热处理时间对CF/PPS结晶度与力学性能的影响分析

采用差示扫描量热仪(DSC)研究了不同热处理时间对碳纤维增强聚苯硫醚(CF/PPS)结晶度的影响;利用动态力学分析仪(DMA)研究了不同热处理时间的CF/PPS试样的储能模量、损耗模量以及阻尼因子的变化情况。结果表明,150℃下CF/PPS试样的结晶度随热处理时间的增加(1～3 h)呈先增大后减小的趋势,相对结晶度最大值为65.3%,最小值为53.5%。这样的变化与不同热处理时间条件下PPS分子链活性以及热氧交联反应程度有关,分子链活性与交联程度会影响聚合物的晶核形成与生长,进而影响材料的结晶度;材料结晶度的升高会提高CF/PPS的储能模量,同时降低其损耗模量,且从阻尼因子图谱中可以得到不同结晶度的CF/PPS试样的玻璃化转变温度随结晶度的增大呈下降的趋势。     

熔融时间对聚苯硫醚(PPS)结晶度与结晶行为的影响分析

利用差示扫描量热仪(DSC)研究了制备过程中不同熔融时间对聚苯硫醚(PPS)树脂的结晶度及结晶行为的影响;利用热失重分析仪(TGA)研究了不同熔融时间对PPS成型过程中热氧交联程度的影响。结果表明,在熔融时间为10~30 min范围内,PPS树脂的结晶度随熔融时间的增加逐渐减小,相对结晶度最大值为54.28%,最小值为48.66%;结晶峰向低温方向移动,峰宽增加、峰强减弱。这是由于PPS分子活性、分子链的热氧交联反应随熔融时间的不同具有不同的表现形式,进而影响PPS的结晶度与结晶行为;PPS树脂的热失重率随熔融时间的增加而减小,失重率最大值为51.88%,最小值为49.07%。这是由于PPS在空气中随着熔融时间的增加,链增长与交联反应程度加剧,使其难以在高温下发生热降解。     

国产线性聚苯硫醚树脂流变行为研究

以国产线性聚苯硫醚树脂为原料,研究了分子质量、剪切速率、温度对PPS树脂流变行为的影响。随着剪切速率的增大,树脂的粘流活化能减小,结构化粘度随温度升高而减少。阐述了树脂流变性能与可纺性关系。研究表明剪切速率和温度共同影响着PPS的表观粘度:低剪切速率时,温度对表观粘度的影响明显;高剪切速率时,表观粘度对温度的依赖性降低。     

聚苯硫醚长丝热稳定性的研究

采用热烘处理方法,研究了聚苯硫醚(PPS)长丝在不同温度条件下的热稳定性能及力学性能。结果表明:PPS长丝在热处理过程中的失重率随温度的提高和时间的延长而增加;断裂伸长率随热处理温度的提高而下降;在80℃恒温下断裂强度几乎不随时间变化,120℃或180℃恒温下断裂强度随热处理时间的延长先增加后减小,但变化不大;当温度为250℃时,断裂强度随热处理时间显著下降;PPS纤维180℃以下性能稳定。     

聚苯硫醚流变行为研究

采用高压毛细管流变仪研究了进口聚苯硫醚(PPS)树脂的流变性能,分析了剪切速率、温度对PPS树脂流变行为的影响。结果表明,PPS树脂的非牛顿指数均小于1;在低剪切速率下,PPS树脂的表观黏度对温度的依赖程度高于高剪切速率下的依赖程度;PPS树脂的黏流活化能随剪切速率的增加呈减小趋势,其结构黏度指数随温度升高而减小。     

