PRODUCTION AND CHARACTERISATION OF PLASTIC SHEETS FROM POLYETHYLENE WASTE BLENDED WITH HYDROLYSED CASSAVA STARCH

Abstract

This study focused on the production and characterisation of plastic sheets from polyethylene waste blended with hydrolysed cassava starch. Polyethylene waste was melt blended with hydrolysed starch in a twin screw extruder to form blends of various ratios in percentage weight: 100:0, 90:10, 80:20, 70:30, 60:40, and 50:50. The morphology and microstructures of the cassava starch and hydrolysed cassava starch obtained from the high-resolution scanning electron microscopy (HRSEM) study revealed that the particles in the cassava starch are spherical, smooth and clustered. While the features in the hydrolysed cassava starch are etched, rough and clogged, indicating the etching of the amorphous regions of the starch granule by dilute H2SO4. The elemental composition of the cassava starch and hydrolysed cassava starch using energy dispersion X-Ray spectroscopy (EDX) revealed the presence of C (60 %) and O (39.46 %) for cassava starch and C (55.23 %) and O (44.77 %) for hydrolysed cassava starch respectively. The thermal properties of the polyethylene waste and hydrolysed cassava starch blends using thermogravimetric analysis showed that as hydrolysed starch increased from 0 % to 50 %, the thermal stability of polyethylene decreased from 442.54 °C to 345.71 °C. Water absorption capacity of the polyethylene waste/hydrolysed cassava starch blend increased from 0.642 to 1.285 % as the amount of the hydrolysed starch in the blend increased. Hardness and impact strength results showed that increase in amount of hydrolysed cassava starch content in the blends led to a decrease from 1.981 to 0.376 J/m2 and 98.667 to 96.333 Nmm2 respectively. The plastic sheets produced from polyethylene waste and hydrolysed cassava starch blends were studied under compositing conditions for 22 weeks. The 100 % polyethylene waste did not lose weight while the highest percentage weight loss observed was 5.92 % for the 50 % hydrolysed cassava starch blend. The morphology and microstructures of polyethylene waste and polyethylene waste/hydrolysed cassava starch blend obtained from HRSEM study showed that the hydrolysed starch decomposed out of the polyethylene matrix leaving pores in the matrix, however the matrix did not decompose. The addition of hydrolysed starch to plastic may reduce the amount of plastics in circulation.