EFFECT OF PROCESSING CONDITIONS ON THE DYNAMIC-MECHANICAL PROPERTIES OF STARCH AND ANHYDRIDE FUNCTIONAL POLYMER BLENDS

Reactive blending of starch with ethylene-propylene-g-maleic anhydride (EPMA) and styrene maleic anhydride (SMA) copolymers was carried out in a batch mixer. The effect of processing conditions, such as mixer speed and mixing time, on the dynamic mechanical properties and morphology, was studied. Starch/EPMA blends showed two distinct glass transitions in the G' and G'' plots, one corresponding to the starch and the other corresponding to EPMA. Starch/SMA blends exhibited one broad transition, since the glass transition temperatures of starch and SMA were in close proximity to one another. The starch in the blend was sensitive to the processing conditions used in this study. Increasing the mixing time from 10 to 20 min and increasing mixing speed from 50 to 100 rev min(-1) resulted in increased melting of starch granules. Increasing the mixing speed and mixing time also resulted in increased degradation of starch, as evident from the gel permeation chromatography.