聚甲醛及其纤维的热分析研究

用Ozawa法和Mo法对聚甲醛(POM)的非等温结晶动力学进行研究。采用双螺杆纺丝机熔融纺得POM初生纤维,再用水浴拉伸方法制得POM纤维,研究拉伸倍数、水浴温度对POM纤维结晶性能的影响。结果表明:在不同的降温速率下,随着降温速率的提高,POM结晶峰峰值温度降低,半结晶时间缩短,结晶速率加快;采用Mo法研究POM的非等温结晶过程比较理想,而Ozawa法不适用;水浴拉伸有利于纤维的结晶,而随着水浴温度的提高,POM纤维的结晶度提高。     

UHMWPP／UHMWPE合金纤维非等温结晶动力学研究

运用DSC手段研究了UHMWPP／UHMWPE合金纤维的等温结晶行为，对所得的实验数据用修正Avrami方程的Jeziorny法进行处理，发现随冷却速率的提高，半结晶的时间t1/2缩短，表明冷却速率加快时，结晶速率也随之加快，纯UHMWPP主要是以三维球晶的方式进行结晶生长，UHMWPE的加入起到核剂的作用，随着成核剂含量的增加，UHMWPP的结晶维数将降低.     

拉伸条件对涤纶四孔中空纤维结构性能的影响

应用ＷＡＸＤ、声速法等研究了涤纶四孔中空纤维在不同拉伸条件下结晶、取向变化,讨论了拉伸工艺变化对涤纶四孔中空纤维结构与性能的影响。结果表明,由于拉伸方式和拉伸温度的不同,纤维结晶和取向程度有明显的区别,导致了中空纤维成品质量的差异。     

聚苯硫醚纤维的制备及性能研究

对聚苯硫醚(PPS)切片进行了熔融纺丝,测定了拉伸倍率、拉伸温度、热定型温度对纤维性能的影响。结果发现,随着拉伸倍率和热定型温度的提高,纤维的断裂强度和熔点都提高,断裂伸长则下降;随着拉伸温度的提高,纤维的熔点降低,断裂强度和双折射率则先降低后升高,出现最低值。在初生纤维的冷结晶温度110℃附近进行拉伸,纤维的断裂强度最低。在310℃对PPS进行纺丝,初生纤维在90℃拉伸4.5倍后,再在180℃紧张热定型5min,获得了断裂强度为3.9 cN/dtex的PPS纤维。     

热拉伸处理温度对PPTA纤维结晶和力学性能的影响

为提高国产聚对苯二甲酰对苯二胺(PPTA)纤维的拉伸模量，采用热拉伸法在不同温度下对PPTA纤维进行处理，利用纤维强伸度仪、乌氏黏度计、X射线散射仪对纤维进行测试，研究热拉伸处理温度对纤维结晶性能和力学性能的影响。结果表明：随着热处理温度的升高，PPTA纤维的拉伸强度降低，模量先增大后减小，在440～480℃时综合力学性能较好；PPTA纤维的结晶度与模量变化趋势相似，在拉伸温度为500℃时结晶度最大为74.0%;与未处理PPTA纤维相比，热拉伸处理后纤维的晶粒尺寸增大，取向度提高；比浓对数黏度与拉伸强度的变化趋势一致，随着热处理温度的升高而降低。     

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。     

二步法制备高强度聚甲醛纤维的工艺及性能研究

首先采用熔融纺丝工艺制备聚甲醛(POM)初生纤维,然后采用二级热箱对初生纤维进行热拉伸及热定型,制备高强度POM纤维;根据POM初生纤维的熔融结晶曲线和等温结晶性能,确定了初生纤维的热拉伸温度;研究了拉伸倍数对纤维力学性能、结晶度和取向度的影响。结果表明:POM初生纤维的热拉伸温度即第一级热箱温度为155℃,热定型温度即第二级热箱温度为120℃;POM纤维的拉伸强度和结晶度随拉伸倍数的增大先增加后降低,初生纤维经9倍拉伸时均达到最大;POM纤维取向度随拉伸倍数的增加而增加,初生纤维经9倍拉伸后趋于稳定;POM初生纤维经9倍拉伸时,所得POM纤维的拉伸强度达到最大值为1.23 GPa,断裂伸长率为21.07%。     

低纤度聚酰胺6长丝的结构与性能

借助X射线衍射及差示扫描量热技术,研究并分析了不同拉伸热定形工艺条件下低纤度聚酰胺6纤维的结晶取向的变化及对纤维力学性能的影响。结果表明:总拉伸倍数不变的情况下,适当提高牵伸辊的拉伸倍数更能有效地提高纤维强度;在一定温度范围内,适当提高热定形温度有利于改善晶区结构,但对纤维的取向度影响不明显,当热定形温度高于175℃时,纤维断裂强度出现下降;保持拉伸倍数及热定形温度不变,改变纺丝速度,纤维结构和力学性能的变化不显著。     

