45–51. http://dx.doi.org/10.1177/095441199420800106.
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One aim of custom acetabular hip replacement sockets is to achieve fixation through a uniform cement layer of selected thickness. In vitro experiments demonstrate that curing temperatures are determined by cement thickness and position relative to the socket rim. A maximum thickness of 7 mm is indicated by interpretation of curing temperature-time relationships in terms of predicted bone necrosis. It is concluded that the results contribute to the establishment of an optimum cement layer thickness, but other factors require investigation to complement this work to gain further understanding of the problem.
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Al Bakri Abdullah, Mohd Mustafa, Mukridz Md Mohtar, Liew Yun Ming, Muhammad Faheem Mohd Tahir, Kamarudin Husin, and Januarti Jaya Ekaputri. "Flood Mud as Geopolymer Precursor Materials: Effect of Curing Regime on Compressive Strength." Applied Mechanics and Materials 815 (November 2015): 177–81. http://dx.doi.org/10.4028/www.scientific.net/amm.815.177.
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This paper studies the effect of curing temperature and curing duration to the flood mud based geopolymer on compressive strength properties. Flood mud was used as a raw material for geopolymer and geopolymer samples were synthesized by using sodium silicate and sodium hydroxide 14M solution. These samples were cured at different temperature (100°C, 150°C, 200°C and 250°) for different curing duration (6h, 12h and 24h) respectively. Compressive strength tests were carried out at after 28 days. The compressive strength and SEM analysis of geopolymer products were evaluated. Result showed that the maximum compressive strength was 24 MPa at temperature of 150°C for 24 hours. With increasing ageing day, densification of geopolymer gel was observed.
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Millen, Christopher, Martyn Ormond, Gillian Richardson, Ario Santini, Vesna Miletic, and Peter kew. "A Study of Temperature Rise in the Pulp Chamber during Composite Polymerization with Different Light-curing Units." Journal of Contemporary Dental Practice 8, no. 7 (2007): 29–37. http://dx.doi.org/10.5005/jcdp-8-7-29.
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Abstract Aim The study compared pulp temperature rise during polymerization of resin-based composites (RBCs) using halogen and LED light-curing units (LCUs). Methods and Materials A total of 32 teeth extracted from patients aged 11-18 years were used in the study. Thermocouples placed on the roof of the pulp chamber using a novel ‘split-tooth’ method. In Group 1 a halogen LCU with a light intensity of 450 mWcm-2 was used and in Group 2, an LED LCU with a light intensity of 1100 mWcm-2 was used. The teeth were placed in a water bath with the temperature regulated until both the pulp temperature and the ambient temperature were stable at 37°C. Continuous temperature records were made via a data logger and computer. The increase in temperature from baseline to maximum was calculated for each specimen during the curing of both the bonding agent and the RBC. Results The rise in pulp temperature was significantly higher with the LED LCU than with the halogen LCU for bonding and RBC curing (p<0.05). The major rise in temperature occured during the curing of the bonding agent. During the curing of the RBC, rises were smaller. Conclusions Curing of bonding agents should be done with low intensity light and high intensity used only for curing RBC regardless of whether LED or halogen LCUs are used. Citation Millen C, Ormond M, Richardson G, Santini A, Miletic V, Kew P. A Study of Temperature Rise in the Pulp Chamber during Composite Polymerization with Different Light-curing Units. J Contemp Dent Pract 2007 November; (8)7:029-037.
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Boukendakdji, M., M. Touahmia, B. Achour, et al. "The Effects of Steam-Curing on the Properties of Concrete." Engineering, Technology & Applied Science Research 11, no. 2 (2021): 6974–78. http://dx.doi.org/10.48084/etasr.4014.
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Worldwide, concrete is the most preferred construction material. The steam curing method is favored when there is a need for accelerating strength. This paper presents the study of the compressive and flexural tensile strength of concrete subjected to eight different steam cures. In addition, the stress-strain curve and the modulus of elasticity were determined at the age of 28 days. The compressive strength test results show that after treatment, strength increases with concrete maturity. A cycle with a pre-heating period gives better results than a cycle without a pre-heating period. The longer the duration of the maximum temperature period, the lower the strength drop compared to the control concrete. The best results were obtained for concrete treated according to the following cycle: a 3-hour pre-heating period at 20oC, a 2-hour increase of temperature from 20 to 70oC, and a 3 hour of maximum temperature of 70oC.
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Cai, Xiao Ping, Wen Cui Yang, Jie Yuan, Guo Hui Xia, Yong Ge, and Bao Sheng Zhang. "Mechanics Properties of Concrete at Low Temperature." Advanced Materials Research 261-263 (May 2011): 389–93. http://dx.doi.org/10.4028/www.scientific.net/amr.261-263.389.
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Mechanical properties at low temperature (-5°C, -20°C and -30°C) including compression strength, flexure strength, splitting tensile strength and modulus of elasticity of concrete with fly ash were investigated. In order to remain the temperature of the specimens unchanged during the test, a new insulation device was designed. In addition, the effects of curing ages on mechanical properties of concrete were studied. The results showed, at low temperature, all of the mechanical properties were improved; as the temperature decreases, the growth ratio increased continuously. The relative growth ratios of compression strength and flexure strength achieved the maximum value when the temperature decreased from -5°C to -20°C, and the relative growth ratios of splitting tensile strength and modulus of elasticity kept increasing during the whole process of cooling. At -35°C, all of the mechanical properties were improved at each curing age.
