高强高模聚乙烯醇(PVA)纤维的研究进展

高强高模PVA纤维是PVA纤维研究的重要方向,它具有极其优异的性能和广泛的应用领域。本文概述了高强高模PVA纤维近年来的研究进展,主要包括制备方法、特性、应用以及发展前景。     

纺丝原料对高强高模聚乙烯醇纤维结构性能的影响

研究了纺丝原料聚合度、转化率对聚乙烯醇(PVA)纤维高强高模化的影响。结果表明:高聚合度有利于减少端基缺陷,提高纤维性能;低转化率PVA相对高转化率PVA具有高的聚合度和线性程度,所得纤维力学性能更高。同时发现,低转化率原料纺得纤维在高倍拉伸后有强度模量较高的横纹丝产生,因此适合制备高强高模纤维。     

高强高模PVA纤维存放过程中力学性能的衰减规律

以2.0 dtex高强高模聚乙烯醇(PVA)纤维为例,采用单纤维强伸仪,测试纤维在存放期间(1～360 d)的断裂强度、断裂伸长率和初始模量,考察高强高模PVA纤维力学性能随存放时间的衰减规律。结果表明:随存放时间的延长,高强高模PVA纤维的断裂强度和初始模量逐渐减小,断裂伸长率逐渐增大,存放时间达270 d后均趋于稳定;高强高模PVA纤维存放90 d内断裂强度、断裂伸长率和初始模量变化较小,存放时间超过90 d后纤维力学性能明显下降,存放时间达270 d时,纤维断裂强度下降2.9%,断裂伸长率增加6.6%,初始模量下降10.3%;在高强高模PVA纤维的实际应用中,纤维在90 d内使用为宜。     

高强高模PVA纤维在单兵防护装备中的应用

高强高模PVA纤维具有断裂比功大、易于粘接、价格低廉等优点.本文在测试分析PVA纤维的力学性能的基础上,研究了纯PVA纤维和PVA/芳纶复合防弹靶板的防弹性能,揭示了PVA纤维在单兵防护材料领域的应用前景.     

高强高模聚乙烯醇纤维的研究进展

综述了聚合度、纺丝方法、拉伸和后处理工艺对制备高强高模聚乙烯醇 ( PVA )纤维的影响 ,以及高强高模 PVA纤维在建筑、国防军工等领域的应用 ,指出我国应加强 PV A纤维的新产品、新用途的开发     

生产工艺条件对聚乙烯醇纤维结构与性能的影响

用扫描电子显微镜和单丝强伸仪研究了不同生产工艺条件下制备的聚乙烯醇(PVA)纤维的形态、力学性能和耐热水性能。结果表明:通过加硼交联湿法纺丝,采用多段高倍干热拉伸并控制工艺参数,可以得到超高强、高模PVA纤维。结构均匀、缺陷少、高取向、高结晶是获得高强、高模纤维的关键性因素。     

高强高模聚乙烯醇纤维的研究进展

从聚合方法和引发方式综述了国内外合成高相对分子质量及高立构规整度聚乙烯醇(PVA)的研究进展;详述了通过聚新戊酸乙烯酯的醇解来制备PVA微纤的方法;简述了高强高模PVA纤维的特性及应用;指出今后高强高模PVA纤维的研究应在聚合方法、开发新的高效引发剂和醇解工艺作进一步探索。     

超高强超高模PVA纤维的制备

综述了制备超高强、超高模PVA纤维的干湿纺丝法,论述了纺丝工艺及方法与纤维性能的关系,介绍了该纤维的应用领域。     

聚乙烯醇纤维及聚氯乙烯纤维

20002136应用水泥和其他建材的高强度聚乙烯醇(P VA)纤维季国标…;Chem.Fibers Intern.,1999,49(2),p .1 16一1 17(英)高强PVA纤维的密度1.269/c m3、纤度Zdtex、强度11~iZeN/dtex、模量36oeN/dtex,并有良好的耐紫外辐射性和耐酸碱性。高强高模PVA纤维的断裂强度9~11eN/dtex、断裂伸长7~9%、模量24oeN/dtex。高强高模PVA纤维的若干性质,使该纤维适合于用以替代增强水力用的石棉;这些性质包括高抗张强度、与普通水力有良好的化学相容性、良好的亲水性圆形和不规则的纤维截面,以及使能进行良好面际混合的分子结构。PVA增强水泥,具有…     

