Artículos de revistas:

1

Yu, Seoyoon, Wonjoo Lee, Bongkuk Seo y Chung-Sun Lim. "Synthesis of Benzene Tetracarboxamide Polyamine and Its Effect on Epoxy Resin Properties". Polymers 10, n.º 7 (16 de julio de 2018): 782. http://dx.doi.org/10.3390/polym10070782.

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Epoxy resins have found various industrial applications in high-performance thermosetting resins, high-performance composites, electronic-packaging materials, adhesives, protective coatings, etc., due to their outstanding performance, including high toughness, high-temperature performance, chemical and environmental resistance, versatile processability and adhesive properties. However, cured epoxy resins are very brittle, which limits their applications. In this work, we attempted to enhance the toughness of cured epoxy resins by introducing benzene tetracarboxamide polyamine (BTCP), synthesized from pyromellitic dianhydride (PMDA) and diamines in N-methyl-2-pyrrolidone (NMP) solvent. During this reaction, increased viscosity and formation of amic acid could be confirmed. The chemical reactions were monitored and evidenced using 1H-NMR spectroscopy, FT-IR spectroscopy, water gel-phase chromatography (GPC) analysis, amine value determination and acid value determination. We also studied the effect of additives on thermomechanical properties using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamical mechanical analysis (DMA), thermomechanical analysis (TMA) and by measuring mechanical properties. The BTCP-containing epoxy resin exhibited high mechanical strength and adhesion strength proportional to the amount of BTCP. Furthermore, field-emission scanning electron microscopy images were obtained for examining the cross-sectional morphology changes of the epoxy resin specimens with varying amounts of BTCP.

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2

Das, Abhishek y Gautam Sarkhel. "Effect of stoichiometric ratios for synthesized epoxy phenolic novolac (EPN) resins on their physicochemical, thermomechanical and morphological properties". Pigment & Resin Technology 45, n.º 4 (4 de julio de 2016): 265–79. http://dx.doi.org/10.1108/prt-08-2014-0060.

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Purpose The purpose of this paper is to study the effect of various stoichiometric ratios for synthesised epoxy phenolic novolac (EPN) resins on their physicochemical, thermomechanical and morphological properties. Design/methodology/approach In the present study, EPN (EPN-1, EPN-2, EPN-3, EPN-4 and EPN-5) resins were synthesised by varying five types of different stoichiometric ratios for phenol/formaldehyde along with the corresponding molar ratios for novolac/epichlorohydrin. Their different physicochemical properties of interest, thermomechanical properties as well as morphological properties were studied by means of cured samples with the variation of its stoichiometric ratios. Findings The average functionality and reactivity of EPN resin can be controlled by controlling epoxy equivalence as well as cross-linking density upon its curing as all of these factors are internally correlated with each other. Research limitations/implications Epoxy resins are characterised by a three-membered ring known as the epoxy or oxirane group. The capability of the epoxy ring to react with a variety of substrates imparts versatility to the resin. However, these resins have a major drawback of low toughness, and they are also very brittle, which limits their application in products that require high impact and fracture strength. Practical implications Epoxy resins have been widely used as high-performance adhesives and matrix resins for composites because of their outstanding mechanical and thermal properties. Because of their highly cross-linked structure, the epoxy resin disables segmental movement, making them hard, and it is also notch sensitive, having very low fracture energy. Social implications Epoxy resin is widely used in industry as protective coatings and for structural applications, such as laminates and composites, tooling, moulding, casting, bonding and adhesives. Originality/value Systematic study has been done for the first time, as no exact quantitative stoichiometric data for the synthesis of EPN resin were available on the changes of its different properties. Thus, an optimised stoichiometric composition for the synthesis of the EPN resin was found.

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3

Zhou, Haoran, Xupeng Fan, Changwei Liu, Chunyan Qu, Zhen Yuan, Jiaqi Jing, Yao Tang, Daoxiang Zhao, Wanbao Xiao y Kai Su. "Properties of high-temperature epoxy/DDS resin systems for bonding application". High Performance Polymers 32, n.º 5 (22 de noviembre de 2019): 559–68. http://dx.doi.org/10.1177/0954008319888002.

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The choice of basic epoxy resin (ER) is especially important for the design of epoxy adhesive formulations. In the present study, performance of several high-temperature ER systems, prepared using 4,4-diaminodiphenylsulfone as the curing agent by the same curing process, was investigated. The curing behavior was studied by dynamic rheometry and differential scanning calorimetry. The thermal properties of the cured resins were investigated by dynamic thermomechanical analysis, thermomechanical analysis, and thermogravimetric analysis. The peeling properties, mechanical behaviors, and moisture absorptivities of the cured resins were also studied. The results showed traditional diglycidyl ether of bisphenol A epoxy to be insufficient in heat resistance. Naphthalene-based ER and bifunctional cardo ER showed higher glass transition temperature values. However, the processability and adhesive properties may not comply with the application requirements. Biphenyl novolac ER has excellent performance in all aspects, which is suitable for use as a high-temperature adhesive.

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4

Rimdusit, Sarawut, Pathomkorn Kunopast y Isala Dueramae. "Thermomechanical properties of arylamine-based benzoxazine resins alloyed with epoxy resin". Polymer Engineering & Science 51, n.º 9 (11 de abril de 2011): 1797–807. http://dx.doi.org/10.1002/pen.21969.

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5

Lo, Jonathan, Xingyue Zhang, Travis Williams y Steven Nutt. "Eliminating porosity via reformulation of a benzoxazine–epoxy resin transfer molding resin". Journal of Composite Materials 52, n.º 11 (29 de agosto de 2017): 1481–93. http://dx.doi.org/10.1177/0021998317727048.

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Use of benzoxazine resins in composites is limited by volatile-induced porosity, which degrades the thermomechanical properties of the product. In the present study, we demonstrate how to eliminate cure-induced volatilization and volatile-induced defects in benzoxazine composite laminates, using a chemistry-based approach. Like most resins formulated for high-temperature service, benzoxazine and benzoxazine–epoxy blends generally include solvent additives. Consequently, composite parts produced with such resins exhibit higher levels of cure-induced volatile release, often leading to porosity in the final manufactured part. Here, we develop a method to eliminate porosity by analyzing volatile release and the effects of residual solvent in a pre-commercial benzoxazine–epoxy system designed for liquid molding by resin transfer molding. Utilizing thermogravimetric analysis, nuclear magnetic resonance spectroscopy, and dynamic mechanical analysis, we correlate the concentration of residual solvent remaining within the final manufactured part with the Tg, degradation temperature, and dynamic modulus. Lastly, a resin synthesis method is demonstrated that eliminates residual solvent in order to produce composite parts with optimal surface finish and thermomechanical properties. The report outlines a methodology for optimizing blended resin chemistry for production of high-quality composite parts.

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6

Atta, Ayman M., Hamad A. Al-Lohedan, Abdelrahman O. Ezzat y Nourah I. Sabeela. "New Imidazolium Ionic Liquids from Recycled Polyethylene Terephthalate Waste for Curing Epoxy Resins as Organic Coatings of Steel". Coatings 10, n.º 11 (23 de noviembre de 2020): 1139. http://dx.doi.org/10.3390/coatings10111139.

