Study of flame‐resistant acrylic fibers reinforced by poly(vinyl alcohol)

Acrylic fibers [polyacrylonitrile (PAN) fibers] have excellent flame‐retardant properties after they are modified by hydrazine hydrate and metal ions; however, their widespread applications are restricted because of poor mechanical properties. To improve the mechanical properties of these modified PAN fibers, poly(vinyl alcohol) (PVA) was added to the spinning solution of PAN as an effective reinforcing agent. The structure of the fibers before and after modification was studied by Fourier transform infrared spectroscopy, scanning electron microscopy, energy‐dispersive spectroscopy, and wide‐angle X‐ray diffraction. The mechanical properties and flame resistance of the fibers after treatment were also tested by a single‐fiber tensile tester and a limiting oxygen index (LOI) analyzer, respectively. We found that the LOI of the modified fibers was reduced from 54.7 to 29.1 after the introduction of 50 wt % PVA; however, the tensile strength was dramatically improved from about 1.50 cN/dtex to more than 4.00 cN/dtex. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43006.     

The novel alginate/N‐succinyl‐chitosan antibacterial blend fibers

Alginate/ N‐Succinyl‐chitosan (SCS) blend fibers, prepared by spinning their mixture solution through a viscose‐type spinneret into a coagulating bath containing aqueous CaCl₂, were studied for structure and properties with the aid of infrared spectroscopy (IR) and X‐ray diffraction (XRD). The results indicated a good miscibility between alginate and SCS, because of the strong interaction from the intermolecular hydrogen bonds. The best values of the dry tensile strength and breaking elongation were obtained when SCS content was 30 wt %. The wet tensile strength decreased with the increase of SCS content, and the wet breaking elongation achieved maximum value when the SCS content was 30 wt %. Introduction of SCS in the blend fiber improved water‐retention properties of blend fiber compared to pure alginate fiber. Antibacterial fibers, obtained by treating the fibers with aqueous solution of silver nitrate, exhibited good antibacterial activity to Staphylococcus aureus. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of keratin–poly(vinyl alcohol) blend fiber

Keratin–poly(vinyl alcohol) (PVA) blend fibers containing 13–46 wt % of –SSONa⁺ (S‐sulfo) keratin were prepared by the wet‐spinning technique. They were formed by dehydration of an aqueous solution of S‐sulfo keratin and PVA (spinning dope) in a coagulation bath of sodium sulfate–saturated solution and subsequently drawn. Keratin–PVA fibers showed higher tenacity than that of wool, presumably originating from the high mechanical strength of the PVA component. The heat treatment at about 200°C improved the waterproof characteristics such as shrinkage of keratin–PVA fibers more conspicuously than did PVA fibers. That is, after heat treatment at 195°C for 10 min, keratin–PVA blend fiber shrank 20% in water at 60°C, whereas PVA fiber shrank 56%. Differential thermal analysis suggested the crosslinking of disulfide bonds between keratin molecules during the heat treatment, whereas the additional crystallization of PVA component was not observed. Adsorption of heavy metal and toxic gas to keratin–PVA fibers was also investigated. Keratin–PVA fiber was found to adsorb Ag⁺ and formaldehyde gas more efficiently than PVA. Thus, blends of keratin and PVA were advantageous for both polymer fibers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 756–762, 2004     

Preparation of alginate/soy protein isolate blend fibers through a novel coagulating bath

Alginate and soy protein isolate blend fibers were prepared by spinning their solution through a viscose‐type spinneret into a novel coagulating bath containing aqueous CaCl₂, HCl, and ethanol. The structures and properties of the fibers were studied with the aids of infrared spectra (IR), X‐ray diffraction (XRD), and scanning electron micrograph (SEM). Mechanical properties and water‐retention properties were measured. And with the sample of AS1 fiber (soy protein isolate weight content was 10%), the effects of the composition of the novel coagulating bath were also studied. The best values of the tensile strength of AS1 were 14.1 cN/tex in the dry state and 3.46 cN/tex in the wet state, respectively. Both the dry state and wet state breaking elongation were also having the best value 20.71% and 56.7% with AS1. Mechanical properties of the AS1 enhanced with the CaCl₂ content increased in the coagulating bath. When the HCl content was 1%, the mechanical property of the fiber was best. Ethanol in the coagulating bath increased the wet mechanical properties of the fiber by 41.2% (tensile strength) and 45.1% (breaking elongation) when the ethanol weight content in the coagulating bath was 50%; but it had little effect on the dry mechanical properties. And the water‐retention value (WRV) of blend fibers decreased as the amount of soy protein isolate was raised. The structure analysis indicated that there were strong interaction and a certain level of miscibility between alginate and soy protein isolate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 425–431, 2006     

Preparation and properties of chitosan/poly(vinyl alcohol) blend foams for copper adsorption

