【作者】 赵明；

【导师】 王依民；

【作者基本信息】 东华大学 ， 材料科学与工程， 2005， 博士

【摘要】 早在20世纪30年代,聚酰胺(尼龙)就投入工业化生产,早期的聚酰胺主要用于制造纤维,是世界上最早的合成纤维品种,由于聚酰胺良好的耐热性,优异的耐磨性和优良的耐碱性,不发霉、不腐烂、不怕虫蛀等特性,在整个60年代,聚酰胺纤维以15%的速率增长着,广泛应用于军工、航天航空、汽车各种工业领域,以及日常用品中。1950年以后,由于成核剂的进步及纤维增强塑料的开发,使得聚酰胺作为五大工程塑料之一在材料工程领域中得到广泛应用。 尼龙虽然具有以上一些优良的性能,但由于尼龙大分子结构的原因,也存在一些缺点,如模量低,易变形,耐热性差等。无法满足一些场合如高性能轮胎帘子线、输送履带等要求,而受到很大限制。 日本的Y.Fukushima等于1987年首次报导了采用原位插层聚合方法制备PA6/粘土纳米复合材料以来,各国研究人员进行了广泛的研究,在PA6/粘土纳米复合材料(NCH)的制备、表征、结构研究等方面取得了重要的进展,所得到的PA6/纳米复合材料具有高强度、高模量、高热变形温度、良好的阻隔性等性能。然而大多数报道的相关研究采用的是己内酰胺水解开环聚合法,而且开发的相关产品多为塑料和薄膜制品。而采用双螺杆反应挤出PA6/蒙脱土纳米复合材料的纺丝级切片,进行纺丝研究还未见任何报导。 本论文①首次以双螺杆挤出机作为制备的PA6/蒙脱土纳米复合材料的反应器。采用原位聚合法,使己内酰胺单体在双螺杆中短时间内快速反应聚合,制备出PA6/蒙脱土纳米复合材料。此方法可以在双螺杆中通过适当的参数控制(温度、螺杆形状)进行连续聚合,与一般PA6/蒙脱土纳米复合材料原位聚合法相比,时间大大缩短,而且可直接挤出成型,符合生产上对工艺过程的经济性,高效率的要求,为未来的生产工业化提供了可能。 ②专门设计了适合PA6/蒙脱土纳米复合材料聚合反应的双螺杆元件组合。对不同螺杆形状的产生的实验结果进行了对比,对螺杆元件形状和停留时间的关系进行了讨论。实验数据表明采用此方法所获得的PA6/蒙脱土纳米复合材料分子量比较高,可达24000左右,分子量分布比较窄,可以达到1.8。适合于纺制纤维。更多还原

【Abstract】 Polyamide has been found and commercialized since 1935.Early polyamide was mainly produced as raw material for polyamide (Nylon6) fiber, which is the earliest synthetic fiber in the word. For several decades, Nylon6 fiber was developing at the annual rate of 15% and have been applied in various industry fields of military, aerospace, vehicle and daily articles for its excellent mechanical properties such as high strength, excellent resistances to abrasion, chemicals and mildew, etc. Since 1950, Nylon6 has become one of the five most important engineering plastics due to the developments of nucleating agent and fiber reinforcement of plastics.However, it has some disadvantages, such as low Young’s modulus, easy to deforming and poor thermal resistance, which seriously limit its further and wide applications in some special fields, such as high quality tire-cord, conveyer belt etc.On the other hand, hydro-open ring polymerization is a classical method for polymerization of ε -caprolactom with tedious production process and expensive equipments, and polymerization time will take more than 20 hours; it is difficult to prepare modified or differential products by this method; anion polymerization of ε -caprolactom can produce Nylon6 in a short time, such as several minutes, however, with very high molecular weight, wide molecular weight distribution and its product is difficult to be spun into fiber and can only be used as plastics.In situ polymerization of Nylon6/montmorillonite (PA6/MMT) composites was first introduced by professor Y. Fukushima in 1987 and since then great progress has been obtained in preparation, characterization and applications of PA6/MMT with high strength, high modulus and high thermal resistance. However, most of the studies are depended on hydro-open ring polymerization process and their products are on the forms of plastics or films and there is nothing concerned about the fiber grade PA6/MMT composite chip prepared by twin-screw extruder.The thesis focuses on the preparation and characterization of MMT modified PA chips and fibers. The results show that:1. At the first time to prepare MMT modified PA6 chips using twin-screw extruder as reactor, ε -caprolactom was in situ anion polymerized at the presence of MMTin a short time. By control polymerization parameter such as temperature, screw profile, fiber grade PA6/MMT nanocomposite chips was prepared continually in a quite shorter time compared with that by classical hydro-open ring polymerization method.2. The effect of screw profile on polymer properties was studied and a special combination of screw elements was designed in order to obtain a modified polyamide with suitable molecular weight (about 24000), narrow molecular weight distribution (about 1.8) for fiber making.3. The studies on crystallization kinetics and morphological studies show that the nanoMMT added in the system would react as nucleating agent. With the increase of MMT, Avrami index decreases. The spherulite develops rather in three dimensions when the amount of MMT is below l(wt)%, and show two dimensional propagation when the amount reaches 3%.4. The rheological studies on PA6/MMT system show that with the increase of shear rate and temperature, the apparent melt viscosity decreases. With the increase of MMT amount, melt apparent viscosity will increases.5. TGA was used to study PA6/MMT thermal property. The results show that its thermal stability is greatly improved compared with that of pure PA6 sample. The maximal degradation temperature for 3% MMT modified PA reaches 350℃. At same weight loss, such as 10%, pure PA6 was at temperature about 290 ℃, while modified one was 325 ℃.6. PA6/MMT composite chips with different MMT contents were spun and drawn into fibers. Fiber mechanical properties were tested and the results shown that the adding of nano-MMT could improve fiber mechanical properties. Compared with pure PA6 fiber, the tensile strengths of fibers with 1 and 2(wt)% MMT increased by 3% and 4%, while fiber Young’s modulus increased by 10.7% a更多还原