Analysis of factors influencing GFRP shredding energy consumption and the physical properties of the resulting recyclates

Glass fibre reinforced polymer (GFRP) remains the dominant composite produced globally due to its low cost, high specific mechanical properties and chemical resistance performances. These unique features, however, impose significant recycling challenges for their end-of-life parts. Although there are various recycling technologies available, all of them require the waste GFRP to be reduced in size in order to enhance the recycling process efficiency. In this work, a full factorial design analysis was conducted to identify factors that influenced specific shredding energy consumption, average physical size and resin content of shredded GFRP recyclates. Factors investigated were glass fibre fabric architecture in GFRP wastes (non-crimp and nonwoven), GFRP waste feed rate (10-60 kg/h) and screen aperture of the shredding process (6-20 mm). It was observed that specific shredding energy was not significantly affected by the fabric architecture but could be reduced by opting for larger screen aperture and/or lower feed rate. However, improvement to shredding energy efficiency was achieved if 6 mm diameter screen was selected together with 60 kg/h feed rate. The 60 kg/h feed rate was found to be ideal in reducing oversize recyclates content but did not affect the median particle size of the remaining recyclates, which was found to be influenced by screen aperture and fabric architecture. Resin-rich and fibre-rich fractions were identified from the recyclates. The resin content of the former was found to be sensitive to all the studied factors.