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Bhandari, Rishi Babu, Arvind Pathak, and Vinay Kumar Jha. "A Laboratory Scale Synthesis of Geopolymer from Locally Available Coal Fly Ash from Brick Industry." Journal of Nepal Chemical Society 29 (December 3, 2013): 18–23. http://dx.doi.org/10.3126/jncs.v29i0.9232.
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In this work, geopolymers have been synthesized from coal fly ash (CFA) using KOH and Na2SiO3 as activators. Some parameters such as alkali concentration, amount of Na2SiO3 and curing time have been varied in order to improve the quality of geopolymeric product. The geopolymerization process was carried out using 3-8 M KOH solutions, Na2SiO3 to CFA mass ratio of 0.25-2.00 and curing time variation from 6-28 days. The curing temperature was fixed at 40°C in all the cases. During the variation of KOH concentration, the maximum compressive strength of 6.62 MPa was obtained with CFA treated with 7 M KOH solution. Similarly, with the variation of the mass ratio of Na2SiO3 to CFA, the maximum compressive strength of 28.1 MPa was obtained with Na2SiO3 to CFA mass ratio of 1.75. Furthermore, the compressive strength was found to be increased with increasing curing time and 41.9 MPa was achieved with 28 days of curing time. DOI: http://dx.doi.org/10.3126/jncs.v29i0.9232Journal of Nepal Chemical SocietyVol. 29, 2012Page: 18-23Uploaded date : 12/3/2013
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Akca, A. H., and N. Özyurt. "Image analysis on disintegrated concrete at the post-heating stage." Revista ALCONPAT 10, no. 2 (2020): 219–29. http://dx.doi.org/10.21041/ra.v10i2.482.
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The relation between crack growth and reduction in the compressive strength after high temperature exposure and after air re-curing was investigated in this study. Concrete specimens were heated to 1000 ºC and they were subjected to air re-curing for 28 days. During re-curing period, their heated surfaces were monitored by using a digital single-lens reflex camera and the images were analyzed by using image analysis software. After cooling, the maximum reduction in the compressive strength of concrete was 49.5% and that of air re-cured concrete was 66.8%. Image analyses showed high correlations between crack growth and reduction in the compressive strength. This non-destructive method has the potential to represent the extent of damage in concrete after high temperature exposure.
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Jha, Vinay Kumar, and Gautam Prasad Budhamagar. "Synthesis of Geopolymer from Coal Fly Ash." Journal of Nepal Chemical Society 30 (December 15, 2013): 24–28. http://dx.doi.org/10.3126/jncs.v30i0.9331.
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In the present work, geopolymers have been synthesized from coal fly ash (CFA) using NaOH and Na2SiO3 as activators. Some parameters like alkali concentration, amount of Na2SiO3 and curing time have been varied in order to improve the quality of geopolymeric product. The geopolymerization process has been performed using 3-8M NaOH solutions, Na2SiO3 to CFA mass ratios of 0.25-1.25 and curing time variation from 5-15 days. The curing temperature was fixed at 40ºC in all cases. In the variation of NaOH concentration, the maximum compressive strength of 2.3 MPa was obtained with CFA treated with 6M NaOH solution. Similarly during the variation of amount of Na2SiO3, the maximum compressive strength of 17.6 MPa was obtained with Na2SiO3 to CFA mass ratio of 1.25. Furthermore, the compressive strength was found increasing up to 20.3 MPa with increasing curing time.DOI: http://dx.doi.org/10.3126/jncs.v30i0.9331Journal of Nepal Chemical Society Vol. 30, 2012 Page: 24-28 Uploaded date: 12/16/2013
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Adewumi, Adeshina Adewale, Mohd Azreen Mohd Ariffin, Mohammed Maslehuddin, Moruf Olalekan Yusuf, Mohammad Ismail, and Khaled A. Alawi Al-Sodani. "Influence of Silica Modulus and Curing Temperature on the Strength of Alkali-Activated Volcanic Ash and Limestone Powder Mortar." Materials 14, no. 18 (2021): 5204. http://dx.doi.org/10.3390/ma14185204.
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This present study evaluates the effect of silica modulus (Ms) and curing temperature on strengths and the microstructures of binary blended alkali-activated volcanic ash and limestone powder mortar. Mortar samples were prepared using mass ratio of combined Na2SiO3(aq)/10 M NaOH(aq) of 0.5 to 1.5 at an interval of 0.25, corresponding to Ms of 0.52, 0.72, 0.89, 1.05 and 1.18, respectively, and sole 10 M NaOH(aq). Samples were then subjected to ambient room temperature, and the oven-cured temperature was maintained from 45 to 90 °C at an interval of 15 °C for 24 h. The maximum achievable 28-day strength was 27 MPa at Ms value of 0.89 cured at 75 °C. Samples synthesised with the sole 10 M NaOH(aq) activator resulted in a binder with a low 28-day compressive strength (15 MPa) compared to combined usage of Na2SiO3(aq)/10 M NaOH(aq) activators. Results further revealed that curing at low temperatures (25 °C to 45 °C) does not favour strength development, whereas higher curing temperature positively enhanced strength development. More than 70% of the 28-day compressive strength could be achieved within 12 h of curing with the usage of combined Na2SiO3(aq)/10 M NaOH(aq). XRD, FTIR and SEM + EDX characterisations revealed that activation with combined Na2SiO3(aq)/10 M NaOH(aq) leads to the formation of anorthite (CaAl2Si2O8), gehlenite (CaO.Al2O3.SiO2) and albite (NaAlSi3O8) that improve the amorphosity, homogeneity and microstructural density of the binder compared to that of samples synthesised with sole 10 M NaOH(aq).