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Imidazolium ionic liquid (IIL) was prepared from aminolysis of polyethylene terephthalate (PET) waste with pentaethylenehexamine (PEHA) to apply as hardener of epoxy resin. Its purified chemical structures, thermal stability, and thermal characteristics were identified as well as amino phthalamide aminolyzed products. The thermal, thermomechanical, and mechanical properties of the cured epoxy resins with different weight percentages of IIL were investigated to optimize the best weight ratio to obtain homogeneous networks. The adhesion, durability, and corrosion resistance of the cured epoxy resins on the steel surfaces were tested to confirm that the best weight ratio of epoxy: IL was 2:1. This ratio achieved higher adhesion strength and salt spray resistance to seawater extended to 1500 h.

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7

Cui, Yu Qing y Zhong Wei Yin. "Carbon-fibre-reinforced modified cyanate ester winding composites and their thermomechanical properties". High Performance Polymers 31, n.º 2 (21 de enero de 2018): 154–67. http://dx.doi.org/10.1177/0954008317753526.

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Although the extensive research has expanded on the modification of cyanate ester (CE) resins and the mechanical properties of CE composites, very few studies have been conducted on carbon fibre (CF)/modified CE winding composites and the thermomechanical properties of the composites. In this research, epoxy (EP)-modified novolac cyanate ester (NCE) and bismaleimide (BMI)-modified NCE resins were prepared. The CF/modified CE winding composites were manufactured, and their thermomechanical properties were tested. The optimal winding process was determined, and a preheating technique was implemented. Then, the EP/CE resin (10:90) and the BMI–DBA/CE resin (10:90) were selected as the resin matrix of the winding composite based on the viscosity properties, mechanical properties and thermal analysis (using thermogravimetric analysis and differential scanning calorimetry) of the modified CE resin. The selected resin exhibited good manufacturability at 70°C, good thermal stability and high Tg (above 370°C). The thermomechanical property tests indicate that the modified CE resin composite exhibits an outstanding mechanical strength at room temperature and at high temperatures (130°C, 150°C and 180°C) compared with that of the pure CE resin composite. The reasons for this enhancement can be attributed to a toughening mechanism and the effect of sizing agents on the CFs.

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8

Kinaci, Emre, Erde Can, John Scala y Giuseppe Palmese. "Influence of Epoxidized Cardanol Functionality and Reactivity on Network Formation and Properties". Polymers 12, n.º 9 (29 de agosto de 2020): 1956. http://dx.doi.org/10.3390/polym12091956.

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Cardanol is a renewable resource based on cashew nut shell liquid (CNSL), which consists of a phenol ring with a C15 long aliphatic side chain in the meta position with varying degrees of unsaturation. Cardanol glycidyl ether was chemically modified to form side-chain epoxidized cardanol glycidyl ether (SCECGE) with an average epoxy functionality of 2.45 per molecule and was cured with petroleum-based epoxy hardeners, 4-4′-methylenebis(cyclohexanamine) and diethylenetriamine, and a cardanol-based amine hardener. For comparison, cardanol-based diphenol diepoxy resin, NC514 (Cardolite), and a petroleum-based epoxy resin, diglycidyl ether of bisphenol-A (DGEBA) were also evaluated. Chemical and thermomechanical analyses showed that for SCECGE resins, incomplete cure of the secondary epoxides led to reduced cross-link density, reduced thermal stability, and reduced elongation at break when compared with difunctional resins containing only primary epoxides. However, because of functionality greater than two, amine-cured SCECGE produced a Tg very similar to that of NC514 and thus could be useful in formulating epoxy with renewable cardanol content.

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9

Gouda, Krushna, Sumit Bhowmik y Biplab Das. "A review on allotropes of carbon and natural filler-reinforced thermomechanical properties of upgraded epoxy hybrid composite". REVIEWS ON ADVANCED MATERIALS SCIENCE 60, n.º 1 (1 de enero de 2021): 237–75. http://dx.doi.org/10.1515/rams-2021-0024.

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Abstract The scarcity of nonrenewable resource motivated inclination towards the environmental-friendly novel materials and development of waste natural filler-based hybrid composite is encouraged to fulfill the material demand. Epoxy resins-based composites are high-performing thermosetting polymers and have outstanding blending properties, good machinability, and low cost. Due to these advantages, thermoset plastic is largely used in a broad range of engineering applications; however, thermomechanical properties of neat epoxy are low. Thus, to enhance the thermomechanical properties of epoxy, it is interfaced materials such as graphite, graphene nanoplatelet, boron, carbon fiber, aluminium, silver, etc. Among various substances, graphene has been deliberated as an acceptable novel filler because of its exceptional properties. In addition to inorganic filler inclusion, natural filler/fiber like hemp, sisal, flax, bamboo, jute, etc. can be utilized in a higher percentage as biodegradable material. The present article assisted to improve thermomechanical properties of neat epoxy. This work identifies and addresses (i) processes used for graphene modification; (ii) treatment utilized for enhancing the binding properties of natural filler; (iii) various natural filler extraction process employed; (iv) neat epoxy modification; and (v) influence of different dimensions of fillers.

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10

Karami, Z., MJ Zohuriaan-Mehr, K. Kabiri y N. Ghasemi Rad. "Bio-based thermoset alloys from epoxy acrylate, sesame oil- and castor oil-derived resins: Renewable alternatives to vinyl ester and unsaturated polyester resins". Polymers from Renewable Resources 10, n.º 1-3 (febrero de 2019): 27–44. http://dx.doi.org/10.1177/2041247919863633.

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This study deals with the synthesis of vegetable oil (VO)-derived formulated resins with high bio-based content (30–77%) as potential renewable alternatives to conventional fossil-based vinyl ester (VE) and unsaturated polyester (UP) resins. First, epoxy acrylate was synthesized from a commercial epoxy resin via acrylation with acrylic acid. Then, acrylated epoxidized sesame oil (AESSO) and maleated castor oil (MCO) were synthesized and spectrally characterized. Afterward, networks of VE, AESSO, and MCO or their binary blends were prepared. The curing trend of the resins was investigated by differential scanning calorimetry. According to thermal and thermomechanical analysis, all of the VO-based networks possessed slightly inferior properties compared to those of VE. However, the adhesion strength of the VO-based alloying systems was higher than that of their petroleum-based counterpart based on T-peel and lap shear tests. Overall, it was concluded that the bio-resourced alloys could be considered as good alternatives to VE and UP resins, and the novel bio-resin formulations may be designed for adhesives, the polymer–matrix composites, and surface coating applications.

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11

Blanco, I., G. Cicala, C. Lo Faro, O. Motta y G. Recca. "Thermomechanical and morphological properties of epoxy resins modified with functionalized hyperbranched polyester". Polymer Engineering & Science 46, n.º 11 (2006): 1502–11. http://dx.doi.org/10.1002/pen.20604.

