Effect of fiber content on thermal behavior and viscoelastic properties of PALF/Epoxy and COIR/Epoxy composites

The comprehensive cognition of the thermal and viscoelastic behavior of polymeric materials is highly significant in order to determine the structure-property relationship for various applications. The prime goal of this work was to study the effect of fiber content on the thermo-mechanical performance of fiber reinforced composites. In this regard, randomly oriented chopped fibers of length 20 mm with varying fiber volume content (17%, 23%, and 34%) were used as reinforcement in an epoxy polymer matrix for the development of a coir fiber-epoxy and pineapple leaf fiber-epoxy composites by hand lay-up technique. The results of thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) showed that the increase in thermal stability, storage modulus (E'), loss modulus (E ''), and glass transition temperature (T-g) of the matrix polymer with the incorporation of coir and pineapple leaf fiber. The neat epoxy matrix shows highest damping property while 34 vol.% fiber reinforced composites show the highest stiffness than the other samples. In all cases, the storage modulus was decreased with the increase of temperature. The reduction in E' over the temperature range of 45 degrees C-80 degrees C corresponds to the phase transition. The optimum fiber volume content is 23% having the maximum thermal stability. The 23% coir and 34% pineapple leaf fiber reinforced composites have the lowest value of effectiveness coefficient 'C' obtained by the storage modulus analysis. The tan delta and loss modulus peak of polymer matrix was shifted to the higher temperature after the addition of reinforcing fiber, which indicates that the fibers play a major role to increase the stiffness of polymer composites by imposing the restriction in mobility of polymer chains.