共查询到19条相似文献,搜索用时 107 毫秒
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通过界面聚合法对聚偏氟乙烯膜进行表面改性。并利用红外光谱,接触角,扫描电镜等检测手段对基膜和改性膜分别进行表征。研究结果表明,经过改性,聚哌嗪酰胺功能层成功地聚合到功能层表面。改性后,膜的亲水性大大增强,抗污染性提高。 相似文献
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沉淀剂组成对聚偏氟乙烯微孔膜孔结构的影响 总被引:10,自引:6,他引:4
在相转换法制备非对称微孔膜过程中,凝胶化条件是重要的孔结构控制因素之一。本文以乙醇水溶液和甲醇水溶液为沉淀剂,讨论了沉淀剂的溶解度参数对聚偏氟乙烯膜孔结构的影响,利用扫描电镜观察了所得膜的形态结构,发现当沉淀剂的溶解度参数从小到大变化时,膜的形态从海绵状结构逐渐过渡到指状结构;在两种结构各半的转变点处,孔隙率和平均孔径均处于最小值。不同铸膜液体系具有相似的成膜规律,但“转变点”的位置可能有所不同。实验结果表明,沉淀剂的溶解度参数可以作为定量或半定量描述成膜规律的重要物理参数之一。 相似文献
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采用溶液相转化法制备了羽绒粉体/聚偏氟乙烯(PVDF)和苎麻粉体/PVDF复合微孔膜,对膜结构和性能进行了分析和测试。结果显示苎麻粉体/PVDF复合膜、羽绒粉体/PVDF复合膜、纯PVDF膜的形态一致,均为致密皮层和多孔亚层,孔隙率和水通量依次降低,结晶度依次增加;但膜的吸水率按照羽绒粉体/PVDF复合膜、苎麻粉体/PVDF复合膜、纯PVDF膜依次下降;这说明复合膜水通量主要受孔隙率的影响,而膜吸水率主要受纤维粉体吸水性大小的影响。膜力学性能测试显示加入粉体之后,PVDF膜的强度增加,断裂伸长率有所下降。 相似文献
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采用熔体挤出拉伸法以高、低分子量混合聚偏氟乙烯(PVDF)为原料制备微孔膜,研究了不同热拉伸温度对PVDF微孔膜表面形貌及结晶行为的影响,通过扫描电子显微镜、红外光谱仪、X射线衍射仪和差示扫描量热仪等测试手段分别对微孔膜的形态、结构、晶型进行表征.结果表明,热拉伸温度对PVDF微孔膜的成孔形貌、孔隙率、结晶度及β相含量... 相似文献
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不同添加剂对聚偏氟乙烯膜结构和性能的影响 总被引:2,自引:0,他引:2
利用非溶剂相转化法(NIPS),以N,N-二甲基乙酰胺(DMAc)为溶剂,聚乙烯吡咯烷酮(PVPK30)和一水合氯化锂(LiCl·H2O)为混合添加剂,改变PVPK30-LiCl·H2O配比得到不同性能和结构的聚偏氟乙烯(PVDF)膜。考察了不同种类添加剂(PVP、LiCl·H2O、H2O和PEG200)及不同配比的PVPK30-LiCl·H2O添加剂对PVDF成膜分相延时时间、分相速率的影响。实验结果表明,采用PVPK30为添加剂,铸膜液呈瞬时分相行为,膜通量很大;增大混合添加剂中PVPK30/LiCl·H2O的比例,会增加液液分相速率,使膜结构中的大孔贯通整个膜结构。 相似文献
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以环丁砜为稀释剂,采用热致相分离法制备聚偏氟乙烯多孔膜,研究了用不同配比的水和乙醇混合溶液作为萃取剂对膜结构和性能的影响,发现随乙醇含量的提高,多孔膜的孔隙率和平均孔径降低,因此影响多孔膜的力学性能和由其制备的锂离子导电膜的电导率。 相似文献
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采用丙烯酸(AA)作为改性单体,对聚偏氟乙烯(PVDF)中空纤维膜进行等离子体化学沉积改性。通过傅里叶变换衰减全反射光谱仪(ATR-FT-IR)分析发现,改性后的膜表面引入了羧基、羟基等亲水性官能团。经低温等离子体改性后的膜,清水通量提高20%~30%,膜面和膜孔的Zeta电位分别提高了694%和58.66%,在过滤分离凹凸棒悬浊液实验中,改性膜通量衰减百分比,较原膜平均降低了8.44%,仅经水力清洗后的改性膜通量恢复率,较原膜提高8%。 相似文献
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Xian-Kai Lin Xia Feng Li Chen Yi-Ping Zhao 《Frontiers of Materials Science in China》2010,4(4):345-352
In this paper, poly(vinylidene fluoride)-graft-poly(N-isopropylacrylamide) (PVDF-g-PNIPAAm) copolymers were synthesized directly via grafting temperature-sensitive material NIPAAm
on PVDF by atom transfer radical polymerization (ATRP). The chemical structure of the graft copolymers was characterized by
Fourier transform infrared (FTIR) and 1H-NMR spectroscopy. The temperature-sensitive membranes were prepared from the PVDF-g-PNIPAAm copolymers by the immersion
precipitation process of the phase inversion method. The chemical composition and pore structure of the PVDF-g-PNIPAAm membranes
were studied by X-ray photoelectron spectroscopy (XPS) and an automatic mercury porosimeter, respectively. The effects of
temperature on pure water flux and bovine serum albumen (BSA) rejection ratio of the membranes were also investigated. The
results showed that the grafted PNIPAAm chains tended to enrich on the surfaces of the membranes or the membrane pores during
the membrane-forming process. Pore diameter and porosity of the copolymer membranes were larger than those of the pristine
PVDF membranes. Also, the PVDF-g-PNIPAAm membranes could exhibit temperature-sensitive performance in water flux and BSA rejection
measurements. 相似文献
