Plasticizer Enhancement on the Miscibility and Thermomechanical Properties of Polylactic Acid-Chitin-Starch Composites

2022.10.18

The role of natural polymers as substitutes for synthetic polymers has been increasing. Among them, degradable packaging materials to solve the pollution problem have led to the widespread use of biopolymers such as starch, cellulose and chitin. These biopolymers are abundant on Earth and have been used and processed into different forms. But these forms of biopolymers have a major drawback in their mechanical properties.

In previous studies, a polylactic acid chitin starch composite was prepared without solvent to improve miscibility. In this study, a polylactic acid (PLA) chitin starch composite was prepared with chloroform as plasticizer at a ratio of 1:10.

Fig.1. Scanning electron microscope images for samples with the ratios A-92% polylactic acid (P)/8% chitin (C); B-92% P/6% C/2% starch (S); C-92% P/4% C/4% S; D-92% P/2% C/6% S; E-92% P/8% S; F-100% P

The blends of chitin and starch with polylactic acid were 2%~8%. Tensile strength, impact, thermogravimetric analysis-Fourier transform infrared spectroscopy (TGA) -FTIR and differential scanning calorimetry (DSC) were used to test the thermodynamic properties. The morphological properties, water absorption and wear rate of the material were also observed. The results show that the tensile strength, yield strength and impact strength are improved compared with pure POLylactic acid. Compared with pure polylactic acid, the elastic modulus of the sample is increased, but it is also lower. The results of fracture surface morphology show good miscibility, indicating the good mechanical properties recorded in the study. Thermogravimetric analysis (TGA) and derivative thermogravimetric analysis DTA showed a single degradation and peak, respectively, which was also shown in the glass temperature measurements from the DSC analysis. Water absorption test showed that water absorption increased with the increase of starch content, and sample A (92% P/8% C) was the highest. Using chloroform as plasticizer, high miscibility was achieved in the absence of void.

Fig.2. FTIR plot of samples A-92% polylactic acid (P)/8% chitin (C); B-92% P/6% C/2% starch
(S); C-92% P/4% C/4% S; D-92% P/2%C/6% S; E-92% P/8% S; F-10

Plasticizer Enhancement on the Miscibility and Thermomechanical Properties of Polylactic Acid-Chitin-Starch Composites Download

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