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Poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) microporous membrane was prepared by supercritical CO2 extraction of dibutyl phthalate (DBP) template from PVDF‐HFP/DBP film. The effects of extraction conditions such as pressure, temperature, and extraction time on extraction efficiency and the porosity of membrane were studied. The extraction efficiency of DBP and size stability of polymer membrane during extraction was compared with those of solvent extraction process. The structure of the resulting membrane was characterized by scanning electron microphotograph (SEM), X‐ray diffraction (XRD) and differential scanning calorimeter (DSC). With increasing the extraction temperature, pressure and time, the extraction efficiency and the porosity increased. Maximum extraction efficiency is obtained at extraction pressure and temperature higher than 18 MPa and 75°C, respectively. The porosity of membranes depended on the extraction efficiency and shrinkage ratio of membranes. Compared with solvent extraction, supercritical CO2 extraction of the film generated the membrane with more uniform structure and higher porosity. 相似文献
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PVDF/PAN共混超滤膜 总被引:11,自引:0,他引:11
PVDF/PAN共混超滤膜尹秀丽*宋艳秋(天津纺织工学院材料科学系天津300160)关键词聚偏氟乙烯,聚丙烯腈,共混,超滤膜1996-11-20收稿,1997-05-07修回共混是改变高分子材料性能的重要手段,已发现用聚合物共混的方法能制得性能优异的... 相似文献
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Cécile Morel-Salmi Audrey Julia Claire Vigor Joseph Vercauteren 《Chromatographia》2014,77(13-14):957-961
Repeated chromatographic analyses of polyphenolic vine stalks extracts allowed us to note a huge adsorption difference on polyvinylidene fluoride (PVDF), between trans-resveratrol 1 and (+)-trans-ε-viniferin 2. We could optimize the conditions (solvent, saturation of the process), for this polymer to adsorb very selectively 2, with regard to the monomer 1 that remains in solution. Since membrane filters made of PVDF are quite often used for HPLC samples filtration, this observation prompted us to inform phytochemists studying plant stilbenoid contents. Based on this background information, we developed a straightforward and inexpensive enrichment process for either 1 and/or 2, from crude Vitis vinifera stalks extracts, allowing to get them in a pure form. Having at hand large amounts of these two pure compounds, they were tested and compared to a set of other relevant molecules for some biological properties: trans-ε-viniferin 2 was shown to be the most powerful tyrosinase inhibitor, among all samples tested. 相似文献
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聚偏氟乙烯(PVDF)膜材料存在强疏水性的缺陷,亲水化改性是解决该问题的主要途径。以PVDF为基膜材料、聚乙烯醇(PVA)为共混材料、N,N-二甲基乙酰胺(DMAc)为溶剂,采用相转化法制备PVDF/PVA复合膜。考察了复合膜的PVDF/PVA共混比、固含量、低分子化合物添加剂、聚合物添加剂等非溶剂添加剂对复合膜接触角的影响。结果表明,当PVDF/PVA共混比为7/3,固含量为13%时,制备的复合膜接触角为22.92°;当添加剂为无水氯化锂、纳米二氧化硅、聚乙烯吡咯烷酮(PVP)时,复合膜接触角分别从53.12°、30.51°和41.89°都降低到了0°,亲水性提高,其中纳米二氧化硅作为添加剂时复合膜亲水性最好;当添加剂为丙三醇、PMMA、PEG时,复合膜接触角都增大,亲水性变差。 相似文献
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Although water supplies are prominently dependent on desalination technology, desalination plant facing severe issues of discharged brine concentrate. Membrane distillation crystallization is an emerging synergistic technology that resolves the issue of brine concentrate by recovering clean water and value-added minerals simultaneously. In the present study, properties of polyvinylidene fluoride (PVDF) membrane were modified by incorporation of exfoliated fillers of hexagonal boron nitride and polyethylene glycol. The changes in morphology, surface roughness, hydrophobicity, thermal stability, and chemical composition of the prepared membranes were evaluated by scanning electron microscopy, atomic force microscopy, contact angle, thermogravimetric analysis, Fourier-transform infrared spectroscopy, respectively. Membrane distillation crystallization experiments were conducted to observe the effect of modified