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Sanders, Timothy H., Paul D. Blankenship, John R. Vercellotti, and Karen L. Crippen. "Interaction of Curing Temperature and Inherent Maturity Distributions on Descriptive Flavor of Commercial Grade Sizes of Florunner Peanuts1." Peanut Science 17, no. 2 (1990): 85–89. http://dx.doi.org/10.3146/i0095-3679-17-2-10.
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Abstract Windrow-dried Florunner peanuts were harvested and then cured with ambient air (maximum 35 C), ambient +8.4 C increase, and ambient +16.8 C increase in commercial drying operations. Peanuts from the drying wagons were stored inshell as farmers stock or shelled and then cold stored approximately five months before sensory evaluation. A panel trained in peanut flavor descriptive analysis evaluated peanuts from all commercial grade sizes which had been roasted to similar color. Differences between cold- and farmers stock-stored peanuts were not statistically significant and data were thus combined. Curing treatments produced differences in descriptive terms roasted peanutty, fruity fermented and sour. Fruity fermented intensity was noticeably higher in the medium and No. 1 grade sizes from the higher curing temperatures and roasted peanutty decreased in the No. 1 grade with increasing temperature. Significant differences in intensity of seven descriptors were consistently found among the grades within each curing treatment. For each of these descriptors as size decreased, intensity of desirable flavor descriptors decreased and intensity of off-flavor descriptors increased.
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Gómez-Jimenez., S., A. M. Becerra-Ferreiro., E. Jareño-Betancourt., and J. Vázquez-Penagos. "Phenomenological Modeling of the Apparent Viscosity as a Function of the Degree of Curing of an EPDM Elastomer." MRS Advances 5, no. 62 (2020): 3205–14. http://dx.doi.org/10.1557/adv.2020.426.
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AbstractThe moving die rheometer technique (MDR) is used to measure the elastic and viscous components of rubber. The analysis of the rheometry and the kinetic behavior can be used to obtain mathematical models to predict the viscosity of elastomers as a function of the temperature, the time and the degree of curing. These predictions allow the control, the optimization and the design of the process. In this research the phenomenological model of Kamal-Sourour was used to describe the curing kinetics, while the Carreau Macosko model was used to describe the viscous behavior of an ethylene - propylene diene industrial type compound (EPDM). The mathematical parameters for each model where determined by using non-linear regression techniques. Since the viscosity increases significantly while the curing rate decreases, we proposed a mathematical model based on the Carreau expression in order to consider the influence of the kinetic of curing in the apparent viscosity behavior. It was found that after the curing rate reaches its maximum the viscosity tends to infinity; that is, the chemical transition process known as fluidity point or gel point occurs in the vicinity of maximum curing rate. According to the results, it is concluded that rubber viscosity is well described by considering the curing variations; the fluidity point in the vulcanization process can also be obtained by the practical method of phenomenological approach.
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Yener, Engin. "Curing Time and Temperature Effect on the Resistance to Wet-Dry Cycles of Fly Ash Added Pumice Based Geopolymer." Journal of Cement Based Composites 1, no. 2 (2020): 19–25. http://dx.doi.org/10.36937/cebacom.2020.002.004.
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The effects of curing regimes varying combinations of temperatures (ambient, 60 °C, 75 °C, 90 °C, 105 °C) and durations (4h, 8h, 24h, 48h, 96h, 168h) on the performance of fly ash added pumice based geopolymer pastes were investigated in this study. The precursor raw material consists of 70% pumice dust and 30% fly ash (FA). Alkali activator was prepared by mixing 10M sodium hydroxide (SH) solution and liquid sodium silicate (SS) in the ratio of SS/SH=2. Activator to precursor ratio was fixed as 0.45. Compressive strengths were determined at the 28 days of age as well as after exposure 5 wetting-drying (w-d) cycles. In addition, Fourier Transform Infrared Spectroscopy (FTIR) tests were conducted on the fresh and hardened geopolymer pastes in order to examine the effect of curing conditions to the structural changes and reaction products. The results show that in the case of 60 °C and 75 °C, the strength of the w-d conditioned samples increased steadily as the curing time increased. However, longer curing times of more than 24 hours are not beneficial for high curing temperatures (90 °C and 105 °C). The maximum strength after the w-d cycles is obtained for the curing conditions of 60°C/168h (74.4 MPa). Also, FTIR analysis confirmed that the hardened geopolymer paste transformed into a more coordinated structure and soluble carbonate compounds were reduced at 60 °C and 168 hours curing condition.
