共查询到18条相似文献,搜索用时 140 毫秒
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PET/PTT双组分弹性长丝的结晶取向结构和卷曲性能 总被引:8,自引:0,他引:8
为研制军官礼服用PET/PTT双组分弹性长丝,在纺丝加工工艺研究的基础上,通过声速法、WAXD、DSC、Instron5566对典型工艺下的弹性长丝进行了结晶和取向结构及卷曲性能的测试分析.在可纺的前提下,PET/PTT两组分复合纺丝中,PET组分优先结晶,具有高于其单组分纤维的拉伸诱导取向和结晶;而PTT组分只有形变,其结晶度和晶区取向均低于其对应的单组分纤维.在实验条件范围内,两组分粘度差异越大,纤维的卷曲伸长率和收缩率越大、声速取向因子增加、各单组分结晶度增加;两组分质量比为50/50时,纤维有最大的卷曲伸长率和收缩率,且各单组分结晶度随该两组分含量差异的增加而减少,而声速取向变化相反;随牵伸比的增加,纤维的整体取向、各组分结晶度均有所增加,卷曲伸长和收缩率也增加.牵伸温度和定型温度对双组分纤维的结构和卷曲性能影响较小. 相似文献
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采用静电纺丝技术分别制备了无规排列和高度取向排列的聚对苯二甲酸乙二醇酯(PET)和PET/CA(柠檬酸)4种纤维膜,对它们的润湿性能和力学性能进行了研究,同时研究了纤维膜厚度对膜的力学性能的影响.研究结果表明,与无规排列的PET纤维膜相比,取向排列的PET纤维膜沿纤维取向方向的力学性能有了很大的提高,而断裂伸长率略有下降;加入柠檬酸(CA)后,PET/CA复合纤维膜的表面水接触角从132.3!减少到0!,且取向排列的纤维膜比无规排列的纤维膜更易润湿;无规排列的复合纤维膜的力学性能因加入CA而大幅下降,取向排列的PET/CA纤维膜沿纤维取向方向的力学性能下降较小,而无规排列的PET/CA纤维膜的断裂伸长率从284.1%增加到444.5%.无规排列纤维膜的力学性能随膜厚度的增加先提高,后来又下降,而取向排列的纤维膜沿纤维取向方向的力学性能随膜厚度增加而单调增加. 相似文献
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本文应用计算分峰的原理,用系数不同的不对称高斯函数去分别表征PET纤维的中介态和无取向非晶态的X衍射,并在实验上设法把这两种衍射区分开来,从而建立了能够测算纤维中晶态、中介态和无取向非晶态的相对含量的方法。用这方法研究了高速纺PET拉伸丝在各温度下热处理时的结构,结果表明,纤维的结晶度随热处理温度升高而相应增加,但中介态含量、无取向非晶态含量及许多性质在130—160℃之间出现转折。作者从中介态在热理处时可能发生解取向松驰和发生结晶的综合变化加以解释,DSC的研究结果符合上述观点。 相似文献
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Kyoung Hou Kim Hyun Hok Cho Hiroshi Ito Takeshi Kikutani 《Journal of Polymer Science.Polymer Physics》2008,46(9):847-856
To investigate the mechanism of fiber structure development for poly(trimethylene terephthalate) (PTT) in high‐speed spinning, the PTT fiber was spun with take‐up speeds from 1 to 8 km/min and simultaneously birefringence and diameter in spin‐line were measured by on‐line measurement system. The orientation‐induced crystallization of PTT fiber started to be developed at 3–4 km/min, where an abrupt decrease in diameter and an increase in birefringence appeared. The birefringence increased up to 4 km/min, decreased suddenly, and then increased gradually. The sudden decrease of birefringence at 4–5 km/min might be caused by an increase of crystalline fraction due to the fact that the intrinsic crystalline birefringence of PTT is over 10 times as low as that of PET. In WAXD images, crystalline diffraction emerged faintly at 3 km/min and distinct diffraction arcs were observed at 4–5 km/min and above. The diffraction intensity increased and the tilting angle also increased with take‐up speed. The long period structure observed in SAXS pattern started to emerge at 6 km/min, and its scattering intensity increased with take‐up speed. The long period structure was ~11–12 nm long. The cold crystallization temperature in DSC thermogram shifted to lower temperature and diminished due to the orientation‐induced crystallization as take‐up speed increased, but the melting temperature hardly increased unlike PBT and PET. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 847–856, 2008 相似文献
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《Computational and Theoretical Polymer Science》2000,10(1-2):63-72
Computer modeling is applied to discuss hot-tube effects in melt spinning from crystallizing polymers. The set of spinning equations used in the model accounts for stress-induced crystallization, crystallinity-dependent melt viscosity and heat of crystallization. Example computations are performed for polyethylene terephthalate assuming temperature-dependent Newtonian viscosity, strongly modified by crystallization. The consequence of coupling of stress-induced crystallization and crystallinity-controlled solidification is limited range of spinning speeds, and multiple solutions of the dynamic equations of spinning. The range of admissible spinning speeds and multiple (amorphous and crystalline) solutions is strongly affected by the hot-tube temperature.It is predicted that zone heating, with temperatures above glass transition (hot tube), results in considerable increase of amorphous orientation factor for moderate take-up speeds. In the high speed spinning range, the orientation effects saturate and does not exceed the values predicted for high-speed room-temperature spinning. Application of the hot tube is also predicted to reduce considerably take-up stress.Available experimental data on amorphous orientation in PET fibers spun by hot-tube technique are in qualitative agreement with the model predictions. 相似文献
