膜用PVA改性的研究现状及进展

聚乙烯醇(PVA)用于膜材料性能优异。介绍了PVA用作阻隔包装膜、水速溶包装膜、可生物降解膜和液体分离膜的研究现状及进展。故目前国内外对膜用PVA改性的研究日趋活跃。     

改性PVA热塑加工性能研究

采用熔体流动速率试验机研究了以水、甘油、聚乙二醇和己内酰胺为主的四种加工改性剂对聚乙烯醇(PVA)热塑加工性能的影响。采用平板硫化机压膜观察不同改性PVA体系的成膜性能。结果表明,加工改性剂在不同程度上改善了PVA的热塑加工性能,其中己内酰胺改性PVA体系具有最好的热塑加工性能;通过热压成型可以将改性PVA制成透明性很好的薄膜;熔体流动速率试验机可以有效地判断PVA改性体系的热塑加工性能。     

水转印用PVA水解膜的研究

以聚乙烯醇1788(PVA)作为原料,以甘油(丙三醇)作为增塑剂,采用流延法制作水转印膜,研究水解膜溶解时间、平衡含水率及制膜溶液粘度的影响因素。实验发现,聚乙烯醇薄膜的溶解时间会随着溶解水温、甘油比例的增加而减少,随着膜厚的增加而增加;薄膜的平衡含水率随着环境湿度及甘油比例的增加而增加,且平衡含水率在甘油质量分数小于6%时增加平缓,大于6%时增加比较迅速;在聚乙烯醇水溶液中添加一定的甘油后,随着甘油比例的增加,聚乙烯醇水溶液的粘度会相对减小;在低剪切速率下,质量分数为15%聚乙烯醇水溶液粘度会随着剪切速率的增加而增加。     

丙烯酸-丙烯酸酯共取物共混改性聚乙烯醇(PVA)膜用于液层脱水的研究

1 INTRODUCTIONIn 1984,GFT Company,the leader in using PVApervaporation membrane for dehydration of alcohol-water mixtures,sets up the first industrial pervapora-tion plant.Now,about 100 industrial pervaporationplants are in operation in the world.For almostall these plants,PVA membranes are equipped andused to dehydrate alcohol.It has been proved that     

聚乙烯醇（PVA）／纳米TiO2杂化膜的研究与应用

主要介绍了水溶性聚乙烯醇（PVA）／TiO2杂化膜作为包装材料具有的一些优异性能和用途,从发展现状、制备方法和用途三方面对PVA／TiO2杂化膜进行了归纳总结,并分析了PVA／TiO2杂化膜现阶段所存在的问题。PVA材料的亲水性、环保性、生物相容性及纳米TiO2的亲水性、光照后不发生光腐蚀、耐酸碱性、化学稳定性和对生物无毒性等特点将赋予PVA／TiO2杂化膜广泛的应用前景。     

淀粉/PVA材料的改性研究进展

介绍了淀粉/聚乙烯醇（PVA）材料的性能，及加入交联剂、增塑剂、第三相及对改性淀粉的使用的等对其性能进行进一步优化的方法，阐明了淀粉/PVA材料的发展前景。     

PVA分散剂的研究

前言聚醋酸乙烯(PVAC)经不完全醇解成聚乙烯醇(PVA)。■此种PVA含有亲水基团羚基和疏水基团乙酰氧基。只要控制两种基团的比例,就会制得出比较理想的表面活性物质。它做为乳化剂使用时可与高效剧毒的有机农药混合成乳浊液     

PVA/Nano-SiO_2杂化膜的制备及性能研究

以聚乙烯醇(PVA)和正硅酸乙酯(TEOS)为原料,通过溶胶-凝胶(Sol-Gel)技术,制备出不同nano-SiO2含量的PVA/nano-SiO2杂化膜,并采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)等仪器测试和分析了杂化膜的结构和性能。结果表明:随着nano-SiO2含量的增加,PVA杂化膜的耐水性能增强,结晶能力下降,而力学性能呈现先增大后减小的趋势。当nano-SiO2的加入量在10%左右时,断裂伸长率由纯PVA膜的34.74%提高到55.52%,拉伸强度从33.08 MPa增加到49.98 MPa;而当nano-SiO2含量增加到20%以上时,nanoSiO2粒子会发生团聚,使得杂化膜的力学性能变差。     

杂化炭膜的制备及其气体分离应用研究进展

杂化炭膜是一种新型的无机气体分离膜材料,在有效分离气体的应用中有广阔的工业化前景.综述了杂化炭膜制备过程中有机聚合物、掺杂物的选择及采用的涂膜方式和炭化条件对膜分离性能的影响及其在气体分离应用方面的研究进展,并对杂化炭膜的发展方向进行了展望.     

