1. Introduction In recent years, considerable research effort has been devoted to the use of polymeric biodegradable materials in plastics applications, such as packaging, to reduce the environmental impact related to the accumulation of plastics waste from the day-to-day applications of plastic materials based on traditional polymers, such as polyethylene terephthalate (PET), polyethylene (PE), etc. [1, 2]. One of the promising polymers used in these applications was the poly- lactic acid (PLA), which was an aliphatic polyester derived from lactic acid (2-hydroxypropionic acid) [3]. First, PLA with a low-molecular weight was synthe- sized by Carothers in 1932 [4, 5]. Further work by DuPont resulted in a higher-molecular weight prod- uct patented in 1954 [6]. Accordingly, two methods were used to produce the basic block of PLA, lactic acid (LA): the chemical synthesis was based on petrochemical feedstock and carbohydrate fermen- tation (Figure 1). Although the former was more familiar to chemists, the fermentation of natural mate- rials containing carbohydrates, such as rice, corn, etc., was the main method used to produce LA (>90%). Datta and Henry [7] examined the synthe- sis and purification technologies of LA that were found in two enantiomers, L- and D-lactic acid. The results reported in that work showed that a 50/50 optically inactive mixture of L and D could be pro- duced via a chemical route. In contrast, fermenta- tion-derived lactic acid existed almost exclusively as L-lactic acid. The ability to produce the L-isomer in high purity possessed important ramifications in chemistry and the ultimate process/property rela- tionships achievable in the polymers produced from lactic acid. 435 Properties and medical applications of polylactic acid: A review K. Hamad 1 , M. Kaseem 1 , H.W. Yang 1 , F. Deri 2 , Y. G. Ko 1* 1 Plasticity Control & Mechanical Modeling Laboratory, School of Materials Science & Engineering, Yeungnam University, Gyeongsan 712–749, South Korea 2 Laboratory of Materials Rheology, Department of Chemistry, University of Damascus, Damascus, Syria Abstract. Polylactic acid (PLA), one of the well-known biodegradable polyesters, has been studied extensively for tissue engineering and drug delivery systems, and it was also used widely in human medicine. A new method to synthesize PLA (ring-opening polymerization), which allowed the economical production of a high molecular weight PLA polymer, broad- ened its applications, and this processing would be a potential substitute for petroleum-based products. This review described the principles of the polymerization reactions of PLA and, then, outlined the various materials properties affect- ing the performance of PLA polymer, such as rheological, mechanical, thermal, and barrier properties as well as the pro- cessing technologies which were used to fabricate products based on PLA. In addition, the biodegradation processes of products which were shaped from PLA were discussed and reviewed. The potential applications of PLA in the medical fields, such as tissue engineering, wound management, drugs delivery, and orthopedic devices, were also highlighted. Keywords: biodegradable polymers, polylactic acid, properties, medical applications eXPRESS Polymer Letters V Available online at www.expresspolymlett.com * Corresponding author, e-mail: younggun@ynu.ac.kr © BME-PT