The melt spinning process is the most common process to produce poly(ethylene terephthalate) (PET) fibers for textile and technical applications. The process involves extruding molten polymer through a spinneret followed by a drawing process. In the conventional drawing process, there appears to be an upper limit for draw ratio somewhere in the range of 3-9. Overcoming this limitation, superdrawing-based process offers a route to produce very fine denier fibers economically from as-spun fibers of 'normal' textile deniers, and it offers a unique method for quick-response manufacturing of fibers with various finer diameters (deniers) from a single spun supply. During superdrawing, PET fibers undergo large extension without significant crystallization or increase in molecular orientation. This study is directed at understanding the limitations of processing conditions for PET superdrawing process with temperatures ranging from 90 degrees C to 120 degrees C and strain rates from 0.008 s(-1) to 0.425 s(-1). Evolution of crystallinity and molecular orientation of the drawn samples are evaluated using differential scanning calorimetry (DSC) and birefringence measurements. The results indicate that superdrawing is not possible for any strain rate at or below 90 degrees C because of significant strain-induced crystallization. Between 90 degrees C and 105 degrees C, superdrawing occurs only when the strain rate is below a threshold value, which increases from less than 0.333 s(-1) to below 0.425 s(-1) as temperature increases from 105 degrees C to 110 degrees C. Results also show that between 115 degrees C and 120 degrees C, superdrawing is only possible at strain rates higher than 0.016 s(-1). Increasing temperature from 110 degrees C to 120 degrees C leads to more crystallization at low strain rates (0.001 s(-1)), and less crystallization at high strain rates (0.1 s(-1)). The change of strain rate limitation from an upper bound to a lower bound around 110 degrees C for superdrawing suggests a change in molecular deformation mechanism based on a combination of factors such as the temperature, entanglement dynamics, and strain rate. The study also shows that the mechanism of crystallinity development in PET undergoes a transition at drawing temperature near 113 degrees C and strain rate of 0.17 s(-1).

为开发高黑度的细原液着色聚酯纤维,采用原位法连续聚合制备出炭黑质量分数为2％～3％的聚酯/炭黑(简称原位法PET/炭黑)体系,对其流变行为、结晶行为和炭黑分散形态等进行了表征,并制备了高速纺长丝.结果表明:原位法连续聚合使炭黑以直径小于1μm的粒子簇团形式均匀分散在聚酯基体中;炭黑含量较低时的流变行为与PET相似,当炭黑质量分数达到3％时,原位法PET/炭黑熔体的表观黏度随剪切速率增大而快速降低;熔融结晶过程中,炭黑作为高效异相成核剂,显著加快了聚酯结晶速率,同时,聚酯与炭黑的良好相互作用,导致有更多的结晶缺陷,与PET相比,出现了熔融双峰,且高温熔融峰峰顶温、结晶度均降低,这与母粒法PET/炭黑体系明显不同.因为原位法保证了良好的炭黑分散性,原位法PET/炭黑可以稳定制备出炭黑质量分数为3％、单丝线密度为0.52 dtex、断裂强度≥3.31 cN/dtex的长丝.

China’s chemical fiber volume ranks first in the world and is a pillar industry of the national economy. However, there are still prominent problems regarding the development of the chemical fiber industry and promoting the advanced fundamental fiber materials has become the key to the high-quality development of the chemical fiber and textile industries. This study focuses on three types of advanced fiber materials: differential fiber, high-performance fiber, and bio-based fiber. The status, challenges, and development trends of the advanced fiber materials in China are analyzed. On this basis, the key tasks for the future development of the advanced fiber materials are summarized, including developing key technologies to form representative products, improving the intelligent manufacturing level, strengthening the independent innovation capacity, and enhancing the training of scientific and technological talents. This study also proposes development suggestions from the aspects of industrial development strategy, scientific and technological innovation system, the role of science and technology, internationalization of key enterprises, and coordinated development, hoping to provide a theoretical reference for the high-quality development of China’s fiber materials industry.

利用毛细管流变仪及反向压力腔组件研究了压力流场中含炭黑聚对苯二甲酸乙二醇酯(PET)熔体的流变行为,并与普通PET熔体的流变行为进行对比.结果表明:随剪切速率的增加,含炭黑PET熔体的"剪切变稀"行为比普通PET更显著;在相同温度和相同剪切速率下,含炭黑PET的剪切黏度随着压力的增加而增加;在相同剪切速率和相同压力下,随着温度的升高,含炭黑PET熔体的剪切黏度逐渐减小;压力增加△P与温度下降△T对剪切黏度的贡献是等效的;在相同剪切速率下,含炭黑PET熔体的黏-温依赖性随压力的升高而增强;在相同压力下,含炭黑PET熔体的黏-温依赖性随剪切速率的增加而减弱;随着温度的升高,普通PET和含炭黑PET熔体的结构粘度(△η)降低,可纺性提高;当温度为290～295℃时,普通PET和含炭黑PET熔体的可纺性最优.

