改性聚乙烯醇的研究进展

聚乙烯醇的耐水性差以及热塑加工性能差等问题限制了其发展,但其良好的生物可降解性﹑生物相容性使其在材料应用领域受到高度重视。本文对聚乙烯醇的特性以及发展作了概括,同时对聚乙烯醇的未来发展作了展望。     

聚乙烯醇与苯甲醇的接枝合成与性能研究

本文研究了聚乙烯醇与苯甲醇的接枝合成,探讨了在不同温度,不同摩尔比等不同条件对该反应产物性能的影响。获得较好的反应条件:反应温度120℃,浓硫酸作催化剂,聚乙烯醇与苯甲醇的摩尔比为1∶2时,接枝聚合物的耐水性得到了大幅度的提高。     

聚乙烯醇降解的研究

用Ｈ２Ｏ２－催化剂体系或者在不同的ｐＨ下，改变Ｈ２Ｏ２的用量，使聚乙烯醇（ＰＶＡ）降解，可制得所需低聚合度的ＰＶＡ产品。     

Rheological Properties of Thermoplastic Polyvinyl Alcohol and Polypropylene Blend Melts in Capillary Extrusions

A single screw extruder with a static mixer was used to prepare molten blends of thermoplastic polyvinyl alcohol (TPVA) and polypropylene (PP). The effects of shear rate, blending ratio and temperature on rheological properties for the blends in capillary extrusions were investigated, and ends correction was also carried out. Rheological parameters such as non-Newtonian index and activation energy were also calculated and evaluated. It was found that the viscosities of the blends were lower than those of TPVA and PP; moreover, the non-Newtonian indices and the activation energies of the blend melts were higher than those of the homopolymers. In particular, the blend with 60 wt% TPVA had the highest non-Newtonian indices and activation energies among blend melts. These results indicate that TPVA and PP blends are negative deviation blends. Furthermore, at a blending ratio of 60 wt% of TPVA, the shear-sensitivity of the viscosity was the lowest and the temperature dependence of the viscosity was the highest. In addition, an increase in temperature led to an increase in non-Newtonian index, therefore the shear-rate dependence of the blend viscosities decreased with a rise in temperature. As the shear rate was increased, the variation of the viscosity over blending ratios decreased while the activation energy of the blends decreased. Thus the effects of temperature and blending proportion on flow behavior were diminished by increasing shear rate.     

疏水作用色谱用球状交联聚乙烯醇的制备

采用悬浮聚合法成功地制备了PVA白球。本文对水溶液中PVA含量、甲醛用量、表面活性剂、油水体积比、搅拌速度及反应温度等影响因素进行了研究和探索。实验得到了最佳工艺条件为：50ml15％PVA分散在300ml的油相中,以3.0g油酸钠和5．0molSpan－80作表面活性剂,用10ml甲醛溶液作交联剂,在88℃和400r/min的条件下进行悬浮聚合,制备得到了缩醛化度为30％的球状PVA颗粒,其中粒径0．30－0．45mm（40－60目）者约占80％。     

一种新型聚乙烯醇氨基甲酸酯胶粘剂的研究──甲苯二异氰酸酯对聚乙烯醇胶粘剂的改进

本研究是用甲苯二异氰酸酯（ＴＤＩ）为交联剂，对聚乙烯醇胶粘剂改性．讨论其反应原理、合成方法、粘结强度（木／木），以及耐水性能等．本实验结果获得一种新型的聚乙烯醇氨基甲酸醋水乳胶．     

改性剂PVA对Lyocen纤维结构和性能的影响

将聚乙烯醇（PVA）加入到纤维素／NMMO-H20溶液中进行纺丝,制备了不同PVA含量的Lyocell纤维,并对纤维的结构和性能进行了表征。结果表明,添加适量的PVA可以降低纺丝原液的黏度,提高纺丝液的可纺性,明显提高Lyocell纤维的强度和模量;通过x射线衍射测试,发现添加PVA之后Lyocell纤维仍然具有纤维素II晶型的结构;此外,PVA的加入还可以改善Lyocell纤维的抗原纤化性能,提高Lyocell纤维的热稳定性。     

Preparation of Tungsten-Based Polyvinyl Alcohol Waterborne Coating and Development of Photochromic Composite Fabric

A kind of tungsten-based polyvinyl alcohol (PVA) waterborne coating has been synthesized successfully. Two kinds of composite discoloration fabrics are prepared by cotton and polyester with coating method, which have a UV detection function. The color of composite discoloration fabric changes from white to blue under 365 nm UV lamp irradiation for 30 s and sunlight irradiation for 3 s. The influence of PVA concentration on the washability of fabric and the influence of polyurethane seal on discoloration of fabric are studied. In addition, the application of the water-based coating shortens the preparation time of composite fabric, and greatly improves the preparation efficiency. This work lays a foundation for the development and application of photochromism textiles.     