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12

Zhang, Jianwen, Dongwei Wang, Lujia Wang, Wanwan Zuo, Lijun Zhou, Xue Hu y Dingyu Bao. "Effect of Terminal Groups on Thermomechanical and Dielectric Properties of Silica–Epoxy Composite Modified by Hyperbranched Polyester". Polymers 13, n.º 15 (26 de julio de 2021): 2451. http://dx.doi.org/10.3390/polym13152451.

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To study the effect of hyperbranched polyester with different kinds of terminal groups on the thermomechanical and dielectric properties of silica–epoxy resin composite, a molecular dynamics simulation method was utilized. Pure epoxy resin and four groups of silica–epoxy resin composites were established, where the silica surface was hydrogenated, grafted with silane coupling agents, and grafted with hyperbranched polyester with terminal carboxyl and terminal hydroxyl, respectively. Then the thermal conductivity, glass transition temperature, elastic modulus, dielectric constant, free volume fraction, mean square displacement, hydrogen bonds, and binding energy of the five models were calculated. The results showed that the hyperbranched polyester significantly improved the thermomechanical and dielectric properties of the silica–epoxy composites compared with other surface treatments, and the terminal groups had an obvious effect on the enhancement effect. Among them, epoxy composite modified by the hyperbranched polyester with terminal carboxy exhibited the best thermomechanical properties and lowest dielectric constant. Our analysis of the microstructure found that the two systems grafted with hyperbranched polyester had a smaller free volume fraction (FFV) and mean square displacement (MSD), and the larger number of hydrogen bonds and greater binding energy, indicating that weaker strength of molecular segments motion and stronger interfacial bonding between silica and epoxy resin matrix were the reasons for the enhancement of the thermomechanical and dielectric properties.

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13

Zhang, Zuo-Guang, Gang Sui, Wei-Hong Zhong y Zhi-Jie Sun. "Effect of Heat Treatment on Thermomechanical Properties of Electron Beam-cured Epoxy Resins". Polymers and Polymer Composites 10, n.º 6 (septiembre de 2002): 467–80. http://dx.doi.org/10.1177/096739110201000607.

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The effects of thermal post-treatment on EB-cured epoxy resins have been studied. Dynamic mechanical analyses were performed on samples which differed in EB radiation dose, initiator dosage, molecular weight and distribution. When the EB-cured epoxy resins were heated, the crosslink density increased. The glass transition temperature (Tg) was shifted to a higher temperature and the storage modulus (E’) remained at a high level in the heat-treated samples with increasing temperature. But when the temperature of heat treatment exceeded the trigger temperature of the initiator, an α'-relaxation peak derived from the local thermal curing network was observed in the tan δ curve. When the crosslink density induced by radiation increased, the effect of heat treatment was weakened and the temperature of the α′-relaxation peak gradually decreased. The initiator dosage and molecular weight played an important role in determining the Tg and E′ of heat-treated samples with approximately the same radiation crosslink density. When the polydispersity increased in the heat-treated samples with the same molecular weight, a higher temperature for the Tg and the α'-relaxation peak were both shown. The crosslink density and E′ at high temperatures were higher in the heat-treated samples with broad molecular weight distribution.

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14

Mya, Khine Yi, Chaobin He, Junchao Huang, Yang Xiao, Jie Dai y Yeen-Ping Siow. "Preparation and thermomechanical properties of epoxy resins modified by octafunctional cubic silsesquioxane epoxides". Journal of Polymer Science Part A: Polymer Chemistry 42, n.º 14 (2004): 3490–503. http://dx.doi.org/10.1002/pola.20168.

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15

Wei, Kun, Guangming Zhu, Yusheng Tang, Guangming Tian y Jianqiang Xie. "Thermomechanical properties of shape-memory hydro-epoxy resin". Smart Materials and Structures 21, n.º 5 (1 de mayo de 2012): 055022. http://dx.doi.org/10.1088/0964-1726/21/5/055022.

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16

Du, Dongyuan, Yujing Tang, Lu Yang y Chao Tang. "Effects of Different Grafting Density of Amino Silane Coupling Agents on Thermomechanical Properties of Cross-Linked Epoxy Resin". Polymers 12, n.º 8 (26 de julio de 2020): 1662. http://dx.doi.org/10.3390/polym12081662.

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In order to study the influences of amino silane coupling agents with different grafting densities on the surface of nano silica on the thermomechanical properties of cross-linked epoxy resin, the molecular dynamics method was used to establish an amorphous model and calculate the mechanical properties, glass transition temperature, mean square displacement, hydrogen bond, binding energy, and radial distribution function of the composite models in this paper. The results are as follows: with the increase of the grafting density of an amino silane coupling agent on the surface of nano silica particles, the mechanical properties and glass transition temperature of epoxy resin showed a trend of increasing first and then decreasing. When the grafting ratio was 9%, the mechanical properties and glass transition temperature of the epoxy resin were the largest, and the glass transition temperature was increased by 41 K. At the same time, it was found that the higher the grafting ratio, the lower the chain movement ability, but the higher the binding energy. Besides, the binding energy between the nanoparticles of the grafted silane coupling agent and epoxy resin was negatively correlated with the temperature. By analyzing the hydrogen bond and radial distribution function, the results showed that the improvement of the grafted silane coupling agent on the surface of the nanoparticle to the thermomechanical properties of the epoxy resin was related to the OH···O and NH···O hydrogen bonds. The analysis results indicated that the proper grafting density should be selected based on the established model size, selected nanoparticle diameter, and epoxy resin materials in order to better improve the thermomechanical properties of the epoxy resin.

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17

Fu, Kexin, Qing Xie, Fangcheng LÜ, Qijun Duan, Xinjie Wang, Quansheng Zhu y Zhengyong Huang. "Molecular Dynamics Simulation and Experimental Studies on the Thermomechanical Properties of Epoxy Resin with Different Anhydride Curing Agents". Polymers 11, n.º 6 (3 de junio de 2019): 975. http://dx.doi.org/10.3390/polym11060975.

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An investigation of the relationship between the microstructure parameters and thermomechanical properties of epoxy resin can provide a scientific basis for the optimization of epoxy systems. In this paper, the thermomechanical properties of diglycidyl ether of bisphenol A (DGEBA)/methyl tetrahydrophthalic anhydride (MTHPA) and DGEBA/nadic anhydride (NA) were calculated and tested by the method of molecular dynamics (MD) simulation combined with experimental verification. The effects of anhydride curing agents on the thermomechanical properties of epoxy resin were investigated. The results of the simulation and experiment showed that the thermomechanical parameters (glass transition temperature (Tg) and Young’s modulus) of the DGEBA/NA system were higher than those of the DGEBA/MTHPA system. The simulation results had a good agreement with the experimental data, which verified the accuracy of the crosslinking model of epoxy resin cured with anhydride curing agents. The microstructure parameters of the anhydride-epoxy system were analyzed by MD simulation, including bond-length distribution, synergy rotational energy barrier, cohesive energy density (CED) and fraction free volume (FFV). The results indicated that the bond-length distribution of the MTHPA and NA was the same except for C–C bonds. Compared with the DGEBA/MTHPA system, the DGEBA/NA system had a higher synergy rotational energy barrier and CED, and lower FFV. It can be seen that the slight change of curing agent structure has a significant effect on the synergy rotational energy barrier, CED and FFV, thus affecting the Tg and modulus of the system.