高强高模PVA纤维表面改性及耐碱性能

采用疏水二氧化硅涂层与纳米石墨涂层两种方案对高强高模聚乙烯醇(PVA)纤维表面进行改性,并使用接触角测量仪、原子力显微镜及Fourier红外光谱仪对处理后的纤维表面进行表征,研究了高强高模PVA纤维的耐碱性及单丝拔出时的微观力学界面参数。结果表明:经过处理后PVA纤维表面粗糙度增加,由亲水状态成功转变为疏水状态,接触角均大于130°;PVA纤维耐碱性良好,碱浸泡后拉伸强度保持率大于95%;经过表面修饰后PVA纤维的化学粘结力大幅降低。纳米石墨涂层可以很好地调控纤维与水泥基体的界面,使纤维从水泥基体中被完整拔出。     

The effect of degree of polymerization on the structure and properties of polyvinyl alcohol fibers with high strength and high modulus

Polyvinyl alcohol (PVA) fibers were prepared using PVA with different degree of polymerization (DP) under the same wet spinning process. The effect of the DP of PVA on the structures and properties of PVA and PVA fibers were studied by using nuclear magnetic resonance hydrogen spectroscopy (¹H-NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermo gravimetric analysis (TGA), and environmental scanning electron microscope (ESEM). The results showed that DP had little effect on the crystallinity and tacticity of PVA, but had a positive effect on melting temperature, and initial decomposition temperature of PVAs. The hot drawing ratio determined by the spinning process where the PVA fibers could be continuously collected without breaking. The drawing ratio was decreased with an increase of DP, resulting in an increase of the final fiber diameter. The PVA fibers with medium DP and medium size demonstrated high strength and high modulus, but relatively low breaking elongation. It suggested that high DP of PVA was not a guarantee of high strength and high modulus PVA fibers, but rather a primary structure factor. The fiber performance was determined by a comprehensive effect combining a variety of factors including polymer properties and spinning conditions. It provided a guideline for PVA fiber manufacture that the PVAs with different DP require different spinning processes to obtain optimal fiber performance.     

Preparation and characterization of high strength and high modulus PVA fiber via dry-wet spinning with cross-linking of boric acid

To improve the mechanical properties of polyvinyl alcohol (PVA) fibers, a series of PVA fibers were prepared via dry-wet spinning with cross-linking of boric acid (BA) (PVA/BA fibers), and using the mixed solvent of dimethyl sulfoxide and water. Moreover, the final PVA/BA fibers were characterized by Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), differential scanning calorimetery (DSC), thermogravimetric analyzer (TGA), powder X-ray diffraction (XRD) and yarn strength tester. Furthermore, with the increasing of BA content, FTIR analysis showed that the degree of crosslinking of BA with PVA increased. SEM images of final PVA/BA fibers presented smooth surfaces, and the diameters decreased firstly and then increased. DSC, TGA, and XRD analysis indicated that the melting temperatures, thermal properties and crystallinities first increased and then decreased with the increasing of BA content. In addition, mechanical properties measurements illustrated that the cross-linking existed at an optimal BA content of 0.3 wt%, and PVA/BA-0.3 fiber had the highest tensile strength and Young's modulus of 13.1 ± 0.4 and 360.2 ± 10.4 cN/dtex, respectively.     

