Journal articles: 'Polymer ageing'

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Krauklis, Andrey E., Christian W. Karl, Iuri B. C. M. Rocha, Juris Burlakovs, Ruta Ozola-Davidane, Abedin I. Gagani, and Olesja Starkova. "Modelling of Environmental Ageing of Polymers and Polymer Composites—Modular and Multiscale Methods." Polymers 14, no. 1 (January 5, 2022): 216. http://dx.doi.org/10.3390/polym14010216.

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Service lifetimes of polymers and polymer composites are impacted by environmental ageing. The validation of new composites and their environmental durability involves costly testing programs, thus calling for more affordable and safe alternatives, and modelling is seen as such an alternative. The state-of-the-art models are systematized in this work. The review offers a comprehensive overview of the modular and multiscale modelling approaches. These approaches provide means to predict the environmental ageing and degradation of polymers and polymer composites. Furthermore, the systematization of methods and models presented herein leads to a deeper and reliable understanding of the physical and chemical principles of environmental ageing. As a result, it provides better confidence in the modelling methods for predicting the environmental durability of polymeric materials and fibre-reinforced composites.

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Bors, Adriana-Mariana, Marius-Eduard Lungulescu, Nicoleta Oana Nicula (Butoi), Alina-Ruxandra Caramitu, and Iosif Lingvay. "Ageing of Some Lacquers Due to Microbiological Stress." Materiale Plastice 56, no. 2 (June 30, 2019): 330–36. http://dx.doi.org/10.37358/mp.19.2.5181.

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This paper shows the ageing study of some coatings and / or impregnation lacquers due to microbiological stress through fungal attack. Dielectric spectroscopy has shown that the dielectric losses of the investigated materials increase as result of microbiological ageing. The mean recorded increases are about 4 times for the alkyl-epoxy-melamine copolymer, 2 times for epoxy polymer and 1.5 times for urethane polymer in agreement with the mould coverage degree of about 20 %, 10 %, and 3 %, respectively. The fungal attack of the investigated polymers led to a decrease in volume resistivity of about 65 % for the alkyl-epoxy-melamine copolymer, 45 % for the epoxy polymer, and 14 % for polyurethane, in agreement with the increase of dielectric losses and degree of mold coverage of the samples. FTIR determinations have shown that fungal attack significantly increased the number of aliphatic -OH and C-H bonds and decreased the number of C-O bonds, respectively of C-O-C oxiran groups and C-C aromatic bonds. DSC thermograms recorded at different temperature ranges and the activation energies calculation for first major oxidation process indicate that after the fungal attack the thermooxidative reactivity of the investigated polymers increases.

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Lamnii, Hamza, Moussa Nait-Abdelaziz, Georges Ayoub, Jean-Michel Gloaguen, Ulrich Maschke, and Bilal Mansoor. "Effect of UV Ageing on the fatigue life of bulk polyethylene." MATEC Web of Conferences 165 (2018): 08002. http://dx.doi.org/10.1051/matecconf/201816508002.

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Polymers operating in various weathering conditions must be assessed for lifetime performance. Particularly, ultraviolet (UV) radiations alters the chemical structure and therefore affect the mechanical and fatigue properties. The UV irradiation alters the polymer chemical structure, which results into a degradation of the mechanical and fatigue behavior of the polymer. The polymer properties degradation due to UV irradiation is the result of a competitive process of chain scission versus post-crosslinking. Although few studied investigated the effect of UV irradiation on the mechanical behaviour of thermoplastics, fewer examined the UV irradiation effect on the fatigue life of polymers. This study focuses on investigating the effect of UV irradiation on the fatigue properties of bulk semi-crystalline polymer; the low density Polyethylene (LDPE). Tensile specimens were exposed to different dose values of UV irradiation then subjected to fatigue loading. The fatigue tests were achieved under constant stress amplitude at a frequency of 1Hz. The results show an important decrease of the fatigue limit with increasing absorbed UV irradiation dose.

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Glaskova-Kuzmina, Tatjana, Olesja Starkova, Sergejs Gaidukovs, Oskars Platnieks, and Gerda Gaidukova. "Durability of Biodegradable Polymer Nanocomposites." Polymers 13, no. 19 (September 30, 2021): 3375. http://dx.doi.org/10.3390/polym13193375.

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Biodegradable polymers (BP) are often regarded as the materials of the future, which address the rising environmental concerns. The advancement of biorefineries and sustainable technologies has yielded various BP with excellent properties comparable to commodity plastics. Water resistance, high dimensional stability, processability and excellent physicochemical properties limit the reviewed materials to biodegradable polyesters and modified compositions of starch and cellulose, both known for their abundance and relatively low price. The addition of different nanofillers and preparation of polymer nanocomposites can effectively improve BP with controlled functional properties and change the rate of degradation. The lack of data on the durability of biodegradable polymer nanocomposites (BPN) has been the motivation for the current review that summarizes recent literature data on environmental ageing of BPN and the role of nanofillers, their basic engineering properties and potential applications. Various durability tests discussed thermal ageing, photo-oxidative ageing, water absorption, hygrothermal ageing and creep testing. It was discussed that incorporating nanofillers into BP could attenuate the loss of mechanical properties and improve durability. Although, in the case of poor dispersion, the addition of the nanofillers can lead to even faster degradation, depending on the structural integrity and the state of interfacial adhesion. Selected models that describe the durability performance of BPN were considered in the review. These can be applied as a practical tool to design BPN with tailored property degradationand durability.

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Starkova, Olesja, Abedin I. Gagani, Christian W. Karl, Iuri B. C. M. Rocha, Juris Burlakovs, and Andrey E. Krauklis. "Modelling of Environmental Ageing of Polymers and Polymer Composites—Durability Prediction Methods." Polymers 14, no. 5 (February 24, 2022): 907. http://dx.doi.org/10.3390/polym14050907.

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Polymers and polymer composites are negatively impacted by environmental ageing, reducing their service lifetimes. The uncertainty of the material interaction with the environment compromises their superior strength and stiffness. Validation of new composite materials and structures often involves lengthy and expensive testing programs. Therefore, modelling is an affordable alternative that can partly replace extensive testing and thus reduce validation costs. Durability prediction models are often subject to conflicting requirements of versatility and minimum experimental efforts required for their validation. Based on physical observations of composite macroproperties, engineering and phenomenological models provide manageable representations of complex mechanistic models. This review offers a systematised overview of the state-of-the-art models and accelerated testing methodologies for predicting the long-term mechanical performance of polymers and polymer composites. Accelerated testing methods for predicting static, creep, and fatig ue lifetime of various polymers and polymer composites under environmental factors’ single or coupled influence are overviewed. Service lifetimes are predicted by means of degradation rate models, superposition principles, and parametrisation techniques. This review is a continuation of the authors’ work on modelling environmental ageing of polymer composites: the first part of the review covered multiscale and modular modelling methods of environmental degradation. The present work is focused on modelling engineering mechanical properties.

