二元醇/水溶液在渗透蒸发均质膜中的扩散模型

用交联聚乙烯酸膜对不同浓度的乙二醇/水溶液在不同温度下分别进行了渗透蒸发实验研究．针对小分子在致密膜中的扩散行为提出了一个新见解,并借用改进的Vigne方程得到了一个新的热力学扩散系数方程,用此方程结合Lee-Thods方程、Wilke-Chang方程、Vrentas和Duda改进的自由体积理论、扩散方程和溶胀平衡方程预测了水和乙二醇分子在不同温度下通过交联聚乙烯醇膜的渗透蒸发行为,其预测结果与实验值基本一致．     

聚乙烯醇膜的研制及乙醇水溶液的渗透蒸发（PV）分离

选择以聚乙烯醇(PVA)作膜材料,制成具有一定通量及分离效果的聚乙烯醇均质膜及聚乙烯醇/聚砜复合膜。讨论了膜的抗水性及抗化学腐蚀性。用透射电镜及扫描电镜进行了结构测定,并研究了这两种膜在分离95%(重量浓度)乙醇水溶液时的性能以及温度、交联度对膜性能的影响。实验发现聚乙烯醇均质膜具有较高的分离系数;聚乙烯醇/聚砜复合膜在基本维持均质膜分离性能的前提下,通量有较大提高。还发现经Cr~(3 )的饱和溶液处理后再进一步交联的膜,交联度及稳定性都有提高,分离系数略有下降。     

原位交联聚乙烯醇/二氧化硅杂化功能膜的制备与性能

以正硅酸乙酯（TEOS）为前驱体,戊二醛（GA）为交联剂,利用溶胶凝胶法和原位化学交联法相结合的方法,制备了交联的聚乙烯醇/二氧化硅（PVA/SiO2）杂化功能膜。通过FTIR、SEM、溶胀和拉伸实验研究了二氧化硅和原位化学交联对杂化膜结构和性能的影响。结果表明,制备的膜是具有梯度交联结构的有机/无机杂化体系,原位化学交联对膜断面形貌影响不大。二氧化硅的引入和戊二醛原位交联都能有效地降低杂化膜的平衡溶胀度,两种因素在提高杂化膜耐水性方面具有互补作用。     

聚乙烯醇交联膜性能的研究

研究了不同交联剂对聚乙烯醇的交联效果,并对影响交联膜性能的各种因素进行分析。通过检测膜的力学性能和溶胀程度,得到氯乙酸交联膜的性能在所检测的范围内最优。     

渗透汽化膜机理研究

用顺丁烯二酸酐对聚乙烯醇（ＰＶＡ）进行交联制得渗透汽化膜,并用于水－乙醇渗透汽化分离,研究了膜的溶胀平衡过程及选择溶解与渗透汽化关系,结果表明,膜对水优先溶解,其分离系数主要由溶解选择性控制,透过速率主要由溶胀度控制。     

交联壳聚糖/聚乙烯醇共混膜的制备及表征

用乙酸和水为溶剂,通过相转化法制备了三种不同比例混合的壳聚糖(CS)和聚乙烯醇(PVA)共混膜,然后在碱性条件下用环氧氯丙烷对共混膜进行了交联。采用FTIR、DMA、TG、XRD和SEM对所制备的膜进行了表征,测试了交联前后膜的溶胀性能和机械性能。测试结果表明:壳聚糖与聚乙烯醇两组分相容性良好,共混膜的机械性能、热稳定性和结晶度均介于两种纯组分之间;聚乙烯醇的加入提高了壳聚糖膜的机械性能;环氧氯丙烷的交联使共混膜的溶胀性能得到明显改善,而热稳定性和机械性能略有下降。     

交联密度对丁苯橡胶与溶剂Flory-Huggins相互作用参数的影响

研究丁苯橡胶(SBR)的交联密度对SBR与溶剂Flory-Huggins相互作用参数的影响。改变硫黄用量制备了不同交联密度的SBR试样,并采用管道模型计算出交联点间平均相对分子质量,结合平衡溶胀法测得SBR在甲苯、环己烷和乙酸乙酯中溶胀后的体积分数,使用Flory-Rehner方程得到SBR与溶剂的相互作用参数。结果表明:SBR与溶剂的相互作用参数与SBR的体积分数呈线性关系,但溶剂不同,关系式不同。对平衡溶胀法测定交联点的平均相对分子质量的Flory-Rehner方程提出了一个修正式。     

