Preparation and characterization of acorn starch/poly(lactic acid) composites modified with functionalized vegetable oil derivates

• Vegetable oil derivatives dimer fatty acid (DFA), dimer fatty acid polyamide (DFAPA), acorn starch(AS) and PLA are all eco-friendly renewable chemical feedstocks.
• Composites of AS and PLA modified with DFA or DFAPA were produced by a hot-melt extrusion method.
• The prepared composites are a perfect fusion of vegetable oil, acorn starch(AS) and PLA.
• DFA containing carboxyl groups has obvious plasticating effects on PLA matrix of composites.
• DFAPA has certain compatibilization effects on AS/PLA composites due to its amine groups.

Composites of acorn starch (AS) and poly(1actic acid) (PLA) modified with dimer fatty acid (DFA) or dimer fatty acid polyamide (DFAPA) were produced by a hot-melt extrusion method. The effects of DFA and DFAPA contents on the mechanical, hydrophobic, thermal properties and melt fluidity of the composites were studied under an invariable AS-to-PLA mass ratio of 40/60. SEM and DMA research results show that the compatibility of AS/PLA composites are determined by the dosage of DFA or DFAPA. The hydrophobicity and melt fluidity of composites are improved with the addition of DFA and DFAPA. The glass transition temperatures of the composites are all reduced remarkably by additives DFA and DFAPA. However, DFA and DFAPA exert different effects on the mechanical properties of AS/PLA composites. In the DFAPA-modified system, the tensile and flexural strength first increase and then decrease with the increase of DFAPA dosage; the mechanical strength is maximized when the dosage of DFAPA is 2 wt% of total weight. In the DFA-modified system, the tensile and flexural strength decrease with the increase of DFA dosage.