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S. Satapathy Santosh Pawar P. K. Gupta K. B. R. Varma 《Bulletin of Materials Science》2011,34(4):727-733
The γ-phase poly (vinylidene fluoride) (PVDF) films are usually prepared using dimethyl sulfoxide (DMSO) solvent, regardless of
preparation temperature. Here we report the crystallization of both α and γ-phase PVDF films by varying preparation temperature using DMSO solvent. The γ-phase PVDF films were annealed at 70, 90, 110, 130 and 160°C for five hours. The changes in the phase contents in the PVDF
at different annealing conditions have been described. When thin films were annealed at 90°C for 5 h, maximum percentage of
β-phase appears in PVDF thin films. The γ-phase PVDF films completely converted to α-phase when they were annealed at 160°C for 5 h. From X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR),
differential scanning calorimetry (DSC) and Raman studies, it is confirmed that the PVDF thin films, cast from solution and
annealed at 90°C for 5 h, have maximum percentage of β-phase. The β-phase PVDF shows a remnant polarization of 4.9 μC/cm2 at 1400 kV/cm at 1 Hz. 相似文献
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Dielectric parameters have been measured for solution-cast films of poly(vinylidene fluoride) (PVDF) in the temperature range 40 to 120°C and frequency range 50 Hz to 1 MHz. The infrared absorption spectrum shows these films to be predominantly of Phase III crystal structure. The
c relaxation, which has generally been reported in the literature for Phase II PVDF, does not appear in the dielectric loss spectra. A small loss peak is observed which could probably be assigned to relaxation arising from molecular motions in the folds on the surface of the crystallites. Only a part of the
a relaxation is observed due to the limitations of our experimental range of temperature and frequency. Trapped charge carriers make a large contribution to the dielectric parameters at lower frequencies. 相似文献
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The mechanical properties of blends of the crystallizable polymer poly(vinylidene fluoride) and the amorphous material poly(methyl methacrylate) have been investigated as a function of composition both for glassy amorphous materials and for partially crystalline materials. The data obtained were interpreted in terms of the molecular and super-molecular structure of the blends and in terms of their dynamic properties.The main conclusions were that the mechanical properties are not strongly dependent on details of the distribution of the two components in the material nor on the crystal modifications present. The mechanical properties were found to depend primarily on the location of the glass transition temperature relative to the elongation temperature and on the presence or absence of crystalline regions. The degree of crystallinity was found to play an important role in determining the properties only at lower values of this quantity. The advantage of these blends is that the important parameters, namely, the degree of crystallinity and the location of the glass transition temperature, can be adjusted at will by varying the composition appropriately. This allows well-defined variations of the mechanical properties to be achieved. 相似文献
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