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Akinyemi, Banjo A., and Temidayo E. Omoniyi. "Effect of experimental wet and dry cycles on bamboo fibre reinforced acrylic polymer modified cement composites." Journal of the Mechanical Behavior of Materials 29, no. 1 (September 22, 2020): 86–93. http://dx.doi.org/10.1515/jmbm-2020-0009.

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AbstractThis study experimentally evaluated the effect of accelerated wet/dry cycles on the dimensional stability and some selected mechanical properties of polymer modified vegetable fibre cement composites. The bamboo fibres were pre-treated with 10% conc. of sodium hydroxide and varied from 0 – 2.0% while acrylic polymer admixture of 10% w/w of cement was added to improve the properties. The modified fibre-cement composites were subjected to 50 cycles of wet/dry processes to simulate natural weathering process of the environment. The samples were subjected to water absorption, thickness swelling, modulus of rupture (MOR) and modulus of elasticity (MOE) after 28 days of curing and aging cycles respectively using 5 replicates. One way ANOVA at p<0.05 was used to analyse the results. Scanning electron microscope (SEM) and Fourier Transformer Infrared Spectroscopy (FTIR) analyses were conducted on the samples. The results showed improvement of 33.3, 64, 71 and 57% in MOR and 135, 85, 101 and 188% in MOE for samples with 0.5, 1, 1.5 and 2% fibre inclusion after ageing tests. Significantly improved dimensional stability values were observed in this study in comparison with data from similar ageing tests conducted on unmodified vegetable fibre-cement matrix. SEM micrographs showed marginal increase in the size of the pores before and after ageing tests. FTIR analysis indicated increase in intensities during the ageing tests especially for spectra bands located at 3384 – 3520cm−1 which are denoted for OH vibration stretching as well as 1676, 1726 and 1794 cm−1 which depict the presence of carbonyl groups because of absorption of polymers to the fibre surface during the ageing cycles. The study has shown thatwet/dry ageing cycles showed less harmful effect on vegetable fibre cement composites provided the cement matrix is modified with polymer admixtures.

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Lear, G., S. D. M. Maday, V. Gambarini, G. Northcott, R. Abbel, J. M. Kingsbury, L. Weaver, J. A. Wallbank, and O. Pantos. "Microbial abilities to degrade global environmental plastic polymer waste are overstated." Environmental Research Letters 17, no. 4 (March 15, 2022): 043002. http://dx.doi.org/10.1088/1748-9326/ac59a7.

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Abstract Internationally, the environmental damage caused by the improper disposal of approximately 100 Mt of plastic waste per annum is of growing concern. Attempts to address this issue have generated many hundreds of scientific studies announcing the discovery of novel plastic-degrading microorganisms and their respective enzymes. On closer inspection, however, evidence remains sparse for the microbial degradation of most of the plastic polymers produced globally. We systematically surveyed the international literature to confirm how many microorganisms proposed to degrade plastics (n = 664) cause substantial (i.e. ⩾20% mass) losses of virgin polymer, rather than losses of plastic additives, filler, and/or shedding of polymer micro-fragments. We noted where degradation was only demonstrated for artificially aged polymer since physicochemical ageing procedures increase the abundance of monomers and oligomers such that they may be degraded by microbial activity. Additionally, artificial ageing may introduce functional groups to the polymer backbone, creating more locations susceptible to microbial degradation than would otherwise occur in the environment. We identified multiple studies demonstrating the effective microbial degradation of heterochain plastic polymers such as polylactic acid, polycaprolactone and polyethylene terephthalate (i.e. polymers containing elements other than carbon in the backbone structure). However, in the literature, we find no evidence for the substantial degradation of unadulterated polyethylene, polypropylene, polystyrene or polyvinyl chloride, homochain polymers which represent the overwhelming majority of global plastics production. Current research demonstrates that the pre-treatment of plastics with elevated temperature or UV-light may speed physicochemical plastic degradation, with valuable applications for downstream microbial processing. However, evidence for the microbial degradation of most plastic polymers in current circulation is lacking. We outline simple criteria that should be met before announcing the microbial degradation of plastic polymers. We hope this may help to address largely unsubstantiated expectations that microorganisms can degrade many plastic polymers in situ.

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Hall, Finn, and Greg White. "The Effect of Waste Plastics on the Ageing Phenomenon of Bituminous Binders and Asphalt Mixtures." Materials 14, no. 20 (October 18, 2021): 6176. http://dx.doi.org/10.3390/ma14206176.

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The push for environmental sustainability in the civil engineering industry has resulted in an increased interest in the use of recycled construction materials, with one example being the use of waste plastic for the modification of bituminous binder in asphalt mixtures. Existing research has associated waste plastics with various binder and asphalt mixture performance enhancing properties. However, there is a lack of research on the age-related durability of waste plastic-modified roads. This research compared the effect of commercially available waste plastic binder modifiers on the ageing phenomenon of bituminous binders and asphalt mixtures, to the effect of conventional polymers SBS and EVA, through artificial bituminous binder and asphalt mixture ageing performed in a laboratory. The addition of polymers (both waste and virgin) resulted in an increase in binder stiffness after short-term ageing as the polymer content increased. The effect of the waste plastic on ageing was comparable to the effects associated with the conventional polymers, and it was concluded that the waste plastic binder modified products should be considered sustainable alternatives to standard polymers for bituminous binder and asphalt mixture modification.

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Nakonieczny, Damian S., Magdalena Antonowicz, Gražyna SimhaMartynkova, Frank Kern, Lenka Pazourková, Karol Erfurt, and Michał Hüpsch. "PA-12-Zirconia-Alumina-Cenospheres 3D Printed Composites: Accelerated Ageing and Role of the Sterilisation Process for Physicochemical Properties." Polymers 14, no. 15 (August 2, 2022): 3152. http://dx.doi.org/10.3390/polym14153152.

