Abstract:

Glycerol， sodium hexametaphosphate （SHMP）， and polyethylene glycol （PEG） were used to modify cassava starch， and then， the modified starch/PBAT/calcium carbonate composites were prepared. The modified starch and its composites were analyzed by using FTIR， XRD， SEM， DSC and TG. The influence of modified starch on the structure and properties of the composites was investigated. The results indicated that the outer plasticization of glycerol and the inner plasticization of PEG and SHMP changed the chemical structure of starch. The amorphous components of modified starch increased. The starch particles were changed from a full spherical shape to the irregular large one. The thermal stability of the modified starch was improved before 250 ℃ but deteriorated after 250 ℃， which is beneficial to its processing and thermal decomposition. There are differences in the crystallization and melting behavior of the starch modified with different modifiers. In the composites， there was no change in the original crystal forms of PBAT， calcium carbonate， and starch； however， the differences in compatibility led to differences in the thermal and mechanical properties of the composites. The modification of starch improved the toughness of the composites. The synergistic modification of glycerol， SHMP， and PEG resulted in the good compatibility of starch with PBAT and calcium carbonate， and the composites achieved the optimal comprehensive performance.

Key words: cassava starch, poly（butylene adipate terephthalate）, calcium carbonate, composite materials