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G. Russo L. Parravicini F. Auriemma V. Petraccone G. Guerra R. Bianchi G. Di Dino V. M. Vitagliano 《Journal of Polymer Science.Polymer Physics》1997,35(6):889-896
Some properties and structural aspects of fibers obtained by spinning, in a wide range of take-up speed (2,800–4,400 m/min), of commercial samples of PET, produced by dimethyl terephthalate (DMT) and the terephthalic acid (TPA) processes, are compared. For a same take-up speed, the considered fibers from TPA are spun at lower pack pressures and always show higher tenacity and lower ductility than fibers from DMT. X-ray diffraction, density, and birefringence measurements indicate that, for the fibers from the DMT process, an earlier crystallization occurs which prevents the progress of the orientation of the amorphous phase. The lower molecular orientation in the amorphous phase of the fibers from DMT, in turn, accounts for their lower tenacity. The earlier crystallization of the fibers from DMT would be related to their slightly higher melting temperatures and melt viscosities, which could be due to the lower amount of constitutional defects (diethylene glycol content) in the considered PET samples from DMT compared with those from TPA. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 889–896, 1997 相似文献
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Polarized Raman spectroscopy was used to analyze uniaxially oriented fibers of poly(ethylene terephthalate) (PET) fibers. The second-order and fourth-order Legendre polynomials of the orientation distribution function of the 1030-cm−1 vibrational band were determined to be zero for samples of low-to-moderate orientation. Because this band was assigned to the gauche conformation of the ethylene glycol unit, the orientation of the gauche configuration of ethylene glycol units in PET for PET of low-to-moderate orientation was random. This was consistent with the assumptions used by Ward and coworkers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 47–52, 2004 相似文献
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D. W. Tomlin C. M. Roland L. I. Slutsker 《Journal of Polymer Science.Polymer Physics》1993,31(10):1331-1337
X-ray scattering from a series of poly(ethylene terephthalate) (PET) fibers spun at differet speeds is analyzed to probe the morphology in the direction transverse to the fiber axis. Both the apparent crystal modulus, determined from the change in wide-angle X-ray scattering angle with fiber stretching, and the transverse degree of crystallinity indicate there is a substantial interfiberillar amorphous content. In the PET fiber spun at conventional speeds, only roughly one-quarter of the fiber cross-section is actually occupied by fibrils. The transverse crystallinity increases for fibers spun at speeds sufficient to cause crystallization in the spin line. The X-ray moduli and fibril diameters are correspondingly larger in these high speed spun fibers. © 1993 John Wiley & Sons, Inc. 相似文献
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Poly(L ‐lactic acid) (PLLA) filament fibers were prepared by one‐step melt spinning process and the effects of variations in take‐up speed on their thermal properties, mechanical properties, and crystalline structures were investigated. Differential scanning calorimetry (DSC) results revealed that the PLLA fibers showed multiple melting peaks and that the melting peak appearing at a lower temperature moved lower while that at a higher temperature moved higher with increasing take‐up speed. The glass transition temperature (Tg) obtained from dynamic mechanical analysis (DMA) increased with increasing take‐up speed. The tenacity increased and the boiling water shrinkage (BWS) decreased with increasing take‐up speed. However, these mechanical and thermal properties were stabilized at take‐up speeds over 3500 m/min. The melt‐spun PLLA fibers of this study showed an α‐form crystal structure which was not affected by the take‐up speed. The change in the tendency of the thermal and mechanical properties at around 3500 m/min did not appear to result from the change in crystal form but rather from the change in crystallite size and crystallite orientation. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献