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Li, Zhijun, Yongxue Wang, Xiwen Wang, and Guangwei Li. "Effect of Cement Content and Curing Period on Properties of DUT-1 Synthetic Model Ice." Journal of Offshore Mechanics and Arctic Engineering 125, no. 4 (2003): 288–92. http://dx.doi.org/10.1115/1.1596237.
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The effects of cement content and curing period on a new synthetic model ice, DUT-1, are reported. The cement (450#) contents were 10%, 11%, 12%, 13%, 14%, 15% and 16% by dry weight of mixture material. Eight different curing periods were used: 66 h, 92 h, 115 h, 139 h, 163 h, 186 h, 211 h and 235 h. Physical and mechanical properties, such as density, compressive strength, flexural strength, and elastic modulus, were determined. The density and mechanical parameters were found to increase with increasing cement content, whereas the durations of curing period under normal air temperature resulted in increasing these properties to a maximum value, then decreasing values.
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Sukhyy, K. M., E. A. Belyanovskaya, A. N. Nosova, et al. "Properties of epoxy-thiokol materials based on the products of the preliminary reaction of thioetherification." Voprosy Khimii i Khimicheskoi Tekhnologii, no. 3 (May 2021): 128–36. http://dx.doi.org/10.32434/0321-4095-2021-136-3-128-136.
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In order to improve the adhesive and physical-mechanical properties of epoxy-thiocol compositions cured without heat treatment, we propose to carry out the reaction of interaction between thiokol mercaptan groups and oxirane cycles of epoxy resin at an elevated temperature before introducing a curing agent, and then use the product of this thioetherification reaction for curing at room temperature. The temperature range of the thioetherification reaction (90–1800С) was determined by the method of differential scanning calorimetry. The optimal temperature (1600С) and duration of the preliminary thioetherification reaction (2 hours) were determined, which ensure the maximum level of adhesive strength and physical-mechanical properties. It was shown that composite materials based on the products of the thioetherification reaction significantly outperform analogs based on mechanical mixtures of epoxy resin and thiokol in terms of cohesive and adhesive strength, deformation capacity, fracture work and specific impact strength. The impact resistance and shear strength of adhesive joints are especially significantly increased during the curing of the compositions without external heat supply.
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Ruan, Shiling, John J. Lannutti, Stan Prybyla, and Robert R. Seghi. "Increased fracture toughness in nanoporous silica–polyimide matrix composites." Journal of Materials Research 16, no. 7 (2001): 1975–81. http://dx.doi.org/10.1557/jmr.2001.0270.
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Silica–polyimide nanocomposites were prepared by hot-pressing mixtures of polyimide and highly porous silica powder. The silica powder was produced using a sol-gel process that generates pores as small as 15 Å. The effects of loading, cure, and post-cure temperature on fracture toughness were investigated. The addition of silica particles improved the fracture toughness from 0.5 to a maximum of 1.9 MPa m0.5. However, fracture toughness dropped at silica weight percentages ≥30%. The cure and post-curing temperatures have a strong influence on toughness; post-curing exposure ≥400 °C reduced toughness. Transmission electron microscopy examination of the fracture surfaces indicated that the toughness improvements may occur at the nanometer scale due to crack pinning and branching induced by the nanoporous silica particles.
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Belyaeva, E. A., A. F. Kosolapov, V. S. Osypchyk, et al. "Influence of modifiers of different chemical nature on the performance properties of epoxy binders for composites based on fibers from UHMWPE." Plasticheskie massy, no. 7-8 (September 11, 2019): 57–61. http://dx.doi.org/10.35164/0554-2901-2019-7-8-57-61.
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The modified, technologically advanced in preparation and processing, low-temperature curing epoxy binders have been developed. They ensure the maximum possible realization of the properties of UHMWPE fibers in the organic composite. The structural-kinetic role of modifiers of various chemical nature to control the performance properties of epoxy binders cured in the temperature range 20-95ºС is shown.
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Yao, Xing Fang, and Shi Feng Zhang. "Crossover of the Curing Mechanisms and Double Glass Transition Temperatures of Tetrabromo-Bisphenol-a Epoxy Resin with 4,4-Diaminodiphenylsulfone." Advanced Materials Research 233-235 (May 2011): 2029–33. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.2029.
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The curing process of tetrabromo-bisphenol-A epoxy resin (TBBPAER) with 4,4´-diaminodiphenylsulfone (DDS) was investigated by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and torsional braid analysis (TBA) methods. FTIR results indicated that the maximum reaction velocity was observed at initial stages at higher temperature, but it was occurred at conversion =10 - 40 % at lower temperature. It showed that there is the crossover from the autocatalytic model to the nth-order mechanism when the temperature was increased. While the double glass transition temperatures occuring in the system, according to the microstructure of the reactant, a theoretical and reasonable explanation may arise from this article.
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Ke, Guizhen, Zhiheng Xiao, Xinya Jin, Lixiang Yu, Jianqiang Li, and Huixia Zhang. "Wrinkle recovery angle enhancement and tensile strength loss of 1,2,3,4-butanetetracarboxylic acid finished lyocell fabrics." Textile Research Journal 90, no. 17-18 (2020): 2097–108. http://dx.doi.org/10.1177/0040517520912035.
