Aging and biodegradation

The biological degradation of PLA is less than other aliphatic polyesters such as PBS and PCL (Hirotsu et al, 2000). PLA degrades in moisture and at elevated temperatures. Reformation monomer, hydrolysis, and thermolysis are 

10 DSC curves of physical aged poly (lactic acid) (PLA)/starch/ methylenediphenyl diisocyanate (MDI) (55/45/0.1) blends (Wang eta/., 2003). 

A t5 ical degradation of PLA under composting conditions is shown in Fig. 10.11 (Baiardo et al, 2003). For a product of at least 1mm thickness, degradation is faster inside than at the surface because of diffusion-reaction 

0 37 No Random in amorphous region Random in amorphous region Random in amorphous region Bulk Bulk Surface 

4 37 Proteinase K Predominant cleavage at chains with free ends and tie chains in amorphous region Surface 

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Melcher, R. J., Apitz, S. E. Hemmingsen, B. B. (2002). Impact of irradiation and polycyclic aromatic hydrocarbon spiking on microbial populations in marine sediment for future aging and biodegradability studies. Applied and Environmental Microbiology, 68, 2858-68. 

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