高分子量PET溶液纺初生纤维结构和性能

利用高分子量PET进行溶液纺丝是目前制取高强高模PET纤维的一种重要方法.本文主要对不同凝固剂的初生纤维的结构和性能进行了研究,这些凝固剂分别是甲醇、乙醇和丙酮,而甲醇是最为理想的凝固剂,由甲醇凝固的初生纤维结晶度小,晶粒完整性差,并且有较好的拉伸性能,这样的结构有利于纤维的高倍拉伸.     

PHB/PLLA/PEO共混纤维的晶态结构与拉伸性能研究

采用溶液干纺法制备了聚β-羟基丁酸酯/聚乳酸/聚氧乙烯(PHB/PLLA/PEO)共混纤维,研究了PHB/PLLA/PEO初生纤维的晶态结构、在50℃和110℃下拉伸后共混纤维的力学性能及表面形态。结果表明:PHB与PLLA在PHB/PLLA/PEO共混纤维中的晶型均为α晶型;初生纤维经50℃和110℃拉伸2倍后,纤维的断裂强度均有所增加,断裂伸长率减小,50℃拉伸的纤维断裂强度高于110℃拉伸,其断裂方式均为韧性断裂;w(PEO)为5%,PHB/PLLA质量比为1:1,50℃拉伸2倍的PHB/PLLA/PEO共混纤维断裂强度为0.471 cN/dtex,断裂伸长率为34.05%     

拉伸条件对高强PVA纤维结构和性能的影响

将聚乙烯醇(PVA)加入到二甲基亚砜(DMSO)和水(质量比94:6)的混合溶剂中,以甲醇为凝固剂,采用干湿法凝胶纺丝,经热拉伸和热定型后,制得高强度PVA纤维。探讨了拉伸工艺对高强PVA纤维结构和性能的影响。结果表明:对于负拉伸为40%,初拉伸2倍,220℃热拉伸9.9倍,热定型2 min的PVA纤维,纤维的结晶结构比较完善,断裂强度为17.8 cN/dtex,初始模量为310.7 cN/dtex;PVA纤维在光学显微镜下观察到的横纹反映出结晶聚集体的光学现象,横纹较多时,纤维的断裂强度和初始模量较高。     

I_2/KI溶液改性PVA纤维的制备及其性能研究

采用摩尔浓度比为1∶2的I2/KI溶液对聚乙烯醇(PVA)初生凝胶丝条进行超声浸泡处理,制备了改性PVA(I-PVA)纤维;探讨了I2/KI溶液浓度对纤维拉伸性能的影响,并对I-PVA纤维的结构与性能进行了研究。结果表明:I2在PVA纤维中主要以I-5的形态存在,I2的加入会阻碍PVA分子链之间的氢键形成,纤维的拉伸倍数得到提高,强度和模量也有提高;I-PVA纤维的最佳热拉伸温度为150℃,比未改性PVA纤维最佳热拉伸温度降低了50℃;PVA初生纤维在空气中拉伸3倍,采用0.1 mol/L的I2/KI溶液于40℃超声浸泡1 h后,于150℃拉伸10倍,得到的I-PVA纤维的断裂强度可达14.7 c N/dtex,比未改性PVA纤维提高9.7%,最大拉伸倍数提高到36。     

聚乙烯醇熔纺初生纤维的拉伸行为研究（英文）

采用去离子水溶胀聚乙烯醇(PVA),通过熔融纺丝法制备PVA纤维。研究了水质量分数35%和5%的PVA熔纺初生纤维在不同拉伸温度下的应力-应变曲线,以及其拉伸活化机制。结果表明:拉伸温度对水质量分数35%的PVA熔纺初生纤维表观拉伸黏度的影响分为3个区,即30~100℃,100~190℃,190~210℃,纤维在热拉伸时存在3个不同机制的活化过程,至少可采用三级拉伸;初生纤维拉伸受体系中水含量的影响,水含量减少,PVA分子链运动能力降低,表观拉伸黏度增大,水质量分数5%的PVA熔纺初生纤维的表观拉伸黏度随温度变化呈现两个区,活化机制改变,可采用两步拉伸。     

