Synergistic environmental degradation of glass reinforced polymer composites

Abstract

Synergistic effects involved in the environmental degradation of Glass Reinforced Polymer (GRP) composites were examined in this research. Six GRPs based on E-glass and ECR-glass fibers with four different polymer resins were exposed either individually or in combination to ultraviolet (UV) radiation, water condensation and elevated temperature for approximately 1000 hours. The composites were monitored for weight changes as a function of time and their surfaces were examined after the tests using optical and scanning electron microscopes. A new model of synergistic aging of polymers under UV and water contestation was also proposed. It has been shown that the selected aging conditions created noticeable synergistic effects causing extensive erosion of the polymer matrices of the tested composites which appeared to be much stronger under the combined actions than under individual exposures. The differences in the aging rates under the individual and combined situations were adequately explained using the newly proposed model. It is suggested that the surface erosion of polymer matrices of the GRPs by combined UV and water condensation creates the most effective condition for small polymer particles formed by UV to be subsequently removed by water condensation exposing fresh still undamaged surfaces to further UV degradation. It has also been shown that depending on the size of the particles different particle removal mechanisms occur on polymer surfaces eroded by a cyclic exposure to UV and water condensation.

The influence of ultraviolet radiation on the optical properties of glass fibre reinforcements for polyurethane matrix composites

“…This phenomenon was caused by either the polymer becoming excessively brittle because of increased crosslinking, or by the formation of micro‐cracking due to chain scission resulting from photo‐oxidation reactions induced by UV irradiation. Similar phenomena have been observed previously . Figure E shows that the erosion was not as significant for sample A.…”

“…Similar phenomena have been observed previously. 20 Figure 2E shows that the erosion was not as significant for sample A. Thus it was concluded that sample A was more UV-stable or that UV radiation was unable to penetrate through the entire glass fabric, confirming the results of the YI analysis.…”

Micromechanics analysis of carbon fiber/epoxy microdroplet composite under UV light irradiation by micro‐Raman spectroscopy

“…This phenomenon could potentially be chalking of the polymer, and the tiny particles might be the photodegradation products of carbon fiber/epoxy microdroplet composite as a result of the photo‐oxidation induced crosslinking or chain scission from the UV radiation. Lu et al reported the formation of tiny particles in their study of glass fiber‐reinforced polymer composites under synergistic environmental conditions, and particles larger (20 μm) than those observed in our sample were observed, owing to greater UV irradiation intensity. Furthermore, upon increasing the exposure time of the microdroplet composite surface to 300, 560, 800, and 940 hours, respectively, the tiny particles became bigger and greater in number than those in the 40 hours aging sample (Figure 5C‐F).…”

“…The erosion of material properties due to UV irradiation and the degradation mechanism of epoxy and its composites has been investigated, and it has been suggested that the short‐term exposure to UV causes changes in surface morphology alone, such as discoloration, chalking, micro‐cracking, and pitting and flaking of composites . Furthermore, the discoloration observed was attributed to the formation of a quinone methide structure .…”

Aging of Polymer Composites in Extremely Cold Climates

“…Деструкция поверхности ПКМ при совместном воздействии УФ-облучения и термовлажностных режимов оказывается интенсивнее, чем при их последовательном действии (синергизм). Это доказано при исследовании потерь массы серии СП в работе [56]. Убедительным примером ускорения деструкции полимерных матриц в открытых климатических условиях является наложение термоциклов, имитирующих условия эксплуатации авиационной техники (режим «взлет -посадка») на конструктивно подобные эле-менты и образцы свидетели из СП и УП [10].…”