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The aim of this study was to conduct artificial ageing tests on polymer-ceramic composites prepared from polyamide PA-12 polymer matrix for medical applications and three different variants of ceramic fillers: zirconia, alumina and cenospheres. Before ageing, the samples were subjected to ethyl oxide sterilization. The composite variants were prepared for 3D printing using the fused deposition modeling method. The control group consisted of unsterilized samples. Samples were subjected to artificial ageing in a high-pressure autoclave. Ageing conditions were calculated from the modified Hammerlich Arrhenius kinetic equation. Ageing was carried out in artificial saliva. After ageing the composites were subjected to mechanical (tensile strength, hardness, surface roughness) testing, chemical and structural (MS, FTIR) analysis, electron microscopy observations (SEM/EDS) and absorbability measurements.

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Młyniec, A., and T. Uhl. "Modelling and testing of ageing of short fibre reinforced polymer composites." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 1 (September 19, 2011): 16–31. http://dx.doi.org/10.1177/0954406211411552.

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A study in accelerated humidity–temperature ageing and it is numerical modelling for short fibre reinforced polymer composites (SFRPC) based on poly(butylene terephthalate) (PBT) is reported. Authors described experimental results of humidity–temperature ageing of PBT reinforced with glass fibres and proposed a novel computation method of strength and durability analysis for SFRPC parts. Experimental results showed different ageing behaviours, which depend on fibre alignment, e.g. a decrease of Young’s modulus in longitudinal fibre alignment in tension after ageing, an increase of Young’s modulus in transverse direction in tension after ageing, and the increase of the shear modulus and decrease of shear strength after ageing in both directions. Proposed modelling procedure takes the fibre orientation from mould filling analysis as an independent material orientation, using a developed ageing dependent material model, based on tensile, compressive, and shear properties for longitudinal and transverse fibre alignments, and calculates failure criteria as a function of the ageing time and fibre alignment. An innovative approach is to create a fibre alignment dependent material ageing model which takes into account changes of material properties depending on the direction of the reinforcement. This methodology was extended to arbitrary models and validated on real parts made of SFRPC.

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López-Montero, T., and R. Miró. "Ageing and temperature effect on the fatigue performance of bituminous mixtures." Materiales de Construcción 7, no. 080 (June 27, 2017): 126. http://dx.doi.org/10.3989/mc.2017.04216.

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The ageing of asphalt mixes, together with their exposure to low temperatures, causes a progressive increase of cracking. In this paper, the effect of ageing and temperature on the fatigue of asphalt concretes made with two types of binders, conventional (50/70) and polymer modified bitumen (PMB), is studied. For this purpose, specimens previously subjected to an accelerated laboratory ageing process were tested by a strain sweep test at different temperatures (-5ºC, 5ºC and 20°C). Results were compared with the obtained from the unaged specimens showing the relative importance of ageing, temperature and type of bitumen on the parameters that determine the fatigue life of the mixture. The mixtures behaviour becomes more brittle with ageing and the decrease of temperature. However, ageing hardly has an effect on fatigue at lower temperatures. In general, mixtures made with polymer modified bitumen have a better fatigue performance to ageing and temperature.

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SZUMNIAK, Jerzy, Zbigniew SMOCZYŃSKI, and Krzysztof SZCZEŚNIAK. "ARMAMENT AND MILITARY EQUIPMENT POLYMER COMPOSITE AGEING." Scientific Journal of the Military University of Land Forces 159, no. 1 (January 3, 2011): 271–85. http://dx.doi.org/10.5604/01.3001.0002.2934.

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In the process of planning military operations, it is necessary to know technical and combat readiness of vehicles. Knowledge of the pass mode potential of individual vehicles is very important while organizing transport operations. So far, in a situation where the elements determining the suitability of a vehicle were made of metal, such potential has been estimated on the basis of the difference between the service life of a vehicle and meter readings. The following study demonstrates the inappropriateness of such an approach in relation to elements made of polymers. A simplified way of assessing loss of the pass mode potential (based on measurements of the labor symptoms) has been presented based on an example of a rubber and metal joint of a caterpillar. It was found that during 8 years the storage of these elements, their utility potential loss is up to 40% of the initial potential.

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Celauro, Clara, Rosalia Teresi, and Nadka Tz Dintcheva. "Effect of Short-Term and UV Irradiation Aging on the Behaviour of SBS-Modified Bitumen." Sustainability 14, no. 11 (June 6, 2022): 6915. http://dx.doi.org/10.3390/su14116915.

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To obtain road bitumen with improved temperature and fatigue resistance, polymers and/or rubbers could be added to it. A particularly suitable polymer for bitumen modification is styrene-butadiene-styrene (SBS) copolymer but limited information is available about the ageing behaviour of modified binders. In this work, two neat bitumens, with different penetration grades, and two SBS-modified bitumens, containing different SBS amounts, were selected, and their short-term and UVB ageing behaviour were investigated considering dynamic shear rheometry and Attenuated Total Reflectance-Fourier Transformation InfraRed spectroscopy (ATR-FTIR). Short-time ageing behaviour was investigated performing the rolling thin film oven test (RTFOT), while artificial UV ageing was examined/investigated using UVB lamps. The structural changes in bitumen were monitored at different UV exposure times. All the results suggest that the bitumen having higher penetration grade is more stable than the one with a lower penetration grade in the RTFOT ageing condition, and SBS addition exerts a beneficial effect on thermal stability during processing. Further, SBS addition also has a beneficial effect on the UV ageing resistance of bitumen, reducing its oxidation tendency.

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Barcellona, Simone, Morris Brenna, Federica Foiadelli, Michela Longo, and Luigi Piegari. "Analysis of Ageing Effect on Li-Polymer Batteries." Scientific World Journal 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/979321.

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Lithium-ion batteries are a key technology for current and future energy storage in mobile and stationary application. In particular, they play an important role in the electrification of mobility and therefore the battery lifetime prediction is a fundamental aspect for successful market introduction. Numerous studies developed ageing models capable of predicting battery life span. Most of the previous works compared the effect of the ageing factors to a battery’s cycle life. These cycles are identical, which is not the case for electric vehicles applications. Indeed, most of the available information is based on results from laboratory testing, under very controlled environments, and using ageing protocols, which may not correctly reflect the actual utilization. For this reason, it is important to link the effect of duty cycles with the ageing of the batteries. This paper proposes a simple method to investigate the effect of the duty cycle on the batteries lifetime through tests performed on different cells for different kinds of cycle. In this way, a generic complex cycle can be seen as a composition of elemental cycles by means of Rainflow procedures. Consequently, the ageing due to any cycle can be estimated starting from the knowledge of simpler cycles.

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Zhao, Rong Guo, Wen Bo Luo, Qi Fu Li, and Chao Zhong Chen. "Application of Time-Ageing Time and Time-Temperature-Stress Equivalence to Nonlinear Creep of Polymeric Materials." Materials Science Forum 575-578 (April 2008): 1151–56. http://dx.doi.org/10.4028/www.scientific.net/msf.575-578.1151.