PLA/PCL纤维及其支架的制备与力学性能研究

将一定质量比聚乳酸(PLA)与聚己内酯(PCL)进行共混,通过熔融纺丝得到PLA/PCL初生纤维,再经过热拉伸后得到PLA/PCL纤维;利用自制模具采用手工编织的方法制备了PLA/PCL管道支架;对PLA/PCL纤维及其支架的结构与性能进行了表征。结果表明:当PLA/PCL质量比为40:60时,PLA/PCL初生纤维的综合力学性能较好;拉伸温度和拉伸倍数对PLA/PCL初生纤维的力学性能影响较大,当拉伸温度为85℃、拉伸倍数为7时,所得的PLA/PCL纤维力学性能最好;在一定温度区间内,PLA/PCL支架的支撑力随着定型温度的升高而升高,合适的定型温度应为其玻璃化转变温度至130℃之间,制备的PLA/PCL支架具有良好的弯曲性、压缩性和支撑性能,能满足支架应用的需求。     

PVA/PANI导电复合纤维的制备

以聚合度2000的聚乙烯醇(PYA)为原料,采用干湿法凝胶纺丝制备PVA初生纤维,经拉伸、热定型后,在苯胺(ANI)溶液中浸渍聚合制备PVA/PANI导电纤维,研究了导电纤维的结构与性能。结果表明:采用干湿法制备的PVA初生纤维在常温下拉伸2倍,经ANI溶液浸渍聚合,得到的PVA/PANI导电纤维的体积电阻率达34Ω·cm,该导电纤维直接热定型后断裂强度达2.8 cN/dtex。     

改性聚对苯二甲酰间苯二胺的溶解性及其纤维性能研究（英文）

采用核磁共振氢谱(~1H-NMR)对经4,4'-二氨基二苯砜(4,4'-DDS)改性后的聚对苯二甲酰间苯二胺(co-PMTA_3)进行化学结构表征;研究了co-PMTA_3的溶解性和热性能,并与对位聚芳砜酰胺(p-PSA)和常规聚芳砜酰胺(co-PSA)进行了比较;采用湿法纺丝方法制得了co-PMTA_3初生纤维,将初生纤维经340℃热拉伸1.4倍后制得线密度为10 dtex的co-PMTA_3纤维,研究了co-PMTA_3纤维的力学性能。结果表明:coPMTA_3为4,4'-DDS与间苯二胺及对苯二甲酰氯按其摩尔比为2.5/7.5/10的共聚物;co-PMTA_3的溶解性强于pPAS,但比co-PSA要弱;co-PMTA_3有较好的耐热性,其玻璃化转变温度达318.4℃,低于p-PSA的367.7℃和coPSA的343.1℃;co-PMTA_3纤维的断裂强度为4.7 cN/dtex,初始模量为56.5 cN/dtex,打结强度为2.2 cN/dtex。     

共混纺丝制聚苯硫醚超细纤维及其形态结构研究

以聚苯硫醚(PPS)和聚丙烯(PP)为原料,采用熔融共混纺丝法制备PPS/PP共混海岛纤维,经对二甲苯溶除剥离基体相PP,制得PPS超细纤维;研究了共混纺丝温度、共混比例、拉伸、溶解剥离对PPS超细纤维形态结构的影响。结果表明:PPS/PP最佳共混纺丝温度为290~300℃;随着PPS/PP质量比增大,PPS超细纤维直径逐渐变大,PPS/PP质量比从30/70增至60/40时,PPS超细纤维平均直径从228 nm增至408nm;当PPS/PP质量比大于60/40时,开始出现相转变现象;提高拉伸倍数有利于PPS超细纤维的细化,PPS/PP质量比为40/60时,3倍拉伸得到PPS超细纤维的直径分布范围为158~488 nm,平均直径为312 nm,大于3倍拉伸时,易出现毛丝断丝现象;当对二甲苯体积与共混纤维质量比为500∶1时,PPS超细纤维的最佳剥离温度为120℃、剥离时间2 h。     

