Molecular weight reduction biodegradability

The polyesters in the form of films of 5x5 cm in size and approximately 2 mm thickness, prepared in a hydraulic press, were placed in petries containing phosphate buffer solution (pH 7.2) with 1 mg/mL Rhizopus delemar lipase. Usually enzymatic hydrolysis studies are performed at 37°C. However this temperature is very close to the melting point of PPSu. So, in this case the tests were performed at 30 1°C. The degree of biodegradation was estimated from the mass loss and molecular weight reduction as measured by GPC. 

On the contrary, chitosan holding in an acetic acid solution in the presence of the enzymes leads to considerate reduction in the sedimentation constant and increase of the diffusion coefficient (see Table 8.1). Thus, it results in significant reduction of the chitosan molecular weight taking place during the biodegradation process. 

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