改变纺程参数制取高模量低收缩PET纤维

介绍在高速熔融纺丝线经过的空气介质中设置液体等温槽以改变纺程参数,制取高性能聚对苯二甲酸乙二醇酯（ＰＥＴ）纤维的一种新工艺,制得的初生纤维具有优异的力学性能。分析了此法制得的纤维的结构和力学性能的变化以及工艺条件的影响,指出其性能的提高是由纤维结构中取向非晶态含量大大增加所引起。对制得的初生纤维进一步拉伸热处理后,其性能优于一般高模量低收缩ＰＥＴ纤维。     

载体法制备聚四氟乙烯纤维及烧结工艺研究

以载体法制备出聚四氟乙烯纤维(PTFE)/聚乙烯醇(PVA)初生丝,然后对初生丝进行不同时间的烧结,以除去PVA制得PTFE纤维,对PTFE纤维进行不同程度的拉伸,检测不同烧结时间和拉伸倍数对纤维力学性能的影响。     

Determination of the structure of the noncrystalline regions in isotropic and oriented poly(ethylene terephthalate)

The mechanical properties of polymers are influenced strongly by the structure of the noncrystalline regions. The different methods for characterization of these regions are reported and the results obtained on polyethylene terephthalate, are discussed. The orientation function of the noncrystalline chains can be determined by measurements of the X-ray scattering and the birefringence. The fraction of taut noncrystalline chains is obtained from NMR measurements combined with a determination of the degree of crystallinity. For a further evaluation of the results it is also necessary to use calculations of the NMR- line-width and the birefringence of chains with fixeu ends. With help of such calculations the end-to-end distance of the taut and mobile non-crystalline chains can be determined, It is also possible to distinguish between tie molecules and loops. With increasing orientation, the amount of taut noncrystalline chains increases. The taut chains are tie molecule rather than taut loops. The end-to-end distances increase with increasing crystallization temperature.     

拉伸方式对聚醚醚酮纤维结构和性能的影响

采用进口聚醚醚酮(PEEK)树脂为原料,熔融纺丝制备了PEEK初生纤维,研究了一次拉伸和二次拉伸对PEEK纤维结构和力学性能的影响。结果表明:在150～270℃内,随着拉伸温度的提高,PEEK初生纤维的最大拉伸倍数增大,纤维的取向因子和力学性能提高;一次拉伸和二次拉伸时纤维的最大拉伸倍数相同,纤维的取向度、结晶度和力学性能基本相当,但二次拉伸纤维干热收缩率较低。二次拉伸时,总拉伸倍数相同,随着一段拉伸倍数的增大,纤维取向因子增大,力学性能提高;随着二段拉伸温度的提高,纤维结晶度增大,干热收缩率减小,取向因子基本相同,力学性能更优。     

The effect of a liquid isothermal bath in the threadline on the structure and properties of poly(ethylene terephthalate) fibers

The process of melt-spinning poly(ethylene terephthalate) (PET) filament at high speeds was modified through the inclusion of a liquid isothermal bath (LIB) in the spinline. A wide range of positions, temperatures, and depths associated with the operation of the LIB were utilized in this study. The structural characteristics and mechanical properties of the as-spun fibers were characterized by birefringence, wide-angle X-ray diffraction (WAXD), infrared spectroscopy, and tensile testing. Experimental results showed that the structure and mechanical properties of the as-spun fibers were significantly influenced by the LIB operating conditions. The as-spun fibers prepared under optimum LIB conditions exhibit high birefringence and excellent mechanical properties. Results suggest the development of a critical value of threadline stress that is determined primarily by LIB depth and take-up velocity. Below this critical value, raising of LIB temperature, LIB depth, and take-up velocity resulted in increases of the apparent crystallite size, sample crystallinity, and both the crystalline and amorphous orientation. As would be expected, the mechanical properties of the fiber samples were improved in a corresponding manner. Above this critical stress value, molecular chains in the amorphous phase are stretched tautly, but the crystal growth process is restricted, resulting in a decrease in crystallite size and crystallinity, as well as a continued increase in mechanical properties. The fiber properties were also found to be very responsive to the relative location of the LIB. A unique structure, believed never before obtained in a one-step high-speed PET melt-spinning process, has been achieved that combines high amorphous orientation, low crystallinity, and high tenacity. © 1995 John Wiley & Sons, Inc.     

