成膜溶剂对聚4-甲基戊烯-1膜的形态结构和透过行为的影响——Ⅰ.膜的结晶性质与表面形态

以聚4－甲基戊烯－1（PMP）为膜材质，分别以环己烷、三氯乙烯、四氯乙烯、环己烷／三氯乙烯及环己烷／四氯乙烯为溶,他这些溶液浇铸膜垢结晶性质和表面形态。结果表明，溶剂对PMP的相对溶解能力和挥发速度同所成膜内PMP的结晶形式和结晶度密切相关；不同溶剂体系的PMP溶液浇铸膜的表面形态也不尽相同。并发现以四氯乙烯（或三氯乙烯）为溶剂或溶剂组分之一的PMP溶液浇铸膜存在未见报道的Ⅵ型结晶。     

成膜溶剂对聚4-甲基戊烯-1膜的形态结构和透过行为的影响——Ⅱ.膜的气体透过行为

以聚4－甲基戊烯－1（PMP）为膜材质，分别以环己烷、三氯乙烯、四氯乙烯及环己烷／三氯乙烯为溶剂，研究了这些溶液浇铸膜对O2、N2、H2及CO2等气体的透过行为。结果表明，气体的透过主要发生在PMP的无定形区域，但也在PMP的晶区进行。PMP的Ⅵ型结晶比Ⅰ型结晶具有较低的氧化透过活化能。     

成膜溶剂对聚4-甲基戊烯-1膜的形态结构和透过行为的影响——Ⅰ.膜的结晶性质与表面形态

以聚4-甲基戊烯-1(PMP)为膜材质,分别以环己烷、三氯乙烯、四氯乙烯、环己烷/三氯乙烯及环己烷/四氯乙烯为溶剂,研究了这些溶液浇铸膜的结晶性质和表面形态。结果表明,溶剂对PMP的相对溶解能力和挥发速度同所成膜内PMP的结晶形式和结晶度密切相关;不同溶剂体系的PMP溶液浇铸膜的表面形态也不尽相同。并发现以四氯乙烯(或三氯乙烯)为溶剂或溶剂组分之一的PMP溶液浇铸膜存在未见报道的Ⅵ型结晶。     

成膜溶剂对聚4-甲基戊烯-1膜的形态结构和透过行为的影响——Ⅱ.膜的气体透过行为

以聚4-甲基戊烯-1(PMP)为膜材质,分别以环己烷、三氯乙烯、四氯乙烯及环已烷/三氯乙烯为溶剂,研究了这些溶液浇铸膜对O_2、N_2、H_2及CO_2等气体的透过行为。结果表明,气体的透过主要发生在PMP的无定形区域,但也在PMP的晶区进行。PMP的Ⅵ型结晶比Ⅰ型结晶具有较低的气体透过活化能。     

聚4-甲基-1-戊烯膜的制备与应用研究进展

聚4-甲基-1-戊烯是一种具有低密度、高透气性等优良性质的膜材料,具有广泛的应用前景.本文从制备方法和具体应用两个方面综述了近年来国内外PMP膜的研究进展,重点介绍了热致相分离法、熔融拉伸法、溶剂挥发法及静电纺丝法、非溶剂致相分离法、热致相分离-熔融拉伸耦合法等其它方法进行PMP膜制备的原理及影响因素,并对PMP膜在体...     

干／湿相转换法制备聚芳醚砜致密皮层不对称膜

以聚芳醚砜为膜材料，采用干／湿相转换法．在非挥发性溶剂－挥发性添加剂以及挥发性溶剂／共溶剂－弱挥发性添加剂两种溶剂体系中研究了致密皮层不对称膜的制备和形成条件，并对它们的结构及氮、氢气体透过性能进行了测试。结果表明，采用前一种溶剂体系。虽然可以在一定范围内控制膜平均孔径的变化，却难以得到致密皮层不对称膜。而后一种溶剂体系，在控制铸膜液组成、适当的制膜条件下可以得到具有海绵状支撑结构的不对称气体分离膜。     

甲基丙烯酸-苯乙烯嵌段共聚物的XPS研究

对甲基丙烯酸-苯乙烯嵌段共聚物DMF溶液涂制膜(接着经过或不经其它溶剂的处理)的XPS研究表明,共聚物本体组成对膜的表面组成没有明显的影响。从DMF溶液直接涂膜时,按照两相模型,PMAA在表面的面积分数最大可达0.55。在用溶剂处理时,膜表面组成基本上决定于所用溶剂的溶解度参数,PMAA的表面面积分数按下列顺序降低:水>乙醇>环己烷>石油醚。     