S-9228抗氧剂改善聚苯硫醚热氧化性能的研究

以乙醇为分散剂,将抗氧剂双(2,4-二枯基苯基)季戊四醇二亚磷酸酯(S-9228)与聚苯硫醚(PPS)按一定比例混合,制得不同S-9228含量的PPS/S-9228树脂,将PPS/S-9228树脂在200℃空气中处理0.5 h,制得抗热氧化PPS树脂,研究了PPS/S-9228树脂及抗热氧化PPS树脂的结构与热氧化性能。结果表明:S-9228均匀分散于PPS树脂中,且与PPS树脂有较好的相容性;适宜的S-9228加入量其质量分数为1%;纯PPS树脂的氧化诱导温度为476.7℃,加有S-9228质量分数为1%的PPS/S-9228树脂的氧化诱导温度为481.9℃,抗热氧化PPS树脂的结晶温度、熔融温度、熔融热焓和结晶热焓相比纯PPS的低。     

热处理对聚丙烯结晶结构和力学性能的影响

研究了不同热处理温度和热处理时间对聚丙烯(PP)结晶结构和力学性能的影响.结果表明:热处理对PP球晶分布、晶粒尺寸影响不大;退火处理使PP晶格参数略为下降;在90℃以上,随着热处理温度的提高,PP的结晶度不断增大;随热处理时间的延长,PP的结晶度先增大后趋于稳定;随热处理温度的提高和热处理时间的延长,PP拉伸强度提高,屈服强度增大,弹性模量增大,断裂伸长率和静力韧度下降,其变化规律与结晶度的变化相对应.     

聚苯硫醚/有机蒙脱土复合材料热氧化研究

以十六烷基三甲基溴化铵作为插层剂,采用阳离子交换法对钠基蒙脱土粉体进行有机改性制备有机蒙脱土(OMMT);采用熔融插层法制得聚苯硫醚(PPS)/OMMT复合材料并将复合材料进行热处理;利用红外光谱技术研究热处理前后PPS树脂及其复合材料的结构变化,对PPS的热氧化机理进行探讨;利用电脑测色配色仪对热处理前后的PPS树脂及其复合材料颜色的变化值进行测试。结果表明:与纯PPS树脂相比,OMMT的添加可以在一定程度上提高PPS树脂的抗氧化性;经过热处理后PPS树脂及PPS/OMMT复合材料均发生不同程度的氧化,苯环上发生交联,C—S键上发生氧化;C—H的面外弯曲振动峰及苯环C—O伸缩振动峰均发生蓝移;PPS/OMMT复合材料的色度变化程度明显降低,其中添加质量分数为5%的OMMT的复合材料的抗氧化效果较好。     

热处理聚苯硫醚的红外光谱分析

利用红外光谱技术对不同温度下在密炼机中热处理的聚苯硫醚(PPS)树脂进行分析;研究了热处理前后PPS的结构变化,探讨了PPS的热交联机理。结果表明:与未处理PPS相比,热处理后PPS的苯环的C—CH而内变形振动峰、笨环C—H面外弯曲振动峰、亚砜基伸缩振动峰及C—S面内伸缩振动峰向高位偏移;PPS经热处理后发生了氧化交联,且交联发生在苯环上,氧化发生在硫醚键上。     

碳纤维增强聚苯硫醚复合材料结晶结构与性能调控

使用碳纤维斜纹布与聚苯硫醚(PPS)薄膜通过热压成型制备了碳纤维增强PPS (PPS/CF)复合材料层压板,通过在保温保压过程中设置不同的等温结晶温度,对复合材料中PPS结晶结构进行调控,系统讨论了不同等温结晶温度下,PPS结晶度及晶粒尺寸对PPS/CF复合材料力学性能的影响。使用X射线衍射仪观察了复合材料中PPS的晶体结构,通过场发射扫描电子显微镜观察了复合材料的微观形貌,并利用动态机械分析测试探究了复合材料的黏弹性与PPS晶体结构之间的关系。结果表明,当等温结晶温度为230℃时,复合材料中PPS在保持较小晶粒尺寸的同时结晶度高达46.58%,此时复合材料具有良好的强度、刚性和界面粘结强度,其弯曲强度、弯曲弹性模量和层间剪切强度分别达到709 MPa,81.9 GPa和23.8 MPa。     

Annealing effects in poly(phenylene sulfide) as observed by dynamic mechanical analysis