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Based on the observations that high temperature accelerates creep rate of polymer while physical ageing plays a reverse role, and that there is an analogy between the influences of stress and temperature on the intrinsic times of polymers, the time-ageing time superposition principle (TASP) and the time-temperature-stress superposition principle (TTSSP) are used to evaluate the long-term creep behavior of poly(methyl methacrylate) (PMMA). PMMA specimens were aged for 2 to 120 hours at identical temperature, their short-term creep strains with 2-hour test duration were measured under various stress levels ranging from 14 to 30 MPa at room temperature, and modeled by means of time-ageing time equivalence and time-stress equivalence. The results show that the creep rate increases with stress, but decreases with ageing time. The ageing time shift factors vary with the stresses at which the shifts are applied. The ageing shift rate is independent on imposed stress in linear viscoelastic region, while it decreases with increasing stress when the material behaves in a nonlinear viscoelastic manner. The master creep compliance curve up to about 1-month at reference ageing time 120 hours and stress 18 MPa, which is nearly 2.5 decades longer than the test duration, is constructed by shifting the creep curves horizontally along the logarithmic time axis. The result illustrates that TTSSP, combined with TASP, provides an effective accelerated test technique for long-term mechanical behaviors of polymers.

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Zheng, Chuanfeng, Genze Li, Yazhi Xu, Danni Wang, and Dan Lv. "Analysis of the Effects of Ageing on the Cohesive Strength of Polymer-Modified Bitumen at Low Temperatures." Baltic Journal of Road and Bridge Engineering 13, no. 2 (June 25, 2018): 156–64. http://dx.doi.org/10.7250/bjrbe.2018-13.410.

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The decay law on the ageing process of the cohesive strength of styrene-butadiene-styrene(SBS)- and polyethylene(PE)-modified bitumens at low temperatures was investigated. The rotated-thin-film oven test was used to age the two types of polymer-modified bitumens. The cohesive strengths at different low-temperature conditions were tested quantitatively according to technology for testing the low-temperature cohesive strength of bitumen. The decay curve of bitumen low-temperature cohesive strengths was drawn, and the embrittlement time of bitumen at different ageing states was obtained according to the decay curve. Results showed that ageing time definitely influenced the attenuation degree of the low-temperature cohesive strength of the two types of polymer-modified bitumens and influenced the appearance of the low-temperature cohesive strength peak, i.e., the bitumen embrittlement time, which advanced after ageing. The lightweight components of polymer-modified bitumen were lost after ageing. The bitumen embrittlement time was advanced, and the sharp attenuation of the low-temperature cohesive strength of bitumen appeared. In the future, bitumen antiageing technology and lighter part pre-supplement technology should be studied in-depth.

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Oulidi, Oumayma, Asmae Nakkabi, Mohammed Fahim, and Noureddine Elmoualij. "Natural hydrolytic ageing of PA6 and bio-reinforced composites." MATEC Web of Conferences 360 (2022): 00008. http://dx.doi.org/10.1051/matecconf/202236000008.

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Hydrolytic ageing or hydrolysis is the destruction of chemical bonds by the action of water. Among the polymers most affected by hydrolysis are the polyamides, since PA6 is hygroscopic, due to the amide groups. PA6 with its interesting technical applications could be found in humid environments, which probably impedes its durability. The estimation of the modifications that PA6 could undergo has attracted the attention of several research subjects, which have recorded a deterioration of the mechanical and thermal properties. The objective of this study is to compare the hydrolytic ageing of PA6 with its composites reinforced with peanut shell powder (PSP), olive pomace powder (OPP), and plaster (PL). The aim is to evaluate the impact of the reinforcements on the ageing of the composite. The weight changes, the structural properties, and the morphology were monitored and related to the modification of the polymer encountered during the ageing process thanks to the weight gain, DRX and SEM methods.

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Chen, Jean Hong, Jian Yi Li, Lung Chuan Chen, and Ching Iuan Su. "Morphology and Microstructure of Aggregates and Gelation Behaviour of Poly(3-hexylthiophene) in Xylene Solution." Applied Mechanics and Materials 479-480 (December 2013): 115–20. http://dx.doi.org/10.4028/www.scientific.net/amm.479-480.115.

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In this work, we investigate the morphology and microstructure of the aggregates, and the gelation behaviour of Poly(3-hexylthiophene) (P3HT) conjugated polymer in xylene solution as functions of P3HT concentration and aging time by the means of ageing time test, wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), UV-visible absorption (UV-vis) and photoluminescence (PL) spectra. The result reveals that the gelation time of P3HT/xylene solution decreases markedly with increasing P3HT concentration. The photophysical properties of the P3HT aggregates in P3HT/xylene solution increase as P3HT concentration and ageing time are raised. It indicates that the well soluble P3HT polymer chains in xylene solution present microphase separation and self-assemble into stiff sheetlike structure, which associates by rodlike nanowhiskers of P3HT polymers during aging. Upon prolonged aging, the sheetlike structure of P3HT aggregates to from the three-dimension network that improves the electronic particle mobility in the organic solar cell.

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Verney, Vincent, Audrey Ramoné, Florence Delor-Jestin, Sophie Commereuc, Marek Koutny, Geoffrey Perchet, and Julien Troquet. "Melt Viscoelastic Assessment of Poly(Lactic Acid) Composting: Influence of UV Ageing." Molecules 23, no. 10 (October 18, 2018): 2682. http://dx.doi.org/10.3390/molecules23102682.

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This study is devoted to the degradation pathway (bio, photo degradation and photo/bio) of Poly(Lactic acid) PLA polymers by means of melt viscoelasticity. A comparison was made between three PLA polymers with different microstructures (L, D stereoisomers). Biodegradability was determined during composting by burying the polymer films in compost at 58 °C. Melt viscoelasticity was used to assess the molecular evolution of the materials during the composting process. Viscoelastic data were plotted in the complex plane. We used this methodology to check the kinetics of the molecular weight decrease during the initial stages of the degradation, through the evolution of Newtonian viscosity. After a few days in compost, the Newtonian viscosity decreased sharply, meaning that macromolecular chain scissions began at the beginning of the experiments. However, a double molar mass distribution was also observed on Cole–Cole plots, indicating that there is also a chain recombination mechanism competing with the chain scission mechanism. PLA hydrolysis was observed by infra-red spectroscopy, where acid characteristic peaks appeared and became more intense during experiments, confirming hydrolytic activity during the first step of biodegradation. During UV ageing, polymer materials undergo a deep molecular evolution. After photo-degradation, lower viscosities were measured during biodegradation, but no significant differences in composting were found.

