Vegetable oil based additives to enhance the properties of PLA/Starch composites: The effect of reaction parameters
Balázs Nagy, F. Török, Sz. Tomasek, Norbert Miskolczi
Abstract
The aim of this work was to synthesize vegetable oil-based additives that can compensate poor tensile properties and Charpy impact strength caused by the limited compatibility between PLA and starch. Three types of vegetable oils with different degrees of unsaturated compounds were used for additive synthesis: sunflower, rapeseed and castor oil. The reaction temperature (120, 140, 160 and 180 °C) and the necessity of xylene solvent for the additive synthesis were also investigated. Acid-numbers, unreacted MA-content, TG-FTIR and DSC tests revealed that the xylene solvent could be omitted in case of the castor oil-based additive. The effect of the additives on crystallinity and mechanical properties were also measured on 90/10 and 50/50 injection molded PLA/starch specimens. The mechanical properties of samples with lower starch content showed that the application of additives was successfull. The castor oil-based additive synthesized in the presence of a solvent at a temperature of 140 °C increased the tensile strength of the test specimen containing 10% starch by 20 MPa, its elongation at break by 3.4%, while the value of the Charpy impact strength increased from 1.2 kJm2 to 3.2 kJm2 increased.