Improved mechanical properties of chitosan fibers

A highly deacetylated chitosan from shrimp with a degree of deacetylation of 95 ± 3% was prepared and spun into a monofilament fiber using a solution of 5% by weight chitosan in 5% by volume aqueous acetic acid. Samples of the spun fibers were immersed in separate solutions containing phosphate ions and phthalate ions, and subsequently washed and dried. The various solutions ranged in pH from 4.12 to 7.75. The highest dry mechanical properties resulted from solutions containing phthalate ions between 4.5–5.5 pH, and from solutions containing phosphate ions at pH 5.4. Immersion time was varied between 1 and 60 min at 25.8°C, and temperature was varied between 25.8 and 70.0°C, in the phosphate ion solutions at a pH of 5.8. Dry mechanical properties were highest at 25.8°C and after 1 h of treatment. Chitosan films were subjected to similar treatments in phosphate and phthalate ion solutions. Fourier transform infrared data (FTIR) on the films suggest that some interaction is occurring between the phosphate ions and the amine group on the chitosan backbone. An additional experiment was performed whereby the same chitosan was used to prepare a dope of 4% by weight chitosan in 4% by volume aqueous acetic acid with 30% by volume methanol. This solution was spun into fibers, but was subjected to a “final draw” by increasing the speed of the winder. With increasing the final draw, denier and elongation‐at‐break decreased, while the other mechanical properties showed a marked increase. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1721–1732, 1999     

高密度壳聚糖溶液流变性能及可纺性研究

以乙酸为溶剂,配置了高密度壳聚糖(HDC)纺丝浆液;以氢氧化钠/乙醇溶液为凝固浴,采用湿法纺丝制备HDC中空纤维;研究了纺丝浆液的流变性能及可纺性,并对HDC-中空纤维的结构与性能进行表征。结果表明:在HDC质量分数为2%～6%,温度20～70℃条件下,HDC纺丝浆液属于剪切变稀的假塑性流体,非牛顿指数小于1.0;HDC质量分数为5%的纺丝浆液在20～30℃下,以质量分数3%的氢氧化钠/乙醇(质量比1/1)作为凝固浴进行湿法纺丝,可纺性良好,得到的HDC中空纤维结构较完善,力学性能较好,纤维线密度为0.27 dtex,断裂强度为0.72 cN/dtex,断裂伸长率为6.09%,模量为6.12 GPa。     

羧甲基壳聚糖及其纤维的制备及表征

用氯乙酸改性处理壳聚糖(CS)制备羧甲基壳聚糖(CMCS),采用湿法纺丝法制备CMCS纤维,考察了纺丝原液浓度、醋酸水溶液体积分数、凝固时间对CMCS纤维力学性能的影响;通过傅里叶变换红外光谱、X射线衍射以及热失重分析对CS,CMCS及其纤维进行表征。结果表明:CMCS发生了羧甲基取代,同时CMCS结晶度降低;CMCS纤维结构中含有结合水,热分解温度为270℃;纺丝原液CMCS的质量分数为50%,醋酸水溶液的体积分数为2%、凝固时间为12 min时,CMCS纤维的断裂强度达0.644 cN/dtex。     

甲壳素和甲壳胺纤维质量的影响因素

概述了影响甲壳素和甲壳胺纤维质量的因素,如甲壳素和甲壳胺的品质、纺丝原液的溶剂选择及浓度的确定、凝固浴的确定;简述了通过化学改性来改善甲壳素和甲壳胺纤维性能;介绍了国内外为改善纤维质量所作的最新研究。     

二甲基亚砜法聚丙烯腈原丝干湿纺与湿纺成形工艺的比较

对二甲基亚砜(DMSO)法聚丙烯腈(PAN)原丝干湿纺和湿纺成形工艺进行比较,得出两种不同的成形工艺对PAN原丝表面光洁性和横截面形状的影响。实验表明:干湿纺成形纤维表面光洁,湿纺成形纤维表面凹凸有沟槽;不同的凝固浴浓度条件下,湿纺纤维横截面从圆形到非圆形再到圆形变化,干湿纺纤维横截面从圆形到非圆形变化。     

Sorption properties of the composite fibers made of PAN and chitosan

A composite fiber of polyacrylonitrile (PAN) and chitosan was obtained by spinning the mixture of PAN/chitosan with a certain amount of diluted acetic acid as a plasticizer. Water plasticizes the PAN and acetic acid plasticizes the chitosan. The fiber showed a porous and fibrillar structure, which could be converted easily into pulplike short fiber by pulping. PAN/chitosan pulp showed a much higher amount of uptake for acid dye than that of either powdery chitosan or activated carbon. It is considered that this better sorption capacity of the composite fiber results from the relatively large surface area attributed to its pulplike shape. The adsorption behavior of the composite fiber was considerably affected by temperature and pH because the adsorption is exothermic and proceeds by an acid–base reaction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2505–2511, 2002     