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18

LIM, SHEAU HOOI, KAIYANG ZENG y CHAOBIN HE. "PREPARATION, MORPHOLOGY AND MECHANICAL PROPERTIES OF EPOXY NANOCOMPOSITES WITH ALUMINA FILLERS". International Journal of Modern Physics B 24, n.º 01n02 (20 de enero de 2010): 136–47. http://dx.doi.org/10.1142/s021797921006406x.

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This paper presents recent studies on the processing and characterization of epoxy-alumina nanocomposites. Nano-sized alumina particles are incorporated into epoxy resin via solvent-assisted method, so that the particles are dispersed homogeneously in the epoxy matrix. The morphologies, mechanical and thermomechanical properties of the resulting nanocomposites are studied using transmission electron microscope (TEM), conventional tensile testing and thermomechanical testing methods. TEM results show that the alumina nano-particles with a higher specific surface area tend to agglomerate. Furthermore platelet shape particles shows a better dispersion homogeneity as well as better improvement in the mechanical properties of the composites compared to the rod shape particles.

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19

Ban, Jian Feng, Shao Rong Lu, Dong Guo, Kuo Liu y Chong Xi Luo. "Thermomechanical Properties and Morphology of Liquid Crystalline Polyurethane/Epoxy Resin Composites". Advanced Materials Research 194-196 (febrero de 2011): 1421–25. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.1421.

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One new kind of epoxy resin toughening agent defined as liquid crystalline polyurethane elastomers (LCPUE) containing mesogenic ester groups and trithylene glycol flexible chain was synthesized and its nematic structure was observed by POM and XRD. The LCPUE was to modify the epoxy resin (E-51). The mechanical properties, fracture surface morphology, and thermal properties of the E-51/LCPUE curing system were systematically investigated. Experimental results revealed that the impact strength of the epoxy resin modified with LCPU is 1.9 times higher than that of the unmodified system, enhanced the thermal decomposition temperature by about 12 °C, and the fracture surfaces all modified systems display tough fracture feature.

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20

Lascano, Diego, Luis Quiles-Carrillo, Sergio Torres-Giner, Teodomiro Boronat y Nestor Montanes. "Optimization of the Curing and Post-Curing Conditions for the Manufacturing of Partially Bio-Based Epoxy Resins with Improved Toughness". Polymers 11, n.º 8 (15 de agosto de 2019): 1354. http://dx.doi.org/10.3390/polym11081354.

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This research deals with the influence of different curing and post-curing temperatures on the mechanical and thermomechanical properties as well as the gel time of an epoxy resin prepared by the reaction of diglycidyl ether of bisphenol A (DGEBA) with an amine hardener and a reactive diluent derived from plants at 31 wt %. The highest performance was obtained for the resins cured at moderate-to-high temperatures, that is, 80 ° C and 90 ° C , which additionally showed a significant reduction in the gel time. This effect was ascribed to the formation of a stronger polymer network by an extended cross-linking process of the polymer chains during the resin manufacturing. Furthermore, post-curing at either 125 ° C or 150 ° C yielded thermosets with higher mechanical strength and, more interestingly, improved toughness, particularly for the samples previously cured at moderate temperatures. In particular, the partially bio-based epoxy resin cured at 80 ° C and post-cured at 150 ° C for 1 h and 30 min, respectively, showed the most balanced performance due to the formation of a more homogeneous cross-linked structure.

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21

Ni, Yong y Sixun Zheng. "Epoxy resin containing polyphenylsilsesquioxane: Preparation, morphology, and thermomechanical properties". Journal of Polymer Science Part A: Polymer Chemistry 44, n.º 3 (2005): 1093–105. http://dx.doi.org/10.1002/pola.21222.

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22

Xin, Dongrong y Qiang Han. "Study on thermomechanical properties of cross-linked epoxy resin". Molecular Simulation 41, n.º 13 (21 de julio de 2014): 1081–85. http://dx.doi.org/10.1080/08927022.2014.938334.

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23

Glaskova-Kuzmina, Tatjana, Andrey Aniskevich, Jevgenijs Sevcenko, Anna Borriello y Mauro Zarrelli. "Cyclic Moisture Sorption and its Effects on the Thermomechanical Properties of Epoxy and Epoxy/MWCNT Nanocomposite". Polymers 11, n.º 9 (23 de agosto de 2019): 1383. http://dx.doi.org/10.3390/polym11091383.

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The aim of this work was to reveal the moisture absorption–desorption–resorption characteristics of epoxy and epoxy-based nanocomposites filled with different multiwall carbon nanotubes (MWCNTs) by investigating the reversibility of the moisture effect on their thermomechanical properties. Two types of MWCNTs with average diameters of 9.5 and 140 nm were used. For the neat epoxy and nanocomposite samples, the moisture absorption and resorption tests were performed in atmospheres with 47%, 73%, and 91% relative humidity at room temperature. Dynamic mechanical analysis was employed to evaluate the hygrothermal ageing effect for unconditioned and environmentally “aged” samples. It was found that moisture sorption was not fully reversible, and the extent of the irreversibility on thermomechanical properties was different for the epoxy and the nanocomposite. The addition of both types of MWCNTs to the epoxy resin reduced sorption characteristics for all sorption tests, improved the hygrothermal and reduced the swelling rate after the moisture absorption–desorption.

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24

DINU, ROXANA y ALICE MIJA. ""BIO-BASED EPOXY RESINS AND COMPOSITES FROM EPOXIDIZED LINSEED OIL CROSSLINKED WITH DIFFERENT CYCLIC ANHYDRIDES AND THEIR COMBINATION WITH LIGNIN"". Cellulose Chemistry and Technology 54, n.º 9-10 (11 de noviembre de 2020): 925–38. http://dx.doi.org/10.35812/cellulosechemtechnol.2020.54.89.

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Biobased resins and composites with high biobased carbon content were prepared and characterized. Epoxidized linseed oil (ELO) was copolymerized with four cyclic anhydrides, the initiation step being optimized in terms of initiator nature and its ratio. The optimized ELO/anhydride formulations were combined with a high load of lignin, as biofiller, ~30 wt%. The obtained materials were characterized by TGA, DSC, DMA, gel content, water absorption (WA) and Shore hardness tests. The results revealed very good thermomechanical properties, high gel content and low WA, opening the way to their utilization as a sustainable alternative to oil-based resins and composites.

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25

Cicala, G., A. Recca y C. Restuccia. "Influence of hydroxyl functionalized hyperbranched polymers on the thermomechanical and morphological properties of epoxy resins". Polymer Engineering & Science 45, n.º 2 (2005): 225–37. http://dx.doi.org/10.1002/pen.20242.

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26

Osipchik, V. S., Yu V. Olikhova, L. Kh Nguen, G. A. Lushcheikin y V. M. Aristov. "Determining the Glass Transition Temperature of an Epoxy Siloxane Composite by Thermal Analysis Methods". International Polymer Science and Technology 45, n.º 6 (junio de 2018): 269–74. http://dx.doi.org/10.1177/0307174x1804500605.