剑麻纤维增强聚丙烯复合材料的制备与性能研究

采用动态保压注塑成型技术(DPIM),通过在熔融共混体系中施加往复的剪切应力以改善剑麻纤维(SF)与聚丙烯(PP)复合材料的结构与性能。力学性能测试表明:动态保压获得的样品,拉伸强度与模量获得大幅度提高,但样品冲击性能有所下降。当剑麻纤维质量分数为30%时,动态复合材料的拉伸强度提高了23%。DSC结果表明:由于剑麻纤维充当了结晶成核点的作用,使得复合物的结晶温度提高。     

PET石墨烯复合材料的制备及性能研究

将氧化石墨烯(GO)与精对苯二甲酸(PET)、乙二醇(EG)进行原位聚合,制备了氧化石墨烯/PET(GO/PET)复合材料,研究了氧化石墨烯对PET聚酯的热性能、结晶性能的影响,并制备复合材料纤维,测试了其力学性能.结果表明:GO的加入提高了PET的热稳定性、结晶温度及结晶速率但没有改变PET的成核方式和生长方式.与纯PET相比,加入GO后纤维的拉伸强度降低,断裂伸长率提高,但与低GO含量的PET纤维相比,GO含量较高的PET纤维的拉伸强度更高.     

DSC Study of Syndiotactic Polypropylene/Organoclay Nanocomposite Fibers: Crystallization and Melting Behavior

The effect of anisotropic particles of organophilic layered silicate on the crystallization and melting behavior of prepared nanocomposite systems was studied. The matrix was syndiotactic polypropylene (sPP). Organophilic layered silicate M-QDA filler was prepared by modification of hectorite SOMASIF ME 100 with octadecyl amine. The compatibilizer was isotactic polypropylene (iPP) grafted with maleic anhydride (iPP-g-MA). The silicate was exfoliated in situ within the sPP during the melting process to produce anisotropic nanoparticles. The sPP/M-ODA nanocomposite was spun at different drawing ratios. The resulting fibers were examined by differential scanning calorimetry. It was found that neither the spinning process nor the presence of nanofiller affected the crystallinity of the sPP matrix of the nanocomposite in comparison with the neat sPP. At a raised drawing ratio of the fibers slightly increased crystallinity of matrix was observed; however, it was still lower than the neat sPP fibers prepared at the same drawing ratio. The presence of M/ODA nanofiller in sPP matrix increased the melting temperature of the fibers.     

Mechanical properties and superstructure of isotactic polypropylene fibers prepared by continuous vibrating zone‐drawing

A continuous vibrating zone‐drawing (CVZD) was applied to study the effect of vibration on the mechanical properties and superstructure of isotactic polypropylene fibers. The CVZD treatment was a new drawing method by which the fiber was continuously drawn at a rate of 0.5 m/min under vibration using the specially designed apparatus. The CVZD treatment was carried out in five steps at a drawing temperature of 150°C and a frequency of 100 Hz, and applied tensions increased step by step with processing in the range of 14.8 to 207 MPa. The obtained fiber had a birefringence of 0.0373, crystallinity of 62.4%, tensile modulus of 17.6 GPa, and tensile strength of 1.11 GPa. These values are higher than those of the continuous zone‐drawn isotactic polypropylene fiber previous reported. The vibration added to the fibers during the zone‐drawing was effective in developing amorphous orientation and improving the mechanical properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 600–608, 2001     

The Curling Phenomenon of Polypropylene Yarns

Abstract

Polypropylene is a thermoplastic polymer which, because of its intrinsic properties (it doesn't absorb water, it has low density, low thermal conductivity, good resistance to different chemicals, it doesn't irritate skin etc.), is penetrating new markets at the expense of other polymers. This is why there is a need in industry of polypropylene fibers for developing new products with new or better properties.

In the research work on the polypropylene yarns the conditions for production of polypropylene fibers which crimp after drawing were established.

The goal of research work was to investigate the influence of spinning temperature on the formation of crimps and the degree of crimp.     

