Effects of thermal recycling temperatures on the reinforcement potential of glass fibers

In the present work the reinforcement potential of thermally recycled glass fibers in injection molded Polypropylene (PP) composites was investigated. Microbond tests showed that fiber sizing lost its compatibility to the PP matrix after exposure to temperatures of 250 °C in air. The drop of the adhesion between fibers and PP was mirrored by a large reduction of the tensile strength of the injection molded PP composites. In inert atmosphere the degradation of the fiber sizing and the reduction of the IFSS were less rapid than in air but no significant difference was observed above 400 °C. It was concluded that thermally recycled glass fibers will require a post-treatment to act as an effective reinforcement in injection molded PP composites even if the thermal recycling was performed in an inert atmosphere. The post-treatment will need to improve the compatibility of the fibers to the polymer matrix and the fiber strength.