Improving the ductility and heat deflection temperature of injection molded Poly(lactic acid) products: A comprehensive review

The widely used plastic products which became a part of our everyday life are produced almost entirely from crude oil. There are various estimates on oil resources, but there is an increasing need to use other, preferably renewable resources to produce plastic products. Although plastics from renewable resources, bio-based, and inherently biodegradable plastics, or so-called bioplastics/biopolymers, are already on the market, their properties are not always adequate compared to those of “ordinary” petroleum-based plastics, which the bioplastic is supposed to replace. One of the most promising bioplastics nowadays is Poly(lactic acid) (PLA). Despite the great potential of PLA to replace petroleum-based engineering plastics, such as Acrylonitrile Butadiene Styrene (ABS), Polypropylene (PP), and others, the inherent brittleness and low Heat Deflection Temperature (HDT) hinders the widespread application of PLA. Many methods have been developed to improve the properties of PLA, but its widespread industrial application is still rather an exception than the rule. The current study aims to survey the progress in the modification of the properties of PLA. We focused on the most effective additives to improve the properties of injection molded PLA products, which we selected from a comprehensive literature review. Most of the modification possibilities presented in this review can also be used for other processing technologies, but in the discussion, we focused on their use in injection molding