A new form of polymer blend, macroporous chitosan/poly(vinyl alcohol) (PVA) foams made by a starch expansion process, exhibits the functionalities of chitosan while avoiding its poor mechanical properties and chemical instabilities. The appropriate conditions for foaming are discussed using both insoluble and water‐soluble chitosan. The chitosan/PVA foams demonstrated interconnected and open‐cell structures with large pore size from tens to hundreds of micrometers and high porosities from 73.6 to 84.3%. Glutaraldehyde was employed to improve the retention of chitosan and copper adsorption of the chitosan/PVA foams. While it increased the retention of chitosan and the adsorption capacities, glutaraldehyde decreased the pore size and porosity. The macroporous structure of the chitosan/PVA foams indicates extensive application prospects in terms of the considerable adsorption of heavy metal ions. Copyright © 2006 Society of Chemical Industry     

Preparation and characterization of alginate/gelatin blend fibers

Alginate and gelatin blend fibers were prepared by spinning their solution through a viscose‐type spinneret into a coagulating bath containing aqueous CaCl₂ and ethanol. The structure and properties of the blend fibers were studied with the aid of infrared spectra, scanning electron micrography, X‐ray diffraction, and thermogravimetric analysis. Mechanical properties and water‐retention properties were measured. The best values of the tensile strength and breaking elongation of blend fibers were obtained when gelatin content was 30 wt %. The water‐retention values of blend fibers increase as the amount of gelatin is raised. The structural analysis indicated that there was strong interaction and good miscibility between alginate and gelatin molecules resulted from intermolecular hydrogen bonds. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1625–1629, 2005     

Chitin nanocrystal reinforced wet‐spun chitosan fibers

Chitosan (CS) has been extensively studied and found wide applications in the field of biomedicine because of its favorable biological properties. Normal CS fibers are manufactured either by wet‐spinning or by dry‐jet wet‐spinning. However, the poor tensile strength of CS fibers raises much concern. The present study uses chitin nanocrystal (ChiNC), a stiff rod‐like nanofiller, to enhance the mechanical properties of wet‐spun CS fibers. Owing to the good compatibility between CS and ChiNC, the nanoparticles are well distributed in the CS matrix. When the ChiNCs loading is 5 wt %, the optimal mechanical properties of CS fibers are obtained, and the peak stress is 2.2 cN/dtex and modulus is 145.6 cN/dtex, which are increased by 57% and 84.5%, respectively, compared to that of nonfilled CS fibers under the same processing condition. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40852.     

MF-PVA阻燃纤维结构与性能研究

将三聚氰胺甲醛(MF)树脂和聚乙烯醇(PVA)制得纺丝原液,经湿法纺丝得到MF-PVA阻燃纤维,研究了MF-PVA阻燃纤维的结构与性能。结果表明:MF-PVA纤维截面形状不规则,表面不光滑,且有孔洞;MF-PVA纤维具有较好的力学性能,热性能和阻燃性能,其模量为75 cN/dtex,断裂强度为1.5～2.5 cN/dt- ex,断裂伸长为15%,吸湿率为9.2%,结晶度为20.5%,热分解温度为300℃,极限氧指数达35。MF-PVA纤维耐酸碱性一般,在酸碱溶液中经过98 h浸泡后,纤维的强度保持率低于50%。     

BaSO_4对BaSO_4/PVA共混纤维结构与性能影响的研究

通过冻胶纺丝的方法制得了屏蔽剂BaSO4含量达70％的屏蔽X-射线纤维,讨论了BaSO4含量对共混纤维的力学性能、结晶性能的影响。研究表明,随屏蔽剂BaSO4含量的增加,共混纤维的各项力学性能指标均变差,纤维的结晶度、结晶温度均随之发生变化。     

海藻酸钙/纳米TiO_2共混纤维的制备与表征

将含固体质量分数为5%的海藻酸钠纺丝原液与纳米二氧化钛(TiO2)水分散液均匀混合,制得海藻酸钠/纳米TiO2混合纺丝原液,采用湿法纺丝,通过氯化钙凝固浴,经拉伸、水洗,制备了海藻酸钙/纳米TiO2共混纤维,研究了纳米TiO2含量对共混纤维结构及性能的影响。结果表明:纳米TiO2的加入,提高了共混纤维的力学性能;加入质量分数为0.5%的纳米TiO2,海藻酸钙大分子链上的红外特征吸收峰峰形明显变宽,共混纤维的力学性能最佳,断裂强度为2.93 cN/dtex,断裂伸长率为7.34%,优于海藻酸钙纤维;添加纳米TiO2质量分数为3%时,纳米TiO2在共混纤维中仍能较好的分散,且纤维表面光滑。加入纳米TiO2后,共混纤维的热稳定性提高。     