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Gupta, V., S. Roy, and L. R. Dharani. "Multi-Scale Modelling of Long-Term Mechanical Behaviour in Polymer Composite Laminates with Woven Fibre Architecture." Polymers and Polymer Composites 9, no. 5 (July 2001): 297–317. http://dx.doi.org/10.1177/096739110100900501.

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A comprehensive analytical model for predicting the long-term durability of polymers and polymer matrix composites should in general take into account polymer viscoelastic/viscoplastic creep, hygrothermal effects, and the effects of physical and chemical ageing on material response. These effects, in turn are influenced by a multitude of factors such as polymer morphology, service temperature, ambient relative humidity, internal moisture concentrations, stacking sequence, fibre volume fraction, fibre architecture, applied stress level, degree of damage and ageing time. The primary objective of this paper is to present a multi-scale modelling methodology to simulate the long-term interlaminar properties in polymer matrix woven composites and then predict the critical regions where failure is most likely to occur. A micro-mechanics approach towards modelling the out-of-plane viscoelastic behaviour of a five-harness satin woven-fibre cross-ply composite laminate is presented, taking into consideration the weave architecture and time-dependent effects. In-plane properties are assumed to be dominated by the carbon fibres and are hence deemed elastic. The classical lamination theory model proposed by Raju and Wang is adapted to include the in-plane elastic behaviour of woven fibre composites. For the matrixdominated out-of-plane response, a viscoelastic creep model is employed to model the resin, based on Schapery's nonlinear viscoelastic constitutive law. In addition, physical ageing of the matrix has been included in the model, using the effective time theory proposed by Struik. Furthermore, the effect of large deflections and rotations on the time dependent out-of-plane behaviour is also investigated using the micro-mechanics model. The homogenized in-plane and out-of-plane compliance obtained using the proposed micro-mechanics methodology could be applied within the framework of a structural finite element code to model the macro-scale long-term behaviour of a woven fabric composite structure.

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Cooke, William, Rachel Anne Tomlinson, Richard Burguete, Daniel Johns, and Gaëlle Vanard. "Anisotropy, homogeneity and ageing in an SLS polymer." Rapid Prototyping Journal 17, no. 4 (June 14, 2011): 269–79. http://dx.doi.org/10.1108/13552541111138397.

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Zakrevskii, V. A., V. A. Pakhotin, and N. T. Sudar. "Ageing and breakdown of thin insulating polymer films." Journal of Applied Physics 115, no. 23 (June 21, 2014): 234101. http://dx.doi.org/10.1063/1.4883365.

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Buijs, J. A. H. M., and G. J. Vroege. "Physical ageing in a thermotropic liquid-crystalline polymer." Polymer 34, no. 22 (January 1993): 4692–96. http://dx.doi.org/10.1016/0032-3861(93)90703-d.

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Boussès, Y., N. Brulat-Bouchard, and Y. Tillier. "Effects of ageing on glass-polymer dental composites." Computer Methods in Biomechanics and Biomedical Engineering 23, sup1 (October 19, 2020): S47—S48. http://dx.doi.org/10.1080/10255842.2020.1822044.

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Rek, Vesna, Nina Vranjeś, and Zrinka M. Barjaktaroví. "Evaluation Of Ageing Properties Of Polymer Modified Bitumen." Materials Research Innovations 9, no. 4 (December 2005): 113. http://dx.doi.org/10.1080/14328917.2005.11784917.

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Bychkov, Peter N., and Olga V. Solodovnikova. "Influence of the Radiation Destruction of Polymeric Insulation on its Ageing in the Impulse Electric Field." Advanced Materials Research 880 (January 2014): 88–92. http://dx.doi.org/10.4028/www.scientific.net/amr.880.88.

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Sensitivity of the destructive doses of ionizing radiations, specifically radiolysis gaseous products to multipulse electric intensity of low-density polyethylene (LDPE) and a polymethyl-methacrylate (PMMA) was investigated. LDPE and PMMA were found to differ significantly depending on radiation resistance and gas permeability. The service life of the materials was basically determined by the intensity of the destruction processes at the molecular level, the macrodefects were developed at the last ageing stage . It was shown that microseconds impulses did not cause accumulation of volume charge in LDPE and PMMA. It was concluded that the ageing of polymer dielectrics affected by electric microseconds impulses did not relate to volume charge accumulation in the polymers.

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Ercegović Ražić, Sanja, Anja Ludaš, Tea Kaurin, and Tin Zonjić. "Applicability of polymers printed on textiles with a 3D printer for possible use in car interior." IOP Conference Series: Earth and Environmental Science 1128, no. 1 (January 1, 2023): 012027. http://dx.doi.org/10.1088/1755-1315/1128/1/012027.

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Abstract In the paper, different types of polymers (rPLA, PETG, TPU) printed with a 3D printer are tested on textile material used for car interiors. The primary goal is to examine the possibility of 3D printing on textiles for the automotive industry, its adhesive and other mechanical properties. A further goal is to explore possibilities for new ways of designing and aesthetic efficiency of materials used in vehicles as well as potential ergonomically positive effects. The adhesion properties of the polymer-textile material, the strength printed on the surface using the tape method, the wear resistance of the polymer printed on the textile and the ageing of the polymer under simulated conditions are tested. The results are used to select a suitable polymer for the 3D printer and print it on the selected textile material for automotive industry.

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Senchurov, S. P., and Yu F. Zabashta. "The Formation and Destruction of the Boundary Layer in Polymer Composite Fiber Shells during Their Ageing." Materials Science Forum 482 (April 2005): 295–98. http://dx.doi.org/10.4028/www.scientific.net/msf.482.295.

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This paper considers the composite "core-shell" fibers ageing. A physical model of ageing is proposed. The stress state due to the structural relaxation processes in the shell results from the ageing. The ageing model was verified experimentally. The agreement between the model and experiment is found. A weak periodical boundary layer between the core and the shell is formed as a result of the composite fiber ageing process. The values characterizing the boundary layer (thickness and shear modulus) were obtained.

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Zaikov, G. E. "The Combustion, Ageing, and Stabilisation of Polymers, Polymer Blends, and Composites. General Considerations." International Polymer Science and Technology 38, no. 9 (September 2011): 51–53. http://dx.doi.org/10.1177/0307174x1103800912.

