Durability and integrity studies of environmentally conditioned interfaces in fibrous polymeric composites: Critical concepts and comments

Abstract

Fibre reinforced polymer (FRP) composites are the most promising and elegant material of present century. Their durability and integrity in various service environments can be altered by the response of its constituent i.e. fibre, polymer matrix, and the existing interface/interphase between the fibre and polymer matrix, in that particular environment. The interphase is generally manifested by chemical bonding, molecular segregation and also by van der Waal bonding. The sizing of fibres generally influences the chemistry and character of the interface/interphase and might generate structural gradient in the polymer matrix. Their susceptibilities to degradation are dependent of nature of environments and each of the constituents’ responses differently and uniquely. Among the three constituents, the interface/interphase has very critical role to play on the performance and reliability of FRP composites. The reduced glass transition temperature of the interphase may induct low modulus area, which subsequently affect fracture toughness and local stresses of the composite. These result in high fracture toughness at ambient temperatures, but significantly reduced performance at high temperatures.