聚偏氟乙烯(PVDF)膜化学法亲水改性技术

通过化学表面改性的方法改善PVDF膜的亲水性,从化学处理的时间、体系的温度、碱液的浓度三个因素对改性的条件进行摸索、优化.采用静滴接触角、raman光谱法、傅里叶-红外(FT-IR)、差分扫描热分析(DSC)法、X-射线衍射强度法等方法研究改性后PVDF膜亲水性、结构、组成、晶型变化.结果显示:体系温度在60℃下,碱液...     

超级耐候PVDF树脂的制备和应用

介绍了超级耐候PVDF树脂的性能及国内外生产情况,PVDF树脂的制备方法以及在涂料方面的应用情况。     

Preparation of antibacterial polyvinylidene fluoride (PVDF) ultrafiltration membranes with direct addition of N-halamine polymers

In this study, novel antibacterial ultrafiltration polyvinylidene fluoride (PVDF) flat sheet membranes were produced with addition of synthesized N-halamine polymers. The ternary phase diagrams of PVDF and the synthesized polymers with N-methyl-2-pyrrolidone and water systems were prepared. The water flux and BSA rejection performances of the produced membranes were assessed both with and without PVP addition, and compared with a commercial membrane. The produced membranes were characterized with FTIR, XPS, DSC, and SEM analysis. Addition of N-halamine polymers to the membrane structure significantly improved the biocidal performance of the produced membranes against Staphylococcus aureus and Escherichia coli (10⁵ CFU).     

A Comparative Study of Phospholipase A1 and Phospholipase C on Soybean Oil Degumming

The degumming of crude soybean oil with phospholipase A₁ (PLA₁) and phospholipase C (PLC) was studied, and optimal conditions were obtained for each enzyme. During degumming with PLA₁, more fatty acid was found in the oil than would be expected by hydrolysis of only the terminal fatty acid chains, and glycerophosphophorylcholine and glycerophosphoethanolamine were detected in the gums. These observations indicate that acyl‐migration of phospholipid fatty acids occurred during PLA₁ degumming. In addition, results showed that PLA₁ degumming was capable of reducing the phosphorus content in the oil to levels acceptable for physical refining (<10 mg/kg). During degumming with PLC, an increase of 1,2‐diacylglycerol was found, as most phosphatidylcholine and phosphatidylethanolamine were hydrolyzed by this enzyme. Treatment with either enzyme slightly decreased the oxidative stability of the oil and most metals were separated with the gums fraction.     

聚偏氟乙烯/有机累托土纳米复合超滤膜的制备、表征和性能研究

用溶液插层法制备了聚偏氟乙烯(PVDF)/有机累托土(OREC)纳米复合超滤膜,研究了OREC含量对复合膜力学性能、表面粗糙度、微观形貌、结晶行为和亲水性的影响,并测定了复合膜的性能。结果表明:OREC的加入对复合膜微观形貌有重要影响,使膜的孔隙率从44.6%增加至71.3%;OREC的加入有利于PVDF中亲水性β相的生成,在其含量较高时能显著提高复合膜的表面粗糙度和表面亲水性,并能同时提高复合膜的纯水通量和蛋白截留率;刚性OREC片层的加入,能显著改善复合膜的力学性能,对弹性模量的增强尤为明显,可达纯PVDF膜的5.8倍。     

离子液体接枝型纳米二氧化硅对聚偏氟乙烯膜的亲水化改性研究

采用溶液接枝法合成了离子液体接枝型纳米二氧化硅(IL-Si O2),并利用浸没沉淀相转化法制备了聚偏氟乙烯/离子液体接枝型纳米二氧化硅(PVDF/IL-Si O2)杂化膜,考察了IL-Si O2含量对杂化膜性能的影响。采用流动电位、接触角和水通量等手段分析研究了杂化膜的性能。研究结果表明,PVDF/IL-Si O2杂化膜表面带有正电荷;IL-Si O2的加入显著提高了杂化膜的亲水性、拉伸强度和断裂伸长率;杂化膜纯水通量显著增加的同时,对蛋白质的吸附量和截留率均有一定程度上的提高。     

聚偏氟乙烯有机-无机超滤膜性能影响因素的研究进展

介绍了影响聚偏氟乙烯有机-无机超滤膜性能的主要因素,研究了相转化法制备聚偏氟乙烯有机-无机超滤膜的主要控制参数,如聚偏氟乙烯含量、无机填料、溶剂、添加剂、凝胶浴温度、蒸发时间等,探讨了有机-无机超滤膜的研究方向。     

Plasma Modified Membrane for Daily Recovery of Oil from Repeated Frying Operation with Frequent Oil Replenishment