Gel spinning of polyacrylonitrile fibers with medium molecular weight

A new gel‐spinning method was employed to prepare polyacrylonitrile (PAN) fibers from a PAN spinning solution with dimethylsulfoxide and water as a mixed solvent. Aging at 25 °C for 120 min brought the spinning solution to the sol–gel transition and a three‐dimensional gel formed before entering the coagulation bath. The as‐spun fibers from the solution at the sol–gel transition and in the gel state possess a circular cross‐section. Compared with dry‐jet wet‐spun fibers, the gel‐spun fibers have a more compact structure, fewer voids and better mechanical properties after a three‐stage drawing. Moreover, the gel‐spun fibers obtained from the extraction bath have a more homogeneous microstructure and better packed supermolecular structure. The physical properties of the extracted gel‐spun fibers are also better than those of coagulated gel‐spun fibers. Copyright © 2010 Society of Chemical Industry     

Thermal deformations of oriented noncrystalline poly (ethylene terephthalate) fibers in the presence of mesophase structure

Thermally induced dimensional changes, thermal shrinkage and elongation, in oriented noncrystalline PET fibers were investigated. The fibers exhibited two very distinct thermal responses depending on the fiber orientation. The local structure of the oriented noncrystalline PET chains as studied by the X-ray diffraction and FTIR spectroscopy revealed the mesophase structure with the well extended chain conformation in some fibers of high orientation. It was suggested that the oriented noncrystalline structure of PET consists of partially oriented noncrystalline phase and chain-extended noncrystalline phase. Our results demonstrated that the evolution of mesophase structure, i.e. chain-extended noncrystalline phase in the spin line not only led the drastic increase of packing density but also had a strong effect on thermal deformations upon post heat treatment. The amount of thermal shrinkage or the elongation reduced drastically in the fibers containing the mesophase. The high population of trans conformer and the strong inter-chain interactions of the extended chains provided the dimensional stability of the fibers during the thermal treatment.     

Polyacrylonitrile based carbon fibers: Spinning technology dependent precursor fiber structure and its successive transformation

In this study, the effects of different spinning methods including traditional wet and dry-jet wet spinning, and newly developed dry-jet gel spinning, on the structures and performances of polyacrylonitrile fibers, as well as the structural evolution during stabilization and carbonization, are compared in detail. The structural differences along radial direction, surface roughness, and chain orientation of carbon fibers are inherited from their precursor fibers, and these factors are determined by spinning technologies and processing conditions. Among all spinning methods, dry-jet gel spinning could prepare fibers with the best chain orientation, the highest tensile properties, and the lowest surface roughness, which would be favorable for achieving higher mechanical performance. Additionally, for the resultant carbon fibers, the surface modification of dry-jet gel spun carbon fibers is easier than dry-jet wet spun carbon fibers, and comparable to wet spun carbon fibers. Overall, dry-jet gel spinning is promising to make carbon fibers with both excellent tensile properties and good interfacial adhesion with epoxy matrix.     

尼龙6/PP-g-马来酸酐共混物及其熔纺初生纤维性能研究

用马来酸酐接枝聚丙烯共聚物(PP-g-MAH)对尼龙6进行共混改性,通过双螺杆挤出机共混制成切粒,接着将切粒烘干后进行熔融纺丝,研究共混改性尼龙6(MPA)及其初生纤维的力学性能。研究结果表明:熔体流动速率随着PP-g-MAH的增加而减小;而MPA初生纤维的最大可拉伸比和不同拉伸倍数下的拉伸丝模量都呈先增大后减小的趋势,都是在马来酸酐接枝聚丙烯含量为10%时达到最大值。     

Spinning and drawing properties of ultrahigh‐molecular‐weight polyethylene fibers prepared at varying concentrations and temperatures

