Abstract:
The influence of morphology on mechanical property of several polypropylene/starch (PP/starch) blends of varying compositions was studied. The blends prepared were at wt%PP/wt%starch of 97.5/2.5, 95/5, 92.5/7.7, 90/10, 87.5/12.5 and 85/15. The morphology of the blends observed, using scanning electron microscopy showed them to be immiscible blends with distinct polymer-starch domains at high starch volume fractions (85%PP/15%starch-87.5%PP/12.5%starch), which gradually showed the morphology of well dispersed miscible blends at lower starch volume fractions (97.5%PP/2.5%starch,95%PP/5%starch,92.5%PP/7.7%starch, 90%PP/10%starch ) The starch domains exhibited characteristic voids which could be due to thermal degradation at the processing temperatures employed. The particle size of the starch domains increased with increase in volume fraction, probably due to the agglomeration and formation of aggregates of the starch granules. The mechanical properties of the blends and viscosity of the blends decrease with increase in starch volume fractions. The mechanical properties were explained using the blend morphologies at various volume fractions.