Imidazolium functionalized poly(vinyl alcohol) membranes for direct methanol alkaline fuel cell applications

In this study, imidazolium functionalized poly(vinyl alcohol) (PVA) was synthesized by acetalization and direct quaternization reaction. Afterwards, composite anion exchange membranes based on imidazolium‐ and quaternary ammonium‐ functionalized PVA were used for direct methanol alkaline fuel cell applications. ¹H NMR and Fourier transform infrared spectroscopy data indicated that imidazole functionalized PVA was successfully synthesized. Inductively coupled plasma mass spectrometry data demonstrated that the imidazolium structure was efficiently obtained by direct quaternization of the imidazole group. Composite anion exchange membranes were fabricated by application of the functionalized PVA solution on the surface of porous polycarbonate (PC) membranes. Fuel cell related properties of all prepared membranes were investigated systematically. The imidazolium functionalized composite membrane (PVA‐Im/PC) exhibited higher ionic conductivity (7.8 mS cm^?1 at 30 °C) despite a lower water uptake and ion exchange capacity value compared to that of quaternary ammonium. In addition, PVA‐Im/PC showed the lowest methanol permeation rate and the highest membrane selectivity as well as high alkaline and oxidative stability. Dynamic mechanical analysis results reveal that both composite membranes were mechanically resistant up to 10⁷ Pa at 140 °C. The superior performance of imidazolium functionalized PVA composite membrane compared to quaternary ammonium functionalized membrane makes it a promising candidate for direct methanol alkaline fuel cell applications. © 2020 Society of Chemical Industry     

Surface free energy analysis of poly(vinyl alcohol) films having various molecular parameters

The molecular parameters of poly(vinyl alcohol) have enormous effects on its physical and chemical properties. Therefore, the surface characteristics of poly(vinyl alcohol) films are also determined by the molecular parameters. In this study, the dependence of the surface free energy on the molecular weight, degree of saponification, and stereoregularity of poly(vinyl alcohol) films has been evaluated with contact‐angle measurements. The surface free energy of poly(vinyl alcohol) films increases with decreases in the syndiotactic dyad content, molecular weight, and degree of saponification. The polar component of the surface energy is not affected by the deviation of the molecular weight and degree of saponification very much. However, it decreases with increases in the syndiotactic dyad content and ranges from 11.64 to 4.35 dyn/cm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

On the viscoelastic properties of poly(vinyl alcohol) and chemically crosslinked poly(vinyl alcohol)

Poly(vinyl alcohol)(PVA) films chemically crosslinked with glutaraldehyde(GA) in the presence of HCl were prepared by casting from aqueous solutions. The PVA and PVA gels were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA); their swelling characteristics and tensile strength were also determined. The DSC results for the gels displayed depressions of the melting and crystallization temperatures, as well as a decrease of the heat of fusion, when compared to those of PVA free of crosslinker. The DMA analysis revealed that: (1) The glass transition temperature of the wet PVA was lower than that of the dry one, indicating that the water had a plasticizing effect. (2) The gels had a lower glass transition temperature than PVA. (3) The glass transition temperature of the wet gels increased with increasing crosslink density. Possible explanations are provided for these observations. Whereas the thermogravimetric curves of PVA exhibited a single degradation peak, two degradation peaks were detected for the crosslinked PVA. The wet PVA and PVA gels displayed lower tensile strengths and higher elongations than the dried ones. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1816–1823, 2001     

Role of the stereosequences of poly(vinyl alcohol) in the rheological properties of syndiotacticity‐rich poly(vinyl alcohol)/water solutions

Syndiotacticity‐rich poly(vinyl alcohols) (s‐PVAs) with various syndiotactic dyad (S‐dyad) contents were prepared by the copolymerization of vinyl pivalate and vinyl acetate with various monomer feed ratios, which was followed by the saponification of copoly(vinyl pivalate/vinyl acetate) to investigate the effect of the stereosequences of s‐PVA on the rheological properties of s‐PVA/water solutions. Through a series of experiments, we identified that the syndiotacticity had a profound influence on the rheological properties of s‐PVA/water solutions. Over a frequency range of 10^?1 to 10² rad/s, s‐PVAs with higher S‐dyad contents showed larger values of complex viscosity and storage modulus and more shear thinning at similar molecular weights and degrees of saponification of the polymer, suggesting that poly(vinyl alcohol) molecules were stiffer and more readily oriented as syndiotacticity increased. All the yield stresses of s‐PVA represented positive values, and s‐PVAs with higher syndiotacticity showed higher yield stresses. This suggests that as syndiotacticity increased, more pseudostructures were present in s‐PVA/water solutions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1858–1863, 2003     

An overview of poly(vinyl alcohol) and poly(vinyl pyrrolidone) in pharmaceutical additive manufacturing

Recently, drug personalization has received noticeable attention. Problems arising from standard generalized drug treatments have aroused over the years, particularly among pediatric and geriatric patients. The growing awareness of the limitations of the “one-size-fits-all” approach has progressively led to a rethinking of the current medicine's development, laying the basis of personalized medicine. Three-dimensional printing is a promising tool for realizing personalized therapeutic solutions fitting specific patient needs. This technology offers the possibility to manufacture drug delivery devices with tailored doses, sizes, and release characteristics. Among additive manufacturing techniques, fused deposition modeling (FDM) is the most studied for oral drug delivery device production due to its high precision and cheapness. By playing with factors such as drug loading method, filament production, and printing parameters, the medication release profile of a drug delivery device produced by 3D printing can be tailored depending on the patient's requirements. This review focuses on the applications of FDM in drug fabrication using poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) as drug-loaded matrices. The authors aim to provide an overview of the current trends in this research field, with special attention to the effect of the printing parameters, tablet shape, and drug distribution and concentration on drug customization and personalized drug release.     