不同交联密度对丁苯橡胶与不同溶剂Flory-Huggins相互作用参数χ的影响

本文研究了丁苯橡胶的交联密度对溶剂与橡胶相互作用参数χ的影响。通过采用不同的硫黄用量制备了不同交联密度的橡胶试样,通过管道模型计算得到交联点的平均分子量,最后通过平衡溶胀法测得橡胶在甲苯、环己烷和乙酸乙酯溶胀后的体积分数,最后通过Flory-Rehner方程得到橡胶与溶剂的相互作用参数。结果显示：橡胶与溶剂的相互作用参数χ与橡胶的体积分数呈现出线性关系,但是不同溶剂的关系式并不一致。另外,对平衡溶胀法测定交联点的平均分子量的Flory-Rehner方程提出了一个修正式。     

交联聚乙烯醇膜渗透蒸发分离乙二醇－水混合物的溶解选择性与渗透选择性的关系

交联聚乙烯醇膜渗透蒸发分离乙二醇－水混合物的溶解选择性与渗透选择性的关系陈俸荣，陈洪钫（天津大学化工系，天津３０００７２）关键词渗透蒸发，溶解选择性，渗透选择性，交联聚乙烯醇，乙二醇－水溶液１引言在渗透蒸发膜分离机理的研究中，存在着不同的观点［１－５...     

表面活性剂液膜萃取过程的乳液溶胀(Ⅰ)——载体对乳液溶胀的影响

研究了载体对乳液溶胀的影响。发现膜相中存在载体时使界面张力降低,说明载体能吸附于界面。表面活性剂和载体在界面的竞争吸附是影响乳液溶胀的关键因素。本研究表明,液膜的夹带溶胀随膜相中载体浓度的增大而减小,而渗透溶胀则随之而加剧。提出了估算溶胀率的修正方程,用修正方程对膜相存在载体时的乳液夹带溶胀率进行了估算,计算值与实验数据吻合良好。     

The water state in crosslinked poly(vinyl alcohol)–collagen hydrogel and its swelling behavior

Poly vinyl alcohol (PVA) with pendent carboxyl group was synthesized and verified. The collagen was chemical crosslinked with the produced PVA under the help of crosslinker. Then, the PVA–collagen hydrogels were prepared through the repeated freezing–thawing. Since the water states in hydrogels play an important role in the performance of the product, thermogravimetric (TG) analysis and differential scanning calorimeter (DSC) were conducted to study the different states of water. The results indicated that the weight ratio of nonfreezable water to dry gel in PVA–collagen hydrogels was about 25%. Meanwhile, the swelling behaviors in distilled water and 0.9% saline were studied. The one‐phase exponential associate equation can fit the process very well. Calculated from the simulation equation, the swelling ratios at equilibrium in distilled water and saline were 14.353 g/g dry gel and 14.205 g/g dry gel, respectively. The results illustrated that the ions in solution would decrease the swelling ratio of the hydrogel. At the same time, the lyophilization might have slighter influence to the microstructure of hydrogels and should be more suitable for the swelling research than heat drying. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Structure‐property and swelling behavior of electron beam irradiated poly(vinyl alcohol)/acrylamide/sodium montmorillonite clay composites

Composites based on poly(vinyl alcohol) (PVA), acrylamide monomer (AM) and sodium montmorillonite clay (MMT) were prepared, in the form of thin films, by solution casting. The PVA/AM/MMT composites films were then exposed to electron beam irradiation to form crosslinked network structure. The structure‐property behavior of PVA/AM/MMT hybrids was demonstrated by x‐ray diffraction (XRD), scanning electron microscopy, gel content, color intensity, thermogravimetric analysis (TGA) and swelling behavior in aqueous solutions. The results indicated that the introduction of MMT clay ratio up to 5% decreased the gel content of PVA/AM hydrogels. The color measurements indicated that the introduction of MMT clay ratio up to 5% was shown to affect the color intensity of composite films. It was found that both PVA/AM hydrogels and PVA/AM/MMT composites reached the equilibrium swelling state in water after four hours; however PVA/AM/MMT composites displayed higher swelling than PVA/AM hydrogels. However, the swelling of PVA/AM hydrogels or their composites at the equilibrium state increased with increasing temperature up to 60°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

