Crystallization Behaviors of Poly (Lactic Acid) Modified with ST-NAB3 and Its Improved Mechanical and Thermal Properties

• Published in: Journal of polymers and the environment 2023-12, Vol.31 (12), p.5166-5184
• Main Authors: Dun, Dongxing, Bai, Yu’an, Wang, Longzhen, Xu, Bo, Zhou, Hongfu, Wang, Xiangdong
• Format: Article
• Language: English
• Subjects: Biodegradation; Chemistry; Chemistry and Materials Science; Crystallization; Emissions; Environmental Chemistry; Environmental Engineering/Biotechnology; Greenhouse gases; Heat resistance; Impact strength; Industrial Chemistry/Chemical Engineering; Kinetics; Materials Science; Nucleation; Optical microscopes; Original Paper; Pollution control; Polylactic acid; Polymer Sciences; Thermal properties; Thermal resistance; Thermodynamic properties
• ISSN: 1566-2543; 1572-8919
• DOI: 10.1007/s10924-023-02935-6

Biodegradable poly (lactic acid) (PLA) as a great substitute for petroleum-based plastics was widely used to reduce environmental pollution resulted by greenhouse gas emissions. However, the practical application range of PLA was limited due to the inherently poor crystallization, mechanical and heat resistance properties. In this context, a heterogeneous nucleating agent (HNA) was incorporated into PLA matrix to address the problems mentioned above. The effects of HNA on the crystallization kinetics of PLA were explored by Avrami method. Isothermal and nonisothermal crystallization kinetics of PLA/HNA systems containing various HNA contents (0–0.75 wt.%) proved that HNA could generate the heterogeneous nucleation of PLA matrix and effectively improve its crystallization rates. The t 1/2 of PLA/HNA-0.75 composite decreased to 2.35 min compared with 34.12 min for pure PLA at isothermal temperature of 135 °C. The crystallinity of PLA/HNA-0.75 composite was enhanced by 42.1% in contrast with pure PLA. The “shish-kebab” structure of PLA/HNA composites containing various HNA contents (0.25–0.75 wt.%) was observed by polarized optical microscope as the concentration of HNA exceeded 0.375 wt.%. PLA/HNA-0.75 composite possessed the highest unnotched izod impact strength (33.6 kJ/m 2 ), notched izod impact strength (4.3 kJ/m 2 ) and heat deformation temperature (73.2 °C). In general, a feasible method was proposed for preparation of PLA with excellent mechanical and heat resistance properties through this work.