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Thermomechanical analysis, dynamic mechanical analysis, differential scanning calorimetry, and dielectric thermal analysis were used to determine the glass transition temperature of hot-curing epoxy siloxane composites. The effect of polymethylphenylsiloxane resin on the parameters of the three-dimensional structure and on the deformation and strength properties of epoxy novolac resin during curing by 4,4′-diaminodiphenylmethane was established.

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27

Terekhov, I. V., A. I. Tkachuk, K. I. Donetsky y R. Yu Karavaev. "TECHNOLOGICAL AND OPERATIONAL CHARACTERISTICS OF THE VSE-62 LOW-VISCOSITY EPOXY RESIN WITH INCREASED POT LIFE AND ITS APPLICATION". Aviation Materials and Technologies, n.º 2 (2021): 43–50. http://dx.doi.org/10.18577/2713-0193-2021-0-2-43-50.

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The paper considers the main physical and chemical and thermomechanical characteristics of the VSE-62 epoxy resin. The results of rheological tests of the developed resin in dynamic and isothermal modes, as well as the kinetic parameters of the curing process are presented. They help to determine the technological conditions for obtaining defect-free cured samples. The results of mechanical tests show that this resin’s system is characterized by high values of the glass transition temperature and good mechanical properties at test temperature of 120 °C. The absence of solvents in the composition of the VSE-62 epoxy resin and its low viscosity makes it possible to obtain high-strength materials with reduced porosity.

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28

Chaos-Morán, R., M. Campo, S. G. Prolongo, M. D. Escalera y A. Ureña. "The functionalization of carbon nanofibers with 4,4′-diaminodiphenylmethane, a curing agent for epoxy resins". Journal of Materials Research 24, n.º 4 (abril de 2009): 1435–45. http://dx.doi.org/10.1557/jmr.2009.0159.

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A functionalization technique for carbon nanofibers (CNFs) via acid is described. The integrity and chemical nature of the CNFs during the different stages of the applied treatment (oxidation, activation, and functionalization) were examined using different microscopic, chemical, and thermal analysis techniques. The treatment effect on the dispersion ability of the nanofibers in different solvents (tetrahydrofuran, chloroform, and acetone) was also evaluated. Results show that chloroform is the best medium to reach good dispersions and stability of the CNFs in a wide range of concentrations. Using this medium, the functionalization process using 4,4′-diaminodiphenylmethane (DDM) was adopted for the fabrication of reactive CNFs with linker molecules on their surface capable of binding covalently to thermosetting polymers, such as epoxy. The DDM surface derivatized CNFs have been used as reinforcement in epoxy matrix nanocomposites with improved thermomechanical properties in relation to non-treated carbon nanofibers.

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29

Cano Murillo, Natalia, Media Ghasem Zadeh Khorasani, Dorothee Silbernagl, Farnaz Emamverdi, Karen Cacua, Vasile-Dan Hodoroaba y Heinz Sturm. "Carrier Fibers for the Safe Dosage of Nanoparticles in Nanocomposites: Nanomechanical and Thermomechanical Study on Polycarbonate/Boehmite Electrospun Fibers Embedded in Epoxy Resin". Nanomaterials 11, n.º 6 (17 de junio de 2021): 1591. http://dx.doi.org/10.3390/nano11061591.

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The reinforcing effect of boehmite nanoparticles (BNP) in epoxy resins for fiber composite lightweight construction is related to the formation of a soft but bound interphase between filler and polymer. The interphase is able to dissipate crack propagation energy and consequently increases the fracture toughness of the epoxy resin. Usually, the nanoparticles are dispersed in the resin and then mixed with the hardener to form an applicable mixture to impregnate the fibers. If one wishes to locally increase the fracture toughness at particularly stressed positions of the fiber-reinforced polymer composites (FRPC), this could be done by spraying nanoparticles from a suspension. However, this would entail high costs for removing the nanoparticles from the ambient air. We propose that a fiber fleece containing bound nanoparticles be inserted at exposed locations. For the present proof-of-concept study, an electrospun polycarbonate nonwoven and taurine modified BNP are proposed. After fabrication of suitable PC/EP/BNP composites, the thermomechanical properties were tested by dynamic mechanical analysis (DMA). Comparatively, the local nanomechanical properties such as stiffness and elastic modulus were determined by atomic force microscopy (AFM). An additional investigation of the distribution of the nanoparticles in the epoxy matrix, which is a prerequisite for an effective nanocomposite, is carried out by scanning electron microscopy in transmission mode (TSEM). From the results it can be concluded that the concept of carrier fibers for nanoparticles is viable.

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30

Wang, Hongyu, Shichao Li, Yuhuan Yuan, Xin Liu, Tao Sun y Zhanjun Wu. "Study of the epoxy/amine equivalent ratio on thermal properties, cryogenic mechanical properties, and liquid oxygen compatibility of the bisphenol A epoxy resin containing phosphorus". High Performance Polymers 32, n.º 4 (28 de agosto de 2019): 429–43. http://dx.doi.org/10.1177/0954008319871340.

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A liquid oxygen-compatible epoxy resin is successfully prepared by changing the epoxy/amine equivalent ratio (SR) of a phosphorus-containing epoxy resin. The liquid oxygen impact test results showed that the modified resin was compatible with liquid oxygen only when the SR was 0.8. The mechanical properties at 90 K showed that the strain energy and impact toughness reached the maximum when the SR was 0.8, which suggested that the reduced rigidity might be beneficial to improve the liquid oxygen compatibility of the polymer. The thermomechanical and thermal results showed that the cross-linking density and thermal stability was proportional to SR. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis showed that the P=O group in the resin decomposed into phosphoric oxidative solids and P–N intermediates to inhibit the resin from decomposing and contacting with liquid oxygen during impact. Overall, this study provides a new idea for the design of liquid oxygen-compatible epoxy resin.

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31

Li, Kai, Ni Huo, Xinping Liu, Jue Cheng y Junying Zhang. "Effects of the furan ring in epoxy resin on the thermomechanical properties of highly cross-linked epoxy networks: a molecular simulation study". RSC Advances 6, n.º 1 (2016): 769–77. http://dx.doi.org/10.1039/c5ra22955c.

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32

Berta, Marco, Sébastien Maria, Trang N. T. Phan, Didier Gigmes, Alberto Fina y Giovanni Camino. "Reworkable layered silicate-epoxy nanocomposites: synthesis, thermomechanical properties and combustion behaviour". Journal of Polymer Engineering 37, n.º 1 (1 de enero de 2017): 21–30. http://dx.doi.org/10.1515/polyeng-2015-0483.

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Abstract Epoxy resin/montmorillonite nanocomposites were obtained via in situ intercalative polymerisation. The polymer matrix consists of anhydride-cured epoxy, and the choice of catalyst allows exchange reactions without depolymerisation. This makes the resin insoluble and reprocessable at the same time and potentially recyclable. In this study, reprocessing of the nanocomposites was done by mechanical grinding and re-welding by compression moulding at high temperature, similarly to thermoplastics. The effect of this process on the level of clay dispersion is discussed. Nanocomposite superstructures were imaged by means of transmission electron microscopy, and montmorillonite interlayer spacings were estimated by small angle X-ray scattering. The thermomechanical and combustion properties of the nanocomposites were investigated by means of dynamic mechanical thermal analysis, thermogravimetric analysis and cone calorimetry. The material tensile complex modulus E* was improved by nanocomposite formation, also after the glass transition occurred. Flammability of the material was moderately affected by the dispersed clay.