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The formaldehyde-free crease-proof finishing agent 1,2,3,4,-butanetetracarboxylic acid (BTCA) was used to treat lyocell fabrics. The effects of BTCA concentration and curing temperature on the wrinkle recovery angle (WRA) and tensile breaking strength of lyocell fabrics were discussed. The results showed that with the increase of BTCA concentration and curing temperature, the WRA value of lyocell fabrics increased obviously and the maximum WRA reached 147°, but breaking strength decreased gradually and the minimum strength retention was 68%. The WRA was durable against laundering. The fabric whiteness difference was not obvious and the whiteness retention of all samples exceeded 98%. After further alkali treatment, the WRA of the treated lyocell fabrics decreased and the fracture strength retention recovered to varying degrees (0.45–10.8%). The developed regression equations were found to be in good correlation ( r2 > 92%) with the selected variables (tensile strength, BTCA concentration, curing temperature). Fourier transform infrared spectroscopy analysis confirmed that the tensile strength loss of BTCA-treated lyocell fabrics was caused by cross-linking of cellulose molecules and acid degradation. Tensile strength loss that resulted from ester bonding could be restored after hydrolysis in alkaline solution. The recoverable magnitude of tensile strength was related to the curing temperature. A high temperature not only promoted the cross-linking of cellulose macromolecules, but also accelerated the acid degradation of cellulose.
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Wang, Yong Zhou, Hong Hai Huang, Hong Xing Gui, Tao Chen, Fu Quan Zhang, and Ri Zhong Zeng. "Effect of CMCS on Cure Characteristics of Natural Rubber." Advanced Materials Research 402 (November 2011): 606–9. http://dx.doi.org/10.4028/www.scientific.net/amr.402.606.
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The effect of carboxymethyl chitosan (CMCS) as preservation on cure characteristics of nature rubber (NR) was studied, which compared with NR using ammonia water as preservative agent. The results showed that the induction period and optimum cure time of sample N (Ammonia water dosage is 0.15% of the mass of fresh latex), CMCS-1(CMCS dosage is 0.05% of the mass of fresh latex) and CMCS-2(CMCS dosage is 0.1% of the mass of fresh latex) were obviously decreased with the increasing of temperature, corresponding to Arrhenius equation perfectly. The maximum torque was linear dependence on curing temperature and decreased with the increasing of curing temperature. The relation of MH0 were as follows: N>CMCS-1>CMCS-2, respectively.
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Janeczek, Maciej, Katarzyna Herman, Katarzyna Fita, et al. "Assessment of Heat Hazard during the Polymerization of Selected Light-Sensitive Dental Materials." BioMed Research International 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/4158376.
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Introduction.Polymerization of light-cured dental materials used for restoration of hard tooth tissue may lead to an increase in temperature that may have negative consequence for pulp vitality.Aim.The aim of this study was to determine maximum temperatures reached during the polymerization of selected dental materials, as well as the time that is needed for samples of sizes similar to those used in clinical practice to reach these temperatures.Materials and Methods.The study involved four composite restorative materials, one lining material and a dentine bonding agent. The polymerization was conducted with the use of a diode light-curing unit. The measurements of the external surface temperature of the samples were carried out using the Thermovision®550 thermal camera.Results.The examined materials significantly differed in terms of the maximum temperatures values they reached, as well as the time required for reaching the temperatures. A statistically significant positive correlation of the maximum temperature and the sample weight was observed.Conclusions.In clinical practice, it is crucial to bear in mind the risk of thermal damage involved in the application of light-cured materials. It can be reduced by using thin increments of composite materials.
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Silvani, Carina, Mozara Benetti, and Nilo Cesar Consoli. "Maximum Tensile Strength of Sand - Coal Fly Ash - Lime Blends for Varying Curing Period and Temperature." Soils and Rocks 42, no. 1 (2019): 83–89. http://dx.doi.org/10.28927/sr.421083.
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Al Bakri Abdullah, Mohd Mustafa, Kamarudin Hussin, Mohammed Binhussain, Ismail Khairul Nizar, Rafiza Abd Razak, and Yahya Zarina. "Microstructure Study on Optimization of High Strength Fly Ash Based Geopolymer." Advanced Materials Research 476-478 (February 2012): 2173–80. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.2173.
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The compressive strength and microstructural characteristics of fly ash based geopolymer with alkaline activator solution were investigated. The sodium hydroxide and sodium silicate were mixed together to form an alkaline activator. Three parameters including NaOH molarity, mix design (fly ash/alkaline activator ratio and Na2SiO3/NaOH ratio), and curing temperature were examined. The maximum strength of 71 MPa was obtained when the NaOH solution of 12M, fly ash/alkaline activator of 2.0, Na2SiO3/NaOH of 2.5 and curing temperature of 60°C were used at 7th days of testing. The results of SEM indicated that for geopolymer with highest strength, the structure was dense matrix and contains less unreacted fly ash with alkaline activator
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Mahadevan, Barath Kanna, Sahar Naghibi, Fariborz Kargar, and Alexander A. Balandin. "Non-Curing Thermal Interface Materials with Graphene Fillers for Thermal Management of Concentrated Photovoltaic Solar Cells." C — Journal of Carbon Research 6, no. 1 (2019): 2. http://dx.doi.org/10.3390/c6010002.
