Preparation And Properties Of Polylactic Acid / Polycarbonate / Clay Composite Membrane

Based on the pathway analysis, three lactic acid bacteria named syl, sy3and sy4were screened from10bacteria stains isolates from the sour fish which are made by Dai people families in the Prefecture of De Hong. And they were identified as Lactobacillus plautarum by conventional identification methods and16S rDNA sequencing analysis. The fermentation analysis showed that three strains of bacteria produce lactic acid quickly within24-hour cycle, and they can grow in the condition that pH value was fall below3.5, furthermore, the calcium lactate content76g/L for syl,90g/L for sy3and84g/L for sy4was detected in96-hour fermentation broth.In this paper, a suitable synthetic method was chosen to get trimethylene carbonate (TMC) monomer, using ethyl acetate to purify TMC monomer, so that the polymerization of PTMC can achieve ideal effect.Poly(L-lactic acid)(PLA) is now a very attractive polymer for food packaging applications. In this study, PLA/poly(trimethylene carbonate)(PTMC)/composite films were prepared by solvent casting. The influence of the talc loading (0,1,2, and3wt%) on the phase morphology of the PLA/PTMC/talc composites and the improvement in the resulting properties are reported in this article. The scanning electron microscopy images of the composite films demonstrated good compatibility between the PLA and PTMC, whereas talc was not thoroughly distributed in the PLA matrix at talc contents exceeding3wt%. The tensile strength and elongation at break of the composite films significantly improved (p<0.05). On the contrary, the water vapor permeability and oxygen properties of the composite films decreased by24.7and39.2%, respectively, at the2wt%talc loading. Differential scanning calorimetry showed that the crystallinity of the PLA phase increased with the presence of talc filler in the PLA/PTMC/talc composites.Poly(1-lactide)-co-poly(trimethylene carbonate)(PLA-PTMC) composites with various talc content as food packaging materials were prepared by solvent casting method. The effect of talc filler loading (0,1,2, and3wt%) on phase morphology of PLA-PTMC/talc composites and improvement in resultingproperties were reported. The X-ray diffraction (XRD) patterns and differential scanning calorimetry(DSC) curves indicated that the crystallinity of PLA-PTMC/talc composites increased. Fourier transforminfrared spectroscopy (FTIR) suggested that there were strong interactions between PLA-PTMC copoly-mer and talc filler. The scanning electron microscopy (SEM) image of composite films revealed certainhomogeneity between PLA-PTMC and talc, when the talc filler did not exceed3wt%. The elongation atbreak of composite films significantly (p<0.05) improved with the addition of talc filler. Furthermore,there were23%,31%, and14%improvement in water vapor barrier properties at1,2, and3wt%of talc inPLA-PTMC/talc composites, respectively. This had been confirmed by thermogravimetric analysis (TGA).In the study, the methods for preparation food packaging materials which needs to improve the barrier properties have certain application reference value. The results showed that the composite films which we have developed can be used for the development of new type of food packaging materials.