Abstract:-The authors prepared a biodegradable composite using waste polypropylene (wPP) and coconut flour (CF). Each polymer composite was prepared with different ratios of CF introduced in the matrix. The composite prepared contained 10%, 20%, 30%, 40% and 50% CF respectively. 100% wPP was the control sample. The composite showed an increase in tensile strength and modulus, flexural strength and modulus, water absorption and impact strength with increase in CF. However  there was a slight reduction in density  of the NFRPCs with increase in CF due to poor dispersion of the fibres and void spaces in the matrix of the composites. The biodegradation rates of the NFRPCs were higher than that of wPP, with the highest biodegradation rate of 2.93% at 50% CF content after six months. The CF in the composites helped to increase the biodegradation rate as a result of its hydrophilic nature which permits the ingress of water into the matrix of the NFRPCs which aided degradation by action of micro-organism, photo-thermal and oxidative degradation. NFRPCs produced can be utilised for industrial and domestic applications and can also undergo biodegradation when disposed, indicating a more environmental friendly substitute compared to wPP. However to increase the rate of biodegradation additives such as transition metals may be incorporated into the matrix structure to increase biodegradation at a scale that would be much faster and economically  more viable.

Thermal properties of M30 normal concrete block (NC) were compared with concrete filled with waste poly ethylene terephthalate and waste low density polyethylene aggregates which were used as partial replacement of sand in the production of concrete blocks (plast-cretes). Tests were carried out using 100mm×100mm Cubes and 100mm×200mm Cylinder for Compressive and Split tensile Test respectively. The mechanical properties of normal concrete and plast-crete were studied and compared over two temperature regimes at 100°C-400°C and 400°C-800°C. The compressive and Split Tensile strength of normal concrete increased slightly from 100°C-400°C, and reduced from 400°C-800°C. However, the compressive and split tensile strength of the plast-crete showed a gradual reduction from 100°C-400°C and this continued from 400°C-800°C, and became more pronounced as the percentage of waste plastics in the plast-crete increased. The percentage of weight loss for the normal concrete increased from 100°C-400°C, this increase continued from 400°C-800°C. The plast-crete also showed an increase in the percentage weight loss for both temperature regimes and the percent weight loss became more pronounced as the percentage of waste plastics in the plast-crete increased. The normal concrete showed greater spalling than the plat-cretes. Even with the slight reduction in strength with increasing temperature, Plast-cretes can still be applied in areas where low temperature and minimal load bearing applications are needed such as fancy blocks, pedestrian walk ways, slabs, partition walls, fences, houses and light traffic structures.