Effect of aggressive environments on composite properties

Abstract

Glass-fiber-reinforced epoxy and unsaturated polyester (UPE) composites were fabricated from diglycidyl ether of bisphenol-A (DGEBA) using 10% diethyl triamine (DETA) as a hardener and unsaturated polyester (UPE) using 1.5% each of methyl ethyl ketone peroxide (MEKP) and cobalt naphthanate as a catalyst and an accelerator, respectively. The fabricated composites were exposed to different aggressive environments, such as heat, water ageing, lubricating oil, fuel, and seawater. The exposed specimens were characterized by physical, chemical, mechanical, and thermal properties. A marginal increase (12%) in the mechanical properties in heat ageing, but a reduction in properties in other exposed systems of the epoxy and polyester glassfiber-reinforced (GFRP) composites, were observed. ReinforcementE-glass fiber cloth, of 0.315-mm thickness, 0°/90°b idirectional, plain weave with specifications IS-5746 type 1, variety 2, was used.

Environmental durability of banana‐fiber‐reinforced phenol formaldehyde composites

“…This was attributed to interfacial degradation and also to microstructural changes in rice husk that reduced its efficiency in acting as a reinforcer. Siddaramiah et al9 exposed glass‐fiber‐reinforced epoxy and unsaturated polyester composites to different aggressive environments, including heat aging, water aging, lubricating oil, fuel, and seawater and obtained a marginal increase in properties with heat aging but a reduction in properties in the other exposed systems.…”

New aspects of aging in epoxy networks. II. Hydrothermal aging

“…In service, structural metal joints, polymer coatings, and fiber-reinforced composites are often operating in humid and warm conditions, which leads to hydrothermal aging of the bond. 1,2 The hydrothermal aging behavior of epoxy systems is often focused because they are widely used in structural applications. For epoxies adhesives, many studies are reported in literature concerning the degradation of the joint strength during a variety of hydrothermal loading.…”

Flexural Characteristics of Sunlight-Aged Polyester Composites: Influence of Processing Variables

“…Styrene is the crosslinking agent in unsaturated polyesters. Several authors have suggested that some unreacted resin and catalyst that did not take part in the polymerization reaction are still present [9][10][11]42]. It is well known that three types of reactions are inherent in unsatured polyesters: curing polymerization of polyester vinyl groups, polyester and styrene CBC bond polymerization, and styrene homopolymerization [42][43][44][45][46].…”

“…Wiles [53,54] suggested a mixed mechanism of thermal and photolytic oxidation in polymers containing carbonyl groups in the form of acid, ester, aldehyde, ketone, amide, or peroxide. Glass fiber reinforced polyester composites continuously exposed to a temperature of 50°C do not lose their mechanical characteristics in the absence of solar radiation, as shown in a number of references [9][10][11]30]. The prevalent mechanism during composite irradiation is photoluminic, while thermal aging would produce higher losses due to fiber-matrix interface degradation [12,13,55].…”

“…The state of heat degradation of polyester-based composites has been reviewed by Dudgeon [1]. Nevertheless, recent studies have been focused on the durability of these materials in organic and aqueous [2][3][4][5][6][7][8][9][10][11][12][13][14][15], alkaline [9,16,17], and acid media [9][10][11][17][18][19]. Effects of sunlight and high-energy radiation on nonreinforced polymers are well known [20][21][22][23][24][25][26][27], but similar information is scarce regarding composites.…”