溴代与氯代聚-4-甲基戊烯-1的化学组成及氯、溴原子性质与膜的透气性能的关系

聚-4-甲基戊烯-1(PMP)是一种半结晶性高聚物,主链结构为饱和碳-碳链,由于其大侧基的存在,高分子链间间隙较大,利于气体分子的扩散,因而其均质膜对氧气的透过系数比同样是碳-碳主链的聚乙烯约高一个数量级。 PMP有较高的强度,但在室温下很难溶于一般烃类溶剂中,前文已报道,在PMP结构中引入电负性较大的溴原子后明显地改善了其在有机烃类溶剂中的溶解性。 然而,     

铌酸催化合成环己酮1,2-丙二醇缩酮

将铌酸应用于催化缩酮反应，以环己酮和1，2－丙二醇的缩酮反应为探针，详细探索了影响缩合反应的各种因素，并得出了铌酸催化环己酮与丙二醇反应的最佳条件：mol环己酮：mol丙二醇＝1：1.5，环己烷作带水剂，环己烷和铌酸催化剂的用量分别为反应物总体积、总质量的35％和1．2％，回流搅拌反应3.5h，产品环己酮1，2－丙二醇缩酮的总收率为73．5％。     

高硅ZSM—5沸石填充硅橡胶膜的研究（Ⅳ）：沸石粒径和不同品…

研究了粒径为１５μｍ和５μｍ的水热处理Ｓｉｌｉｃａｌｉｔｅ－Ｉ填充ＰＤＭＳ膜以及酸处理Ｓｉｌｉｃａｌｉｔｅ－Ｉ填充不同品种硅像胶膜对低浓度乙醇－水混合物的渗透发分离性能的影响。结果表明，沸石粒径的减小，不利于乙醇－水分离系数的提高；不同品种硅橡胶有沸石充膜对乙醇－水的渗透蒸发分离性能与硅橡胶本身的性质有关。     

Extraordinary transport behavior of gases in isothermally annealed poly(4‐methyl‐1‐pentene) membranes

Poly(4‐methyl‐1‐pentene) (PMP) membranes were modified through isothermal annealing to investigate the change of their crystalline structure and rigid and mobile amorphous fractions (RAF and MAF), assuming a three‐phase model, affected the gas transport behavior. The crystalline structure was characterized by wide‐angle X‐ray diffraction (WAXD) and small‐angle X‐ray scattering (SAXS) techniques, and the free volume properties were analyzed by positron annihilation lifetime spectroscopy. Compared with the pristine membrane, the annealed membranes show higher crystallinity; the crystals undergo partial structural change from form III to form I. The lamellar crystal thickness, rigid amorphous fraction thickness, and long period in the lamellar stacks increase with crystallinity. The annealed PMP membranes exhibit higher permeability due to the increase in larger size free volumes in MAF and higher selectivity due to the increase in smaller size free volumes in RAF, respectively. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2368–2376     

GAS SORPTION,DIFFUSION AND PERMEATION OF ORDERED POLYMERIC MEMBRANES

He, CO_2, O_2, N_2, CH_4, C_3H_8, and t-C_4H_(10) gas permeability coefficients and diffusion coefficients of poly(4-methylpentene-1) (PMP) with various degrees of crystallization were plotted against the degree of crystallization. The plotdemonstrated a linear relationship. The gas permeability coefficient and diffusion coefficient of pure amorphous and purecrystalline PMPs were evaluated by a linear extrapolation to zero and 100% crystallinity, respectively. The relationshipbetween the diffusion coefficient of crystalline parts of PMP and the kinetic diameter of penetrant gases was discussed.Syndiotactic polystyrene (SPS) could exist as δ form crystals complexed with organic solvents such as benzene, toluene,xylene, and ethylbenzene. The mesophase of SPS is prepared by annealing the δ form of crystalline complexes at a certaintemperature for 1 h. The desorption of solvent during annealing almost does not result in changes of both the conformation ofbackbone chains and the crystal lattice. We could prepare the mesophase containing molecular cavities with the size andshape of the organic solvent molecules. The mesophase could sorb the same solvent after the manner of Langmuir sorption atlow vapor pressure range while this would not be the case for solvents of different size and shape. This suggests a molecularrecognition of organic solvent, and mesophase SPS might be useful for separation membrane and adsorptive material.     

