Mikael Stolt

Properties of lactic acid based polymers and their correlation with composition

Abstract This review focuses on the properties of lactic acid based polymers and the correlation to the structure of the polymers. Lactic acid based polymers prepared by polycondensation (PC), ring-opening polymerization (ROP), and other methods (chain extension, grafting) are discussed as well as modifications where structural changes have occurred due to post-polymerization reactions (peroxide melt-modification, radiation processing). The different types of polymers include copolymers prepared by ROP from l , l -lactide and d , d -lactide, glycolide (GA), e-caprolactone (CL), trimethylene carbonate (TMC), 1,5-dioxepan-2-one (DXO), and other cyclic analogues. The thermophysical properties, the solubility, the miscibility, and the mechanical properties have been reviewed. In addition the hydrolytic stability, the thermal stability, the radiation degradation, and the biodegradation of the polymers have been covered.

Readily Controllable Step-Growth Polymerization Method for Poly(lactic acid) Copolymers Having a High Glass Transition Temperature

Poly(lactic acid) (PLA) copolymers having a significantly higher glass transition temperature (T(g)) than that of high molar mass PLA homopolymers (typically 60 +/- 5 degrees C) were prepared. Lactic acid was copolymerized with 1,4:3,6-dianhydro-D-glucitol (isosorbide, ISB) and succinic acid (SA-2), 1,2,3,4-butanetetracarboxylic acid (BTCA-4) or 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (HCA-6). The highest T(g)s obtained for the copolymers containing BTCA-4 and HCA-6 were 80 and 86 degrees C, respectively. The polymers were prepared by step-growth polymerization in the melt phase, which is an easily operable and simple PLA production method in comparison to the ring-opening polymerization (ROP) route. It was shown that the T(g) and the cross-linking induced by the polyfunctional carboxylic acid comonomers could be readily controlled by choosing a suitable polymerization time and temperature. Similar improvement in the T(g) as achieved for the copolymers of BTCA-4 and HCA-6 was not observed for linear copolymers containing ISB and SA-2.