Gas permeation through water‐swollen polysaccharide/poly(vinyl alcohol) membranes

The effect of Na‐alginate content on the gas permeation properties of water‐swollen membranes prepared by varying Na‐alginate and poly(vinyl alcohol) (PVA) content in membranes was investigated. The influences of water content and crystallinity of the membranes on the gas permeation performance of the water‐swollen membranes were studied. The gas permeation rate and selectivity of Na‐alginate/PVA water‐swollen membranes were compared with those of the dry membranes. The permeation rates of nitrogen and carbon dioxide through water‐swollen membranes were in the range of 0.4–7.6 × 10^?7 to 3.7–8.5 × 10^?6 cm³ (STP)/cm² s^?1 cmHg^?1, which were 10,000 times higher than those of dry‐state membranes. The permeation rates of mixture gases through water‐swollen Na‐alginate/PVA membranes were found to increase exponentially with the increase of Na‐alginate content, whereas carbon dioxide concentration in permeates was decreased linearly. It was found that the gas permeance of the water‐swollen membranes increased with increasing the Na‐alginate content in the membrane. Gas permeation rates of the water‐swollen Na‐alginate/PVA membranes increased with increasing the water content in the membrane and decreasing the crystallinity of the membrane. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3225–3232, 2004     

聚乙烯醇水凝胶自修复性能

高浓度聚乙烯醇（PVA）水凝胶具有一定的修复功能,但其自修复机理及制备工艺参数对其修复性能的影响缺乏研究。本文采用冷冻-解冻法制备了高浓度自修复PVA水凝胶,通过调整PVA水凝胶制备工艺参数（PVA分子量、PVA浓度、冷冻时间、解冻时间、冷冻-解冻次数、修复时间、冷冻温度等）得到了最佳工艺条件,分析了水凝胶自修复机理,并研究了PVA水凝胶的多次自修复性能。研究结果表明：相对分子质量大的PVA制备的水凝胶自修复性能好;其中冷冻时间为2h,解冻时间为1h,一次冷冻-解冻循环制备得到的水凝胶自修复性能最好,最佳修复时间为12h,能较好地进行反复自修复。指出水凝胶自修复性能主要是由其内部可逆氢键的相互作用形成的,其主要影响源于冷冻-解冻处理后水凝胶内部羟基含量及PVA分子的流动性。     

Swelling kinetics of modified poly(vinyl alcohol) hydrogels

Interpenetrating polymer network (IPN) hydrogels composed of poly(vinyl alcohol) (PVA) and monomer, N‐isopropylacrylamide (NIPAAm), diallyldimethylammonium chloride (DADMAC), or methacrylic acid (MAA) were prepared by using the sequential‐IPN method. The equilibrium swelling ratios of PVA/NIPAAm (VANP), PVA/DADMAC (VADC), and PVA/MAA (VAMA) are 412, 370, and 297 at 25°C, respectively. VANP had the highest swelling ratio in time‐dependent swelling behavior, whereas the swelling ratio of VAMA had the lowest. The n values of VANP, VADC, and VAMA are 0.72, 0.81, and 0.96, respectively. Transport of all IPN hydrogels is anomalous and their transport mechanisms are dominated by a combination of diffusion‐controlled and relaxation‐controlled systems. VAMA has the highest activation energy and VANP has the lowest activation energy. The values of all IPN hydrogels are from 4.66 to 16.49 kJ/mol, which proves that all IPN hydrogels are hydrophilic. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3310–3313, 2003     

Optical studies of pure and gelatin‐doped poly(vinyl alcohol) films irradiated with fast neutrons

The ultraviolet (UV) and infrared (IR) spectra of pure poly(vinyl alcohol) (PVA) and gelatin–doped PVA films with concentrations (2, 5, 7, 10, and 15 wt %) were studied before and after irradiation with neutron fluences in the range of 10⁵–10⁸ n/cm². The obtained data revealed that the addition of gelatin and neutron irradiation causes structural variation in the PVA network. The analysis of the UV spectra showed that the increase of dopant concentration above 5 wt % gelatin makes the sample less resistant to a degradation effect caused by neutron irradiation. It was also found that the intensity of the band at 210 nm increases by increasing dopant concentration. Careful examination of the infrared spectra indicated that the induced percent crystallinity of the sample containing 5 wt % gelatin has more stability than the other doped samples. Neutron irradiation also results in the appearance of new absorption bands and irregular change in the absorbance of some IR bands. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1395–1406, 1999