Studies on the Combined Impact of Starch Source and Multiple Processing on Selected Properties of Thermoplastic Starch/Ethylene-Vinyl Acetate Blends
2019
Hejna, Aleksander | Lenża, Joanna | Formela, Krzysztof | Korol, Jerzy
Thermoplastic starch (TPS)/ethylene vinyl acetate (EVA) blends compatibilized with polyethylene-graft-maleic anhydride (PE-g-MA) were prepared from various native starches (potato, maize and waxy maize) and subjected to multiple extrusion cycles. Source of starch has significant impact on its composition, hence properties of obtained TPS and their blends with EVA. Higher content of amylopectin in waxy maize starch, comparing to other types, enhanced the mechanical performance and increased tensile strength and elastic modulus even by 41 and 71%, respectively. Such effect was related to the branching of amylopectin and was confirmed by SEM analysis of fracture areas, which showed more ductile behavior for blends with higher content of amylose. Multiple processing had beneficial impact on the performance of blends, due to the increasing compatibility and more homogenous structure after additional processing time. FTIR analysis indicated higher extent of compatibilization reaction, which, together with finer morphology, resulted in the enhancement of mechanical performance. Such effect is very beneficial from application point of view, because materials can be reprocessed without the loss of properties.
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