Recycling and reinforcement potential for the fly ash and sisal fiber reinforced hybrid polypropylene composite

The investigation explores mechanical, thermal and thermomechanical behavior of hybrid composites post-recycling, and subsequent, 5 wt.% additional reinforcement to the recyclate of sisal (SSL) fiber fly ash (FA)/polypropylene (PP) hybrid composite. Impact of recycling and 5 wt.% of SSL fiber reinforcement of the recyclate on mechanical properties of hybrid composites made of 15-30 wt.% SSL and 5-15 wt.% FA were investigated. Noticeably, after recycling, a minimal loss of 2.39% only in tensile and 2.20% in flexural strength were recorded for the hybrid composites fabricated with 15 wt.% each of FA and SSL. The highest loss in tensile (10.32%) and flexural (4.22%) strength were reported for only 30 wt.% SSL fiber reinforced PP indicating that hybridization with FA has a benign effect on reducing property degradation. These lost properties were regained by reinforcing recycled composites with 5 wt.% of SSL fiber. Mechanical studies showed that the composite with 30 wt.% SSL fibers recycled and reinforced with additional 5 wt.% fibers showed a substantial improvement of similar to 10% and similar to 4% in the tensile and flexural strength while keeping the impact strength stable. FE-SEM images confirmed a reduction (similar to 67%) in aspect ratio of the SSL fiber due to reprocessing. DMA demonstrated a decrease of similar to 11% in storage modulus of the composites after first recycling. TGA confirmed an insignificant change in the degradation temperature of the recycled and re-reinforced recycled composites versus fresh composites. The study paves the way for potential future recycling applications of waste natural fiber reinforced PP.

Automated summary

The study investigates the mechanical, thermal and thermomechanical behavior of hybrid composites post-recycling and the impact of additional reinforcement. The results show that recycling and additional reinforcement have a significant influence on the properties of hybrid composites, and reinforcing with SSL fibers can effectively restore lost properties.