【作者】 田菁；

【导师】 王依民；

【作者基本信息】 东华大学 ， 材料加工工程， 2007， 硕士

【摘要】 聚苯硫醚(PPS)树脂最早由美国菲利浦石油有限公司首先研制成功，是一种性能优良的热塑性材料。PPS的分子链由苯环和硫原子交替排列构成，根据排列方式不同主要有三种结构，即高分子线形PPS．架桥型PPS和超支化PPS。高分子线形PPS具有良好的加工性能，用其制备的聚苯硫醚(PPS)纤维具有很强的耐化学腐蚀性和耐热性，阻燃性，以及良好的纺织加工性能。加工成的过滤毡主要用于过滤高温以及化学腐蚀性流体，比如作为燃煤发电厂和垃圾焚烧站的烟室过滤袋材料，减少有害气体的排放，实现环境的可持续发展。本课题主要从四个方面研究了聚苯硫醚，包括树脂材料的合成、长纤维的制备、超支化聚苯硫醚的合成并将其作为纺丝添加剂用以改善线形PPS的可纺性。本研究采用能够工业化生产聚苯硫醚的方法即硫化钠和对二氯苯在极性溶剂N-甲基吡咯烷酮中缩聚法。研究发现原料必须严格控制含水量，反应分二阶段进行，第一阶段温度大约在220℃保持1hr，第二阶段在260℃保持4～6hr。物料的摩尔比要严格控制，对二氯苯对硫化钠的摩尔比大约为1.03：1。升高温度有利于聚合的进行，得到产物的结晶度较高。在达到反应温度以后，反应4hr即可，过长反应时间对产物结晶度提高不显著。PPS的最佳纺丝条件为纺丝温度330℃，卷绕速度600m／min；后拉伸最佳条件为150℃，分级拉伸总倍数为4倍。升高拉伸温度和拉伸比有利于得到结晶度和拉伸强度更高，延伸率低的PPS纤维。使用异形纤维截面模拟软件来设计能得到最低堆砌密度的喷丝孔形状尺寸，即Y形截面的底部的分支长度是顶部分支长度两倍，此时在一定面积内堆砌密度最低，过滤效率高。异形截面PPS纤维比圆形截面PPS纤维具有更高的拉伸强度和相对较低的延伸率。其中Y形截面纤维的截面周长和比表面积比三叶形更大，且由于分支不等长，产生大量空隙，能有效避免三叶形截面纤维因为等长的分支易于互相嵌入而降低比表面积，使过滤效率降低的缺点。通过3，4-二氯硫酚和无水碳酸钾在极性溶剂NMP条件下150℃反应8.5hr可以得到超支化PPS。高度支化的结构具有与线形PPS所不同的特征，它为无定形结构，在DSC曲线上没有熔融峰。此外，超支化PPS能溶解于几种常见的溶剂。将超支化PPS和线形PPS在双螺杆挤出机中共混挤出抽丝即可得到超支化PPS／PPS共混纤维。非等温结晶动力学测试发现结晶时超支化PPS能起到异相成核剂作用。与纯PPS纤维相比，超支化PPS／PPS共混纤维的结晶温度和结晶速度有所提高。此外，加入超支化PPS能提高PPS的热稳定性和结晶度，有利于扩大超支化PPS／PPS共混纤维的使用温度范围，提高力学性能。超支化PPS能形成大量缠结，有利于拉伸应力的传递，形成提高纤维力学性能的界面结构，改善PPS基体的韧性，随着添加量的增加，挤出物断裂面表现得更为均匀。最佳添加量控制在3～4％之间。在改善流动性能方面，添加超支化PPS能够减小流体偏离牛顿流体的程度。在共混过程中，球状的超支化PPS由于附壁效应能够起到如同表面活性剂一样的作用，向聚合物表面迁移。挤出时，如同滚珠一样减小了熔体和毛细管之间的摩擦力，熔体在相同的剪切速率下和相对较低的纺丝温度下具有较小的表观粘度，可纺性得到改善，有利于得到优良力学性能纤维，拉伸强度达到4.15cN／dtex。更多还原