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Rondinella, Alfredo, Francesco Andreatta, Daniele Turrin, and Lorenzo Fedrizzi. "Degradation Mechanisms Occurring in PTFE-Based Coatings Employed in Food-Processing Applications." Coatings 11, no. 11 (November 20, 2021): 1419. http://dx.doi.org/10.3390/coatings11111419.

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The application of polytetrafluoroethylene (PTFE) coatings to metal surfaces is a well-known procedure carried out to avoid fouling phenomena on food-processing surfaces. Fluorine-based polymers are generally chemically and thermally stable, thus allowing them to be the preferred choice when designing anti-stick coatings in the food service industry. Their lifespan, however, depends on the environmental conditions. It is well known that thermal ageing can affect the properties of PTFE polymers and reduce their mechanical, thermal, and chemical properties causing failures and contaminating food. The main goal of the study is to identify the different failure mechanisms occurring in PTFE-based coatings, using both SEM/EDXS and ATR FT-IR data to reveal the starting point of degradation phenomena in food processing applications. The results from this research reveal that the preferential points for failures are mainly the polymer/substrate interfaces, the polymer/filler interfaces, or the polymer matrix itself.

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Maléchaux, Astrid, Juliette Colombani, Sandrine Amat, Sylvain R. A. Marque, and Nathalie Dupuy. "Influence of Gamma Irradiation on Electric Cables Models: Study of Additive Effects by Mid-Infrared Spectroscopy." Polymers 13, no. 9 (April 30, 2021): 1451. http://dx.doi.org/10.3390/polym13091451.

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Cables, especially their insulation and jacket materials made of polymers, are vulnerable to ageing degradation during normal operation. However, they must remain functional for the entire life of a nuclear power plant, or even in the event of an accident for cables with a safety requirement. This study focuses on models of crosslinked polyethylene (XLPE)-based insulation of cables and deals with the structure modification and the behavior of XLPE for nuclear applications due to the effect of additives. Various additives are added to the polymer formulation to evaluate their impact on ageing. The samples are irradiated at room temperature by several gamma doses, up to 374 kGy, with two dose rates (40 Gy/h and 300 Gy/h) and compared with a non-irradiated sample used as reference. To understand the impact of gamma irradiation on the materials, the principal component analysis (PCA) method is applied on spectra recorded through attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy. The results highlight the effects of ageing depending on the dose rate and on the formulation of the materials, with the identification of different degradation products. A curve resolution study compares the effects of different additives on polymer oxidation and shows that the low dose rate leads to a higher degradation than the high dose rate.

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Niedzielska, Ewelina, and Anna Masek. "Polymer materials with controlled degradation time." E3S Web of Conferences 44 (2018): 00122. http://dx.doi.org/10.1051/e3sconf/20184400122.

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The aim of this work was carry out accelarated process of ageing for cyclic olefin copolymer ethylene – norbornene (Topas). The Topas cyclic olefin copolymer (COC) family characterize high transparency, excellent mechanical properties and low water permeability. The influence of external factors such as UV radiation, elevated temperature, oxygen effect and humidity causing degradation of polymer macroparticles was also investigated. The properties of the polymer before and after weathering and UV radiation were also compared. Degradability was examinated by measuring color change, FTIR spectrum analysis and determination of the ageing factor k. The tensile strength, elongation at break and hardness of composites by Shore A method were measured. The synergistic effect of temperature, humidity and UV radiation reduces the mechanical properties of the samples tested, while the interaction of only UV radiation on the samples causes a significant change color.

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Wojcieszak, Damian, Agata Poniedziałek, Michał Mazur, Jarosław Domaradzki, Danuta Kaczmarek, and Jerzy Dora. "Influence of plasma treatment on wettability and scratch resistance of Ag-coated polymer substrates." Materials Science-Poland 34, no. 2 (June 1, 2016): 418–26. http://dx.doi.org/10.1515/msp-2016-0058.

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AbstractRapid progress in thin-film coatings based on metals, which can be deposited on polymers, has been recently observed. In this work discussion on the properties of modified polymers and silver thin films deposited on polytetrafluoroethylene (PTFE) and polycarbonate (PC) substrates has been presented. Surface of these polymer substrates were exposed to argon plasma discharge. Additionally, silver thin films were deposited on their surface by electron beam evaporation method. The surfaces of the modified polymers were studied by different methods, i.e. topography, wettability and scratch resistance measurements were performed. The ageing effect of treated substrates was also discussed. It was shown that plasma modification of PTFE and PC substrates increased wettability of their surfaces. The value of water contact angle decreased of about 40 % and 25 % for PTFE and PC surface, respectively. The change of hydrophobic to hydrophilic properties was observed. Plasma modification of substrates improved adhesion between silver coating and polymer substrates. However, it did not influence wettability of Ag coating.

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Kandola, Baljinder K., S. Ilker Mistik, Wiwat Pornwannachai, and A. Richard Horrocks. "Effects of Water and Chemical Solutions Ageing on the Physical, Mechanical, Thermal and Flammability Properties of Natural Fibre-Reinforced Thermoplastic Composites." Molecules 26, no. 15 (July 29, 2021): 4581. http://dx.doi.org/10.3390/molecules26154581.

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Biocomposites comprising a combination of natural fibres and bio-based polymers are good alternatives to those produced from synthetic components in terms of sustainability and environmental issues. However, it is well known that water or aqueous chemical solutions affect natural polymers/fibres more than the respective synthetic components. In this study the effects of water, salt water, acidic and alkali solutions ageing on water uptake, mechanical properties and flammability of natural fibre-reinforced polypropylene (PP) and poly(lactic acid) (PLA) composites were compared. Jute, sisal and wool fibre- reinforced PP and PLA composites were prepared using a novel, patented nonwoven technology followed by the hot press method. The prepared composites were aged in water and chemical solutions for up to 3 week periods. Water absorption, flexural properties and the thermal and flammability performances of the composites were investigated before and after ageing each process. The effect of post-ageing drying on the retention of mechanical and flammability properties has also been studied. A linear relationship between irreversible flexural modulus reduction and water adsorption/desorption was observed. The aqueous chemical solutions caused further but minor effects in terms of moisture sorption and flexural modulus changes. PLA composites were affected more than the respective PP composites, because of their hydrolytic sensitivity. From thermal analytical results, these changes in PP composites could be attributed to ageing effects on fibres, whereas in PLA composite changes related to both those of fibres present and of the polymer. Ageing however, had no adverse effect on the flammability of the composites.

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Klopffer, Marie Hélène, Philippe Berne, Mathilde Weber, Sylvie Castagnet, Gilles Hochstetter, and Eliane Espuche. "New Materials for Hydrogen Distribution Networks: Materials Development & Technico-Economic Benchmark." Defect and Diffusion Forum 323-325 (April 2012): 407–12. http://dx.doi.org/10.4028/www.scientific.net/ddf.323-325.407.