MF树脂羟甲基化度对MF/PVA共混纤维结构及性能的影响

采用不同羟甲基化度的三聚氰胺甲醛(MF)树脂与聚乙烯醇(PVA)溶液共混湿法纺丝,制备MF/PVA共混纤维;借助扫描电子显微镜研究了MF与PVA的相容性,凯氏定氮法分析了共混纤维在纺丝过程中氮流失率,并对纤维的力学性能、阻燃性能、耐热水性能及热稳定性进行了测试表征。结果表明:改变甲醛与三聚氰胺的比例可以获得不同羟甲基化度的MF树脂;随着MF树脂羟甲基化度的提高,共混纤维的氮流失率逐渐降低;当MF树脂的羟甲基化度增大至1.15时,共混纤维氮流失率为0.20%;高羟甲基化度MF制成的共混纤维经220℃处理后,断裂强度和断裂伸长率分别为3.19 cN/dtex和25.1%,极限氧指数为33.2%,水中软化点为86℃,在氮气氛围下的初始热分解温度为258.8℃,600℃时残炭量为24.63%。     

聚乙烯醇纤维的形态结构及性能研究

用ＳＥＭ,ＩＲ,ＤＳＣ等研究了聚醋酸乙烯（ＰＶＡｃ）醇解纺丝得到的聚乙烯醇（ＰＶＡ）纤维的形态结构、分子结构及热性能。用纤维电子强伸仪研究了纤维的力学性能。证明由ＰＶＡｃ醇解纺丝可得到强度和模量分别为１３．２７ｃＮ／ｄｔｅｘ和３５０．１０ｃＮ／ｄｔｅｘ的高性能ＰＶＡ纤维。     

高线密度胶原蛋白/PVA共混纤维的制备及其结构性能

在胶原蛋白与聚乙烯醇(PVA)共混溶液中,改变原液中胶原蛋白和聚乙烯醇的组成,由湿法纺丝得到初生纤维,经热拉伸、热定形、缩醛化反应制得线密度大于25dtex的胶原蛋白/PVA共混纤维。共混纤维横截面呈圆形,纤维内部无孔洞及裂纹,表面光滑,断裂强度和初始模量分别达到4.63cN/dtex和160.2cN/dtex,断裂伸长率为25.4%,结晶度为48.6%,水中软化点和回潮率分别为104℃和13.67%。     

Influence of ethylene vinyl acetate on the spinnability and mechanical properties of poly(propylene)/zeolite‐Ag blend fibers

The spinnability and mechanical properties of poly(propylene) (PP)/zeolite‐supported Ag⁺ (zeolite‐Ag)/ethylene vinyl acetate (EVA) ternary blend fibers were studied. It was found that the spinning temperature of the ternary blend fibers was decreased in the presence of EVA. The addition of 2 wt % EVA substantially improved the spinnability of the blend system by enhancing its flowability. It was also found that the ternary fiber with EVA₂₈ (28 wt % vinyl acetate content) showed balanced improvement of mechanical properties by a concomitant increase in modulus and tensile strength. The improvements of spinnability and mechanical properties suggested that a core–shell structure of zeolite‐Ag/EVA₂₈ particles, with zeolite‐Ag as the core and EVA₂₈ as the shell, was formed and remained during the melt‐mixing process of the blended chips and during the course of fiber processing. EVA probably enhanced the binding between the zeolite‐Ag and the PP matrix, as made evident in SEM microphotographs. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1460–1466, 2005     

Infrared Spectroscopic Investigation of Hydrogen Bonding in EVOH Containing PVA Fibers

Fibers of poly(vinyl alcohol) (PVA) containing ethylene‐vinyl alcohol copolymer (EVOH) are made by gel spinning. By using IR spectroscopy, the hydrogen bonds of the PVA/EVOH fibers with different EVOH content and different draw ratio are discussed. The peaks in the neighborhood of 3 400 cm^–1 and the peaks near 3 600 cm^–1 are used to analyze the hydroxyl absorption engaged in hydrogen bonds and the free hydroxyl absorption, respectively. As for PVA/EVOH films, with increasing EVOH content the H‐bond is gradually weakened. As for fibers, however, with increasing EVOH content the strength of the H‐bond increases, while the number of H‐bonds is decreased. Similarly, with increasing draw ratio of the PVA/EVOH fibers, the strength of H‐bond increases, while the number of H‐bonds seems decreased. Higher EVOH content in the PVA/EVOH fibers causes a higher maximum draw ratio because of weakening of the H‐bond. However, higher draw ratio does not always cause better mechanical properties of PVA/EVOH fibers.     