溴代聚-4-甲基戊烯-1的溶解性能及其膜的形态结构和结晶状态

<正> 迄今为止,用于气体分离的高分子膜,其气体透过速率和选择分离系数仍不够高。究其原因,一是膜材料的气体透过系数较低;二是某些气体透过系数较高的高分子材料又难以形成超薄膜层。     

Small‐angle neutron scattering investigation of structural changes in nafion membranes induced by swelling with various solvents

The structure of Nafion‐117 perfluorosulfonate ionomer membranes was investigated with small‐angle neutron scattering techniques. Structural changes induced by the swelling of the membranes with water, alcohols, and dipolar, aprotic solvents were monitored at solvent‐swelling levels ranging from approximately 2 vol % to greater than 50 vol %. Membranes swollen up to approximately 50 vol % solvent exhibited two scattering maxima, one known to be associated with ionic regions of the membrane structure and one known to be associated with correlation distances between crystalline regions in the membrane structure. The positions of both maxima shifted toward lower scattering vector values as the solvent content in the membrane increased. The shift in the position of both maxima was linearly related to the solvent volume fraction in the membrane. The Bragg spacings corresponding to both the ionic‐feature scattering maximum and the crystalline‐feature scattering maximum were plotted versus the solvent volume fraction in the membranes, and the data fit with linear regression. The slopes associated with the curves of the spacing versus the solvent volume fraction were greater for the crystalline‐feature spacing than for the ionic‐feature spacing for all solvents other than water; this was indicative of preferential segregation of nonaqueous solvents into regions of the structure not directly associated with the ionic scattering maximum. © 2002 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 387–400, 2002; DOI 10.1002/polb.10092     

Crosslinking and stabilization of nanoparticle filled PMP nanocomposite membranes for gas separations

Poly(4-methyl-2-pentyne) (PMP) has been crosslinked using 4,4′-(hexafluoroisopropylidene) diphenyl azide (HFBAA) to improve its chemical and physical stability over time. Crosslinking PMP renders it insoluble in good solvents for the uncrosslinked polymer. Gas permeability and fractional free volume (FFV) decreased as crosslinker content increased, while gas sorption was unaffected by crosslinking. Therefore, the reduction in permeability upon crosslinking PMP was due to decrease in diffusion coefficient. Compared to the pure PMP membrane, the permeability of the crosslinked membrane is initially reduced for all gases tested due to the crosslinking. By adding nanoparticles (FS, TiO₂), the permeability is again increased; permeability reductions due to crosslinking could be offset by adding nanoparticles to the membranes. Increased selectivity is documented for the gas pairs O₂/N₂, H₂/N₂, CO₂/N₂, CO₂/CH₄ and H₂/CH₄ using crosslinking and addition of nanoparticles. Crosslinking is successful in maintaining the permeability and selectivity of PMP membranes and PMP/filler nanocomposites over time.     

Vibrational Dynamics,Phonon Dispersion and Specific Heat in Gas Permeable Poly(4-Methyl-2-Pentyne)

Poly(4-methyl-2-pentyne) (PMP) is an amorphous glassy disubstituted acetylene based polymer. The excellent gas-separation and mechanical properties of these polymers have stipulated their use as membrane material for vapor and gas separation. PMP is among the hydrocarbon disubstituted polyacetylenes which have been synthesized to date. This polymer combines excellent gas and vapor permeability with good resistance to organic solvents. As was shown recently, PMP offers promise in the manufacture of nanocomposite membranes for the separation of various hydrocarbon mixtures. It is also of importance as its monomer, 4-methyl- 2-pentyne, can be easily derived from commercial compounds, 4-methyl-2-pentene or methyl isobutyl ketone, produced on a large scale. It is known that PMP exists in cis and trans configurations. Synthetic conditions, e.g., the used catalyst, temperature, solvent etc., of substituted polyacetylenes decide percentage of different configurations (cis or trans). Different geometries of macromolecules can influence the supramolecular structure of the polymer, which primarily defines its properties, such as solubility, permeability, sorption, etc. Qualitative assignments of few bands of IR spectra are reported earlier. We present here, complete normal mode analysis and dispersion curves for PMP using Wilson GF matrix method modified by Higgs using Urey-Bradley force field. Dispersion curves for PMP are drawn and salient features are discussed. Predicted values of specific heat via density-of-states are also reported.