Polydactic acid

Poly(lactic acid)s (PLA)s have been produced for many years. PLAs resemble clear poly(styrene) and have good gloss and clarity for aesthetic appeal, along with physical properties weU suited for use as fibers, films, and thermo-formed packaging. PLA is biocompatible and have been used extensively in medical and surgical applications, i.e. sutures and drug delivery devices (1). 

PLA can exist as two optically active forms L-PLA and D-PLA (2). PLA can have any suitable D/L ratio. The ratio of D/L plays an important role for the thermal and physical properties of the PLA. PLA having a high L-enantiomer content t5 ically is more crystalline and has a longer degradation time, whereas PLA having a high D-enantiomer content is more amorphous and has a shorter degradation time (2). 

Atactic PLA has been prepared by polymerization of a lactide race-mate. It has an amorphous structure. Isotactic PLA has been prepared by the polymerization of D-lactide or a L-lactide and it is crystalline. Syndiotactic PLA can be obtained from cyclic dimer of lactic acid, e.g., meso-lactide (3). Production processes of PLA resins include (4)  

A process of subjecting lactic acid or a mixture of lactic acid 

A process of ring-opening polymerization in which a cyclic dimer of lactic acid (lactide) is melted and pol5m erized (6,7) 

---

T.Ochi, Y. Maeda, and H. Ohme, Polymer alloy fibers with good biodegradability and abrasion resistance consisting of blends comprising polydactic acid) and polyacetals, Japanese patent JP 2003227037 A2, assigned to Toray Industries, Inc., Japan, August 15, 2003. 

Starch is the major carbohydrate reserve in higher plants and has been a material of choice since the early days of human technology. Recently starch gained new importance as a raw material in the production of plastics, in particular, for the synthesis of monomers to produce polymers such as polydactic acid) and, after chemical modification (e.g. esterification) and thermomechanical processing, to produce thermoplastic starch. This chapter gives a general overview of the most recent research on the development of materials from starch, focusing on thermoplastic starch and the perspectives for future development in this field. A brief review on reactive extrusion of thermoplastic starch is also provided. 

A degradable high molecular weight polydactic acid) can be produced by the following mechanism (1) Having a terminal end group of one of the... 

Keywords Polydactic acid), poly(lactide), biopolymer, PLA synthesis, degradation, crystallization, mechanical properties, barrier properties, process, applications, automotive, packaging... 

Verrecchia T, Spenlehauer G, Bazile DV, Murry-Brelier A, Archimbaud Y, Veillard M. Non-stealth (polyflactic acid/ albumin)) and stealth (polydactic acid-polyethylene glycol)) nanoparticles as injectable drug carriers. J Contr Rel 1995 36 49-61. 

Poly(alkyl cyanoaaylate) Polydysine) derivatives Polydactic acid) Polydactide-co-glycolide) Poly(P-hydroxy butyrate) Ethyl cellulose Poly(alkyl methacrylate) Polydactic add) Polydactide-co-glycoUde) Poly(l -caprolactone) Cellulose acetate phthalate Poly(alkyl methacrylate) Ethyl cellulose Polydactic acid) Polydactide-co-glycolide) Albumin Casein Gelatin... 

Figure 8.4 Thermal history of PLA polymer during one- and two-stage PLA bottle manufacturing. (Reprinted from Polydactic acid) - Synthesis, Structures, Properties, Processing, and Applications-, Chapter 14, L.-T. Urn., Processing of Polydactic Acid), Copyright (2010), with permission from John Wiley Sons, Inc. [94J.)...

Hirata, M. and Kimura, T. (2010) Structure and properties of stereocomplex-type polydactic acid), in Poly(Lactic Acid) Synthesis, Structures, Properties, Processing, and Applications (eds R. Auras, L.-T. Lim, S.E.M. Selke and H. Tsuji), John WUey Sons, Inc., NJ, pp. 59-65. 

Tsuji, H., Nakano, M., Hashimoto, M. etal. (2006) Electrospinning of polydactic acid) stereocoraplex nanofibers. Biomacromolecules, 7, 3316-3320. 

Hyon, S.H., Jamshidi, K., Ikada, Y. et al (1985) Bone Filler from Polydactic acid)-Hydroxyapatite Composites. Kobunshi Ronbunshu, 42,771-776. 

Blending of starch with aliphatic polyesters improves their processability and biodegradability Particularly suitable polyesters are poly(s caprolactone) and its copolymers, or polymers of higher melting point formed by the reaction of 1,4-butandiol with succinic acid or with sebacic acid, azelaic acid, or polydactic acid), poly(hydroxyalkanoates), and aliphatic-aromatic polyesters. 

Cellulose Fiber Reinforced Polydactic acid) (PLA) Composites 183... 

---