利用毛细管流变仪及反向压力腔组件研究了压力场下高黏聚对苯二甲酸乙二醇酯(PET)熔体的流变行为.结果 表明,随着剪切速率的增加,高黏PET熔体剪切黏度逐渐降低,表现出明显的“切力变稀”行为,是一种典型的假塑性流体;随着熔体所受压力的增加,高黏PET熔体剪切黏度呈指数增长增加,变化规律符合Barus方程;随着温度的升高,高黏PET熔体的剪切黏度逐渐减小;高黏PET熔体的换算因子为3.4,压力增加与温度下降对剪切黏度的贡献是等效的.高黏PET熔体为非牛顿流体,随着温度的逐渐升高,高黏PET熔体非牛顿指数逐渐增大,高黏PET熔体的流动行为逐渐接近牛顿流体特性.高黏PET熔体的剪切黏度-温度依赖性随压力的增加逐渐增强;高黏PET熔体的剪切黏度的温度敏感性随剪切速率的增加逐渐降低.随着剪切速率增加和温度升高,高黏PET熔体剪切黏度对压力的依赖性逐渐降低.

The textile industry is a pillar of China’s national economy and advanced base materials for industrial textiles are critical for China’s textile industry. In this article, we focus on three types of said materials that are widely demanded by the textile industry—nonwoven fiber materials, textile structural materials, and textile composites—considering the key technologies for material manufacturing, material production modes, and industry status. Subsequently, we analyze the development status and trend of the advanced base materials for industrial textiles in China and abroad, summarize the main problems faced by China in this field, and expound the key tasks and core technologies for their development in China. To promote the development of these materials, China should strengthen the overall planning for the industry, improve the national system for supporting science and technology innovation, and foster a group of specialized and excellent enterprises to participate in international competition.

利用毛细管流变仪及反向压力腔组件研究了高压条件下温度、压力和剪切速率等因素对聚对苯二甲酸丁二醇酯(PBT)熔体的流变行为影响规律.结果 表明,随着温度的升高,PBT熔体的剪切黏度呈现不同程度的下降趋势,且温度较高时剪切黏度下降幅度增大;PBT熔体剪切黏度的温度敏感性在高剪切下显著减弱,在高压下缓慢增强;PBT熔体剪切黏度随压力的增大呈指数增加,符合Barus方程;在相同温度、相同剪切速率下,随着压力的增加,PBT熔体剪切黏度逐渐增大;PBT熔体剪切黏度随着剪切速率的增加逐渐降低,表现出典型的“剪切变稀”假塑性流体现象.

为研究高压条件下聚合物的流变性能,以熔融共混挤出的方法制备聚对苯二甲酸乙二醇酯-聚酰胺6嵌段共聚物(PET-PA6)与聚酰胺6(PA6)共混物,利用安装在反向压力腔末端的旋塞控制毛细管出口压力,研究该共混物在出口压力为5～50 MPa条件下,剪切速率和温度对PET-PA6/PA6共混物流变行为的影响.结果表明:PET-PA6/PA6共混物的剪切黏度随压力的变化规律符合Barus方程;在恒定剪切速率下,随着毛细管内平均压力的增加,剪切黏度逐渐增大;当剪切速率从108 s-1增加到1080 s-1时,压力系数减小19.24％,当温度从265℃增加到290℃ 时,压力系数减小32.33％,共混物熔体剪切黏度对压力的依赖性随剪切速率和温度的增加逐渐减小.

The heat-resistant aromatic imide ring and fluorine-containing group were introduced into the macromolecular main chain of polyethylene terephthalate via molecular design. Diimide diacid monomer (DIDA) was synthesized through thermal cyclization reaction using 6FDA and 11-aminoundecanoic acid as raw materials. Fluorine-containing polyethylene terephthalate were prepared through esterification polycondensation among the as-synthesized DIDA,dimethyl terephthalate (DMT) and ethylene glycol (EG). The non-isothermal crystallization behaviors of the polyesters were tested by differential scanning calorimetry (DSC), and the results show that pure PET has the highnest crystallization ability,which is decreased with the increasing fluoride content. Non-isothermal crystallization kinetics of the polyesters are analyzed by the Jeziorny method. The kinetics datas indicate that the crystallization rate constant decreases with the increasing fluoride chain segment,and the crystallization ability of PET is reduced with the incorporation of the fluoride segment.

