Study On Biodegradable Polyester Pha And Its Modification

With the rapid development of biotechnology, besides zymin, biosurfactant and some other biochemical engineering basic material, microbial polyesters, a structural material which is prepared from fermentation, is included in macromolecular material. And polyhydroxyalkanoates(PHA) has become one of the hot research on biodegradable materials. Because of the thermoplasticity as other polymers, biodegradable, environmental friendly and raw material is agricultural products, PHA is of great importance in reducing the needs for the basic natural resouce crude oil.The fourth generation of PHA-P(3HB-co-4HB) is the copolymer of3-hydroxybutyrate (3HB) and4-hydroxybutyrate(4HB), which is superior in physical and chemical properties and application than the ones of former generations. Because of the controllability of4HB content and the advantages of physical and chemical properties, the P(3HB-co-4HB) is advanced in machinability, thermostability, reducing melt temperature and degree of crystallization. Also the compatibility with other biodegradable materials of P(3HB-co-4HB) is preferably. With the increase of4HB content, the elasticity of P(3HB-co-4HB) is rising. So it can be made into biodegradable elastomer and adhesion agent. Besides, P(3HB-co-4HB) can be made into many other biodegradable products and modifier of other materials.In our research, OMMT, PEG10000and chain extender are used as modifier to the fourth generation of PHA--P(3HB-co-4HB). And polarizing microscope with a heating stage, capillary rheometer, differential scanning calorimeter(DSC) and thermogravimetric analysis(TGA) are used to investigate P(3HB-co-4HB) and OMMT/PEG10000/chain extender modified P(3HB-co-4HB). The fiber of P(3HB-co-4HB) and P(3HB-co-4HB)/PEG10000are also prepared and electronic single-yarn strength tester, sound velocimeter are used to investigate the mechanical property and sound speed of the fiber. Scanning electron microscope(SEM) is used to observe P(3HB-co-4HB)/PEG10000blending system. The result shows that:the crystallization of P(3HB-co-4HB) is sphaerocrystal; pure P(3HB-co-4HB) is sensitive to both temperature and shear rate; the rheology property is improved with the addition of PEG10000, which also lower the activation energy; the addition of chain extender lower the sensitivities both to temperature and shear rate.Our research in P(3HB-co-4HB) and the modification to P(3HB-co-4HB) is of importance to the fourth generation in the process from theoretical research to practical application.