磺化β-环糊精/PVA凝胶电刺激响应行为的研究

首先将β-环糊精(β-CD)和聚乙烯醇(PVA)用戊二醛交联制成凝胶;然后以浓硫酸作为改性剂,将磺酸根引入凝胶中,制备出一种阴离子型磺化β-CD/PVA凝胶,并对该凝胶的平衡溶胀率、粘接性能和电刺激响应行为等进行了研究。结果表明:该凝胶在Na2SO4水溶液中的平衡溶胀率随离子强度增加而减小;其剪切强度随PVA含量增加呈先升后降态势,并且在w(PVA)=5%时相对最大(3.8 MPa)。在非接触性直流电场作用下,该凝胶在Na2SO4水溶液中弯向电场负极,其弯曲偏转速率和应变随外加电压增加而增大,并且在离子强度为0.15 mol/L时相对最大;在循环电场作用下,该凝胶的电刺激响应行为具有良好的重现性和可逆性。     

A novel pH‐sensitive and freeze‐thawed carboxymethyl chitosan/poly(vinyl alcohol) blended hydrogel for protein delivery

BACKGROUND: Blended hydrogels are widely applied in medical fields. They can provide many advantages, such as biocompatibility and biodegradability. Many materials and methods are used to obtain blended hydrogels. In this work, carboxymethyl chitosan (CMCS) and poly(vinyl alcohol) (PVA) blended hydrogels were prepared using the freezing and thawing technique. The properties of the hydrogels prepared, i.e. gel fraction, swelling and pH‐responsive behaviors, were investigated. RESULTS: The gel fraction increased with increasing time of freezing and thawing as determined through gravimetric analysis. It was also found that the equilibrium degree of swelling improved obviously due to the addition of CMCS compared to pure PVA hydrogel. The blended hydrogel with composition CMCS/PVA 80/20 (by weight) possessed the highest swelling ratio. The results of the influence of pH values on the swelling behavior showed that minimum swelling ratios of the hydrogels occurred near the isoelectric point of CMCS. Protein release studies were performed under various pH conditions: the release was much slower under acid than under basic conditions. The release showed a burst in the first 15 h and then steadily increased. CONCLUSION: The addition of CMCS can improve the physical properties of pure PVA hydrogels and provide pH sensitivity. It is concluded that PVA hydrogels containing CMCS could be potentially applied as oral delivery systems for protein drugs. Copyright © 2009 Society of Chemical Industry     

Relationship between the structure and the swelling of polyvinyl alcohol fibres

Conclusions 1. The kinetics of the swelling of PVA fibres in aqueous sodium sulphate solution can be characterised fairly accurately by a first-order kinetic equation.2. The anisotropy of swelling and the initial rate of swelling of PVA fibres depend on the orientation and the supermolecular structure of the fibres. These magnitudes can be used as characteristics of the structural changes in the fibres caused by their drawing.3. The coefficients of the rate of swelling of transverse sections of PVA fibres not subjected to heat treatment are in direct relationship with the strength of the fibres.S.M. Kirov Leningrad Institute for the Textile and Light Industries. Translated from Khimicheskie Volokna, No. 2, pp. 23–25, March–April, 1969.     