membranes on the permeate flux and salts recovery at different feed temperatures. The results showed a significant improvement in the permeate flux with modified membranes compared with pure PVDF membrane. It was found that hexagonal boron nitride/polyethylene glycol200 incorporated PVDF membrane gave the higher permeate flux (3.41 kg/m2 h for K2SO4 and 2.62 kg/m2 h for KNO3) at a temperature of 80 °C along with higher salts recovery than pure PVDF membranes. A 100 h long run test was conducted on modified membranes, which showed consistency in permeate flux with a marginal increase in conductivity. 相似文献
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以聚偏氟乙烯(PVDF)为成膜聚合物,石墨烯(GE)、疏水二氧化硅为添加剂、邻苯二甲酸二辛酯(DOP)为成孔剂、N,N-二甲基乙酰胺(DMAc)为溶剂,调制铸膜液,分别采用涂覆法和溶液相转化法(NIPS)在聚对苯二甲酸乙二酯-聚酰胺(PET-PA)无纺布表面构筑分离层,制备了PET-PA无纺布增强型PVDF/GE复合吸油膜(NR-PGM),分析并讨论了其形貌、疏水亲油性以及力学性能等.结果表明,NR-PGM具有疏水超亲油特性,其纯水渗透压可达0.14 MPa,对煤油、柴油的通量可达118.22、218.25 L/m2h;将其制成中空管状物,在负压作用下可实现连续油水分离,分离效率可达97%左右,经10次循环使用后分离效率仍可保持在95%左右. 相似文献
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TEP-DMAc混合溶剂对PVDF膜性能的影响 总被引:1,自引:0,他引:1
利用非溶剂相转化法(NIPS)制备聚偏氟乙烯(PVDF)膜,考察了聚乙二醇(PEG200)与N,N-二甲基乙酰胺(DMAc)的质量比对膜分相速率和膜性能的影响,讨论了以磷酸三乙酯(TEP)和DMAc的混合液作溶剂对PVDF膜凝胶速率、膜结构和膜通量的影响。结果表明:PEG200的加入减弱了溶剂对聚合物的溶解能力,但铸膜液的分相行为由延迟分相转变为瞬时分相,膜通量提高。随着混合溶剂中TEP含量的增大,铸膜液的黏度增大,分相速率减慢;在高质量比m(TEP)/m(DMAc)时,膜表面的孔增多,指状孔膜结构逐渐消失,整个膜截面呈海绵状,膜通量变大,力学性能提高。 相似文献
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PMMI/PVDF共混体系相分离的时温依赖性 总被引:1,自引:0,他引:1
用小角激光光散射(SALLS)研究了聚(N-甲基甲基丙烯酰亚胺)/聚偏氟乙烯(PMMI/PVDF)共混体系的相分离行为.通过升温法获得了PMMI/PVDF体系的浊点温度,发现体系的浊点温度强烈依赖于升温速率,呈明显的非线性关系,即升温速率大于1 K.min-1时,升温速率是影响I(t)的唯一因素;升温速率较小时,高分子链松弛速率的差别得以体现,则该情况下升温速率与松弛速率共同影响浊点温度.该体系具有典型的最低临界共溶温度(LCST)特征.恒温法相分离结果表明,在实验温度范围内该体系相分离行为对温度的依赖性遵循时温叠加(time-temperature superposition,TTS)原理. 相似文献
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PVDF基两性离子交换树脂的辐射合成及性能 总被引:1,自引:0,他引:1
以聚偏氟乙烯(PVDF)树脂为基材,采用共辐射接枝方法,在PVDF树脂上接枝苯乙烯(St)/甲基丙烯酸二甲氨基乙酯(DMAEMA)二元单体,随后对接枝产物进行磺化和质子化反应引入磺酸基和叔氨基正离子得到了一种新型的PVDF基两性离子交换树脂.红外光谱、X射线光电子能谱(XPS)、热重和扫描电镜(SEM)分析证明了辐射引发接枝共聚及功能化反应的成功进行.接枝反应条件如溶剂、剂量和二元单体浓度对接枝率(GY)有明显的影响.随着接枝率的增加,功能树脂的离子交换容量随之增大,但接枝链St与DMAEMA的摩尔比不变,其阳离子及阴离子交换容量最大分别可达2.16 mmol/g,1.06 mmol/g. 相似文献
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采用差示扫描量热法测试了在不同降温速率下的聚偏氟乙烯(PVDF),以及不同配比的聚偏氟乙烯(PVDF)/聚乙烯醇缩丁醛(PVB)共混物的DSC曲线,采用Jeziorny法和莫志深法分析了各组样品的非等温结晶动力学。结果表明:在同一降温速率下,PVB含量的增加使得结晶温度范围先减小后增加,峰值温度先升高后降低,结晶度先增大后减小,说明PVB的加入对共混物的结晶起到先促进后抑制的作用;而且随着PVB含量的增加,共混物的n值增大,说明其晶体生长方式从接近二维片晶生长向三维球晶生长转变,PVB的加入促进共混物生成多维复杂晶体。 相似文献
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In this paper, we report the results of a study of microstructure and thermal behavior of ceramic–polymer composites composed of barium strontium titanate Ba0.6Sr0.4TiO3 (BST60/40) and polyvinylidene fluoride (PVDF). The Ba0.6Sr0.4TiO3 ceramic powder was prepared by the sol–gel method. Thermal evolution of the dried gel as well as ceramic powder was studied by simultaneous thermal analysis. The composite BST60/40//PVDF was obtained by hot pressing method for volume fraction of BST60/40 ceramic powder c v = 50 %. The morphology of BST60/40//PVDF composite powder was observed by transmission electron microscopy and the morphology of BST60/40//PVDF composite sample was observed by scanning electron microscopy. Temperature dependence of dielectric constant and dielectric loss factor of BST60/40//PVDF composites was measured in the frequency range of f = (10 × 103–1 × 106) Hz. Dynamic mechanical properties of BST60/40//PVDF composites were measured by dynamic mechanical thermal analysis DMTA. 相似文献
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超临界二氧化碳体系中PVDF微孔膜的表面接枝改性 总被引:10,自引:0,他引:10
超临界二氧化碳(SCCO2)是一种T〉31.1℃,P〉7.38MPa的二氧化碳流体,不仅具有类似于气体的粘度和类似于液体的密度,而且可以通过改变温度或压力控制SCCO2的密度及溶解性.SCCO2对有机小分子具有优良的溶解、扩散和渗透性能,化学惰性,无污染,易于分离,作为一种聚合反应介质,受到学术界日益增多重视.SCCO2极低的粘度使其具有良好的流动性和扩散渗透性能,零表面张力使其对聚合物具有良好的润湿和增塑性,这将促进引发剂和聚合单体向微孔膜的外表面及内表面扩散.利用温度和压力改变SCCO2的溶解性能调整单体在聚合物相和SCCO2相之间的分布,进而控制微孔膜内外表面的接枝程度.所以SCCO2接枝聚合反应对于聚合物膜的表面改性具有极其重要的意义. 相似文献