PROCESSING TECHNOLOGIES, PROPERTIES AND APPLICATION OF POLY (LACTIC ACID) (PLA)

Abstract

Poly (lactic acid) (PLA) is a one of substitutions to fossil-based polymers because they have a less influence on the environment. Material sustainability requirements have increased importance of PLA polymers and others similar biopolymers. PLA polymeris an aliphatic polyester, usually produced by ring-opening polymerization or by polycondensation of lactic acid. For the production of PLA components, melt processing is one of the most commonly used techniques. Today, processing technologies of PLA components include injection moulding, hot pressing, spinning, blow moulding, foam moulding, electrospinning, 3D printing, and so on. PLA polymers have better thermal workability than most bio-based polymers. The analysis of mechanical properties, structure in processes, and an appropriate application of PLA is done in this paper. Also this paper summarizes variations in thermal degradation, recyclability, biodegradation and aging during PLA processing and application. The tensile strength and modulus of elasticity of PLA polymers is similar to those of conventional polyesters. But, because PLA polymers are biodegradable, they can change properties if exposed to uncontrolled temperature and humidity conditions. PLA polymers have lower toughness than those of conventional polyesters. Toughness could be improved by development of PLA composites. PLA is safe for use in the manufacturing of products that are in contact with food. European Food Safety Authority (EFSA) recognize PLA as material which can be safely employed as a food packaging material without causing adverse health effects. PLA possesses barrier properties that are just as effective as LDPE and PS. Limited antibacterial properties of PLA can be improved by application of antibacterial agents. Generally high price of PLA polymers limits their application as a packaging material. Biodegradable PLA polymers are suitable for a wide range of industrial, biomedical and pharmaceutical applications, such as material for medical implants, resorbable prostheses, controlled drug release, biodegradable joints and supports for tissue engineering. Development of processing methods is needed for sufficient increase the industrial application of PLA polymers. Suitable methods to minimize the disadvantages of PLA can be blending PLA with other materials, creating micro- and nanocomposites, coating with high-barrier materials, and polymer modification.