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33

Matykiewicz, Danuta. "Hybrid Epoxy Composites with Both Powder and Fiber Filler: A Review of Mechanical and Thermomechanical Properties". Materials 13, n.º 8 (11 de abril de 2020): 1802. http://dx.doi.org/10.3390/ma13081802.

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Fiber-reinforced epoxy composites are used in various branches of industry because of their favorable strength and thermal properties, resistance to chemical and atmospheric conditions, as well as low specific gravity. This review discusses the mechanical and thermomechanical properties of hybrid epoxy composites that were reinforced with glass, carbon, and basalt fabric modified with powder filler. The modification of the epoxy matrix mainly leads to an improvement in its adhesion to the layers of reinforcing fibers in the form of laminate fabrics. Some commonly used epoxy matrix modifiers in powder form include carbon nanotubes, graphene, nanoclay, silica, and natural fillers. Fiber fabric reinforcement can be unidirectional, multidirectional, biaxial, or have plain, twill, and satin weave, etc. Commonly used methods of laminating epoxy composites are hand lay-up process, resin transfer molding, vacuum-assisted resin transfer molding, and hot or cold pressing. The following review is a valuable source of information on multiscale epoxy composites due to the multitude of technological and material solutions.

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34

Glaskova-Kuzmina, Tatjana, Andrey Aniskevich, George Papanicolaou, Diana Portan, Aldobenedetto Zotti, Anna Borriello y Mauro Zarrelli. "Hydrothermal Aging of an Epoxy Resin Filled with Carbon Nanofillers". Polymers 12, n.º 5 (18 de mayo de 2020): 1153. http://dx.doi.org/10.3390/polym12051153.

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The effects of temperature and moisture on flexural and thermomechanical properties of neat and filled epoxy with both multiwall carbon nanotubes (CNT), carbon nanofibers (CNF), and their hybrid components were investigated. Two regimes of environmental aging were applied: Water absorption at 70 °C until equilibrium moisture content and thermal heating at 70 °C for the same time period. Three-point bending and dynamic mechanical tests were carried out for all samples before and after conditioning. The property prediction model (PPM) was successfully applied for the prediction of the modulus of elasticity in bending of manufactured specimens subjected to both water absorption and thermal aging. It was experimentally confirmed that, due to addition of carbon nanofillers to the epoxy resin, the sorption, flexural, and thermomechanical characteristics were slightly improved compared to the neat system. Considering experimental and theoretical results, most of the epoxy composites filled with hybrid carbon nanofiller revealed the lowest effect of temperature and moisture on material properties, along with the lowest sorption characteristics.

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35

dos Santos, D. J., L. B. Tavares, J. R. Gouveia y G. F. Batalha. "Lignin-based polyurethane and epoxy adhesives: a short review". Archives of Materials Science and Engineering 2, n.º 107 (1 de febrero de 2021): 56–63. http://dx.doi.org/10.5604/01.3001.0015.0242.

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Purpose: of this paper was to review and summarize significant papers related to the development and characterization of lignin-containing adhesives: polyurethane and epoxy types. In the last decades, several efforts have been dedicated on the development of renewable raw materials for polymer synthesis, mainly due to petroleum depletion and sustainability. In this context, lignin emerged as a potential candidate to substitute fossilbased raw materials in adhesive synthesis and formulations. Design/methodology/approach: Recent and other relevant papers were reviewed, aiming to identify the main advantages and limitations involved in lignin incorporation into epoxy and polyurethane adhesives formulations. First, effects of unmodified lignin addition were presented. Afterwards, the main lignin chemical modification methods were presented and discussed, based on thermomechanical results. Findings: Incorporation of unmodified lignin usually is limited to 30 %wt., otherwise mechanical properties are drastically affected as consequence of poor lignin solubility and excessive brittleness. Lignin chemical modification can be used to increase the reactivity of hydroxyl groups and/or add new moieties in its molecular structure, improving solubility and thermomechanical properties of cured adhesives. Practical implications: In the last years, some industrial plants started to operate and produce technical grade lignin at industrial scale, with reproducible properties and controlled molecular structure. Therefore, increasing efforts have been dedicated from researchers and chemists to develop lignin-based technologies, in which this work can directly contribute with. Originality/value: As consequence of the high content of phenol groups in its molecular structure, lignin was mostly applied on the development of phenolic resins applied as wood adhesives. For the first time in the literature, this work summarizes the advances related to synthesis and characterization of polyurethane and epoxy, applied as adhesives. Results can support the development and application of biobased, as well as contribute to the revalorization of this valuable and readily available biomass.

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36

Lin, Yi-Sheng, Steve Lien-Chung Hsu, Tsung-Han Ho, Li-Cheng Jheng y Yu-Hsiang Hsiao. "Preparation and Thermomechanical Properties of Ketone Mesogenic Liquid Crystalline Epoxy Resin Composites with Functionalized Boron Nitride". Polymers 12, n.º 9 (25 de agosto de 2020): 1913. http://dx.doi.org/10.3390/polym12091913.

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In order to enhance the thermomechanical behaviors of epoxy molding compounds, the hexagonal boron nitride (h-BN) fillers were incorporated in a ketone mesogenic liquid crystalline epoxy (K–LCE) matrix to prepare a high-performance epoxy composites. The h-BN was modified by surface coupling agent 3-aminopropyltriethoxysilane (APTES). The grafting of silane molecules onto the surface of BN fillers improved the compatibility and homogeneous dispersion state of BN fillers in the K–LCE matrix with a strong interface interaction. The surface-modified BN fillers were characterized using Fourier transform infrared spectroscopy. The thermomechanical properties and morphologies of K–LCE/BN composites loading with different contents of modified BN fillers, ranging from 0.50 to 5.00 wt%, were investigated. These results show that modified BN fillers uniformly dispersed in K–LCE matrix, contributing to the enhancement in storage modulus, glass transition temperatures, impact strength and reduction in the coefficient of thermal expansion (CTE). The thermal stability and char yield of the K–LCE/BN composites were increased by increasing the amount of modified BN fillers and the thermal decomposition temperatures of composites were over 370 °C. The thermal conductivity of the K–LCE/BN composites was up to 0.6 W/m·K, for LC epoxy filled with 5.00-wt%-modified BN fillers. Furthermore, the K–LCE/BN composites have excellent thermal and mechanical properties compared to those of the DGEBA/BN composites.

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37

Wang, Zhenyu, Pitchaimari Gnanasekar, Sandeep Sudhakaran Nair, Songlin Yi y Ning Yan. "Curing Behavior and Thermomechanical Performance of Bioepoxy Resin Synthesized from Vanillyl Alcohol: Effects of the Curing Agent". Polymers 13, n.º 17 (27 de agosto de 2021): 2891. http://dx.doi.org/10.3390/polym13172891.