The concentrations and temperatures of ultrahigh‐molecular‐weight polyethylene (UHMWPE) gel solutions exhibited a significant influence on their rheological and spinning properties. The shear viscosities of UHMWPE solutions increased consistently with increasing concentrations at a constant temperature above 80°C. Tremendously high shear viscosities of UHMWPE gel solutions were found as the temperatures reached 120–140°C, at which their shear viscosity values approached the maximum. The spinnable solutions are those gel solutions with optimum shear viscosities and relatively good homogeneity in nature. Moreover, the gel solution concentrations and spinning temperatures exhibited a significant influence on the drawability and microstructure of the as‐spun fibers. At each spinning temperature, the achievable draw ratios obtained for as‐spun fibers prepared near the optimum concentration are significantly higher than those of as‐spun fibers prepared at other concentrations. The critical draw ratio of the as‐spun fiber prepared at the optimum concentration approached a maximum value, as the spinning temperature reached the optimum value of 150°C. Further investigations indicated that the best orientation of the precursors of shish‐kebab‐like entities, birefringence, crystallinity, thermal and tensile properties were always accompanied with the as‐spun fiber prepared at the optimum concentration and temperature. Similar to those found for the as‐spun fibers, the birefringence and tensile properties of the draw fibers prepared at the optimum condition were always higher than those of drawn fibers prepared at other conditions but stretched to the same draw ratio. Possible mechanisms accounting for these interesting phenomena are proposed.     

Effects of modified air quenches on the high-speed melt spinning process

A high molecular weight polyethylene terephthalate was spun into fibers in the speed range from 3,000–7,000 mpm. The effect of modifying threadline dynamics through a combination of enhanced and/or retarding air quenches on the resulting spinning performance, fiber structure, and mechanical properties was examined. Particular combinations of these threadline temperature profile modifications were shown to result in significant improvements in spinning performance and as-spun fiber structure. Extensive characterization of select fiber samples revealed higher orientation and crystallinity, larger crystal dimensions, and greater mechanical properties. These results also demonstrated the ability to provide continued improvement in fiber properties at very high take-up speeds where typically a decline is observed. It is concluded that the threadline temperature profile can be altered in such a way as to significantly enhance the resulting spinning performance and fiber structure over a wide range of take-up speeds.     

Enhancement of the dimensional stability of poly(ethylene‐2,6‐naphthalene dicarboxylate) filament by multistep zone annealing spinning

Both good tensile properties and good resistance to thermal shrinkage are prerequisites for tire cord applications. For these purposes, poly(ethylene‐2,6‐naphthalene dicarboxylate) (PEN) filaments were prepared by multistep zone annealing (MSZA) spinning with a specially devised system. The melting temperature of the PEN filaments so obtained was slightly increased with an increasing total draw ratio. All the filaments exhibited a sharp melting peak around 270°C, but glass‐transition behavior was barely visible via differential scanning calorimetry. Rheovibron experiments showed α relaxation in the vicinity of 175°C. Increasing the draw ratio above 4 did not increase the birefringence value much, but it did lead to increases in the tensile properties. The PEN filaments consisted exclusively of α‐form crystals. The PEN filaments showed excellent resistance to thermal shrinkage, which was less than 1% even with heating to 140°C. In the MSZA spinning process, increasing the degree of hot drawing proved more effective than increasing the degree of cold drawing for obtaining PEN filaments with better dimensional stability at elevated temperatures. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 916–922, 2002     

聚丙烯纺丝中纤维不均匀性的研究

本文研究了聚丙烯树脂、纺丝条件等对聚丙烯纺丝过程中纤维不均匀性的影响。试验证明仅仅从流变学的角度来研究聚丙烯纺丝过程中纤维直径的不均匀性是不够的,因为初生纤维的屈服应力和初始模量的不均匀性主要取决于其取向的不均匀性和结晶性的差别。因而为了改善初生纤维的牵伸性能、提高聚丙烯纤维的质量,应该以控制初生纤维的织构和织构的均匀性为原则来合理选择聚丙烯树脂原料和控制纺丝工艺条件。     

Preparation of high performance PET fiber by solution spinning technique

High molecular weight poly(ethylene terephthalate) (PET, IV = 3.30 dL/g) was extruded in attempts to prepare high performance fiber using the solution spinning method. Solution preparation, fiber coagulation, and mechanical properties of resultant fibers were examined. An as-spun fiber exhibited high deformability when appropriate coagulation conditions were used. Tenacity and modulus of the resultant drawn fibers achieved 12.9 and 230 gpd, respectively, at draw ratio above 10. © 1995 John Wiley & Sons, Inc.     