The oil-paper insulation of valve-side windings in a high voltage direct current (HVDC) converter transformer is subjected to both complicated voltage and severe thermal stresses. Partial discharge (PD) occurring in oil-paper bounded cavities is influenced by voltage stress type as well as temperature. This paper presents PD behaviors in an oil-paper bounded gas cavity under pulsating DC voltages. The voltage across the gas cavity and PD inception voltages at different test conditions are analyzed. Influences of temperature on statistical PD distributions and parameters are also presented. A numerical model is used to interpret PD behaviors under pulsating DC voltages and various temperatures. Experimental results and theoretical statements show that the temperature exhibits a great influence on the behaviors of cavity discharge under pulsating DC voltages. Volume resistivity, gas pressure, charge decay time constant, and electron generation rate are the primary parameters influencing PD behaviors at different temperatures.

A capillary rheometer with an attached counter pressure chamber was used to determine the effect of pressure on the shear viscosity of several polymer melts, i.e., poly(ϵ-caprolactam) (PA6), poly(ethylene terephthalate) (PET), low-density polyethylene (LDPE), and polypropylene (PP). In order to study the rheological properties of the polymer melts at a constant pressure, the measured values of shear viscosity were recalculated with respect to a series of pressures by the least square fitting based on the Barus equation. Different calculation methods were used to calculate the pressure coefficients from the recalculated viscosity values. The resulting pressure coefficients of the shear viscosity demonstrated that the degree of the pressure dependence was highest for PP, followed by PET and then LDPE. PA6 exhibited the lowest pressure coefficient.

In this study, the variation in the rheological behavior of poly (ethylene terephthalate) (PET) melt was investigated by the capillary rheometer and counter pressure chamber where the pressure at the outlet of the capillary was higher than the normal pressure. The investigation revealed that the shear viscosity of PET decreased with increasing temperature. Noticeably, the effect of temperature on the shear viscosity displayed variation under all the conditions of shear rates and pressures, and this effect was more significant at 50 MPa or at 216 s(-1). The viscous fluid activation energy of PET was measured to be 42.97-79.22 KJ.mol(-1), which increased with an increase in pressure and decrease in shear rate.

采用毛细管流变仪及其配套的反向压力腔组件控制毛细管出口压力,在平均压力为5 ～50 MPa下研究了3种不同特性黏度的聚酯(PET)的流变行为.结果表明:PET的剪切黏度随着平均压力的增大都呈指数增加,符合Barus方程.压力系数随着特性黏度的增大而减小,当特性黏度由0.48增加至0.67 dL/g时,压力系数显著减小,且这种变化随着剪切速率的增大而衰减,当特性黏度≥0.67 dL/g时,压力系数随剪切速率的变化不大.压力系数随剪切速率的增大而减小,特性黏度为0.48 dL/g时变化显著,当特性黏度≥0.67 dL/g时,压力系数随剪切速率的变化不大.压力系数随着温度的升高而减小,且变化率随着温度的升高显著减小.不同特性黏度PET压力系数的变化表明,特性黏度较低时,自由体积较大,表现在玻璃化转变温度低,受压力的影响显著;当特性黏度为0.67和1.00 dL/g时,自由体积的减小不再明显,因此受压力的影响也不再明显.

The effect of reverse pressure.on rheological behavior has been studied. The apparatus is a capillary rheometer with counter pressure chamber being held at a high reverse pressure by means of a cock. The results show that with the increase in temperature, the shear viscosity of hydrophilic PET is reduced. It is different that the effect of temperature on shear viscosity is varied under the condition of all shear rates or all pressures, and the effect is more prominent at 50 MPa or at 216 s −1 . At the same time, the pressure coefficients decrease with increasing the shear rate and the temperature and tend to reach a constant value nearly at the temperature of 290 °C.

The rheological behavior of polyethylene terephthalate/polyamides 6(PET/PA6) copolymer melt was investigated through the capillary rheometer and counter pressure chamber when the pressure at the outlet of capillary was higher than normal pressure. The results show that when the shear rate is a fixed constant, the shear viscosity of copolymer increases with the increase of average capillary pressure, and the shear viscosity increases from 130 Pa��s to 215 Pa��s along with pm increasing from 10MPa to 50 MPa while the temperature is 300��C and the shear rate is 108 s-1. It is found that effect of the average capillary pressure on the shear rate decreases with the increase of the shear rate or the temperature; the pressure coefficient shows a downward trend with the increase of the shear rate and the temperature.