Poly(phenylene sulfide) (PPS) is a semicrystalline engineering resin with exceptional solvent resistance and thermal performance. Properties such as these are directly related to the high crystallinity of PPS. In order to exploit its crystalline nature, PPS should be molded at a high tool temperature (hot oil tool) to allow for the highest crystallization rate, and therefore the highest percent crystallinity. Alternately, if a low mold temperature is used, the molded parts should be annealed. This latter process has been studied for injection molded neat PPS resin for various annealing temperatures. Two different grades of PPS were studied that represent cured and linear types. Samples were studied as-molded, and annealed at 160, 180, 200 and 220°C. Increases in glass transition temperature were noted upon annealing. An increase in storage modulus was also noted for annealed samples. This increase persisted up to approximately the annealing temperature. Differential scanning calorimetry has been used to show that annealing PPS allows for a secondary crystallization to occur whereby an endotherm appears that corresponds to the secondary crystalline phase melting near the annealing temperature. As the annealing temperature is increased, the area of the endotherm increases. The secondary crystallization explains the higher storage modulus that persists up to the annealing temperature. These results are discussed in terms of crystallinity and overall effect on heat distortion temperature.     

注塑级PPES/PPS共混合金热性能及结晶性能的研究

通过熔融挤出、注塑成型的方法制备了配比不同的含二氮杂萘酮结构的聚芳醚砜(PPES)和聚苯硫醚(PPS）的共混物，对材料的热性能及结晶性能进行了研究。热失重研究表明，在所组成范围内PPS的加入并未降低共混物的热性能，但使共混物的热变形温度有所降低；PPES的加入使PPS的结晶受到阻碍，当PPES质量分数达80％时，PPS产生了晶格缺陷，从而不能形成完善的球晶，退火过程有利于提高共混物的热变形温度，使PPS形成更完善的球晶。     

特种工装用聚苯硫醚长丝热性能的研究

本研究以日本宝理株式会社的聚苯硫醚（PPS）树脂为原料,采用熔融纺丝方法,在我校的LHF j030纺丝一牵伸设备上制得特种工装用PPS长丝。然后取一定长度的PPS长丝,将其进行干热处理和沸水处理,研究了不同热处理条件对其收缩率与断裂强度性能的影响规律。实验结果表明：PPS纤维在175—185℃期间,干热收缩率为2％～6％,在185—190℃期间,随着温度的升高,干热收缩率急剧增加,幅度达10％;经沸水长时间处理PPS纤维的收缩率无明显变化;干热和沸水处理,对PPS纤维的断裂强度基本没有影响。     

拉伸与热定型对聚苯硫醚长丝结构性能的影响

以国产聚苯硫醚(PPS)树脂为原料,用熔融法纺丝制得PPS长丝。采用差示扫描量热仪、热重分析仪研究了后处理对纤维结晶和热性能的影响;利用声速取向测量仪研究了拉伸对纤维取向的影响;用单纱电子强力仪测量了纤维力学性能。结果表明:热拉伸倍数增大,PPS纤维取向度、结晶度增加,纤维的断裂强度增加,断裂伸长减小;拉伸倍数大于5,会出现较多毛丝和断头;控制热拉伸温度85～105℃,热定型温度100℃以上;纤维的结晶主要在热拉伸过程中基本完成,热定型进一步完善结晶结构;高温下氧气的存在,会使PPS纤维发生严重的氧化降解。     

Thermal and crystallization behavior of engineering polyblends. I. Glass reinforced polyphenylene sulfide with polyethylene terephthalate