Electroactive characteristics of interpenetrating polymer network hydrogels composed of poly(vinyl alcohol) and poly(N‐isopropylacrylamide)

An interpenetrating polymer network (IPN) composed of poly(vinyl alcohol) (PVA) and poly(N‐isopropylacrylamide) (PNIPAAm) was prepared by the sequential IPN method. The equilibrium swelling ratio and bending behavior under electric fields of the IPN hydrogel were measured in an aqueous NaCl solution. The IPN exhibited a high equilibrium swelling ratio, in the range 280–380%. When the IPN in aqueous NaCl solution was subjected to an electric field, the IPN showed significant and quick bending toward the cathode. The IPN hydrogel also showed stepwise bending behavior, depending on the electric stimulus. In addition, the ionic conductivity of the IPN hydrogel was measured using dielectric analysis, and its conductive behavior followed the Arrhenius equation. The conductivity of the IPN hydrogel and the activation energy for the form of the IPN were 1.68 × 10^?5 S/cm at 36°C and 61.0 kJ/mol, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 890–894, 2003     

Thermally crosslinked anionic hydrogels composed of poly(vinyl alcohol) and poly(γ‐glutamic acid): Preparation,characterization, and drug permeation behavior

pH‐sensitive anionic hydrogels composed of poly(vinyl alcohol) (PVA) and poly(γ‐glutamic acid) (γ‐PGA) were prepared by the freeze drying method and thermally crosslinked to suppress hydrogel deformation in water. The physical properties, swelling, and drug‐diffusion behaviors were characterized for the hydrogels. In the equilibrium swelling study, PVA/γ‐PGA hydrogels shrunk in pH regions below the pK_a (2.27) of γ‐PGA, whereas they swelled above the pK_a. In the drug‐diffusion study, the drug permeation rates of the PVA/γ‐PGA hydrogels were directly proportional to their swelling behaviors. The cytocompatibility test showed no cytotoxicity of the PVA/γ‐PGA hydrogels for the 3T3 fibroblast cell lines. The results of these studies suggest that hydrogels prepared from PVA and γ‐PGA could be used as orally administrable drug‐delivery systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Swelling behavior and cell viability of dehydrothermally crosslinked poly(vinyl alcohol) hydrogel grafted with N‐vinyl pyrrolidone or acrylic acid using γ‐radiation

To improve equilibrium water content, dehydrothermally crosslinked poly(vinyl alcohol) (PVA) hydrogel was grafted with N‐vinyl pyrrolidone (NVP) or acrylic acid (AA) monomer using γ‐radiation. Swelling behavior of the grafted hydrogels was studied in phosphate‐buffered saline, and cell viability was evaluated using fibroblast cells from mouse connective tissue. Equilibrium water content of AA‐ and NVP‐grafted PVA hydrogel ranged between 40–60% and 60–80%, respectively, depending on radiation dose and monomer concentration. For maximum degree of swelling, the optimum monomer concentration and radiation dose were 20% by weight and 20 kGy, respectively. Fibroblast cells seeded on NVP‐grafted hydrogel had an extended oval morphology while those seeded on AA‐grafted PVA had a rounded spherical morphology. These results support the use of NVP for grafting PVA to increase swelling and improve cell viability. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2862–2868, 2004     

Swelling effect of semicrystalline poly(vinyl alcohol) in hydrogen peroxide

The effect of hydrogen peroxide on the physicochemical properties of semicrystalline poly(vinyl alcohol) (PVA) has been investigated. Significant and irreversible increases in equilibrium water swelling, dissolved oxygen permeability, and surface wettability have been observed in PVA samples treated with concentrated hydrogen peroxide. Based on the small amount of carbonyl content detected and the crystallinity reduction in hydrogen-peroxide-treated poly(vinyl alcohol) samples, a mechanism involving a combination of hydrogen-peroxide-induced oxidative chain scission and dissolution of crystalline regions in poly(vinyl alcohol) is proposed for the observed swelling kinetics and associated changes in polymer properties.     

Synthesis and characterization of poly(vinyl alcohol)-β-cyclodextrin copolymer

A poly(vinyl alcohol)-β-cyclodextrin (PVA-BCD) copolymer was prepared by successive reaction of BCD with toluylene diisocyanate and PVA. Copolymer formation was evidenced by infrared spectroscopy, differential scanning calorimetry and gel permeation chromatography. Scanning electron micrographs show morphological differences between PVA and the copolymer. The copolymer, being almost insoluble in common solvents with an equilibrium swelling in water of 50%, is a potential membrane material.