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In order to reduce the dependency of resin synthesis on petroleum resources, vanillyl alcohol which is a renewable material that can be produced from lignin has been used to synthesize bioepoxy resin. Although it has been widely reported that the curing reaction and properties of the cured epoxies can be greatly affected by the molecular structure of the curing agents, the exact influence remains unknown for bioepoxies. In this study, four aliphatic amines with different molecular structures and amine functionalities, namely triethylenetetramine (TETA), Tris(2-aminoethyl)amine (TREN), diethylenetriamine (DETA), and ethylenediamine (EDA), were used to cure the synthesized vanillyl alcohol–based bioepoxy resin (VE). The curing reaction of VE and the physicochemical properties, especially the thermomechanical performance of the cured bioepoxies with different amine functionalities, were systematically investigated and compared using different characterization methods, such as DSC, ATR–FTIR, TGA, DMA, and tensile testing, etc. Despite a higher curing temperature needed in the VE–TETA resin system, the cured VE–TETA epoxy showed a better chemical resistance, particularly acidic resistance, as well as a lower swelling ratio than the others. The higher thermal decomposition temperature, storage modulus, and relaxation temperature of VE–TETA epoxy indicated its superior thermal stability and thermomechanical properties. Moreover, the tensile strength of VE cured by TETA was 1.4~2.6 times higher than those of other curing systems. In conclusion, TETA was shown to be the optimum epoxy curing agent for vanillyl alcohol–based bioepoxy resin.

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38

Matykiewicz, Danuta, Mateusz Barczewski y Tomasz Sterzyński. "Morphology and thermomechanical properties of epoxy composites highly filled with waste bulk molding compounds (BMC)". Journal of Polymer Engineering 35, n.º 8 (1 de octubre de 2015): 805–11. http://dx.doi.org/10.1515/polyeng-2014-0330.

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Abstract The aim of this study was to produce epoxy composites highly filled with waste bulk molding compounds (BMC). The used amount of filler ranged from 30 wt% to 60 wt%. The influence of BMC on the epoxy resin curing process was monitored with the differential scanning calorimetry (DSC) method. Fourier transform infrared (FTIR) spectroscopy was used to evaluate the chemical structure of composites. The mechanical and thermal properties were examined by means of dynamic mechanical thermal analysis (DMTA), the Charpy method and the Shore D test. The fracture surface morphology of composites was observed with scanning electron microscopy (SEM). The storage modulus G′ of the epoxy composites with BMC was higher than the reference epoxy sample and significantly dependent on filler content. All investigated materials showed similar values of hardness, but at the same time low values of impact strength. Therefore, obtained composites can be used as low cost coating materials.

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39

Wei, Kun, Biao Ma, Hainian Wang y Ning Li. "Effect of a tetra functional epoxy monomer on the thermomechanical properties of shape-memory epoxy resin". Fibers and Polymers 16, n.º 11 (noviembre de 2015): 2343–48. http://dx.doi.org/10.1007/s12221-015-5405-8.

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40

Wang, Tao, Li J. Ma, Ping Y. Wan, Jin P. Liu y Fang Wang. "A study of the photoactivities and thermomechanical properties of epoxy resins using novel [cyclopentadien-Fe-arene]+PF6− photoinitiators". Journal of Photochemistry and Photobiology A: Chemistry 163, n.º 1-2 (abril de 2004): 77–86. http://dx.doi.org/10.1016/s1010-6030(03)00432-5.

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41

Karmazsin, E., P. Satre y J. F. Rochas. "Use of cotinuous and pul sed microwaves for quick polymerization of epoxy resins: study of some thermomechanical properties". Thermochimica Acta 93 (septiembre de 1985): 305–8. http://dx.doi.org/10.1016/0040-6031(85)85078-4.

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42

Isarn, Isaac, Francesco Gamardella, Xavier Fernàndez-Francos, Àngels Serra y Francesc Ferrando. "Thermal Conductive Composites Prepared by Addition of Several Ceramic Fillers to Thermally Cationic Curing Cycloaliphatic Epoxy Resins". Polymers 11, n.º 1 (15 de enero de 2019): 138. http://dx.doi.org/10.3390/polym11010138.

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Novel composite coatings prepared from 3,4-epoxy cyclohexylmethyl 3,4-epoxycyclohexane carboxylate (ECC) and different ceramic fillers have been prepared to improve the thermal dissipation of electronic devices. As latent cationic initiator, a benzylanilinium salt with triethanolamine has been used, which leads to a polyether matrix. Different proportions of Al2O3, AlN and SiC as fillers were added to the reactive formulation. The effect of the fillers selected and their proportions on the evolution of the curing was studied by calorimetry and rheometry. The thermal conductivity, thermal stability, thermal expansion coefficient and thermomechanical and mechanical properties of the composites were evaluated. An improvement of 820% in thermal conductivity in reference to the neat material was reached with a 75 wt % of AlN, whereas glass transition temperatures higher than 200 °C were determined in all the composites.

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43

Hosur, Mahesh, Tanjheel H. Mahdi, Mohammad E. Islam y S. Jeelani. "Mechanical and viscoelastic properties of epoxy nanocomposites reinforced with carbon nanotubes, nanoclay, and binary nanoparticles". Journal of Reinforced Plastics and Composites 36, n.º 9 (7 de febrero de 2017): 667–84. http://dx.doi.org/10.1177/0731684417691365.

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Mechanical and viscoelastic properties of polymer nanocomposites reinforced with carboxyl functionalized multiwalled carbon nanotubes (COOH-MWCNT), montmorillonite nanoclays (MMT), and MWCNT/MMT binary nanoparticle were investigated. In this study, 0.3 wt% of COOH-MWCNT, 2 wt% of MMT, and 0.1 wt% COOH-MWCNT/2 wt% MMT binary nanoparticles by weight of epoxy were incorporated to modify SC-15 epoxy resin system. Nanocomposites were subjected to flexural test, dynamic mechanical, and thermomechanical analyses. Morphological study was conducted with microscopy. Addition of each of the nanoparticles in epoxy showed significant improvement in the mechanical and viscoelastic properties compared to those of the control ones. However, best results were obtained by addition of 0.1% MWCNT/2% MMT binary nanoparticles in epoxy. Nanocomposites modified with binary nanoparticles exhibited about 20% increase in storage modulus as well as 25℃ increase in the glass transition temperature. Flexural modulus for binary nanoparticle modified composites depicted about 30% improvement compared to the control ones. Thus, improvement of mechanical and viscoelastic properties was achieved by incorporating binary nanoparticles to epoxy nanocomposites. The increase in properties was attributed to the synergistic effect of MWCNTs and nanoclay in chemically interacting with each other and epoxy resin as well as in arresting and delaying the crack growth, once initiated.

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44

LU, SHAORONG, XIAOWANG YANG y CHUN WEI. "STUDY ON THE THERMOMECHANICAL PROPERTIES AND MORPHOLOGY OF POLYACID AMIDE/EPOXY RESIN COMPOSITES". Functional Materials Letters 03, n.º 03 (septiembre de 2010): 165–68. http://dx.doi.org/10.1142/s1793604710001160.

