Development of Various Industrial Lime Sludge Waste-Filled Hybrid Polymeric Composites for Environmental Sustainability

Abstract

A potentially hazardous industrial waste material in our society is lime sludge which is sourced mainly from various industries (fertilizer, paper, sugar and soda ash) and generally disposed off in dumpyards or used in unauthorized land filling—both causing pollution. Hence, an alternative idea of environmental sustainability is by reusing lime sludge as reinforcing agent in polymeric composites. In this line of thought, lime sludge waste is used as filler in HDPE and epoxy matrices in order to investigate the effects of lime sludge on its composite properties. This would ultimately, throw light on the feasibility and commercial viability of lime sludge reuse in polymeric composites. Mechanical properties of HDPE composites are studied with maleic anhydride-grafted polyethylene (MAPE) as compatibilizer for effective adhesion at the filler/matrix boundary. Lime sludge waste was also used as filler in conjunction with randomly dispersed short coir fibre reinforced HDPE composites along with 5 wt% MAPE as compatibilizer. It is observed the properties such as flexural strength and mechanical rigidity (tensile and flexural) of the lime sludge infused composites improved with filler addition. The tensile strength increased up to 20 wt% filler addition due to effective reinforcement; however, beyond that the tensile strength decreased due to particle agglomeration. Additionally, lime sludge is used as filler in short and long coir fibre added epoxy composites. It is found that lime sludge content of 6 wt% results in superior tensile strength in coir fibre reinforced epoxy composites. In general, lime sludge is found to improve the bending strength and mechanical rigidity (tensile and flexural modulus) with increasing filler weight fraction. Thus, the reuse of lime sludge filler in polymeric composites not only results in the enhancement of various mechanical properties, but also reduces pollution, decreases the cost of the composites and improves the commercial viability of lime sludge waste.