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     

A new synthetic fiber made of nylon 3

Nylon 3 fibers were produced by wet spinning, and properties and structures of the fibers were investigated. Fiber- and film-forming abilities of nylon 3 dopes in various coagulants, using various solvents, were investigated and it was found that only the nylon 3 spinning dope dissolved in formic acid showed excellent fiber- and film-forming abilities in coagulation baths of ethers, esters, or alcohols. As for mass transportation in these coagulants, solvent (formic acid) was diffused into coagulants, with scarce penetration of the coagulants into protofibers. This was due to the fact that these coagulants had moderate solubility parameter values and moderate proton-accepting power, which means the existence of some interaction between solvent and coagulants and no interaction between coagulants and polymer. Protofibers thus obtained were already crystallized and stretching them at room temperature was impossible. However, in such media as silicone oil, hot air, and Wood's metal, which were thought to have no interaction with polyamides, nylon 3 fibers were stretchable above their glass transition temperature (170°–180°C), while in such media as hot water, hot glycerin, and hot steam, which were thought to have some interaction with polyamides, nylon 3 fibers could not be stretched. Mechanical properties of nylon 3 fibers were as follow: strength, 2–3 g/d; elongation, 10%–20%; Young's modulus, 11 × 10⁵–17 × 10⁵ psi. High Young's modulus, high transition temperature, and high moisture regain are pointed out as characteristic features of nylon 3 fibers, compared with other synthetic fibers.     

超高分子量PET溶解过程中的降解

利用超高分子量PET进行溶液纺丝是目前制取高强度高模量PET纤维的一种重要方法。本文对于超高分子量PET在溶解过程中的降解情况进行了研究,认为浓度、温度、时间以及凝固剂是影响其降解的主要因素,并探索了其降解动力学。     

超高分子量聚乙烯纤维 第一讲 超高分子量聚乙烯纤维发展概况

冻胶纺是一种新颖纺丝技术,用此法制取超高分子量聚乙烯纤维(UHMW-PE)的工艺过程包括:溶解UHMW-PE在适当的溶剂中,制成半稀溶液,经喷丝孔挤出,以空气或水骤冷纺丝溶液,将其凝固成冻胶原丝。从大分子观点出发,在溶液中聚乙烯大分子处于解缠状态并在冻胶原丝中保持这种大分子的解缠状态。拉伸冻胶原丝使大分子链取向和高度结晶,进而使呈折叠链的大分子转变为伸直链,从而制得高强、高模纤维。本讲座分以下五讲:第一讲超高分子量聚乙烯纤维发展概况;第二讲超高分子量聚乙烯冻胶纺工艺过程剖析;第三讲超高分子量聚乙烯的溶解和冻胶纺,第四讲聚乙烯冻胶原丝的萃取和干燥;第五讲聚乙烯冻胶原丝的超拉伸。     

Fibers spinning from poly(trimethylsilylpropyne) solutions

This study for the first time directs in assessment of the necessary conditions for spinning fibers from poly[1-(trimethylsilyl)1-propyne], one of the best for gas separation. It includes a search of appropriate solvents, investigation of rheological properties of solutions, a preparation of dopes with reasonable polymer content and a choice of effective coagulants based on their solubility parameters in frames of wet fiber spinning. The fibers were obtained with diameter of 7 ± 1 μm and strength of up to 200 MPa. The morphology of the surface and core of the PTMSP fibers was distinctively different: dense skin and friable core. From the viewpoint of membrane properties, it looks like asymmetrical membrane. In addition, the hollow fibers we prepared by dry spinning method. Overall, the stable fiber spinning process from PTMSP solutions was developed for the first time, and monolith and hollow PTMSP fibers of good quality were obtained. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48511.     

二甲基亚砜干湿法制备高强度聚乙烯醇纤维的研究

以常规聚合度聚合的乙烯醇（PVA,聚合度1 700～2 600）为原料,以二甲基亚砜（DMSO）为溶剂,乙醇为凝固剂,甲醇为萃取剂,采用干湿法纺丝制备高强度的PVA纤维,最高强度可以达到19.4 cN/dtex。使用扫描电子显微镜对PVA纤维样品进行观测,纤维样品的形貌结构十分均匀,这对提高PVA纤维的断裂强度十分有利...     

