Evaluation of stearic acid modified industrial lime sludge waste as a filler in high density polyethylene composites

Industrial lime sludge (LS), an environmental hazard, is surface modified by stearic acid (SA) in order to reinforce high density polyethylene (HDPE) composites. Uncoated and SA-coated LS-reinforced HDPE composites are prepared and their mechanical, thermal, and morphological properties are studied and compared with each other. FTIR spectroscopy revealed successful grafting of SA onto LS particles while SEM morphology showed that SA coating hinders particle agglomeration in the HDPE matrix at higher filler loading. Mechanical properties such as tensile and flexural strength and modulus, elongation at break, and impact strength increased significantly for SA-coated LS composites due to uniform particle dispersion and effective filler-matrix interfacial interaction. The SA coating increased the entanglement at the filler-matrix interface thereby increasing the thermal decomposition of the coated composites from 500 degrees C to 600 degrees C. Additionally, it also reduced the water absorption rate of the coated composites in comparison with its uncoated counterpart. Thus, SA proves to be an efficient surface modifier for LS to produce HDPE composites with superior properties at a low cost. Needless to say, this study also suggests an alternative LS waste management route which offers benefits of reusing an industrial waste, decreasing the pollution, and developing fresh polymeric products.