Sunflower oil was used for deep frying of potatoes at 170 ± 5 °C and for 8 h per day for 5 days in a fryer with an automatic oil filtration system. Three different frying operations were performed: operation (OP)-1, OP-2 and OP-3; that correspond to the oil unfiltered at the end of each frying day, the oil filtered through the fryer's own filter (passive filtration) and the oil firstly subjected to passive filtration and then filtered through a polyethersulfone membrane modified with hexamethyldisiloxane via radio frequency plasma (75 W-5 min, discharge power–time), respectively. The performance of each operation was investigated in terms of free fatty acids (FFA), conjugated dienoic acids (CD), TOTOX value, total polar content (TPC), Hunter color, viscosity, fatty acid composition, and tocopherol content. The results showed that OP-3 could decrease FFA, CD, TOTOX, TPC, L*a*b* value, viscosity and linoleic acid (18:2)/palmitic acid (16:0) ratio in 29.6, 11.7, 25, 30.8, 6.1*11.3*20.8*, 7.8, 12.2 %, respectively, compared to the unfiltered oil (OP-1). Regenerated oil from OP-3 had a frying life approximately 17 h more than oils from both OP-1 and OP-2.     

聚偏氟乙烯微孔膜制备方法研究进展

介绍了浸没沉淀法、热致相分离法以及蒸发助热致相分离法制备聚偏氟乙烯(PVDF)微孔膜的研究进展.重点介绍了溶剂、凝固浴组成、凝固浴温度、添加剂和蒸发时间等因素对浸没沉淀法制备PVDF膜的影响,并对制备PVDF膜的发展提出建议和展望.同时简单介绍了PVDF微孔膜的亲水性改性.     

聚偏氟乙烯共混隔膜的制备与性能

以乙二醇二甲基丙烯酸酯和丙烯腈为单体,合成了聚合物poly(AN-co-PEGDMA),然后与聚偏氟乙烯(PVDF)共混,制备了不同poly(AN-co-PEGDMA)含量的PVDF/poly(AN-co-PEGDMA)共混隔膜,利用X射线衍射、扫描电子显微镜(SEM)、差示扫描量热对共混隔膜的性能进行表征。结果表明,随着poly(AN-co-PEGDMA)含量的增加,PVDF/poly(AN-co-PEGDMA)的玻璃化转变温度逐渐提高,衍射峰的谱峰强度逐渐降低,隔膜的结晶度降低。SEM结果显示,随着poly(AN-co-PEGDMA)含量的增加共混隔膜的孔隙变大,有利于电解液的有效吸收。通过对PVDF/poly(AN-co-PEGDMA)共混隔膜电导率、吸液率的测定,表明在poly(AN-co-PEGDMA)质量分数为30%时,制得的共混隔膜的性能较佳。在此基础上,对共混隔膜构建的聚合物锂离子电池的电化学稳定窗口、电池容量和循环性能进行测试,其电化学稳定窗口为0～4.7 V(vs Li+/Li),放电电容为1.433～1.151 mAh,可以满足商业使用要求,具有广阔的应用前景。     

膜法分离二氧化碳研究现状及发展趋势

从膜法气体分离的优点出发,阐述了膜法分离CO2的原理、工艺流程,并将其应用于分离烟道气中的CO2.介绍了几种常见的分离CO2的膜材料,针对现有膜材料的缺点,提出了改进方法,展望了膜法分离CO2的发展方向.     

Formation of multilayer poly(acrylic acid)/poly(vinylidene fluoride) composite membranes for pervaporation

Dual‐ and multilayer composite membranes, consisting of poly(acrylic acid) (PAA) and poly(vinylidene fluoride) (PVDF), were synthesized by the plasma‐induced polymerization technique. The dual‐layer membrane had a dense PAA layer grafted onto a microporous PVDF substrate, whereas in the multilayer membranes, the grafted PAA and the PVDF layers were arranged in an alternating sequence (e.g., PAA/PVDF/PAA and PAA/PVDF/PAA/PVDF/PAA). These membranes were used in a pervaporation process to separate ethanol–water solutions. For the dual‐layer membranes, the results indicated that the separation factor increased and the permeation flux decreased with increasing amounts of grafted PAA. For the case of grafting yield < 0.6 mg/cm², the composite membrane demonstrated poor separation. As the grafting yield reached 0.85 mg/cm², a sharp increase of the separation factor was observed. For the multilayer membranes, the pervaporation performances were very good, with high separation factors (on the order of 100) and reasonable permeation fluxes over a wide ethanol concentration range. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2266–2274, 2004     

固定化酶用聚偏氟乙烯分离膜的制备及性能表征

为研究膜技术在生物反应器中的应用,选用聚偏氟乙烯为膜材料,聚乙二醇为添加剂,溶于不同的有机溶剂中,以相转化法成膜,以用于酶固定化。文章讨论了挥发时间、凝固浴温度及铸膜液温度等因素的影响,并对聚偏氟乙烯膜的通透性和固定化性能进行了研究。     

PU/PVC共混超滤膜的制备及性能

采用湿法相转化制膜技术制备PU/PVC共混膜、PU/PVC/SiO2共混膜。PVC可以改变铸膜液体系在凝固浴中的分相速度,提高成膜性及改善膜的微孔结构,在此共混物中加入SiO2可以显著改善膜的微孔结构,并提高PU共混膜的水通量,可用于超滤。用扫描电镜对膜的结构形态进行了观察。     

逆向热致相分离法(RTIPS)制备PES/DMAc/DEG体系微孔膜及其性能表征

以PES/DMAc/DEG低临界共溶温度(LCST)体系为铸膜液,利用低临界共溶温度(LCST)的热致相分离(LCST-TIPS,简称RTIPS)法制备PES微孔膜.探究影响PES微孔膜理化性能及其结构的2个主要因素:凝胶浴温度、非溶剂(DEG)/溶剂(DMAc)的质量比.运用扫描电镜(SEM)﹑纯水通量﹑BSA截留率...     