Dry-jet wet spinning of aromatic polyamic acid fiber using chemical imidization

A solution of about 15% polyamic acid (PAA) prepared from 4,4′-oxydianiline and pyromellitic dianhyride in N,N-dimethyl acetamide (DMAc) was used for fiber spinning. To obtain a high draw ratio of the PAA fiber during spinning, acetic anhydride or acetic anhydride and pyridine were added to the PAA solution to make it slightly gelled; such gelling contributed to high drawing of the PAA fibers during spinning. Before spinning the properties of the solution after acetic anhydride or acetic anhydride and pyridine were added, and the diffusion property of DMAc into various coagulants were examined. Even though acetic anhydride was only added to the spinning solution, the diffusion rate became slower and the solution viscosity increased, because PAA was converted to the corresponding polyimide (PI). Pyridine affected the rate dramatically. The mechanical properties of the PAA fibers obtained in this system were examined. Solid PI fibers were also obtained by annealing of the PAA fibers. The ultimate stress and initial modulus of the PAA fiber were around 268 MPa and 4.1 GPa, respectively. After the fiber was annealed at 350°C without tension for 30 min under nitrogen, these values increased to around 399 MPa and 5.2 GPa, respectively.     

Effect of coagulation conditions on solvent diffusions and the structures and tensile properties of solution spun polyacrylonitrile fibers

Polyacrylonitrile (PAN) fibers were spun by solution spinning. In this work, two coagulation compositions, dimethyl sulfoxide (DMSO)/water and methanol, were used, and coagulation temperatures were varied from ?20 to 0 to 20 °C. The coagulation compositions and temperatures strongly affected the solvent diffusion processes, the structures of as‐spun fibers, and the tensile properties of final drawn fibers. When DMSO/water was used as coagulation bath, non‐solvent (water) diffused into PAN fibers and led to a quick PAN solidification. By comparison, when methanol was used as coagulation bath, no or minimal amount of methanol diffused inward to the fibers. The different solvent diffusion behaviors in DMSO/water and methanol baths led to different structures of as‐spun PAN fibers. It was observed that the tensile properties of final drawn fibers strongly depended on the coagulation conditions. When methanol was used as coagulation bath and the bath temperature was ?20 °C, PAN fibers was found to possess the best tensile properties, a tensile strength of 0.89 GPa and young modulus of 20.4 GPa. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44390.     

Preparation and properties of polyimide fibers

Polyimides were synthesized from 4,4′-diamino diphenyl methane and pyromellitic dianhydride using low-temperature solution polycondensation. Solutions of these polyamic acids in dimethyl-formamide (DMF) were spun into fibers by the wet spinning technique using a mixture of DMF and water as coagulants. Various spinning parameters such as dope concentration, bath composition, and jet stretch were standardized to get polyimide fibers with optimum properties. It was observed that fibers spun at higher jet stretch did not cyclize satisfactorily. Higher dope concentrations gave fibers with better properties. Cyclodehydrated fibers were hot-drawn at 300°C. Fibers with a tenacity of 380 mN/tex, an extension at break of 10%, and initial modulus of 4060 mN/tex were obtained. Mechanical properties of fibers at elevated temperatures, i.e., 100 and 200°C were also measured. Heat aging at 100, 200, and 300°C was carried out for 10 hr. This resulted in an increase in the initial modulus of fibers. However, a 28% decrease in tenacity was observed when the fibers were heat-aged at 300°C. The dynamic thermogravimetry in air showed that fibers were stable up to 400°C. The activation energy of decomposition, calculated from these thermograms in the temperature range 540–610°C was 101 kJ/mole.     

Chitosan: Aspects of fiber spinnability

The preparation of useful fibers from chitosan remains an interesting challenge. Chitosan is easily solubilized in aqueous acids, but these solutions generally have high solution viscosities because of the polyelectrolyte effect. The high viscosity affects the processibility of chitosan during extrusion by wet‐spinning techniques. The coagulation rate, which also includes the regeneration of the free amine form of chitosan is also expected to be influenced by viscosity. In this study, the solution rheology of chitosan solutions was examined; our aim was to find the optimum compositions, in terms of chitosan, acid, and added salts, for spinnability. The diffusion of coagulants into chitosan spinning solutions is also reported. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1162–1168, 2006