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Temperature rise in multi-junction solar cells reduces their efficiency and shortens their lifetime. We report the results of the feasibility study of passive thermal management of concentrated multi-junction solar cells with the non-curing graphene-enhanced thermal interface materials. Using an inexpensive, scalable technique, graphene and few-layer graphene fillers were incorporated in the non-curing mineral oil matrix, with the filler concentration of up to 40 wt% and applied as the thermal interface material between the solar cell and the heat sink. The performance parameters of the solar cells were tested using an industry-standard solar simulator with concentrated light illumination at 70× and 200× suns. It was found that the non-curing graphene-enhanced thermal interface material substantially reduces the temperature rise in the solar cell and improves its open-circuit voltage. The decrease in the maximum temperature rise enhances the solar cell performance compared to that with the commercial non-cured thermal interface material. The obtained results are important for the development of the thermal management technologies for the next generation of photovoltaic solar cells.
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Zhang, Hanqi, Bing Wang, Yanna Wang, and Heng Zhou. "Novolac/Phenol-Containing Phthalonitrile Blends: Curing Characteristics and Composite Mechanical Properties." Polymers 12, no. 1 (2020): 126. http://dx.doi.org/10.3390/polym12010126.
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The phenol-containing phthalonitrile resin is a kind of self-curing phthalonitrile resin with high-temperature resistance and excellent properties. However, the onefold phthalonitrile resin is unattainable to cured completely, and the brittleness of the cured product is non-negligible. This paper focuses on solving the above problems by blending novolac resin into phenol-containing phthalonitrile. Under the action of abundant hydroxyl group, the initial curing temperature and gelation time at 170 °C decrease by 88 °C and 2820 s, respectively, monitored by DSC and rheological analysis. FT-IR spectra of copolymers showed that the addition of novolac increased the conversion rate of nitrile. When the novolac mass fraction is 10%, the peak of nitrile group disappears, which means the complete reaction. The mechanical test of blends composites shows that the maximum fracture strain of 10 wt% novolac addition is 122% higher than those of neat phthalonitrile composites on account of the introduction of flexible novolac chain segments. The mechanical properties are sensitive to elevated post-cured temperature; this is consistent with the result of morphological investigation using SEM. Finally, the dynamic mechanical analysis indicated that the glass transition temperature heightened with the increase of novolac content and post-curing temperature.
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Meng, Yi Ding, and Hong Wei Li. "The Structure and Properties of UV-Curable Cationic Waterborne Polyurethane Acrylate." Advanced Materials Research 1090 (February 2015): 31–37. http://dx.doi.org/10.4028/www.scientific.net/amr.1090.31.
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A series of stable double-terminated UV reactive cationic waterborne polyurethane dispersions was synthesized, while the structure was confirmed by infrared spectroscopy,laser particle size analysis and free NCO root titration; modified by co-monomerhydroxyethyl acrylate with the UV radiation fast curing, the influence of hydroxyethyl acrylate proportion and the polyurethane’s nNCO/nOH(R value) to the thermal properties, mechanical properties and yellowing of the product was investigated. The investigation illustrated the UV-curable cationic waterborne polyurethaneacrylate film effectively forming a semi-interpenetrating network system to achieve rapid curing coating.The results showedthe product cured by WPU dispersion of R=1.5 mixed with equimolar HEA obtained lowyellowing, the maximum breaking strength, high elongation at break, high thermal decomposition temperature, high crystallization temperature of hard segment, low glass transition temperature of soft segment, high degree of phase separation, better overall performance.
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Demircan, Emrah, Sivaram Harendra, and Cumaraswamy Vipulanandan. "Artificial Neural Network and Nonlinear Models for Gelling Time and Maximum Curing Temperature Rise in Polymer Grouts." Journal of Materials in Civil Engineering 23, no. 4 (2011): 372–77. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0000172.
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Lee, Sang Il, Dong Jin Yoon, Seung Seok Lee, and Joung Man Park. "Cure Monitoring and Stress-Strain Sensing of Single-Carbon Fiber Composites by the Measurement of Electrical Resistance." Key Engineering Materials 297-300 (November 2005): 676–84. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.676.
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Cure monitoring and stress-strain sensing of single-carbon fiber composites were nondestructively evaluated by the measurement of electrical resistance. The difference of electrical resistance before and after curing increased highest when gauge length of the specimen was the smallest. As curing temperature increased, the electrical behavior of steel fiber was different from that of semi-conductive carbon and SiC fibers. Residual stress built in the fiber was the highest at the fiber axis direction. Whereas residual stress built in the matrix was relatively high at the fiber circumference and radius directions. Residual stress calculated from the experiment was consistent with the results from the finite element analysis (FEA). The strain at low curing temperature was larger than that of higher temperature until the load reached maximum value. The apparent modulus of the electrodeposited composites was higher than that of the untreated composites due to the improved interfacial shear strength (IFSS). The electrical resistance was responded quantitatively with stress-strain behavior during the test. Electrical resistance measurement can be feasible nondestructive techniques to evaluate cure monitoring and stress-strain sensing in the conductive fiber composites.
