【作者】 迟蕾；

【导师】 吴大诚；

【作者基本信息】 四川大学 ， 材料学， 2005， 硕士

【摘要】 纳米科技的发展给纤维科学与工程带来了新的观念。聚合物纳米纤维已经成为纳米科学研究中一个值得关注的焦点。紫外线防护纤维、远红外纤维以及抗菌防臭除臭纤维等功能型织物对人体的保健作用已经得到证实,因此开发新材料新方法制备纳米纤维具有十分重要的意义。本文采用熔融缩聚法生产了不同分子量的聚对苯二甲酸乙二酯(PET),并用气流/静电纺丝方法制备了PET纳米纤维,所得纤维的直径主要分布在100nm以下,讨论了影响纤维形态和直径分布的各个过程参数因素。 聚对苯二甲酸乙二酯(PET)的合成工艺十分成熟,采用直接聚合法生产工艺简单,控制温度、催化剂用量等反应条件可以制备得到一系列不同分子量的PET产物。研究PET溶液流体的流变性发现,高聚物的流变性与高聚物流体的温度、高聚物的分子量、溶液浓度以及所施加的剪切速率有很大的关系,实验证实了PET溶液流体属于非牛顿流体,具有非牛顿流体所具有的典型特征。 采用气流/静电纺丝方法制备PET纳米纤维,经过实验确定了最佳的纺丝工艺参数:电压32Kv,喷丝头与收集板之间的距离为23cm,气流为10L/min,纺丝液浓度为18%。实验比较了各个操作参数对所得的纳米纤维的形态和直径分布的影响:电压增大,纺丝液射流所受到的拉伸力也随之增大,这就相当于传统纺丝工艺中的增大纺丝机的卷绕速度,有利于得到更细的纤维;气流/静电纺丝中气流是对射流的另一股拉伸力,气流增大,也会使射流受的拉伸力增大,但气流过大时纤维形态要受到影响,不利于射流成丝;喷丝头与收集板之间的距离是纺丝过程中的一个重要的参数,距离过小时,纺丝液中的溶剂来不及挥发,射流会凝成液滴沉积在收集板上,所形成的纤维上有大量的珠粒,距离增更多还原

【Abstract】 The new concept about fiber science and engineering has been developed with the development of nanofiber science. The research of nanometer science has focused on polymer nanofibers. The hygienical function to human by functional fabrics, such as fiber resistant to ultraviolet light, far infrared fiber and the fiber resistant to bacterium and deodorization, has already been approved, so there is great significance of the exploitation of the new materials and the new method to produce new materials. Using a series poly(ethylene terephthalate) with different molecular weight made by direct esterification, we obtained the PET nanofibers by gas/electrospinning. The distribution of fiber diameter was under 100nm mainly. At the same time, the process factors, which affect the distribution of the diameter and the morphology of the nanofibers were investigated in this article.The syntheses technology of PET is well known, the direct esterification technologically is simple. It is easy to obtain PET with different molecular weights by controlling the temperature, dosage of catalyzer, and other reaction condition. It was understood that the rheological properties of the PET solution depend on the characters of the solution such as temperature, molecular weight, concentration of polymer and shear rate. As well known, PET solution is the non-Newtonian fluid, its flow processes typical characters of non-Newtonian flow.For PET nanofibers spun by gas/electrospinning in this work, the optimal technical parameters were as follows: the voltage was 32kV, the distance between the spinneret and the collector was 23 cm, the volume rate of air flow was 1 0L/min, theconcentration of the spinning solution was 18%. The effects of the each processing parameter on the morphology and the diameter distribution of the nanofibers were investigated experimentally. The driven force of the spinning jet is increasing with the increase of the voltage. At the same time the gas flow is another added driven force. However, if the gas flow is too great, the jet is difficult to be produced in the stabilized form. The distance between the spinneret and the collector is another important processing parameter. When the distance is small, the volatilization of the solvent is insufficient, the jet splits to drops aggregated on the collector. As the result, there are many beads on the nanofibers. The concentration of polymer in spinning fluid is another remarkable factor to affect the process. If the concentration is too low, the solvent could not volatile timely and the solution drops also aggregate on the collector. When the concentration is too high, the fluidity is bad, what is disadvantage to spinning.Different collect methods may give different morphology and diameter distribution for nanofibers. Comparing the nanofibers spun by dry and wet spinning, we can know that the diameter distribution of the fiber spun by wet spinning is narrow than that spun by dry spinning. However, the morphology of the fiber spun by dry spinning is better than that by wet spinning. At the same time, the effect of different coagulant on morphology of PET nanofibers was investigated. Different coagulants have different polarity, so its interaction with the solvent is different. As the result, the diffusion rate of solvent in spinning fluid to the coagulant is different; the solidified rate of the fiber from the coagulant is different. It was understood that these effects would give the different morphology and diameter distribution of the nanofibers. It was known from the experimental results that the choice of mixture of water and ethanol as the coagulant is correct, the nanofibers collected in such a coagulant are the best. At last, the reasons to form the beads in nanofibers were analyzed.更多还原