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In France, the steel transportation network for natural gas is connected to the distribution network which operates at lower pressure. This one (total length of 165 000 km) is mainly made of polymer pipes like polyethylene. With the introduction of hydrogen in mixture with natural gas and finally the transport of pure hydrogen, the key challenge is the high level of permeability that is to say the flow rate of hydrogen through polymer infrastructures (pipes or components like connecting parts). This high flow rate of hydrogen has to be taken into account for safety and economic requirements. Long-term behaviour must be carefully assessed: permeation/diffusion properties, thermo-mechanical behaviour and ageing. It is important to characterize the existing distribution network and to propose more innovative materials than polyethylene that could meet the targets for future hydrogen distribution applications. The aim of this project was to develop and assess material solutions to cope with today problems in term of high flow rate of hydrogen and ageing under a hydrogen environment. Polyethylene is considered as a reference material since it is used today in natural gas distribution pipes. Test benches and protocols for testing materials in term of mechanical and barrier properties were first developed. On the other hand, technical polymers (multi-layers, other thermoplastics, polymer blends) have been proposed and studied to improve gas-barrier performances compared to polyethylene. Step by step, permeation and basic mechanical tests have been performed and then more specific characterisations have been done (for long-term ageing under various conditions) in order to choose one or several materials that could meet the specifications required by hydrogen distribution. The design of a pipe prototype was also carried out at the end the project and an economic study was performed for the different potential solutions.

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Broudin, Morgane, and Mohamed Ben Chouikha. "Methodologies for efficient and reliable NPP polymer ageing management." EPJ Nuclear Sciences & Technologies 8 (2022): 22. http://dx.doi.org/10.1051/epjn/2022013.

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The lifetime of existing Nuclear Power Plants (NPPs) can potentially be extended to between 60 and 80 years if safety and operability of facilities can be guaranteed. This requires efforts in terms of equipment qualification and ageing management to support stakeholders and decision makers. Polymer ageing is of concern due to their widespread use in NPPs (e.g. each NPP contains approximately 1500 km of cables). Predicting their lifetime and monitoring their integrity remain a challenge. Here, we present a cross-cutting review of two on-going Horizon 2020 projects (TeaM Cables and El Peacetolero). The combination of these 2 projects allows to provide the community with non-destructive and predictive tools that can help assess the reliability and functionality of polymer-based components such as cables or pipes. The paper discusses scientific challenges faced in the beginning and achievements made throughout the projects, including the industrial impact and lessons learnt. Two specific aspects highlighted concern the way the projects sought contact with end users and the balance between industrial and academic partners. The paper concludes with an outlook on follow-up issues related to the long-term operation of NPPs.

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Heim, H. P., and A. Desjean. "Climatic Ageing of Components of Polymer Based Electrochromic Devices." International Polymer Processing 28, no. 3 (July 2013): 256–60. http://dx.doi.org/10.3139/217.2657.

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Kawana, S., and R. A. L. Jones. "Effect of physical ageing in thin glassy polymer films." European Physical Journal E 10, no. 3 (March 2003): 223–30. http://dx.doi.org/10.1140/epje/i2002-10111-4.

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Dissado, L., A. Thabet, and S. Dodd. "Simulation of DC electrical ageing in insulating polymer films." IEEE Transactions on Dielectrics and Electrical Insulation 17, no. 3 (June 2010): 890–97. http://dx.doi.org/10.1109/tdei.2010.5492263.

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White, Jim R. "Polymer ageing: physics, chemistry or engineering? Time to reflect." Comptes Rendus Chimie 9, no. 11-12 (November 2006): 1396–408. http://dx.doi.org/10.1016/j.crci.2006.07.008.

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41

Coll, H., and C. G. Searles. "Solvent permeation rates and ageing phenomena in polymer coatings." Polymer 29, no. 7 (July 1988): 1266–72. http://dx.doi.org/10.1016/0032-3861(88)90054-7.

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Dippel, Benedikt, Michael Johlitz, and Alexander Lion. "Ageing of polymer bonds: a coupled chemomechanical modelling approach." Continuum Mechanics and Thermodynamics 26, no. 3 (April 13, 2014): 247–57. http://dx.doi.org/10.1007/s00161-014-0353-x.

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Osburg, Andrea, Alexander Gypser, and Martin Ulrich. "Development of Polymer Concrete with Non-Standardised Fillers for Innovative Building Materials." Advanced Materials Research 1129 (November 2015): 484–91. http://dx.doi.org/10.4028/www.scientific.net/amr.1129.484.

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The use of polymer concrete in building construction is a relatively new application. A building block system (Modular Assembly System: MAS-System) and the mobile fabrication technology for the reversible construction of buildings with regionally available aggregates, were developed in a project of applied research. The aspects of the successful material development are described, especially with regard to the characterisation of both the binders and the polymer concretes, considering strength and durability. The polymer concrete consists approximately of 90 % fillers, 10 % polymer binder and additives. The investigation of the binder-system included the determination of gel time and temperature development, shrinkage, wetting of formwork materials and immersion tests with marine water. The aim was an adaptation and optimisation of the binder system. The characterisation of mechanical properties of the polymer concrete was realised by determining its strength in a temperature range between - 40 °C and 60 °C. Compression tests on wall segments were also realised. Ageing is an important aspect of the durability of polymer bonded materials. Special tests were used for an accelerated ageing, including impacts of temperature change, cold rain water and natural radiation.

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Wong, King Jye, Haris Ahmad Israr, and Mohd Nasir Tamin. "Characterisation of Moisture Absorption Effects on the Strength of Composite Materials." Advanced Materials Research 1125 (October 2015): 69–73. http://dx.doi.org/10.4028/www.scientific.net/amr.1125.69.

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In the present work, the variation of the tensile strengths of various polymers and polymer composites due to moisture ageing is investigated. The stacking sequences of the composites include 0o, 90o, ±45o and quasi-isotropic laminates. The variation in the strength of material is then fitted using a residual property model. Results show that the proposed model characterises well the variation in the strengths that exhibits a typical trend, where there is no obvious scattered data. In fibre dominated laminates (0o), the degradation parameter seems to be influenced by the type of material, whereas for matrix dominated laminates (90o), ageing temperature appears to be the dominant factor that affects the degradation trend. As for [±45]2S and adhesives, exponential decay trend is observed. This model could be further improved to include the material and temperature factors.