Preparation of high-strength poly(vinyl alcohol) fibers by crosslinking wet spinning

High-strength poly(vinyl alcohol) (PVA) fiber was obtained by the crosslinking wet-spinning technique, which is an improved technique of the conventional non-crosslinked type wet-spinning of PVA. High tensile strength as well as high Young's modulus was achieved by introduction of the borate ion-aided crosslinks during the coagulation process. The drawability of the as-spun fiber greatly depends on the fiber thickness. The thinner the fiber, the higher the drawability. Since thinner fiber is subject to a very high shear rate on extrusion, the crosslinks introduced are believed to maintain topological memory of the oriented chains, which have a low density of entanglements. This allows drawing the fiber to a higher draw ratio. The strength and Young's modulus of the resultant highly drawn PVA fiber were achieved to be 22 g/d (2.3 GPa) and 430 g/d (50 GPa), respectively. The mechanism of the spinning was discussed and the spinning condition was carefully examined in order to optimize the final mechanical properties of the PVA fibers.     

PAN基高模量碳纤维成型过程中的结构性能关联性

以实验室自制T800级聚丙烯腈（PAN）基高强中模碳纤维为原料，经连续石墨化处理得到M50J级、M55J级高模量碳纤维，以X射线衍射（XRD）、Raman光谱为表征手段研究了高强碳纤维向高模量碳纤维转变过程中石墨微晶、取向、微孔含量、石墨化度等石墨特征结构的演变规律，并开展了PAN基碳纤维石墨特征结构与力学性能的关联性研究。研究结果表明：在高强碳纤维向高模量碳纤维转变过程中，随着石墨微晶层间距d ₀₀₂的下降以及石墨微晶堆砌厚度L _c的增加，碳纤维的拉伸模量逐渐提升；石墨微晶层间距和微晶取向是影响碳纤维拉伸强度的两个主要因素，石墨微晶层间距d ₀₀₂值增加、石墨微晶取向越高，纤维拉伸强度也越高；在高模量碳纤维的成型过程中，纤维内部微孔含量随着石墨化程度的提高而降低；经过高温石墨化处理后，碳纤维的拉伸强度会随着Raman光谱中无序结构D峰和石墨特征结构G峰积分强度比值I _D /I _G的下降而下降。     

Effective mechanical properties of polyvinylalcohol biocomposites with reinforcement of date palm leaf fibers

Polyvinylalcohol/date palm leaf fiber (PVA/DPL) biocomposites were prepared by the melt mixing fabrication technique with various proportions of fibers. DPL fibers were chemically modified with the purpose of improving the dispersion and better compatibility with PVA matrix. Different chemical processes of modification were adopted and the tensile strengths of both treated and untreated fibers were compared. It was noticed that the tensile strength of acrylic acid treated fiber was optimum in comparison to other methods. The interaction of DPL fibers with PVA matrix were studied by Fourier transforms infrared spectroscopy (FTIR). Field emission scanning electron microscope (FESEM) was used to study the morphology of biocomposites. The tensile strength, Young's modulus, elongation at break, flexural strength, and impact strength of PVA/DPL biocomposites were investigated and compared with that of virgin PVA matrix. It was found that the above properties were first increased with fiber loading and then decreased. The optimum properties were obtained at 28 wt% of DPL fiber. The storage modulus and tan delta values of PVA/DPL biocomposites were analyzed. The thermal properties of biocomposites were also studied through the results of thermogravimetric (TGA). POLYM. COMPOS., 34:959–966, 2013. © 2013 Society of Plastics Engineers     

High‐tensile‐strength polyvinyl alcohol films prepared from freeze/thaw cycled gels

The mechanical properties and molecular structure of a poly(vinyl alcohol) (PVA) film, which was obtained by eliminating water from a PVA hydrogel using repeated freeze/thaw cycles, were investigated by tensile tests, thermal analysis, and X‐ray diffraction measurements. The mechanical properties of PVA with 99.9% saponification were measured as a function of the number of freeze/thaw cycles performed. The tensile strength and Young's modulus increased and the elongation at break decreased with increasing freeze/thaw cycles. The tensile strength and Young's modulus of PVA films obtained after seven freeze/thaw cycles were as high as 255 MPa and 13.5 GPa after annealing at 130°C. Thermal analysis and X‐ray diffraction measurements revealed that this is because of a high crystallinity and a large crystallite size. A good relationship between the tensile strength and the glass transition temperature was obtained, regardless of the degree of saponification and annealing conditions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40578.