| With the rapid development, polymers are becoming more and more important in our daily life and are used in many fields for its excellent properties. But most synthetic polymers do not degrade in nature, which cause environment pollution. It is impending to put new Polymer materials into use. It can before seen that natural polymers being capable of regeneration, will playa significant role in the future.Therefore, natural polymer materials have attracted much attention recently. Amongnatural polymer materials, cellulose, starch and chitin exist extensively. A lot of research has been focused on starch due to its advantages such as regeneration, biodegradability, easy accessibility and low cost. As we known, starch is a biodegradability material, but if we directly blend the polymer with it witch be used as a additive, it is not work commendably in consistent capability and processing. So this paper makes the originality starch by modifying in the first place.In this paper, Modified tapioca starch was prepared by using epichlorohydrin for cross-linking and orthophosphate for esterification reaction. It is analyzed interaction effect to dual-factor on the degree of substitution (DS) of cross-linking and esterification by the response surface analysis of the design-expert 6.0.10 software. The influences of reaction conditions such as reaction time, reaction temperature, ratios of reactants, etc on the synthesis of modified tapioca starch are . discussed. It can be concluded that Prolonged reaction time, suitable using level of ratios of reactants, and suitable ratio of esterification may raise DS, prolonged reaction time has little effect on starch degradation while elevating reaction temperature will degrade starch severely. The structures of the starch acetates have been characterized by FTIR, DSC, X-ray diffraction measurements. Infrared spectra show that the hydroxyl groups of the samples are really substituted since the stretching peak of hydroxyl around 3000 cm-1~3700 cm-1 decreases dramatically withthe increase of DS. The distinguished stretching peck of phosphate around 1400 cm"1 show that phosphate group is really introduced into starch structure. The results of X-ray diffraction show that the crystal structure of amylose starch and the starch phosphate differs greatly which implies that the crystal structure is damaged during substitution. The results of SEM show that the modified starch surface appears various degrees dent and interstice. The destruction starch granule increases dramatically with the increase of DS.As one of the most important biodegradable materials, PCL is used to blend with phosphate starch in this paper. Just as foregoing mention, if we directly blend the polymer with it witch be used as a additive, it is not work commendably in consistent capability and processing. So the modified starch is selected. DSC result shows that the modified starch and PCL are partly miscible, and there are some interactions between the two components. The addition of the modified starch hinders the order stack of PCL molecular chain. The melt points of the PCL in the blends decrease.The blends of PCL/the modified tapioca starch are spun into fibers in this paper. The properties of fibers are characterized by sound velocity test, mechanical test and X-ray diffraction measurement With the increase of drawing ratios the degrees of orientation crease, especially for the blend fibers. After drawing, the degree of crystallization of the fibers increases to some extent. The tensile strength of PCL/the modified tapioca starch blend fibers increase with the increasing of drawing ratios...
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