【作者】 马晓录；

【导师】 成国祥；

【作者基本信息】 天津大学 ， 材料学， 2005， 博士

【摘要】 大豆蛋白质(SP)、聚羟基丁酸酯(PHB)、3-羟基丁酸与3-羟基戊酸的共聚物(PHBV)均为天然生物可降解聚合物。但SP分子中的氢键作用、自组装和亲水性使其耐水性、耐湿性和力学性质稳定性较差。而PHB、PHBV存在结晶度高、脆性大等不足。本文针对它们的分子结构特点,采用共混、共聚手段,通过在SP与PHB或SP与PHBV之间形成一定程度的大分子组装或调节它们的大分子组装状态,达到了改善SP/PHB、SP/PHBV的综合性质的目的。首先,利用SP的7S和11S在冷水中的不同溶解性,制备了富含11S的大豆分离蛋白(SPIG)。研究表明,SPIG比其它SP产品有更低的吸水性。然后,采用熔融模压法制备了SPIG/PHB和SPIG/PHBV及低分子量PHB(LPHB)与SPIG的共混物,研究了共混改性的效果和机理。以乙二醇、甘油、木糖醇、三油酸甘油酯、环氧大豆油为添加剂,探讨了这些小分子对SP/PHB的改性作用。采用溶液共聚法制备了SPI-co-PHB,探索了PHB共聚改性SP的效应。采用DSC、DMA、FTIR、SEM、PLM、固态13C NMR、拉伸测试、激光粒度仪、SDS-PAG凝胶电泳、吸水率测定、生物降解速率测定等方法表征了共混物或共聚物的聚集态结构和性质。研究表明,在共混物中,PHB、PHBV、LPHB与SP产生了分子间氢键,破坏了各自原刚硬的自组装结构,形成了新的分子间组装结构,使PHB、PHBV在SP含量较高时难以组装成较大的球晶,甚至以片晶束与SP共存,并阻止了PHB、PHBV的二次结晶,且疏水性PHB、PHBV组装到SP亲水性基团上而形成疏水薄膜层,从而,改善了SP的力学性质、耐水性、耐湿性及力学性质稳定性。研究还表明,乙二醇、甘油、木糖醇、三油酸甘油酯、环氧大豆油对SPIG/PHB有良好的增塑效果,但前三者因自身吸水性高而导致共混物持耐水耐湿性有所降低,而后两者的疏水性使共混物耐水性略有增加。研究还表明,PHB可与SP共聚,并改变SP和PHB的自组装状态,改善SP聚合物的强度和韧性,且因在SP中引入PHB,使共聚物具有耐水耐湿性。研究还表明,SP/PHA共混物降解速率高于SP,但添加甘油等小分子使SP/PHB的降解速率低于纯SP,而SPI-co-PHB的降解速率与SP相差不大。更多还原

【Abstract】 Soy protein (SP), poly(3-hydroxybutyrate) (PHB), the polymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid (PHBV) are natural biodegradable polymers. But hydrogen-bonding, self-assembly in SP macromolecules and its hydrophilic property result in low water resistance or moisture resistance and unstable mechanical properties of SP. Moreover, britlleness of PHB and PHBV is high for their high degrees of crystallinity. In the study, based on characteristics of SP, PHB and PHBV, macromolecular assembly was formed to some extent or the states of macromolecular assembly was modified by blending or copolymerization. Resultingly, the properties of SP were improved.Firstly, a soy protein isolate (SPIG) with rich 11S was prepared by the difference in solubility of 7S and 11S in water at relatively low temperature. The water sorption of SPIG is lower than other SP products by the study on it.Secondly, SPIG/PHB, SPIG/PHBV and SPIG/LPHB (the PHB with low molecular-mass) were prepared by blending them respectively. Effects of PHB, PHBV and LPHB on improving properties of SP were researched. Mechanism of the improvement of the properties was proposed. Effects of glycol, glycerol, xylitol, epoxidized soy oil and triolein on SPIG/PHB were investigated. A SPI-co-PHB copolymer was prepared by solution-polymerization. Effect of the copolymeration on improving properties of SP was studied. The morphology and properties of all of the blends prepared here and the SPI-co-PHB were characterized by DSC, DMA, FTIR, SEM, PLM, 13C solid-NMR, the test of strength, BIC Particle Sizing, SDS-PAG, water sorption test and biodegradation rate test.It is revealed that hydrogen-bonds formed between SP and PHB, PHBV, LPHB, respectively, conversely, rigid self-assembling structures of SP, PHB, PHBV and LPHB privately were partly altered into intermacromolecular assembly, resulting in that PHB and PHBV could not assembled into big spherulites, or only formed lamellar-beams distributed in SP. The secondary crystallization of PHB and PHBV was inhibited also. Mechanical properties, water and moisture resistance and the stability of mechanical properties of the blends based on SP were improved because hydrophobic PHB and PHBV assembled to hydrophilic groups of SP and constructed a layer of film round the hydrophilic groups. It is indicated that toughness of SPIG/PHB was enhanced by glycol, glycerol, xylitol, epoxidized soy oil and triolein. However, high hydrophilicity of the former three additives decreased slightly water resistance of their blends. Conversely, hydrophobic nature of the farmer two additives increased lightly water resistance of the blends added the farmer. It is exhibited that PHB may copolymerize with SP. The self-assembly of SP and PHB privately was changed in the copolymerization. The strength and roughness of the copolymer based on SP were improved by copolymerization. Water resistance of the copolymer is high for copolymerizing PHB. It is indicated that the SP/PHA blends have higher biodegradation rates than pure SP. The biodegradation rate of SPI-co-PHB is near to pure SP.更多还原