干-喷湿纺聚丙烯腈纤维拉伸工艺研究

研究了干 -喷湿纺聚丙烯腈 (PAN)初生纤维的喷丝头拉伸比和三级拉伸 (空气拉伸、DMF浴拉伸、热水和沸水拉伸、干热拉伸 )工艺中各拉伸比对纤维性能的影响。结果表明 :提高喷丝头拉伸比可明显地降低初生纤维的线密度 ,提高强度 ;三级拉伸工艺中各拉伸比的提高均有利于PAN纤维线密度的减小及其强度、声速取向度和抗张模量的提高 ;合理调配三级拉伸中各拉伸比可制得强度超过 7.0cN/dtex的PAN纤维     

高浓度纤维素纺丝液湿法纺丝工艺研究

以棉纤维为原料,采用离子液体-二甲基亚砜复合溶剂配制固含量17%的纺丝液,通过湿法纺丝制备纤维素纤维,探讨了凝固牵伸比、水洗牵伸比及水洗温度对纤维结构和性能的影响。研究结果表明:采用凝固正牵伸,可以有效提高纤维力学性能与结晶性能。当凝固牵伸比为1.05、水洗牵伸比为1.3、水洗牵伸温度为60℃时,得到的再生纤维素纤维性能较好,断裂强度为2.11cN/dtex,断裂伸长率为10.29%;纤维素纤维取向度较高,结晶比较完善。     

Development of high‐strength fibers from aliphatic polyketones by melt spinning and drawing

We have investigated the formation of high‐strength, high‐modulus fibers from four aliphatic polyketone resins. One resin was a perfectly alternating copolymer of ethylene and carbon monoxide, while the other three were terpolymers containing up to 6 mol % propylene. The mechanical properties were measured as a function of processing conditions, and the structures of the filaments were characterized using birefringence, WAXS, SAXS, SEM, and thermal analysis. Fibers formed from all resins develop very high molecular orientations and a microfibrillar structure. Fibers having room temperature tenacities as high as 10 gpd (～1.1 GPa) were obtained. Tensile moduli reached values as high as 120 gpd (～13 GPa). The melting point of the fibers was primarily dependent on the composition of the resin, while the maximum strength and modulus were largely determined by the maximum draw ratio achieved. The maximum draw ratio achieved in the present experiments was greater for the terpolymers than for the copolymer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1794–1815, 2001     

高浓度湿法冻胶纺丝制备UHMWPE纤维的研究

研究冻胶湿法路线制备时纺丝温度、溶胀温度、螺杆转速对于纤维强度的影响,通过设计正交试验确定最佳纺丝工艺.通过配置质量分数分别为12％和16％的纺丝溶液,研究黏均分子质量为57×104～ 330×104g/mol的超高分子量聚乙烯(UHMWPE)树脂在不同纺丝溶液质量分数条件下制备成的纤维.结果 表明:影响纺丝强度的因素...     

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。     

一种表征聚丙烯腈纤维预氧化程度的新方法

在工业化连续碳纤维生产线上,对干喷湿纺和湿纺的聚丙烯腈(PAN)原丝进行对比实验,跟踪了这两类原丝在预氧化和碳化过程中力学性能的变化规律。采用密度仪、纤维单丝断裂强力仪等测试分析了不同预氧化条件下预氧化纤维的力学性能与相应碳纤维力学性能之间的内在联系。结果表明,碳纤维的力学性能与预氧化纤维的断裂强力密切相关。通过与不同的预氧化程度表征方法相比较,提出了以预氧化纤维的强力损失率作为表征PAN纤维预氧化程度的新方法。     

Effect of carboxymethylation on the absorption and chelating properties of chitosan fibers

Chitosan fibers were treated with chloroacetic acid to prepare partially substituted carboxymethyl chitosan fibers. Fibers with different levels of carboxymethylation were prepared by controlling the ratio between the fiber and the amount of chloroacetic acid. The absorption properties of the modified fibers for Cu(II) ions were studied at different concentrations, temperature, time, and pH. Results showed that the carboxymethylated chitosan fibers were more effective than the original chitosan fibers in removing Cu(II) ions from aqueous solutions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3110–3115, 2006     

Manufacture and properties of chitosan/N,O‐carboxymethylated chitosan/viscose rayon antibacterial fibers

Chitosan/N,O‐carboxymethylated chitosan/viscose rayon antibacterial fibers (CNVFs) were prepared by blending chitosan emulsion, N,O‐carboxymethylated chitosan (N,O‐CMC), and viscose rayon together for spinning. The fibers were characterized by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). TEM micrographs showed that chitosan microparticles dispersed uniformly along the oriented direction with the mean size ranging from 0.1 to 0.5 μm. DSC spectra of these fibers showed that no significant change in thermal property was caused by adding chitosan and N,O‐CMC into the viscose rayon. TGA spectra showed that the good moisture retentivity was not affected by the addition of chitosan and N,O‐CMC. Both DSC and TGA suggested that the decomposing tendency of the viscose rayon above 250°C seemed to be weakened by the chitosan. The fibers' mechanical properties and antibacterial activities against Escherchia coli, Staphylococcus aureus, and Candida albicans were measured. Although the addition of chitosan slightly reduced the mechanical properties, the antibacterial fibers' properties were obtained and were found to meet commercial requirements. CNVF exhibited excellent antibacterial activity against E. coli, S. aureus, and C. albicans. The antibacterial activity increased along with the chitosan concentration and was not greatly affected by 15 washings in water. Scanning electron microscopy (SEM) was used to observe the morphology of bacteria cells incubated together with the antibacterial or reference fibers. SEM micrographs demonstrated that greater amounts of bacteria could be adsorbed by the antibacterial fiber than by the reference fiber; these bacteria were overwhelmingly destroyed and killed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2049–2059, 2002; DOI 10.1002/app.10501     

