Use of starch granules melting to control the properties of bio-flour filled polypropylene and poly(butylene succinate) composites: Physico-chemical properties

Bio-composites made from polypropylene (PP) and poly(butylene succinate) (PBS) compounded with pineapple skin (P) bio-flour, non-destarched (CS), and destarched (C) cassava root bio-flours were prepared by twin-screw extrusion. In CS composites, different degrees of starch granules melting were achieved by adjusting extrusion temperature, thus enabling control of the morphological and mechanical properties. FTIR analysis indicated the formation of ester bonds between bio-flours and compatibilizers during extrusion, which confirmed the effectiveness of these compatibilizers for improving interfacial interactions between PP and bio-flours. Thermogravimetric analysis showed that the composites had reduced thermal stability compared to pure PBS and PP materials, due to the lower degradation temperature of the bio-flours (261-351°C). DSC data indicated that bio-flours improved nucleation and crystallinity, whereas, compatibilizers reduced molecular mobility and hence propagation and crystallinity.