Study On Modification Of Biodegradable Poly (Butylenes Succinate)

Poly(butylenes succinate) (PBS), as a aliphatic biodegradable material, is of great importance both to theoretical study and practical application. However, as a crystalline polymer, its performance and as well as its application will be affected by its crystallinity, crystal morphology and crystal structure. In addition, PBS can not be cast, blow molding in the production process due to its low molecular weight and viscosity but high MI. Moreover, the extended use of PBS in the field of biodegradable materials is also blocked with its high production costs which is due to high requirements on the pressure and temperature in the chemical synthesis preparation of PBS.Because of such shortcomings of PBS, the study on the modified PBS was discussed from reducing material costs, improving the mechanical properties and processing performance of PBS in this paper. Three modified PBS materials, containing PBS-based Gelatinized starch blends, modified PBS materials using MDI as chain extender, PBS-based modified starch nanocomposite materials, were prepared in this paper. Moreover, these three modified PBS materials were also discussed.Specific contents are as follows:1. First, the starch was processed by gelatinization treatment to destroy the crystalline regions of starch and so it became amorphous. Then PBS-based starch blends was prepared through the drying starch and PBS blending in the mixer. The influence of the content of gelatinized starch on the mechanical properties, melt index of PBS-based starch blends was discussed by controlling the content of gelatinized starch. The crystallization of PBS-based starch blends was analysed by the X-ray diffraction analysis. The results show that the crystal of PBS does not change, but its crystallinity reduces. The compatibility of PBS and gelatinized starch was observed by the scanning electron microscopy of the composite cross-section.2. Poly(butylene succinate) (PBS) was modified by chain extension using 4,4-diphenylmethane diisocyanate (MDI) as the chain extender. That the chain extension reaction happened between MDI and PBS was proved by Infrared spectra analysis. The thermal performance of modified PBS was characterized by Differential Thermal Analysis (DTA). The influence of the content of MDI on the mechanical properties, melt index, viscosity, and biodegradable properties of modified PBS was discussed by controlling the content of MDI. The results show that when the content of MDI was 1.5g, the effect of chain extension was best. Continuing to increase MDI, the effective chain extension reaction reduced and the cross-linking of PBS chains occurred. It is not conducive to the biodegradation of modified PBS.3. The modified starch nanocrystals were prepared successfully by the grafting reaction of toluene 2,4-diisocyanate(TDI) and starch nanocrystals in organic solvents. The modified starch nanocrystals were characterized by infrared spectroscopy analysis, X-ray diffraction analysis, Wettability tests and Contact angle measurements. The results show that the success of the grafting reaction of TDI and starch nanocrystals and the modified starch nanocrystals having a hydrophobic, low surface energy characteristics. Modified starch nanocrystals were also used as fillers to prepare PBS nanocomposites by melt blending.The PBS nanocomposites were characterized by FTIR, Differential Thermal Analysis (DTA), tensile testing and scanning electron microscopy. It is worth noting that the modified starch nanocrystals can be uniformly dispersed in the PBS matrix and the obtained PBS nanocomposites showed good thermal stability and enhancements in strength.The results of this research concerning the mechanical properties and processing performance of modified PBS provided important scientific foundation for the further study on the modification of PBS. It is conducive to the further application of PBS. Therefore, this study in this paper has theoretical significance and applied prospect on the modification of PBS.