Thermal Stability and Processing of Renewable Polymers

In this section we summarize some of the key temperatures, such as 7)n, Eg, and that for the onset of thermal degradation (Tc) for renewable polymers. In general, most of these 

TABLE 11.10 Summary of Thermal Properties of Renewable Polymers Based on PLA and PHB 

We start with a brief discussion of PLA because of the wide range of structures and associated properties (Rudnik, 2008). The basic chemical structure of PLA is shown in Table 

PLA is a compostable/biodegradable plastic derived from the polymerization of lactic acid, which is predominantly produced via fermentation of sugar or starch and, to a lesser extent, via chemical catalysis. Lactic acid exists in optically active d- or L-enantiomers, and their polymer versions are noted as PDLA and PLLA, respectively. The copolymer of the two enantiomers is also called PDLLA. The proportion of the enantiomers in PLA determines its properties and the process used to form the PLA articles (e.g., blow molding, injection molding, thermoforming). 

are highly dependent on the copolymer ratio of the two enantiomers and, as such, this polymer deserves separate attention as the properties vary widely. Generally, commercial PLA grades are copolymers of poly(L-lactic acid), PLLA, and poly(D,L-lactic acid), PDLLA, which are produced from 

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