Ultra-high molecular weight polyethylene( UHMW-PE) plates were prepared by hot-pressure molding. The effect of different molecular weight,heating method of the mould on the property and output of UHMW-PE plates were studied,the results showed that the tensile strength and the hardness were increased,while the elongation at break was decreased with the increase of molecular weight,when UHMW-PE molecular weight was 4 × 106,the hardness of plate was the highest,but,the Mortar wear rate and wearing capacity was the lowest,so,when the plates were formed with oil heating moulds,the mechanical properties,hardness and friction performance of UHMW-PE plates were better than the foreign samples. Relative to the furnace heating mode,the large volume plates were molded with electrical heating moulds,not only saved energy,and the output could be increased about 40 %.

Poly(ethylene terephthalate) (PET)/carbon black (CB) masterbatch was prepared by melt blending using a separate feeding technique and its homogeneous dispersion morphology was confirmed by transmission electron microscope (TEM). The Avrami and Hoffman-Lauritzen secondary nucleation theories were employed to analyze the effect of high CB content on crystallization kinetics of PET, providing theoretical support for the development of masterbatch with high content of functional components. The Avrami exponents,average values of n,for PET and PET/CB masterbatch are both greater than 3, which indicates three-dimensional growth of crystals. In addition,no significant evidence for regime transition of PET is found applying Hoffman-Lauritzen secondary nucleation theory,though such observations have been reported previously in the literature. Furthermore,appropriate U* value for PET is determined to be 12 800 J/mol. For PET/CB masterbatch,a transition from regime I to regime II around 225℃ is observed with appropriate U* value (12 800 J/mol) . This phenomenon is consistent with a transition point in plot of G versus Tc . The fold surface free energy σe (100. 3 mJ/m 2) of PET is much greater than that of PET/CB masterbatch (48. 3 mJ/m 2) ,which indicates heterogeneous nucleation effect of CB particles.

The variation of the shear viscosity of poly(ethylene terephthalate)(PET) melt was investigated using the capillary rheometer and counter pressure chamber when the pressure at the outlet of capillary was higher than normal pressure,and it was observed that the shear viscosity of PET was dependent on the average capillary pressure and shear rate,respectively.The results show that when shear rate is fixed constant,the shear viscosity of PET increases with the increase of average capillary pressure,but the increase margin varies with shear rate.The effect of pressure is more prominent at low shear rate.When the average capillary is fixed constant,the shear viscosity of PET decreases with the increase of shear rate,as it is shown by less shearing.It was found by computation that the pressure coefficient of PET at 290 ℃ was about 11.94 GPa-1 when shear rate is fixed constant.

Single-screw extruders together with a painstakingly self-made dynamic mixer were applied to mix carbon black (CB) in polymeric matrix. Moreover, the master batch dilution technique was also used. The mixing state of CB was investigated by direct methods including transmission electron microscopy (TEM), scanning electron microscopy (SEM), and optical microscopy (OM). The image analysis software, Image J, was first introduced to analyze the mixing state of CB. By virtue of Image J, the average size, surface density, and area distribution of particles were automatically created. On the basis of TEM results, quantitative evaluation parameters such as Morisita's index (I), skewness (beta), and the Lacey index (M) were employed. The results reveal that CB was well dispersed and uniformly distributed in films. Besides, the area distribution abides by a lognormal equation fitted by origin. In SEM analysis, the area distribution conforms to exponent decay strictly as well as that in OM results. Furthermore, the dispersion index (D) was used to characterize the mixing state of CB. The results imply that CB tends to aggregate with increasing CB loading. Combining the methods mentioned above is favorable to quantitatively characterize the mixing state of CB, in that they can become references between one another.

Two-dimensional carbon fiber felts were densified by film boiling chemical vapor infiltration from xylene pyrolysis at 950~1 150 ℃.Within 30~35 hour densification,carbon/carbon composites with average density of 1.72~1.74 g/cm3 were produced.The density and mechanical property of the composites were measured by Archimedes method and three-point bending test,respectively.The microstructure of pyrocarbon and the morphology of fracture surface were studied using polarized light microscopy and scanning electron microscopy.The results show that the microstructure of pyrocarbon transits gradually from rough laminar(RL) to smooth laminar along both the axial and radial direction of the composites for 950 ℃ deposition.RL pyrocarbon dominates the matrix of the composites for the deposition at 1 050~1 150 ℃,and the composites produced at 1 050 ℃ have more uniform density.As the deposition temperature increases from 950 ℃ to 1 150 ℃,the flexural strength of the composites decreases from 158.9 MPa to 133.6 MPa,and the fracture behavior transits from brittle failure mode to quasi-ductile failure one.