Mechanism of paper wet strength development by polycarboxylic acids with different molecular weight and glutaraldehyde/poly(vinyl alcohol)

In our previous research, we found that crosslinking paper using poly(carboxylic acid)s with different molecular weight or using the combination of glutaraldehyde and poly(vinyl alcohol) (PVA) significantly improved the wet strength of the paper. In this research, we studied the mechanism of paper wet strength development using crosslinking systems with different molecular weight by measuring scanning electron microscopic (SEM) images, wet strength, folding endurance, wet thickness, water retention, and Z‐direction tensile strength of the treated paper. The paper crosslinked by a high‐molecular weight (MW) poly(carboxylic acid) shows more swelling by water than that crosslinked by a low‐MW polycarboxylic acid in the SEM micrographs even though both treated paper samples have similar wet strength. Thus, the data suggest that high‐MW poly(carboxylic acid)s promote the formation of interfiber crosslinking. Crosslinking paper by glutaraldehyde, a crosslinking agent of small molecular size, improves wet strength and reduces flexibility and swellability of paper because of the formation of intrafiber crosslinking. Combining glutaraldehyde with PVA as a coreactant increases wet strength and also retains flexibility and swellability of the treated paper because of the formation of interfiber crosslinking. The hypothesis that PVA reacts with glutaraldehyde to form a polymeric pentanedialated‐PVA crosslinking system and promotes the formation of interfiber crosslinking on the paper is supported by the data of wet strength, folding endurance, wet thickness, water retention, and Z‐direction tensile strength of the treated paper. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 277–284, 2006     

Preparation and characterization of alginate/Hydroxypropyl chitosan blend fibers

Hydroxypropyl chitosan (HPCS) was synthesized from chitosan and propylene oxide under alkali conditions. It was characterized by IR spectroscopy and X-ray diffraction (XRD). We prepared alginate/HPCS blend fibers by spinning their solution through a viscose-type spinneret into a coagulating bath containing aqueous CaCl₂ and ethanol. The structure and properties of the blend fibers were studied with the aid of IR spectroscopy, scanning electron microscopy, and XRD. The results indicate a good miscibility between alginate and HPCS because of the strong interaction of the intermolecular hydrogen bonds. The mechanical properties and water-retention properties were also measured. The best values of the tensile strength and breaking elongation of the blend fibers were obtained when the HPCS content was 30 wt %. The water-retention values of the blend fibers increased as the amount of HPCS increased. Antibacterial fibers, obtained by the treatment of the fibers with an aqueous solution of silver nitrate, exhibited good antibacterial activity to Staphylococcus aureus. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

改性剂对胶原蛋白复合纤维结构性能的影响

在胶原蛋白和聚乙烯醇共混溶液中,添加不同量改性剂制得纺丝原液,经湿法纺丝得到初生纤维,初生纤维再经过热拉伸、热定型和缩醛化处理得到胶原蛋白复合纤维。由该方法制得的复合纤维中胶原蛋白存留率达到91.6%,结晶度为57.8%。由扫描电镜观察纤维横截面为肾形,纤维内部致密、无相分离。纤维断裂强度为4.1 cN/dtex,初始模量为147.5 cN/dtex,断裂伸长为26.9%,纤维水中软化点为104℃。     

Electrospinning fabrication and characterization of poly(vinyl alcohol)/layered double hydroxides composite fibers

Nanofibers of poly(vinyl alcohol) (PVA)/layered double hydroxide (Mg‐Al LDH) composites are prepared by the electrostatic fiber spinning using water as the solvent at a high voltage of 21 kV. Either inorganic LDH carbonate (LDH‐CO₃) or L ‐lactic acid‐modified LDH (Lact‐LDH) is used for incorporating with PVA. Scanning electron microscopy SEM investigations on the nanofibers suggest that the average diameters of PVA/LDH composite fibers are smaller than that of neat PVA. Transmission electron microscopy (TEM) investigations indicate that the dispersity of the LDH in PVA matrix is much improved after modification with L ‐lactic acid. The mechanical properties of the PVA/LDH fibers are obviously enhanced compared to that of neat PVA. For example, the tensile stress and elongation at break of the PVA/Lact‐LDH electrospun fibrous mat with 5 wt % Lact‐LDH are 31.7 MPa and 36.7%, respectively, which are significantly higher than those of neat PVA, and also higher than those of PVA/LDH‐CO₃ owing to the better dispersity of Lact‐LDH nanoparticles. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

聚氨基环磷腈的合成及其在PVA纤维中的应用

将六氯环三磷腈进行氨基取代,高温自聚得到不溶于水的聚氨基环磷腈(PHACTPA);PHACTPA通过粉末化后与聚乙烯醇(PVA)溶液共混纺丝得到阻燃PVA纤维。结果表明:PHACTPA在湿热条件下不稳定,但其干热稳定性好,在400℃高温氮气环境下稳定而不分解。PHACTPA在纤维中的质量分数小于22．5％时,对纤维的强度影响不大;含PHACTPA质量分数为15％的阻燃PVA纤维极限氧指数可达40％。