The thermal and crystallization behavior of blends of glass fiber reinforced polyphenylene sulfide (PPS) with polyethylene terephthalate (PET) has been reported. The blends showed two overlapping melting peaks and two separate crystallization peaks. The heat of crystallization of PPS was found to decrease continuously with increasing PET content, whereas the heat of crystallization of PET was found to increase with increasing PPS content. This indicates that the degree of crystallinity of PPS is reduced whereas that of PET is increased as a result of blending. It is interesting to note that the combined heats of fusion of the blends were marginally higher than those calculated by proportional additivity rule in spite of the drop in the heat of crystallization of PPS. The temperature onset of crystallization of PET in the blends shifted to higher temperature whereas there was no significant change in the crystallization temperature of PPS. The increase in the temperature of crystallization of PET indicates enhanced nucleation. The isothermal crystallization studies of the component polymers revealed that both the component polymers crystallized at a relatively faster rate in the blend. The crystallization rate of PPS was found to increase significantly with increasing PET content. A significant increase in the rate of crystallization of PET was also observed in the blends. The acceleration of crystallization rate of PET in the blends was more pronounced as compared to that of PPS. The acceleration in the PET crystallization rate was attributed to the presence of glass fibers and crystallized PPS.     

The glass transition temperature of poly(phenylene sulfide) with various crystallinities

The glass transition temperature (T_g) of poly(phenylene sulfide) (PPS) with various crystalline fractions has been studied using dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). The DSC measurements show that T_g can be observed from the heating curves for the PPS sample with very low crystallinity, and no T_g is observed when the crystallinity is over 8%. DMA indicates that crystallinity has an important effect on molecular chain segment motion of PPS. When the crystallinity, X_c, of PPS is over 38%, there is only one chain segment motion, which mainly results from the crystalline chain vibration; while three different chain segment motions occur for PPS samples with lower crystallinity (X_c < 26%), which are amorphous chain segment motion, crystalline chain segment motion and constrained amorphous chain segment motion. T_g of PPS is mainly caused by the amorphous chain segment motion which is independent of the crystallinity, while the relaxation temperature corresponding to crystalline chain motion shifts to lower temperature as the crystallinity increases. The reduction of the relaxation temperature can be attributed to the disorder‐order transition of amorphous chains for PPS with lower crystallinity. © 2012 Society of Chemical Industry     

炭黑改性聚苯硫醚纤维性能研究

在聚苯硫醚(PPS)树脂中加入少量的炭黑制成切片,采用熔融纺丝法制得改性PPS纤维。研究了炭黑的加入量对改性PPS纤维的取向、结晶和热性能的影响,以及改性PPS纤维经紫外光老化前后力学性能的变化。结果表明:加入炭黑可使PPS纤维取向度降低,结晶度提高;炭黑质量分数为1.5%的改性PPS纤维耐热性较好;经紫外光照射192 h后,与纯PPS纤维相比,其断裂强度保留率提高了30.3%,断裂伸长保留率提高了41.4%,抗紫外光老化性能得到了改善。     

PTFE/ZrO2复合微孔膜结晶性能的研究

以聚四氟乙烯（PTFE）乳液为原料,选定化学稳定性、热稳定性优异的纳米二氧化锆（ZrO2）为增强剂,制备出PTFE/ZrO2复合微孔膜,并通过X射线衍射仪对PTFE/ZrO2复合微孔膜样品的结晶性能进行了表征,使用单因素法讨论了ZrO2的含量、拉伸倍数、热处理温度及热处理时间等因素对PTFE/ZrO2复合微孔膜结晶性能的影响。结果表明,复合微孔膜的结晶度与拉伸倍数、热处理温度和热处理时间成正比,与ZrO2含量成反比;ZrO2含量为7 %、拉伸倍数为1~2.5倍、热处理温度为310 ℃、热处理时间为10 min时,制成的复合微孔膜综合性能最佳。     

聚苯硫醚/碳纳米管复合材料的非等温结晶性能

利用双螺杆挤出机制备了纤维用聚苯硫醚/多壁碳纳米管(PPS/MWCNTs)复合材料。通过差示扫描量热法(DSC)研究了不同降温速率下纯PPS以及PPS/MWCNTs复合材料的非等温结晶过程,并运用Ozawa模型进行了非等温结晶动力学分析。结果表明:降温速率对PPS/MWCNTs复合材料的结晶性能有很大的影响,当降温速率为20℃/min时,PPS/MWCNTs复合材料的结晶能力及相对结晶度最大;MWCNTs在PPS结晶过程中起异相成核剂的作用,使PPS/MWCNTs复合材料的结晶温度较纯PPS升高。