Improvement of the PLA Crystallinity and Heat Distortion Temperature Optimizing the Content of Nucleating Agents and the Injection Molding Cycle Time

• Published in: Polymers Vol. 14; no. 5; p. 977
• Main Authors: Aliotta, Laura, Sciara, Letizia Maria, Cinelli, Patrizia, Canesi, Ilaria, Lazzeri, Andrea
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 28.02.2022; MDPI
• Subjects: Biopolymers; Calcium carbonate; Crystal structure; Crystallinity; Crystallization; Cycle time; Density; Heat resistance; Impact resistance; Impact strength; Injection molding; Manufacturing; Mechanical properties; Modulus of rupture in bending; Molding parameters; Particle size; Polylactic acid; Polymer blends; Polymers; Quantum dots; Talc; Thermal stability; Thermomechanical properties; France; Italy; Paris France; impact strength; poly (lactic acid); nucleating agent; injection molding; heat deflection temperature
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym14050977

Three different commercial nucleating agents (LAK, talc, and calcium carbonate) were added at different weight percentages into poly (lactic acid) (PLA) in order to investigate the mechanical and thermo-mechanical behavior of blends in correlation to injection molding parameters. After as-sessing the best content of each nucleating agent, analyzing isothermal and non-isothermal crys-tallization, two cycle times that can be industrially adopted were selected. Crystallinity highly impacts the flexural modulus, while it improves the heat deflection temperature only when the crystallinity percentage is above 50%; nevertheless, an excessive crystallinity content leads to a decrement of impact resistance. LAK does not appear to be sensitive to cycle time while talc and calcium carbonate proved to be effective if a cycle time of 60 s is adopted. Since the choice of nu-cleating agent is not univocal, the identification of the best nucleating agents is subject to the technical specifications required by the application, accotuing for the most important commercial requirements (productivity, temperature, and impact resistance).