Degradation studies and moisture uptake of sago-starch-filled linear low-density polyethylene composites

The degradation and moisture uptake of sago-starch-filled linear low-density polyethylene (LLDPE) composites have been studied. Enzymatic hydrolysis of the composites apparently involves surface starch granules; embedded granules are not easily accessible because of the poor moisture absorption or transmission property of the matrix. Exposure of the composites to weathering resulted in massive deterioration typified by turbidity, discoloration, embrittleness and dimensional changes. Soil burial led to a drop in the pH of the soil and the presence of holes on the samples, probably due to microbial activity. Furthermore, the drop in mechanical properties of the composites increased with time of burial for the first four months and decreased gradually thereafter. Moisture uptake increased with increased starch content and immersion time. The time taken for the composites to equilibrate was about three months even when they were immersed completely in water. The mechanical properties of the composite also dropped with increasing moisture uptake.