Preparation and Characterization of Fe2O3/Ammonium Perchlorate (AP) Nanocomposites through Ceramic Membrane Anti‐Solvent Crystallization

A novel ceramic membrane anti‐solvent crystallization (CMASC) method was proposed to prepare Fe₂O₃/AP nanocomposites with core‐shell structure. For the preparation of Fe₂O₃/AP nanocomposites, several key advantages of the CMASC method are as follows. Firstly, both well‐dispersed Fe₂O₃ nanoparticles and the superfine AP preparation can be achieved at one step. Secondly, no non‐component of solid propellant was involved in this composite process. Thirdly, the size and morphology of Fe₂O₃/AP nanocomposites can be effectively controlled by using the ceramic membrane with regular pore structure as feeding template. The morphology and structure of Fe₂O₃/AP nanocomposites were characterized by inductively coupled plasma spectrophotometry (ICP), IR spectroscopy, SEM, and HRTEM. The results verified that the size and morphology of Fe₂O₃/AP nanocomposites are controllable, and the dispersion of Fe₂O₃ nanoparticles is greatly improved in Fe₂O₃/AP nanocomposites. Moreover, the thermal decomposition of the as‐prepared Fe₂O₃/AP nanocomposites was measured with TG‐DSC. The results showed that the Fe₂O₃ nanoparticles in Fe₂O₃/AP nanocomposites exhibit better catalytic activity on the thermal decomposition of AP. In addition, the mechanism was also discussed.     

Differential Effect of Dietary Supplementation with a Soybean Oil Enriched in Oleic Acid versus Linoleic Acid on Plasma Lipids and Atherosclerosis in LDLR-Deficient Mice

Both monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) play important roles in lipid metabolism, and diets enriched with either of these two fatty acids are associated with decreased cardiovascular risk. Conventional soybean oil (CSO), a common food ingredient, predominantly contains linoleic acid (LA; C18:2), a n-6 PUFA. Recently, a modified soybean oil (MSO) enriched in oleic acid (C18:1), a n-9 MUFA, has been developed, because of its improved chemical stability to oxidation. However, the effect of the different dietary soybean oils on cardiovascular disease remains unknown. To test whether diets rich in CSO versus MSO would attenuate atherosclerosis development, LDL receptor knock-out (LDLR-KO) mice were fed a Western diet enriched in saturated fatty acids (control), or a Western diet supplemented with 5% (w/w) LA-rich CSO or high-oleic MSO for 12 weeks. Both soybean oils contained a similar amount of linolenic acid (C18:3 n-3). The CSO diet decreased plasma lipid levels and the cholesterol content of VLDL and LDL by approximately 18% (p < 0.05), likely from increased hepatic levels of PUFA, which favorably regulated genes involved in cholesterol metabolism. The MSO diet, but not the CSO diet, suppressed atherosclerotic plaque size compared to the Western control diet (Control Western diet: 6.5 ± 0.9%; CSO diet: 6.4 ± 0.7%; MSO diet: 4.0 ± 0.5%) (p < 0.05), independent of plasma lipid level changes. The MSO diet also decreased the ratio of n-6/n-3 PUFA in the liver (Control Western diet: 4.5 ± 0.2; CSO diet: 6.1 ± 0.2; MSO diet: 2.9 ± 0.2) (p < 0.05), which correlated with favorable hepatic gene expression changes in lipid metabolism and markers of systemic inflammation. In conclusion, supplementation of the Western diet with MSO, but not CSO, reduced atherosclerosis development in LDLR-KO mice independent of changes in plasma lipids.     

Poly(vinyl chloride) Asymmetric Membrane Modified with Poly (ethylene glycol): Effect of Additive Concentration on the Morphology and Performance

Asymmetric membranes of polyvinyl chloride modified with polyethylene glycol as pore former have been prepared by nonsolvent-induced phase separation method using N,N-dimethylacetamide/water as solvent/nonsolvent system. The phase diagram of polyvinyl chloride/polyethylene glycol/N,N-dimethylacetamide/water system showed that polyethylene glycol favors the demixing process. The prepared membrane is characterized by scanning electron microscopy, ATR-FTIR, equilibrium water content, porosity, pure water flux, and contact angle. The addition of polyethylene glycol favored the formation of finger-like structure of polyvinyl chloride membrane initially, and at higher polyethylene glycol concentration, a spongy structure is obtained. The prepared membrane possesses high water flux, excellent thermal stability, and sufficient mechanical strength suitable for ultrafiltration operation.