Study of effect of multiple recycling on the mechanical properties of Sisal Fiber and Fly ash Reinforced hybrid Composites

Abstract

Introduction: Recycling and reuse of the polymer composites have been gaining popularity these days due to their environmental and disposable concerns. However, the recyclability of natural fiber and fly ash reinforced polymer composite is still not explored much which has restrained the industries not to use them at full potential. Recycling of polymers, polymeric composites, and their wastes are trending nowadays. Researchers have used both recycled reinforcements such as paper, fiber, etc., with matrix and fresh reinforcement with recycled matrix too. In this regard, limited reports have been found on the recycling of the natural fiber reinforced polymer composites. In spite of this, when it comes to the recycling of degradable materials, it is still in the nascent phase. Recycling of the biodegradable materials may lose some of their original properties after every cycle (1). These lost tensile and flexural properties may be exhibited due to the fiber breakage, fiber degradation, change in fiber aspect ratio, and polymer chain shortening. Reinforcement of the recycled composites with fresh fibers to restore their lost tensile and flexural properties could open a new window for the researchers. Current work focuses on the recycling and subsequent reinforcement of the recycled composites to enhance the tensile and flexural properties of the same. Methods: Hybrid composites with 15-30 wt.% sisal fibers and 5-15 wt.% fly ash were formulated with impact modified polypropylene. The impact on mechanical properties due to the recycling and reinforcement was investigated. All the tensile, flexural, and impact testing samples have been fabricated by using Hakke rheomix and Hakke Minijet II micro injection molding machine (2). Results & Discussion: Composite with 15 wt.% sisal fibers showed a minimal ~2 % and ~2 % loss in tensile and flexural strength while the one with 30 wt.% fiber showed a maximum ~10 % and ~4 % loss respectively. In order to restore the lost mechanical properties, recycled composite have been reinforced with 5 wt.% natural fiber. The establishment of a good interfacial adhesion between reinforcing filler and fiber has been confirmed from FTIR studies. Strong interfacial interaction among reinforced SSL fiber and the blended matrix leads to a strong polymer composite. Although there is a decrease in tensile and flexural properties of the hybrid composite due to the increased reinforcement of fly ash, these are the still close to the base matrix. Also, an improvement in notched impact strength of the composite has been observed (3). Recycled, polymer composite samples show that the hybrid composites with highest fly ash content show the least decrease in tensile and flexural properties due to the non-breakage of fly ash particles. However, an insignificant change was, observed in impact strength of the recycled and reinforced composites. Conclusions: Recycling and reinforcement with 5 wt.% of FA of hybrid PP composites consisting of sisal fiber and fly-ash were successfully completed and evaluated. Fly ash plays a vital role in restricting the damage to the mechanical properties due to the recycling. Furthermore, inclusion of 5 wt.% of SSL fiber to the recycled composites sample helped in reclaiming lost mechanical properties. Keywords: Composite Recycling, Hybrid composite, Natural fiber, Fly ash