Effect of mechanical recycling on short glass fibre reinforced polyamide 6,6 from post-industrial waste

Recycling post-industrial plastic waste offers a series of advantages compared to post-consumer recycling, specifically: (1) the waste stream is not contaminated by other materials, (2) its composition is generally known and stable, and (3) limited degradation. This makes it a commercially viable and effective recycling strategy, which is nowadays exploited by many manufacturers. Nonetheless, there’s currently a lack of technical knowledge on the effects of recycling on materials with a complex composition, such as glass fiber-reinforced plastics. For these materials, in fact, compliance with certain dielectric and self-extinguishing properties is often required, as well as good mechanical behavior. This study aims to fill this gap by analyzing the effect of the integration of recyclates into injection-molded parts in percentages ranging from 0% to 20% wt. The material of choice is a polyamide 6,6 composite containing 30% wt. of short glass fibers. The recycled granules are produced by grinding injection molded parts and subsequently extruding the resulting ground material. These are then mixed with virgin granules in different percentages by weight (5, 10, 15, and 20%) and the mixtures are used to produce the specimens to be tested. A wide characterization of the mechanical, thermal, rheological, and dielectric behavior of the different materials is performed to verify compliance with the stringent requirements for this class of materials. This approach will help to further increase the level of technical knowledge on the post-industrial recycling of glass-fiber reinforced polyamide, providing manufacturers with useful data for the industrial implementation of the process. The benefits deriving from the introduction of closed-loop recycling are evident: not only from an economic point of view (material savings) but also from an environmental perspective, as in fact, mechanical recycling has significantly lower impacts than the production of virgin plastic.