聚乙烯醇产品用途的新进展

介绍了近年来聚乙烯醇产品在各个工业领域中的新途径,说明这种化工原料有广泛的使用价值。     

纳米二氧化硅改性聚乙烯醇胶粘剂的研究

采用纳米二氧化硅粒子对聚乙烯醇胶粘剂力学性能进行改性,分析了纳米粒子掺量对聚乙烯醇胶粘剂力学性能影响的规律,并取得最佳配比,具有一定理论及应用价值。     

Synthesis of Chemically Modified Polyvinyl Alcohol Membranes for Dehydration of Dioxane by Pervaporation

Abstract

Polyvinyl alcohol (PVOH) has been chemically modified by polymerizing hydroxyethylmethacrylate (HEMA) in aqueous solution of PVOH and finally crosslinking PVOH with glutaraldehyde to produce a semi-interpenetrating network (SIPN) membrane. Accordingly, three such SIPNs i.e., SIPNI, SIPNII, and SIPNIII were synthesized with different weight ratio of PVOH: HEMA i.e., 1:0.25 (SIPNI), 1:0.50 (SIPNII) and 1:0.75 (SIPNIII). These SIPN membranes were used for pervaporative dehydration of dioxane. PVOH without any chemical modification but crosslinked with the same amount of glutaraldehyde has also been used for this study for comparison. All the SIPN membranes were also characterized with various conventional methods like mechanical properties, DSC and TGA. Water permeability and water selectivity of the IPN membranes were found to be much higher than those of the crosslinked PVOH membrane which was not chemically modified. The permeability of the membranes were also found to increase with increase in the HEMA content in PVOH matrix.     

聚乙烯醇在石英陶瓷天线罩上的应用

采用泥浆浇注工艺方法制备石英陶瓷天线罩,对比了石英料浆中添加与未添加聚乙烯醇(PVA)对石英陶瓷天线罩轴向各部位弯曲强度、体积密度、介电常数的影响情况。结果显示:聚乙烯醇(PVA)的加入对于提高石英陶瓷天线罩各部位力学性能、介电性能的均匀性有着明显的效果。     

改性聚乙烯醇的性能研究

在聚乙烯醇(PVA)中加入增塑剂甘油对其进行改性,结果表明,甘油对PVA有很强的增塑作用,降低了其熔点,提高了其断裂伸长率,并由X射线衍射仪表征得知,甘油主要影响PVA的非晶区,在晶区中对其晶型没有很大的影响。     

聚乙烯醇市场现状分析

分析了国内外聚乙烯醇市场需求及其发展,重点对国内聚乙烯醇的市场情况作了详细预测。     

聚乙烯醇改性研究的概况

本文对聚乙烯醇的水溶性、成膜性、热塑加工性等使用性能进行了讨论。提出影响目前聚乙烯醇产品大量使用的主要原因是分子的高聚合度与大量分子间的氢键作用等因素,详细介绍了国内外对聚乙烯醇热塑性、水速溶性、生物降解性、耐水性等方面的改性技术特点及发展趋势。结论认为通过以上改性技术可以进一步提高PVA性能,开发适用范围更广的产品。     

In Situ Synthesis,Characterization and Conductivity of Copper Sulphide/Polypyrrole/Polyvinyl Alcohol Blend Nanocomposite

This work focused on the preparation, characterization and conductivity studies of copper sulphide nanoparticle incorporated polypyrrole (PPy)/polyvinyl alcohol (PVA) blend by in situ chemical oxidative polymerization. The blend nanocomposites were examined by FTIR, SEM, XRD, TGA and electrical studies. The complexation of CuS with the polymer was confirmed by FTIR. The surface observed in the SEM image clarifies the uniformity in morphology. The XRD pattern reveals that the nanoparticle incorporated PPy and their blend showed a crystalline nature. TGA and conductivity studies indicated that the blend nanocomposites attain better thermal stability and conductivity than original polypyrrole and PPy/PVA blend.     

含聚乙烯醇废水处理技术研究进展

聚乙烯醇因其优良的化学、物理性能被广泛应用于工业生产中,但由于可生化性差的特点,含有聚乙烯醇废水的处理已成为环保工作者亟需解决的问题。文章总结了国内外含聚乙烯醇废水的处理方法,并展望了其处理技术的发展方向。     

聚乙烯醇脂质体的制备及性能研究

以大豆卵磷脂为包封材料,用反相蒸发法制备脂质体,同时用不同浓度的聚乙烯醇(PVA)进行包覆。实验结果表明,PVA在脂质体外形成了一层膜,而且包覆量随其浓度的增加而增加。相比较于未包覆的脂质体,PVA包覆的脂质体具有较高的包封率和较小的泄露率。当ρ(PVA)=3g/L时,脂质体的包封率最高为58%,当ρ(PVA)=4g/L时,脂质体的泄漏最慢。     

柠檬酸改性聚乙烯醇制备可生物降解膜的研究

选择柠檬酸（CA）作为单体在聚乙烯醇（PVA）水溶液中制备柠檬酸改性的聚乙烯醇交联聚合物,并用红外光谱表征膜的结构：重点考察了反应时间和反应温度对柠檬酸改性聚乙烯醇键合度的影响;使用淀粉与聚乙烯醇交联聚合物共混,制备了柠檬酸改性聚乙烯醇（CA—SP）,并将其延流成膜,采用溶菌酶体外降解实验,测定CA—SP膜的降解性能,与柠檬酸键合量对生物降解的影响。测试了降解的CA—SP膜的力学性能考察。结果表明：柠檬酸的多羧基结构,能与PVA的羟基发生酯化,从而改性淀粉／聚乙烯醇（SP）;在60℃下,反应3h时,柠檬酸的键合量可达到最大,为3．92g/g。使用溶菌酶对其进行降解,通过降解的失重率测定,发现柠檬酸的键合量越高,膜降解性能越好。柠檬酸改性的SP膜几乎可以达到完全降解。     

我国聚乙烯醇工业技术进步方向

综述我国聚乙烯醇工业的生产现状、新技术采用程度、装置经济规模及多品种应用开发,并提出其发展方向和建议。