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Matveev, E. V., A. V. Mamontov, A. I. Gajdar, B. A. Lapshinov, and A. N. Vinogradov. "Measurement of strength and microstructural characteristics of epoxypolimers cured by thermal and microwave methods." Izmeritel`naya Tekhnika, no. 12 (2020): 35–41. http://dx.doi.org/10.32446/0368-1025it.2020-12-35-41.
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In this work, we studied the strength parameters, fractographic patterns, and the microstructure of epoxy polymer samples cured both by thermal and microwave methods at various temperature, power, and time conditions. The dependence of strength on curing conditions is determined using the tensile test method. To achieve maximum strength for both curing methods optimum conditions were found. A comparative fractographic analysis of microwave and thermal cured samples fractures having similar strength characteristics was carried out by electron microscopy. It was found that microwave field curing leads to the globules size increase in the cured epoxy polymer and an increase in the number of nanopores in the material. Plastic samples local deformation is also more pronounced during fracture, which leads to a greater difference of the main and secondary cracks propagation velocities ratio. The relationship between the studied samples optical density in the wavelength range from 360 to 2500 nm and the parameters of both curing methods (microwave and thermal) was established.
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Chandrakanth, V., and Srikanth Koniki. "Effect of Review elevated temperature on geo-polymer concrete – A Review." E3S Web of Conferences 184 (2020): 01090. http://dx.doi.org/10.1051/e3sconf/202018401090.
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The study on the effect of elevated temperature on Geo-polymer concrete (GPC) got its significance because conventional concrete start to deteriorate around 4000C. GPC gains attention as it is eco-friendly and economical, by utilizing industrial by-products. GPC also an alternate solution as the raw materials to produce cement are depleting day by day. GPC gains strength by geo-polymerization with the reactions between mineral admixtures and alkaline solutions. This paper presents the studies on general properties and advantages of GPC over conventional concrete which depend on properties of binder, type of curing etc. Current study mainly concentrates on effect of elevated temperatures and post fire properties of GPC depending upon rate of heating, duration of fire and maximum high temperature. Strength and durability recovery of fire damaged concrete is discussed.
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Zhou, Li An, and Jia Long Chen. "Study on Compressive Strength of Recycled Aggregate Brick with Construction Waste." Key Engineering Materials 477 (April 2011): 301–7. http://dx.doi.org/10.4028/www.scientific.net/kem.477.301.
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Recycling and reusing construction waste has become one of the focus issues which should be solved urgently in China with the rapid urbanization, construction of new countryside and large scale urban renewal. There are some researchers take study on the recycling and application of construction waste, but hasn’t systematic study about compressive strength of recycled aggregate brick until now though production and application of recycled aggregate brick is an important approach to reuse construction waste. This test has discussed the impact on the compressive strength of recycled aggregate brick due to recycled aggregate maximum particle size and fine particle content, water-cement ratio, cement-aggregate ratio, forming pressure and curing mode. These results showed that the finer maximum particle size, the higher fine particle content, forming pressure, curing temperature and humidity have notable impact on the compressive strength of recycled aggregate brick.
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Parthasarathy, Sanjay, Susan C. Mantell, and Kim A. Stelson. "Estimation, Control and Optimization of Curing in Thick-Sectioned Composite Parts." Journal of Dynamic Systems, Measurement, and Control 126, no. 4 (2004): 824–33. http://dx.doi.org/10.1115/1.1850536.
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A nonlinear model-based control method is proposed and validated for controlling, estimating and optimizing the cure in composite parts. During the cure, the exothermic reaction causes temperature gradients through the thickness that can lead to a nonuniform cure and high residual stress. A predictive control and optimization approach is proposed to ensure that temperature gradients are kept within acceptable limits and the cure state is fairly uniform, regardless of the part thickness. A reduced order process model is derived and used to formulate a dynamic inversion controller. A nonlinear observer is constructed to estimate the unknown temperature and cure states within the composite. An on-line optimizer determines the maximum allowable heating rate. The optimizer is run at discrete intervals throughout the process to account for process and part variability. The control, estimation and optimization algorithms were validated through a series of simulations and experiments of composite parts cured in a press. Parts that were cured with the proposed control method were compared with parts cured following a manufacturer’s recommended cure cycle. The results demonstrate the success of the proposed control method in achieving uniform temperature and cure, and in decreasing the residual stress, without increasing cycle time.
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Kim, Ryan Jin-Young, In-Bog Lee, Jin-Young Yoo, et al. "Real-Time Analysis of Temperature Changes in Composite Increments and Pulp Chamber during Photopolymerization." BioMed Research International 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/923808.
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Objective. The aim of this study was to evaluate the temperature change at various sites within the composite and on the pulpal side of dentin during polymerization of two composite increments.Materials and Methods. Class I cavities prepared in third molars were restored in two composite increments (n= 5). Temperatures were measured for 110 s using eight thermocouples: bottom center of cavity (BC), top center of 1st increment (MC), top center of 2nd increment (TC), bottom corner of cavity (BE), top corner of 1st increment (ME), top corner of 2nd increment (TE), pulpal side of dentin (PD), and center of curing light guide tip (CL).Results. Maximum temperature values (°C) measured during polymerization of 1st increment were MC (59.8); BC (52.8); ME (51.3); CL (50.7); BE (48.4); and PD (39.8). Maximum temperature values during polymerization of 2nd increment were TC 58.5; TE (52.6); MC (51.7); CL (50.0); ME (48.0); BC (46.7); BE (44.5); and PD (38.8).Conclusion. Temperature at the floor of the cavity was significantly higher during polymerization of 1st increment compared to 2nd increment. Temperature rise was higher at the center than at the corner and at the top surface than at the bottom surface of each increment.