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Polyamic acid (PAA) containing aromatic ester was synthesized and used to modify the epoxy resin (E-51)/PAA curing system. The mechanical properties, dynamic mechanical properties, fracture surface morphology, and thermal properties of the E-51/PAA curing systems were systematically investigated. Experimental results revealed that the impact strength of the cured systems modified with PAA are 3 to 4 times higher than that of the unmodified system, and enhanced the thermal decomposition temperature by about 15°C, while the storage modulus is also higher than that of the unmodified system, and the fracture surfaces of modified systems display tough fracture feature.

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45

Chang, Yu-Hsun y King-Fu Lin. "Physisorption of ionic salts to carbon nanotubes for enhancing dispersion and thermomechanical properties of carbon nanotube-filled epoxy resins". Composites Science and Technology 90 (enero de 2014): 174–79. http://dx.doi.org/10.1016/j.compscitech.2013.11.011.

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46

Lin, Yi-Sheng, Steve Lien-Chung Hsu, Tsung-Han Ho, Shi-Shiun Cheng y Yu-Hsiang Hsiao. "Synthesis, characterization, and thermomechanical properties of liquid crystalline epoxy resin containing ketone mesogen". Polymer Engineering & Science 57, n.º 4 (8 de septiembre de 2016): 424–31. http://dx.doi.org/10.1002/pen.24437.

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47

Li, Rui, Cheng Zhou, Yang Chen, Huawei Zou, Mei Liang y Yi Li. "Preparation, characterization, and properties of organic silicone intermediate-modified epoxy resin copolymers". High Performance Polymers 29, n.º 1 (28 de julio de 2016): 36–45. http://dx.doi.org/10.1177/0954008315627375.

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In this work, a series of silicone-containing epoxy copolymers (E231) were synthesized through a condensation reaction between the Si-OCH3 of SY231 and the –OH of E51. The chemical structural determinations of the copolymer were carried out with the Fourier transform infrared spectroscopy, nuclear magnetic resonance (NMR), and an epoxy equivalent weight test. Besides, the grafting content of SY231 in E231 copolymers was determined by the proton (1H) NMR integration technique. The mechanical properties, thermal stabilities, and morphology of impact fractured surface of cured products were also investigated. The experimental results show that increased impact strength was observed for the cured E231 products, meanwhile the improvement of the impact strength was closely related to the content of silicone in copolymers. A smooth surface was observed on the neat epoxy specimen, while a rough surface was observed by scanning electron microscopic examination on the impact fractured surface of the cured E231 products. The data of TGA indicated that silicone exerted its thermal stability through thermal decomposition energy dissipation, acted as thermal insulation, and finally enhanced the solid residue at 800°C. Dynamic thermomechanical analysis tests displayed that the glass transition temperature of epoxy systems decreased slightly with the introduction of the flexible organosilicone.

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48

Solala, Iina, Toni Antikainen, Mehedi Reza, Leena-Sisko Johansson, Mark Hughes y Tapani Vuorinen. "Spruce fiber properties after high-temperature thermomechanical pulping (HT-TMP)". Holzforschung 68, n.º 2 (1 de febrero de 2014): 195–201. http://dx.doi.org/10.1515/hf-2013-0083.

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Abstract Spruce was submitted to high-temperature (150°C–170°C) refining for 2 or 5 min to produce thermomechanical pulp (TMP) fibers with decreased electrical energy consumption. The pulp was characterized in terms of specific energy consumption as well as tensile and surface properties. The fibers from high-temperature TMP contained more surface lignin even if all sample types usually broke at the S1–S2 cell wall region. They also produced significantly weaker paper sheets, whereas their dry zero-span strength did not suffer substantial losses, indicating decreased fiber-fiber bonding. Tensile strength properties were also determined of a bisphenol-A-epichlorohydrin-based epoxy resin mixed with 5% fiber as a test for fiber-matrix compatibility in composite applications. Based on these preliminary results, high-temperature TMP shows potential for composite reinforcement due to its lower tendency to aggregate and its better compatibility with the tested matrix material.

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49

Bréthous, R., V. Nassiet y B. Hassoune-Rhabbour. "Models of Adhesive Bonding of Hybrid Structures". Key Engineering Materials 550 (abril de 2013): 143–55. http://dx.doi.org/10.4028/www.scientific.net/kem.550.143.

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Adhesives are often based on polymers materials. They are good candidates in order to manufacture adhesives joint because of their thermomechanical properties and their processing which is easier than other materials. Epoxy resins are widely used as adhesives joint. We can meet them in various industrial areas like car, spatial and aerospace domains. Because of numerous combinations between epoxy and amine chemical functions, these joints may be efficient at high or at low temperature. Indeed, close to their glassy transition temperature (Tg), exists an elastic modulus / ductility couple for which, shear stress is optimum: the Optimum Stress Zone (OSZ)[ which is restricted on limited temperatures range. Our study consists in formulating an epoxy amine joint able to be efficient on an extended temperatures rangei.e.a joint able to ensure a stress continuity over a large range of temperatures, for example-50°C to 100°C. To reach this objective, we propose an evolution of the Multi Adhesive Joints (MAJ): an adhesive joint presenting a gradient of mechanical properties. To make this adhesive joint formulation possible, its necessary to control kinetics diffusion at the adhesive scale (200μm to 500μm) between the low temperature adhesive (LTA) and the high temperature adhesive (HTA). The diffusion study will be carried out by using a rheometer. For such adhesive thickness, the rheometer compliance may have an influence on the results. Therefore, this present work proposes to identify and to set up the key parameters, which allow following kinetics diffusion in a rheometer for dimensions similar to those of bonding assembly, by checking the measurements are performed in the linear viscoelastic domain. In a first part, the morphological, mechanical and thermomechanical properties of the nanostructured thermosets versus time are performed. And, the second part will deal with the optimization of the key parameters by performing dynamic shear tests versus time on HTA and LTA samples in sight of kinetics diffusion study.

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50

Liu, Yue E., Cheng En He, Ren Gui Peng, Wei Tang y Ying Kui Yang. "Ionic Liquid Assisted Dispersion of Reduced Graphene Oxide in Epoxy Composites with Improved Mechanical Properties". Advanced Materials Research 738 (agosto de 2013): 56–60. http://dx.doi.org/10.4028/www.scientific.net/amr.738.56.

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Graphene nanosheets were prepared by chemical reduction of the exfoliated graphite oxide using sodium borohydride (NaBH4). The graphene/epoxy composites were separately fabricated in the absence or presence of imidazolium-based ionic liquids, and their dynamic thermomechanical and tensile properties were studied. TEM examinations show that graphene sheets are well dispersed in the epoxy resin and have strong interface adhesion with the matrix due to the π-π and/or cation-π interactions between graphene and imidazolium ions. The composite fabricated by assistance of ionic liquids shows larger increases in Youngs modulus, tensile strength, storage modulus and glass transition temperature compared to the composite without using ionic liquids. This work provides a method for the fabrication of multifunctional graphene-based polymer composites.

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