【作者】 李婷婷；

【导师】 俞建勇；

【作者基本信息】 东华大学 ， 纺织材料与纺织品设计， 2007， 硕士

【摘要】 随着固体废弃物所带来的环境污染问题的日益严重，生物可降解高分子材料越来越引起人们的重视。脂肪族／芳香族共聚物结合了脂肪族聚酯的生物可降解性能和芳香族聚酯优良的机械性能已成为可降解材料中的研究热点，共聚酯聚丁二酸丁二醇-共-对苯二甲酸丁二醇酯(PBST)就是其中之一。目前，PBST共聚酯的研究仅限于薄膜，如能利用PBST共聚酯制备纤维，将极大地扩展其应用领域。在此背景下，本文通过缩聚反应合成PBST共聚酯，着重研究了PBST的流变性能、成纤性能，分析了纺丝工艺对PBST纤维的结构和性能的影响，成功研制出力学性能优良的PBST纤维，为PBST纤维工业化生产提供了理论依据和实践经验。首先，以对苯二甲酸二甲酯、丁二酸二甲酯、1，4-丁二醇为原料，以四异丙氧基钛为催化剂合成PBST共聚酯。通过氢谱核磁共振(~1H NMR)表明共聚物结构中芳香族BT链锻含量约为70％，与投料比例相近；凝胶渗透色谱仪(GPC)表明所合成的PBST共聚酯重均分子量分布在9×10~4～1.4x10~5；通过乌氏粘度计测试其特性粘度η分布在0.7～1.1dL／g；熔融指数测定仪测试其熔融指数MI分布在23～50／10min；采用密度梯度法测定共聚物密度ρ分布在1.28～1.29g／cm~3，为聚合物的应用提供了的重要参数。其次，利用差示扫描量热仪(DSC)、热重分析仪(TGA)、广角X衍射仪(WAXD)、偏光显微镜(POM)等研究了PBST共聚酯的热学及结晶性能，结果表明共聚物有良好的热性能，熔融温度T_m、热分解温度T_d分别可达180℃、380℃；共聚物为半结晶高聚物，有着近似PBT的晶体结构。利用毛细管流变仪分析了PBST共聚酯的流变性能，研究结果表明PBST的表观粘度随剪切速率的增加而降低，是典型的切力变稀型非牛顿流体；随着熔体温度的上升，表观粘度对剪切速率的依赖性下降；PBST熔体的粘流活化能随剪切速率的上升而降低，故其温度敏感性也随着剪切速率的上升而下降；在相同的剪切速率下，分子量越大，PBST熔体的剪切应力σ，表观粘度η_a和结构粘度指数△η增大，非牛顿指数n减小。通过对不同分子量PBST共聚物进行熔融纺丝实验，分析了分子量对PBST成纤性能的影响，研究并优化了PBST共聚酯的熔融纺丝工艺。研究结果表明，当PBST共聚酯重均分子量大于1.1×10~5时，纺丝稳定性好，成纤性能优良；PBST共聚物具有较宽的可纺温度范围，其中在210～225℃时最为合适；PBST纤维适合较高的纺速，纺速可达1000m／min；基于反复实验，探索PBST纤维较佳的后牵伸工艺为牵伸温度80℃，定型温度160℃，牵伸倍数在1.5～205。通过最优纺丝工艺所纺PBST纤维强度可达3.5cN／dtex。此外还利用脂肪酶PS(?)、活性污泥和不同pH值的磷酸盐缓冲溶液对PBST纤维进行了降解实验，通过对降解前后纤维的分子量、质量、强力、热性能及表面形态等的比较初步研究了PBST纤维的降解行为。结果发现：随着降解时间的延长，纤维样品的分子量、质量、单丝强力等呈现稳定的下降；PBST纤维降解速率几乎不受分子量的影响；PBST纤维只有在特定生物酶的环境中降解显著，在一般的酸碱环境中变化很小。更多还原

【Abstract】 In recent years, biodegradable polymers have received more and more attention due to the global concern about the increasing synthetic nonbiodegradable waste pollution. Among them, aliphatic/aromatic copolymer is an important category for the balance of its biodegradability and physical properties. Poly (butylene succinate-co-butylene terephthalate) (PBST) just belongs to this kind of copolymers. In addition, there are increasing demands of biodegradable fibers in both agricultural and medical fields, however, all the researches on PBST focused on film samples until now. In the above cases, this investigation is expected to yield information on biodegradable fiber processing and resultant fiber properties.Firstly, the aliphatic/aromatic poly(butylene succinate-co-butylene terephthalate) (PBST) copolyesters with different molecular weight were efficiently synthesized from the starting materials of dimethyl succinate, dimethyl terephthalate and 1,4-butanediol in the presence of tetraisopropoxide titanium as the bulk polycondensation catalyst. ~1H NMR results proved the molar fraction of BT comonomers of the prepared products were almost 70%. GPC results showed that the weight average molecular weights (M_w) of the PBST copoyesters were in the range of 9×10~4～1.4×l0~5. In addtion the intrinsic viscosity was in the range of 0.7～1.1dL/g,melt index was in the range of 23～50g/10min and the density was in the range of 1.28～1.29g/cm~3, which were respectively determined by Ubbelohde, Melt indexer and Density-Gradient Technique. According to DSC, TGA and WAXD investigations, it was found that good thermal properties were entitled to PBST copolyesters, whose melting peak temperatures at about 180°C and decomposion temperatures at about 380°C, and the crystal structure of PBST similar as that of PBT. In order to study the spinnability, the rheological behavior of different molecular weights PBST copolyesters was investigated by capillary rheometer. The results showed that the apparent viscosity of PBST decreased with the increase of shear rate and temperature. The shear-thinning results indicated the PBST melts belonged to non-Newtonian pseudoplastic fluid. The flow activation energy of PBST decreased with the increasing of shear rate, so the sensitivity to temperature decreased. With the increase of temperature, structural viscosity index of PBST tended to decrease, however, the possibility of thermal decomposition increased. In the same shear rate, the higher molecular weight of PBST was, the larger shear stress, apparent viscosity and structural viscosity index were, but the smaller non-Newtonian index became.Furthermore the melt-spinning process of PBST copolymer was investigated as the key point. Based on the studies, the molecular weight plays a dominant role in spinnability of PBST. When the molecular weight exceeded 1.1×10~5, the PBST copolyesters appeared the good spinnability. Moreover, there was a wide range of melt-spinning temperature for PBST copolyesters and the optimum was 210～225°C. The mechanical properties of PBST fiber was improved by increasing take-up velocity, the optimum spinning speed was 1000m/min. From the experiments, the suitable drawn processing temperatures were selected for 80°C and heat-setting for 160°C. In the above parameters, the strength of last drawn PBST fibers can get maximum of 3.5cN/dtex.In addition the enzymatic degradation of PBST fiber was carried out in the presence of a lipase originated from Pseudomonas cepacia (Lipase PS(?)), activated sludge and other environment. The difference of molecular weight, strength, weight and the surface between the orignal and degraded fibers were studyed. The results showed that clearly degradation of PBST fiber was observed under enzymatic environment and the degradable rate was independent of the molecular weight of PBST fiber.更多还原