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Sawpan, Moyeen Ahmad. "Durability of Pultruded Glass Fibre Reinforced Polymer Composite Subjected to Hygrothermal Ageing in Sea Water." Applied Mechanics and Materials 884 (August 2018): 14–22. http://dx.doi.org/10.4028/www.scientific.net/amm.884.14.

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Durability of glass fibre reinforced polymer (GFRP) composite is an important research topic because the changes occur in GFRP composite with ageing can affect its properties and lifetime. For long term use, GFRP composites should be examined in real time and with reasonable in-service environments. However, this is not practical because the time involved would significantly delay product development and therefore, accelerated ageing technique is required. Conditioning in wet and elevated temperatures known as hygrothermal ageing is a very useful technique to evaluate the durability of GFRP composites in a reasonable timeframe. In this work, pultruded GFRP composites were aged in sea water and in dry conditions at 23, 55 and 75°C for 0, 8 and 20 months to assess the changes in shear properties (e.g. short beam shear strength, SBSS and transverse shear strength, TSS) and in glass transition temperature, Tg. After ageing in sea water for 20 months, SBSS was found to retain by about 101, 102 and 95% at 23, 55 and 75°C, respectively. On the other hand, SBSS was retained by around 106% after ageing in dry condition for 20 months at 55 and 75°C. TSS was found to retain by approximately 99, 95 and 91% after ageing in sea water for 20 months at 23, 55 and 75°C, respectively, whereas TSS of dry conditioned samples was retained by about 105 and 107% at 55 and 75°C, respectively. Tg, measured by dynamic mechanical thermal analyser, showed little change both in wet and dry conditions at different temperatures and time.

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Haerst, Miriam Johanna, Romano Wolf, Markus Schönberger, Erich Wintermantel, Kurt Engelsing, Peter Heidemeyer, and Martin Bastian. "Ageing processes in laser sintered and injection moulded PA12 following hygienic reprocessing." Rapid Prototyping Journal 21, no. 3 (April 20, 2015): 279–86. http://dx.doi.org/10.1108/rpj-06-2013-0061.

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Purpose – The purpose of this paper is to describe the ageing behaviour of polyamide 12 (PA12) after clinical use. The research is focused on the comparison of the processing methods injection moulding and laser sintering. Design/methodology/approach – Test specimens are subjected to a cyclic stress of defined bending, cleaning, disinfection and sterilization. The focus of interest in this research is the degradation and reduction of mechanical properties. Findings – Mechanical and optical changes of the materials after clinical use and hygienic reprocessing are evaluated and discussed. Research limitations/implications – This article is focused on PA12 and, therefore, enables a very specific statement for the clinical use of PA12. The processing methods could have different impacts depending on the polymer. Originality/value – With the increasing application of polymers in medical devices, the mechanical properties must be ensured even after long-term clinical use. A systematic research with a realistic and still-defined cyclic stress is shown in this paper. Especially the testing of laser sintered polymers compared to injection moulded material has an important message for future patient-specific products.

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Fujiki, Michiya, and Shosei Yoshimoto. "Time-evolved, far-red, circularly polarised luminescent polymer aggregates endowed with sacrificial helical Si–Si bond polymers." Materials Chemistry Frontiers 1, no. 9 (2017): 1773–85. http://dx.doi.org/10.1039/c7qm00096k.

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Non-charged helical polysilanes (PSi) were spontaneously endowed with CPL on the order of g_em = ±0.02 at 700 nm when non-helical red- and far-red π-conjugated polymeric (PF8DBT) aggregates were employed after ageing at 20–25 °C for 24 h, followed by PSi-selective photoscissoring at 313 nm for 60 s.

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Wu, Shao Peng, Ling Pang, and Guo Jun Zhu. "The Effect of Ageing on Rheological Properties and Chemical Conversions of Asphalts." Key Engineering Materials 385-387 (July 2008): 481–84. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.481.

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Asphalt ageing induced by heat, oxidation and ultraviolet (UV) radiation was investigated using various laboratory simulation ageing methods and outdoor ageing. One normal 70 penetration asphalt and its styrene-butadiene-styrene (SBS) modified asphalt were employed to assess the changes in chemical and rheological properties by infrared spectroscopy and dynamic shear rheometer under various ageing conditions, thus the relationship among rolling thin-film oven(RTFO), pressurized ageing vessel (PAV) and UV radiation ageing was distinguished. Experimental results showed that photodegradation caused by outdoor exposure UV ageing of 50~200µm thin films for a month, was found to be the most severe, following by PAV and then RTFO with respects to rehological and chemical changes. Photodegradation effect decreased as the thickness of asphalt film increases. Dynamic shear tests indicated that polymer networks were gradually destroyed during ageing, but the aged SBS modified asphalts still displayed better rheological properties than the corresponding base asphalt. The weight percent of oxygen as carbonyl increased and of SBS as butadiene decreased after ageing based on infrared spectrums. However, chemical and rheological changes were not generally consistent, and ageing susceptibility may be ranked differently when different evaluation methods were used.

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García-Moreno, Irene, Miguel Caminero, Gloria Rodríguez, and Juan López-Cela. "Effect of Thermal Ageing on the Impact and Flexural Damage Behaviour of Carbon Fibre-Reinforced Epoxy Laminates." Polymers 11, no. 1 (January 7, 2019): 80. http://dx.doi.org/10.3390/polym11010080.

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Most of the composite materials that are used in aerospace structures have been manufactured using a thermostable matrix, as epoxy resin. The region of stability of these polymers is defined by the glass transition temperature (Tg). However, operating temperatures close and above the Tg can cause a variation in the properties of the polymer and consequently, modify the mechanical properties of the composite material. Therefore, it is necessary to understand the failure mechanisms that occur in the material in order to ensure stability and durability. The effect of temperature and time of exposure on the impact and flexural mechanical responses of carbon/epoxy composites are studied in this work. For that purpose, ageing treatments at temperatures below and above the Tg have been considered and then, impact and flexural tests have been performed. It was observed that thermal ageing cause two different effects: at temperatures below the Tg, there is an increase of the maximum strength because of a post-curing effect; however, the mechanical properties decrease at higher temperatures of thermal ageing due to the thermo-oxidation of the epoxy resin and the loss of adhesion in the matrix/fibre interface.

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Makdessi, M., A. Sari, and P. Venet. "Metallized polymer film capacitors ageing law based on capacitance degradation." Microelectronics Reliability 54, no. 9-10 (September 2014): 1823–27. http://dx.doi.org/10.1016/j.microrel.2014.07.103.

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Journal articles on the topic 'Polymer ageing'

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