【Abstract】 Polyphenylene sulfide (PPS), an advanced thermoplastic material, was first developed by Philip-Chevron Petroleum Co. Ltd. The molecular chain of PPS is constructed with benzene ring and sulfur atom arranged alternately, and consists three types of structure, linear, cross linked as well as hyperbranched molecular configuration. Linear PPS possess good processing ability, and can be fabricated into fibers. PPS polymer has excellent properties such as chemical resistant, thermal stability, fire retard, etc Filtration fell fabricated by PPS fiber is mainly utilized to filtrate fh id of high temperature and corrosive chemical agents in such situation as coal power station and rubbish burning plant. The filtration felts can decrease the release of toxic gas and carry on sustainable environment development.In this study, four aspects were discussed including the synthesis of PPS, the spinning of PPS filament, synthesis of hyperbranched PPS and its use in melt spinning of normal PPS chips as rheological modifier.In this study, the method to svnthesize PPS was by polycondensation of sodium sulfide and p-dichlorobenzene in polarized solvent as NMP that can he industrialized. It has been found that moisture content must be controlled during the process and the polycondensation was carried out in two steps. The appropriate temperature and time for first step was 220℃and 1hr respectively while the second was 260℃and 4-6hr. The mol ratio of p-dichlorobenzene to sodium sulfide should be strictly 1.03: 1. Higher temperature will result in a higher crystallinity and is therefore preferred. 4hr was enough if the temperature reaches: polymerization with too long time was not encouraged.The results showed that optimum conditions for the preparation of PPS fiber were, spinning temperature of 330℃, winding speed of 600m/min, drawing temperature of 150℃and total draw ratio of four. Fiber with higher crystallinity, tensile strength and lower elongation percentage could be obtained by increasing draw temperature and draw ratio. Computer program for profiled fiber cross-section simulation was developed to obtain the optimum shape and dimension of spinneret die. The result showed that Y-shaped PPS fiber possessed lowest bulk density and filtrate efficiency when the cross-section of bottom branch was twice as long as the upper branch. Profiled PPS fiber, compared to regular round one, possessed higher tensile strength and lower elongation at break. Above all, Y-shaped PPS fiber had the largest perimeter and surface area. Different lengths of branch could get rid of the overlap phenomenon of trilobal fiber with branches embedded into each other due to the equal branch length and width.Hyperbranched PPS was synthesized by 3,4-dichlorobenzenethiol with potassium carbonate in polarized solvent NMP at 150℃for 8.5hr. Highly branched structure endows hyperbranched PPS with entirely different properties to linear PPS. For instance, hyperbranched PPS is amorphous while linear PPS is semi-crystal polymer. Linear PPS wiil not dissolve in most solvents at room temperature for while hyperbrancned PPS can easily be dissolved in common solvents such as DMSO and THF.Hyperbranched PPS/PPS fiber was prepared by blending the raw material with twin-screw extruder. Non-isothermal crystallization test indicated that hyperbranched PPS could serve as heterogeneous nuclear agent during the course of crystallization to accelerate the crystallization rate and increase the crystallization temperature. In addition, the addition of hyperbranched PPS could enhance the thermal stability and crystallinity, and as a result to extend its ranges of application temperature and improve the mechanical properties. Hyperbranched PPS could form numerous of entanglements, and benefit to the transportation of stress to form interface structure with higher mechanical properties; therefore the toughness of matrix get enhanced. The adding amount should be in the range of 3 to 4%. During the modification of rheologicai behavior, hyperbranched PPS can decrease the departure of PPS melt from Newtonian fluid. During the blending, hyperbranched PPS with sphere like molecule acted as surface active agent and migrated to the surface of linear PPS melt owning to the wall attachment effect. The friction force between melt and capillary can be decreased and as a result, PPS melt shows a much lower apparent viscosity at same shear rate and lower temperature. In this way, rheologicai behavior could be improved to obtain PPS fiber with outstanding mechanical properties with tensile strength of 4.15 cN/dtex.更多还原