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Lin, Yuan, and Zhidong Guan. "The Use of Machine Learning for the Prediction of the Uniformity of the Degree of Cure of a Composite in an Autoclave." Aerospace 8, no. 5 (2021): 130. http://dx.doi.org/10.3390/aerospace8050130.
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The difference in the degree of cure of the composite in an autoclave is one of the main characterization parameters of the uniformity of the degree of cure of the composite material. Therefore, it is very important to develop an effective method for predicting the difference in the curing degree of a composite autoclave to improve the uniformity of the curing degree of the composite materials. We researched five machine learning models: a fully connected neural network (FCNN) model, a deep neural network (DNN) model, a radial basis function (RBF) neural network model, a support vector regression (SVR) model and a K-nearest neighbors (KNN) model. We regarded the heating rate, holding time and holding temperature of the composite material’s two holding-stage cure profile as input parameters and established a rapid estimation model of the maximum curing degree difference at any time during the molding process. We simulated the molding process of the composite material in an autoclave to obtain the maximum difference in the curing degree as the test sample data to train five machine learning models and compared and verified the different models after the training. The results showed that the RBF neural network model had the best prediction effect among the five models and the RBF was the most suitable algorithm for this model.
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Wang, Lingyun, Weidong Zhu, Qing Wang, Qiang Xu, and Yinglin Ke. "A heat-balance method for autoclave process of composite manufacturing." Journal of Composite Materials 53, no. 5 (2018): 641–52. http://dx.doi.org/10.1177/0021998318788918.
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In composite manufacturing, large composite parts usually exhibit high heating gradients during the autoclave process, which may intensify the process-induced residual stresses and deformations. As the thermal behavior of molds is of crucial importance to the curing performance of composites, a heat-balance method is presented to reduce the heating rate on overheated areas of molds, thus providing a more homogeneous curing process. The method is based on a local-isolation structure installed under the mold plate, which is used to change the local heat transfer coefficient of the mold. In the local-isolation structure application, an optimization process combining numerical simulations with a greedy genetic algorithm is developed to find the optimal layout and geometry of local-isolation structure in molds. The optimization results suggest that more uniform heating condition and more synchronous curing process can be achieved with the optimal design of local-isolation structure. In the case of a typical mold for C spar component, the maximum temperature difference in the composite part is reduce by 45.69%, while the maximum difference in degree of cure is decreased at a rate of 40.16%.
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Singh, Jai Inder Preet, Sehijpal Singh, and Vikas Dhawan. "Influence of fiber volume fraction and curing temperature on mechanical properties of jute/PLA green composites." Polymers and Polymer Composites 28, no. 4 (2019): 273–84. http://dx.doi.org/10.1177/0967391119872875.
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Rising environmental concerns and depletion of petrochemical resources have resulted in an increased interest in biodegradable natural fiber-reinforced polymer composites. In this research work, jute fiber has been used as a reinforcement and polylactic acid (PLA) as the matrix material to develop jute/PLA green composites with the help of compression molding technique. The effect of fiber volume fraction ranging from 25% to 50% and curing temperature ranging from 160°C to 180°C on different samples were investigated for mechanical properties and water absorption. Results obtained from various tests indicate that with an increase in the fiber volume fraction, tensile and flexural strength increases till 30% fiber fraction, thereafter decreases with further increase in fiber content. Maximum tensile and flexural strength of jute/PLA composites was obtained with 30% fiber volume fraction at 160°C curing temperature. The trend obtained from mechanical properties is further justified through the study of surface morphology using scanning electron microscopy.
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Daronch, M., F. A. Rueggeberg, M. F. De Goes, and R. Giudici. "Polymerization Kinetics of Pre-heated Composite." Journal of Dental Research 85, no. 1 (2006): 38–43. http://dx.doi.org/10.1177/154405910608500106.
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Temperature affects the polymerization behavior of dimethacrylate-based materials. This study describes the influence of pre-polymerization temperature and exposure duration on polymerization kinetics of a commercial dental photo-activated composite at the top and at 2-mm depth. We used the temperature-controlled stage of a diamond-attenuated-total-reflectance unit to pre-set composite temperature between 3° and 60°C. Composite was light-exposed by a conventional quartz-tungsten-halogen curing unit for 5, 10, 20, or 40 sec. Real-time conversion, maximum conversion rate ( Rpmax), time to achieve Rpmax, and conversion at Rpmax were calculated from infrared spectra. Composite pre-warming enhanced maximal polymerization rate and overall monomer conversion (top significantly greater than 2 mm). Time when Rpmax occurred did not change with temperature, but occurred sooner at the top than at 2-mm depth. Conversion at Rpmax increased with temperature, allowing more of the reaction to occur prior to vitrification than at room temperature.