Investigation of the Factors Affecting Crystallization Kinetics of PLA in Injection Molding

Abstract

As pollution and climate change become more prevalent issues in today's world, sustainable manufacturing is one way to reduce greenhouse gasses emitted by manufacturing industries. Today, many plastics are manufactured from non-renewable petroleum-based materials due to the many advantages that these materials have over renewable and bio-based materials. PLA (Poly Lactic Acid) is a sustainable alternative to other plastics that can be processed in the same way and suitable for various applications. However, products made of PLA materials cost more to manufacture and develop relatively weaker mechanical properties. Thus, this investigation focused on addressing these two issues to make renewable and biobased materials more appealing. The factors influencing PLA crystallinity and the best parameters for PLA in injection molding machines were studied theoretically and numerically. A relationship between cooling rate and crystallization kinetics and a relationship between cooling rate and crystal size were developed theoretically. The influence of nucleating agents on the crystallinity of injection molded PLA products was investigated. Moreover, Vibration Assisted Injection Molding (VAIM) was utilized and the influence of this technique on crystallinity and crystallization kinetics was investigated. Then, a relationship was drawn of the extent of the influence of nucleating agents on the effect of VAIM on crystallization kinetics and overall crystallinity. Different amounts of Nucleating agents were used and their influence on crystallinity with and without applying vibration was investigated.