Study on gel‐spinning process of ultra‐high molecular weight polyethylene

An ultra‐high molecular weight polyethylene (UHMW‐PE) fiber was prepared by gel spinning using general kerosene as the solvent and gasoline as the extraction solvent. The process of the phase separation of gel as‐spun, spun under various spinning conditions, was investigated. Its extracting and drying process were also studied. The results reveal that the gel as‐spun, spun under a lower spin draft and a lower spin quenching temperature, extracted in times and dried under free‐shrinkage, exhibits a good afterdrawability that eventually endows the fiber with excellent mechanical behaviors. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 670–675, 1999     

PBT纤维的松弛性质

本文用动态力学、X射线衍射等测试手段探索了不同纺速PBT纤维的松弛机理,证实了低速纺PBT初生丝在常温时的蠕变效应显著;纺速较高的PBT初生丝α峰温偏向高温、峰宽度位置偏离常温、峰强度降低,致使蠕变效应可得到改善,低速纺PBT初生丝存放过程中晶区分子链有序性提高,大分子链伸长,而高速纺PBT初生丝在存放过程中分子链的伸长可得到抑制。用这一结论解释了PBT低速纺初生丝经不起贮存的现象,认为在实际工艺中PBT应取中、高速纺为佳。     

聚羟基丁酸羟基戊酸共聚酯纤维干法纺丝成形研究

从生物源聚合体聚羟基丁酸羟基戊酸共聚酯（PHBV）出发,对其干法纺丝成形作了探索。重点研究了纺丝原液的流变行为,初生纤维截面形态,初生纤维可拉伸性能随存放时间的变化,拉伸过程对纤维力学性能的影响等。结果表明,用干法纺丝制备的PHBV初生纤维具有较好的可拉伸性,但需严格控制初生纤维的存放时间;经拉伸及后处理,PHBV纤维的断裂强度可以达到1.8cN/dtex以上,断裂伸长可以达到40％以上。     

Structure and properties development in poly(phenylene sulfide) fibers,part I: Effect of material and melt spinning process variables

The detailed research study of manufacturing PPS fibers using melt spinning and further enhancement of tensile properties by drawing and annealing experiments, a study lacking as of today in open scientific literature, was the focus of this research. This article discusses the effect of polymer molecular weight (MW) and melt spinning process variables on the structure and properties development in melt spun fibers manufactured from proprietary Fortron® linear PPS resins. Structure‐properties relationship was studied using several characterization tools like tensile testing, differential scanning calorimetry, polarized light optical microscopy, and wide‐angle x‐ray scattering. Changes in dynamic mechanical behavior of as‐spun fibers manufactured from resins of varying MW and different melt spinning take‐up speeds were also studied. The study showed that by a combination of higher MW of the polymer and spinning at higher take‐up speeds, tensile properties of as‐spun PPS fibers can be improved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Investigations of the preparation technology for polyglycolic acid fiber with perfect mechanical performance

Polyglycolic acid (PGA) fibers were prepared by melt‐spinning process in this report. The effects of spinning parameters, such as windup rates and drawn ratio, on the mechanical properties of the fibers were discussed by analyzing the internal stress of as‐spun fibers, axial sound velocity, fiber tenacity, etc. The results showed that windup rate had a slight effect on the macromolecular orientation degree of the as‐spun fibers, which was quite unusual for melt spinning, whereas, the subsequent drawing process effectively increased the macromolecular orientation degree of the PGA fibers and consequently increased the tensile strength of the fibers. Low internal stress of as‐spun fibers obtained at lower windup rate led to higher drawing ratio, and the drawn fibers possessed relatively excellent mechanical properties. As a contrast, higher windup rate resulted in the strong internal stress of the as‐spun fibers, which had a negative influence on the drawing process, and so the tensile strength of the drawn fibers was relatively poor. Therefore, PGA fiber with perfect mechanical performance could be prepared at the technical parameters of lower windup rate and higher drawing multiples as well as slow drawing rate. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

溶剂对PET纤维聚集态结构的影响

用密度法、DSC,偏光显微镜(PLM)和测定收缩率研究了1,2-二氯乙烷对不同纺速PET纤维聚集态结构的影响。结果表明,纺速不同,溶剂诱导结晶(SINC)及其动力学过程不同。高速纺纤维系取向晶态结构,对溶剂扩散有抑制作用。低、中速纺纤维基本为非晶态结构,SINC过程易于进行,但中速纺纤维取向非晶态含量高,溶胀度和收缩率较小。从而印证了关于不同纺速PET纤维结构特征的结论。