Study On Selective Degradation Of Poly(3-Hydroxybutyrate-co-4-Hydroxybutyrate)/Polylactide Blends

In recent years, White Pollution has become a serious environmental problem. Therefore,biodegradable materials received widespread attention worldwide. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) and polylactic acid are all this kind ofbiodegradable materials. In this paper, biodegradable poly (3-hydroxybutyrate-co-4-hydroxylbutyrate)(P3HB-co-4HB)/PLA blends were prepared by melt compounding.Pseudomonas mendocina DSWY0601and Aspergillus sp.0906were chose to degrade P(3HB-co-4HB)/PLA.The main results obtained from this work are as follows:1. The strain of Pseudomonas mendocina DSWY0601was cultivated on solid agarmedia which contain the polymer as a sole source of carbon. Around the Pseudomonasmendocina DSWY0601colonies form a large and clear hydrolytic zone on theP(3HB-co-4HB) powder agar medium. Four days later, the diameter of the clearing zones was4centimeters. The biodegradation of P (3HB-co-4HB) films indicated that on the14th day theP (3HB-co-4HB) films were thoroughly degraded under the flask culture in the laboratory.This result suggests that Pseudomonas mendocina DSWY0601has strong ability ofdegradation of P (3HB-co-4HB).2. The optimum temperature、pH、rotation speed and inoculums dose of P(3HB-co-4HB)and P(3HB-co-4HB)/PLA blends-degradation by Pseudomonas mendocina DSWY0601are all35℃、8、140r/min and3~5%,respectively.3. Silica can enhance the the rate of degradation of P(3HB-co-4HB) by Pseudomonasmendocina DSWY0601.The more the content of4HB in P(3HB-co-4HB) is, the faster thedegradation of P(3HB-co-4HB) is. Considering the degradation rate, when the P(3HB-co-4HB) is degraded, mixed bacteria of Pseudomonas mendocina DSWY0601andAspergillus fumigatus0906can be chose. When the P (3HB-co-4HB)/PLA is degraded,Pseudomonas mendocina DSWY0601can be chose.4. When the proportion of P (3HB-co-4HB) and PLA is40:60and50:50, it is suitablefor forming porous structure which has appropriate pore size and pore size distribution. Andthe content of4HB in P (3HB-co-4HB) can be changed to form specific porous structure. Themore the content of4HB in P (3HB-co-4HB) is, the larger and deeper the pore is. But thedirect relationship between porous structure and components remains to need further research.