Investigation on the stress relaxation behavior of milled newsprint filled polyethylene composite

Stress relaxation behavior of milled newsprint/HDPE composite containing coupling agent was studied. Composites containing 25 and 50% filler in weight were produced, and were compared to neat polymer. Melt blending followed by injection molding was the manufacturing process. Results showed that incorporating filler to polymer increases the flexural strength and modulus. It was observed that higher stress is needed to maintain higher strain levels. Furthermore, comparing the stress ratio patterns revealed that the difference among relaxation of different samples develops over time. Power law computed parameters showed that higher strain level results in higher stress relaxation amplitude (A) and lower time exponent (t). It was also found that, almost complete linear relationship could be established between strain level and parameter A, and the effect of strain level on parameter A is more pronounced at higher filler contents.