Thermal, Mechanical, and Viscoelastic Properties of Recycled Poly(ethylene terephthalate) Fiber-Reinforced Unsaturated Polyester Composites

Recycled polyethylene terephthalate (PET) fiber has been used as reinforcing filler for unsaturated polyester resin (UPR) in order to obtain UPR/ PET fiber composites. Different loadings of PET fibers (5-18 phr-parts per hundred parts of resin) of different average lengths (2-3 to 20 mm) were added to the UPR. The mechanical properties of the UPR/ PET fiber composites increased up to 8 phr PET fiber loading with a length lower than 5 mm, because of the high affinity between the UPR and the PET fiber surface and the good dispersion of the fiber into the matrix. However, higher PET fiber loading caused a decrease in the mechanical properties of the composites because of the agglomeration of the fibers. The UPR/ PET fiber composites presented higher storage moduli than the UPR, and an increase of the glass transition temperature in the composites reinforced with 5-8 phr of short PET fiber was found; further, higher degree of crosslinking was reached. The addition of 5-8 phr PET fiber of short length improved the thermal stability of the composites and the post-curing was produced at higher temperature with much reduced enthalpy. (C) 2016 Society of Plastics Engineers