Development of ultrafine chitosan fibers through modified wetspinning technique

Chitosan has been extensively exploited in biomaterials research because of easy tailorable properties. Chitosan fibers are produced through either wetspinning or electrospinning. However, it is difficult to produce few microns fibers using either of these techniques. Present study focuses on production of ultrafine chitosan fibers through modified wetspinning technique by injecting homogenous chitosan solution through a very fine hole of silicone tube into either sodium tripolyphosphate (STPP) or sodium hydroxide (NaOH) bath by applying positive pressure. The gelation behavior of the chitosan was evaluated with STPP and NaOH solution through rheological study for comparative spinnability of chitosan in STPP and NaOH bath. Although gel strength of chitosan–NaOH system (240 Pa) was four times higher than that of chitosan–STPP system, gel breakdown rate was higher in previous case. From Fourier infrared spectroscopy (FTIR) analysis, ionic cross‐linking between TPP and chitosan molecules in chitosan–TPP fibers was confirmed. Scanning electron micrographs showed fine chitosan fibers with average diameter of ～ 10 μm. These nonwoven fibers/scaffolds with interconnected porosity may find potential biomedical applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

超吸水纤维工业化试验装置中纺丝甬道的改造

在超吸水纤维项目工业化试验研究中，针对出现的丝束拉伸不足、纤维强度偏低等问题，对关键设备进行了改造，即在甬道入丝口处加装湿热气流排出装置，创建流变态拉伸区域，有效地解决了纺丝中出现的问题。     

柞蚕丝丝素/壳聚糖共混体系的静电纺丝研究

利用六氟异丙醇和三氟乙酸为溶剂,通过静电纺丝制备了不同共混比的柞蚕丝丝素(TSF)/壳聚糖(CS)纳米纤维。研究了TSF/CS共混比对纺丝液黏度、电导率和纤维形貌的影响。结果表明,TSF/CS共混液的电导率随CS含量的增加而增加;随着CS含量的增加(≤15%),共混液的黏度增加缓慢,纤维由转曲的扁平带状逐渐变为圆柱形且直径逐渐降低;当CS含量超过15%时,共混液的黏度随CS含量的增加而显著增大,纤维出现粗细两极分化现象。     

Rheological behavior of collagen/chitosan blended solutions

Understanding the rheological behavior of collagen/chitosan blends is fundamental to design the optimized collagen/chitosan composite materials. Steady shear, dynamic frequency sweep, thixotropy and creep-recovery tests were investigated to characterize the rheological behavior of collagen/chitosan blends as a function of chitosan content (0%–90% [wt/wt]). All the samples showed pseudoplasticity with shear-thinning behavior. With the increase of chitosan, the viscosity significantly decreased from 862.54 to 0.60 Pa s at 0.05 s⁻¹. The storage modulus and loss modulus also decreased while the dynamic denaturation temperature increased from 39.79 to 45.18°C. Besides, the thixotropy weakened and when the chitosan content reached 70%, the final recovery percentage was only 4.6%. The entanglements between collagen fibers observed by atomic force microscopy became weaker. Finally, the corresponding mathematical models were used to simulate the experimental data, and the obtained parameters might provide some useful theoretical guidance for the processing of the collagen/chitosan blended solutions.     

提高熔体直纺涤纶长丝强度的工艺探讨

通过对聚合及纺丝工艺条件的调整试验,研究原料及工艺条件变化对直纺涤纶全拉伸丝(FDY)断裂强度的影响,找出了影响直纺FDY断裂强度的因素有对苯二甲酸(PTA)质量、熔体黏度、冷却吹风速度、纺丝速度及拉伸比等。结果表明,选用优质的PTA原料,控制较高的聚合物熔体特性黏度,再通过调整纺丝及卷绕工艺条件,可改善纺丝性能,生产的涤纶FDY的强度可达4.8 cN/dtex左右,从而提高了长丝质量。     

熔融纺丝法制备UHMWPE/MMT复合纤维的研究

以超高相对分子质量聚乙烯/蒙脱土(UHMWPE/MMT)纳米复合材料为原料,采用熔融纺丝法,在自行设计制造的实验纺丝机上制备出纤维,利用DSC、XRD、SEM等手段对其结构进行了表征,并对其性能进行了测试。拉伸条件试验表明,水浴温度85℃、拉伸倍率14倍,是纤维最佳拉伸温度与倍率;纤维在拉伸过程中存在一个最佳的甬道停留时间。微观结构分析表明,拉伸后得到的纤维熔点、取向度都得到了提高,并在一定条件下出现了正交晶形到六方晶形的转变。