Optothermomechanical device for the interferometric characterization of fibers

An optothermomechanical (OTM) device was designed and constructed for fiber characterization with a double‐beam interference microscope. This device enabled us to correlate both the mechanical properties and the thermal properties with the optical properties of fibers. The OTM device consisted of three parts, which were used for the drawing (stress–strain), cooling, and heating of the fibers. The designed OTM device (cooling and heating) was attached to the Pluta microscope for the determination of the optical properties of high‐density polyethylene (PE) fibers at different temperatures (0–50°C). Also, this OTM device (drawing and heating), connected to the Pluta microscope, was used to study the influence of the temperature (10–50°C) and draw ratio (1–7) simultaneously on the optical properties of polypropylene (PP) fibers. Microinterferograms were provided for illustration. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 647–658, 2005     

光敏变色聚丙烯纤维的研究

本文采用共混熔融纺丝法比较成功地制得了两种具有良好光致变色能力的光敏变色聚丙烯纤维:经阳光照射后,一种由白色变为蓝色,另一种由黄色变为绿色。文章探索了它们的纺丝及拉伸工艺条件,研究了光敏剂的不同加入量对于纤维变色性能、力学性能以及其结构的影响。并测试了该纤维的耐皂洗性和光照耐久性。     

不同磁粉含量对磁性PP纤维性能的影响

采用皮芯层复合纤维纺丝机纺制不同磁粉含量的聚丙烯 (PP)磁性纤维 ,对纤维的纺丝性能、拉伸性能、热性能进行了研究。结果表明 :随着磁粉含量的增加 ,磁性纤维的纺丝性能、拉伸性能、热性能下降。选择磁粉和聚丙烯的合理配比 ,既可以提高磁性纤维的纺丝性能、拉伸性能和热性能 ,又可以提高磁性纤维的磁粉含量。     

Drawing behavior of polyblend fibers from polypropylene and liquid crystal polymers

Polyblend fibers were made from mixtures of polypropylene (PP) and thermotropic liquid crystal polymers (LCPs). The as-spun fibers were drawn to produce the oriented structure for the PP matrix. The LCPs were found to exist in thin and long fibrils in the as-spun fibers; after drawing, they were split into short fragments. From a simplified model whereby a single LCP fibril is embedded in a PP matrix fiber, it was calculated out that the length of the LCP fibril in the drawn fiber is directly proportional to the fibril diameter and tenacity, and is reversely proportional to the compressional stress on the fibril and the friction coefficient between the fibril and the surrounding matrix. With regard to the drawing conditions, it was found that a long length of the LCP fibrils can be preserved by increasing the drawing temperature, or by reducing the draw rate. The effect of two-stage drawing on the LCP phase morphology was also studied in the present work. © 1994 John Wiley & Sons, Inc.     

The influence of processing parameters on the structural and mechanical properties of drawn polypropylene fibres: A factorial design approach

This article reports a study of multi‐stage polypropylene fiber drawing (stretching) as a continuous, but independent stage of the overall fiber‐forming process. The fibers were drawn according to a factorial experimental design, once appropriate spinning conditions had been devised. The structures of the drawn fibers were studied using wide‐angle X‐ray diffraction and birefringence measurements. In addition, the fibers were characterized with respect to filament tenacity, elongation to break, specific secant modulus, and extent of shrinkage at 130°C. All these properties were quantitatively assessed as responses to nine specially selected process control parameters in the drawing equipment. For every property analyzed, the temperatures of the hot plates in the draw frame were found to exert no significant influence, whereas the temperatures of the initial rollers were in most cases significant. Furthermore, the speed of the final roller also played an influential role, and a number of interactions between process parameters were identified as significant. Explanations are advanced for the parts played by significant process parameters on the properties of the drawn fibers. The article also demonstrates the advantages of factorial experimental design in determining correct settings for process parameters to give drawn fibers with the properties desired. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

抗静电高收缩聚酯纤维的研究

分别以5,-磺酸钠间苯二甲酸二甲酯(SIPM)和聚醚酯为改性剂,采用共聚及共混方法制备具有抗静电性的高收缩聚酯纤维。研究了改性剂种类、用量和拉伸温度对聚酯纤维抗静电性和收缩性的影响,结果发现随聚醚酯含量增加,纤维的电阻率减小,共混纤维的抗静电性优于共聚纤维。在聚酯中引入SIPM可以有效提高纤维的收缩性能,在体系中同时引入聚醚酯时会降低纤维的收缩率。纤维在低温拉伸时获得的收缩率高于高温拉伸。     

高密度聚乙烯熔纺纤维的拉伸工艺

相对分子质量为１４万的高密度聚乙烯（ＨＤＰＥ）通过螺杆挤出机熔纺成形,然后经过高温超拉伸可制成强度为９．７ｃＮ／ｄｔｅｘ的中强聚乙烯纤维。讨论了拉伸温度、拉伸比对纤维力学性能的影响,并通过声速取向、热分析（ＤＳＣ）、广角Ｘ射线衍射（ＷＡＸＤ）和纤维力学性能的测试研究了拉伸过程中聚乙烯纤维结构与性能的变化。结果表明：拉伸温度对纤维稳定拉伸影响较大,最佳温度为１０５～１１５℃;且初生纤维的纤度越小,高倍拉伸纤维强度越大,随拉伸倍数的提高,纤维的强度和声速取向都显著提高并改善了纤维的热性能和力学性能,但断裂伸长却呈下降趋势。