Effect of outdoor exposure on the moisture diffusion and mechanical properties of epoxy polymers

Startsev, V.O.; Лебедев, М. П.; Khrulev, K.A.; Molokov, M. V.; Фролов, А. С.; Nizina, T.A.

doi:10.1016/j.polymertesting.2017.12.007

Cited by 47 publications

(31 citation statements)

References 36 publications

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“…Epoxy resins are often exposed to water due to rain, humidity of the air, and in subsea and offshore applications [13,15]. In such conditions, water molecules can migrate into the polymer and may affect its properties, and lead to leaching [1,16].…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Yellowing: Carbonyl Formation during Hygrothermal Aging in a Common Amine Epoxy

2018

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Epoxies are often exposed to water due to rain and humid air environments. Epoxy yellows during its service time under these conditions, even when protected from UV radiation. The material’s color is not regained upon redrying, indicating irreversible aging mechanisms. Understanding what causes a discoloration is of importance for applications where the visual aspect of the material is significant. In this work, irreversible aging mechanisms and the cause of yellowing were identified. Experiments were performed using a combination of FT-NIR, ATR-FT-IR, EDX, HR-ICP-MS, pH measurements, optical microscopy, SEM, and DMTA. Such extensive material characterization and structured logic of investigation, provided the necessary evidence to investigate the long-term changes. No chain scission (hydrolysis or oxidation-induced) was present in the studied common DGEBA/HDDGE/IPDA/POPA epoxy, whilst it was found that thermo-oxidation and leaching occurred. Thermo-oxidation involved evolution of carbonyl groups in the polymeric carbon–carbon backbone, via nucleophilic radical attack and minor crosslinking of the HDDGE segments. Four probable reactive sites were identified, and respective reactions were proposed. Compounds involved in leaching were identified to be epichlorohydrin and inorganic impurities but were found to be unrelated to yellowing. Carbonyl formation in the epoxy backbone due to thermo-oxidation was the cause for the yellowing of the material.

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Section: Introductionmentioning

confidence: 99%

Mechanism of Yellowing: Carbonyl Formation during Hygrothermal Aging in a Common Amine Epoxy

2018

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“…FRPs are widely used in structural applications in marine and offshore industries, where a typical design lifetime of composite structures is 25 or more years. During this prolonged service period, the structures are in direct contact with water leading to deterioration of the material properties [4,5,6,7]. Knowing and predicting the extent of the material property deterioration in water is of great interest for designers and users of the offshore FRP structures.…”

Section: Introductionmentioning

confidence: 99%

Time–Temperature–Plasticization Superposition Principle: Predicting Creep of a Plasticized Epoxy

et al. 2019

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Long-term creep properties and the effect of water are important for fiber reinforced polymer (FRP) composite materials used in offshore applications. Epoxies are often used as a matrix material in such composites. A typical design lifetime of offshore FRP structures is 25 or more years in direct contact with water leading to some deterioration of the material properties. Knowing and predicting the extent of the material property deterioration in water is of great interest for designers and users of the offshore FRP structures. It has been established that the time–temperature superposition principle (TTSP) is a useful tool for estimating changes in properties of polymer materials at long times or extreme temperatures. In this work, a time–temperature–plasticization superposition principle (TTPSP) is described and used for predicting the long-term creep behavior of an epoxy compound. The studied epoxy does not degrade chemically via hydrolysis or chain scission but is negatively affected by plasticization with water. The methodology enables prediction of the long-term viscoelastic behavior of amorphous polymers at temperatures below the glass transition (Tg) using short-term creep experimental data. The results also indicate that it is possible to estimate the creep behavior of the plasticized polymer based on the short-term creep data of the respective dry material and the difference between Tg values of dry polymer and plasticized polymer. The methodology is useful for accelerated testing and for predicting the time-dependent mechanical properties of a plasticized polymer below the glass transition temperature.

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“…Even if the peak in tan δ curve is an extended parameter for defining T g values, [42][43][44][45] many authors prefer to employ other parameters as the peak value on E" curve 18 or inflection point of E' curve. 46 Startsev et al 47 decline the use of tan δ peak as the universal marker of T g by arguing that significant discrepancies appear between the maximum values on tan δ curve, peaks on E" curve and inflection point on E' curve, when all these parameters reveal the same type of molecular mobility. 47 Instead, it is proposed to use the minimum point of the temperature derivative of the storage modulus (dE'/dT) curve, based on the physical meaning that this point represents, that is, the maximum rate of the α-transition.…”

Section: Dynamic Mechanical Analysismentioning

confidence: 99%

“…47 Instead, it is proposed to use the minimum point of the temperature derivative of the storage modulus (dE'/dT) curve, based on the physical meaning that this point represents, that is, the maximum rate of the α-transition. 47 Moreover, Startsev completes the T g analysis by plotting and checking the E' and E" curves. 35,[47][48][49] In this article, the plasticization effects generated by Type I hydrogen bonds have been analyzed by determining the variation in the T g values between dry and aged specimens.…”

Section: Dynamic Mechanical Analysismentioning

confidence: 99%

“…47 Moreover, Startsev completes the T g analysis by plotting and checking the E' and E" curves. 35,[47][48][49] In this article, the plasticization effects generated by Type I hydrogen bonds have been analyzed by determining the variation in the T g values between dry and aged specimens. For this, the method proposed by Startsev et al 30 for stablishing T g has been employed and, at the same time, the suitability of this method for C-SMC materials has been validated.…”

Section: Dynamic Mechanical Analysismentioning

confidence: 99%

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Effects of hygrothermal aging on the thermomechanical properties of a carbon fiber reinforced epoxy sheet molding compound: An experimental research

Zulueta

Burgoa

Martinez³

2020

J of Applied Polymer Sci

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Carbon fiber sheet molding compounds (C-SMCs) are discontinuous fiber reinforced composite materials. Among them, epoxy-based C-SMCs are becoming relevant materials due to their high thermomechanical performance and better formability than continuous fiber reinforced composites. The thermomechanical performance of epoxy resins and epoxy based continuous carbon fiber composites have shown to be influenced by hygrothermal aging. In this work, this influence is studied for an epoxy-based C-SMC. Epoxy-based C-SMC samples were hygrothermally aged by means of accelerated conditioning, exposing them to 65% relative humidity, and 80 C in a climatic chamber. The equilibrium moisture content, as well as the moisture diffusion coefficient has been determined. The thermomechanical properties of epoxy C-SMC have been analyzed by dynamic mechanical analysis, tensile, 3-point bending, and short beam tests in dry and aged samples. The results showed that epoxy C-SMC is affected by hygrothermal aging in the cases of moisture intake and its effects on T g value, but interestingly, the hygrothermal aging did not generate any degradation effects in the mechanical response of epoxy C-SMC.

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Effect of outdoor exposure on the moisture diffusion and mechanical properties of epoxy polymers

Cited by 47 publications

References 36 publications

Mechanism of Yellowing: Carbonyl Formation during Hygrothermal Aging in a Common Amine Epoxy

Mechanism of Yellowing: Carbonyl Formation during Hygrothermal Aging in a Common Amine Epoxy

Time–Temperature–Plasticization Superposition Principle: Predicting Creep of a Plasticized Epoxy

Effects of hygrothermal aging on the thermomechanical properties of a carbon fiber reinforced epoxy sheet molding compound: An experimental research

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