成膜溶剂对聚4-甲基戊烯-1膜形态结构及渗透汽化特性的影响

以聚4－甲基戊烯－1（PMP）为膜材质、分别以环己烷、三氯乙烯以及环己烷／三氯乙烯为溶剂，以浇铸法制备了PMP的均质致密膜。研究了不同溶剂体系的相对溶解能力和挥发速度对PMP膜结晶度和形态结构的影响，并对成膜的渗透汽化特性的影响进行了研究。     

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。     

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。     

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。     

4-甲基-1-戊烯与烯烃共聚用催化剂的研究进展

4-甲基-1-戊烯(4M1P)是烯烃工业中一种重要的支链α-烯烃,它的主要用途是用于制备均聚物和共聚物。虽然绝大部分4M1P共聚物尚未进入工业化生产阶段,但由于共聚物作为一类新型的合成树脂具有突出的力学性能和光学性能,已成为国外聚烯烃领域的一个研究热点。本文阐述了4M1P与烯烃共聚反应催化剂包括Ziegler-Natta催化剂、茂金属催化剂及后过渡金属催化剂的开发研究现状;重点阐述了催化剂的结构对共聚物分子结构的影响;同时也简要介绍了二亚胺镍催化剂催化4M1P共聚反应作用机理,展望了这一领域的发展趋势。为开发高端聚烯烃新材料提供参考。     

聚4—甲基戊烯—1溶液水面展开制备超薄膜的研究

在聚4-甲基戊烯-1(PMP)的环已烷溶液中,加入对水有一定亲合性的第三组分环已酮作为展开助剂,研究了该三组分溶液体系的界面性质与溶液在水面上展开程度的关系。发现环已酮的加入明显降低了PMP溶液对水的界面张力,使得溶液在水面上的展开系数大为增加,得以制备厚度为10～25nm的PMP超薄膜。     

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,     

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

Bromo- and chloropoly-4-methylpentene-l were obtained from the macromolecular reactions of PMP with chlorine and bromine respectively. The influences of reaction conditions, the contents of bromine and chlorine in halo-PMP and the natures of bromine and chlorine themselves on the gas permeation properties were discussed.     

Crystal structure of isotactic poly(4-methyl-1-pentene)

The crystal structure of isotactic poly(4-methyl-1-pentene) was determined by x-ray analysis. The unit cell is tetragonal, P4 b2, with α = 18.70 Å and c (fiber axis) = 13.68 Å; it contains four molecular chains each consisting of seven monomeric units in the fiber period. The molecular conformation is essentially a (7/2) helix, but deviates slightly from the uniform (7/2) helix. The unusual low density is discussed from the structural point of view.     

Gas sorption-induced dilation of poly(4-methyl-1-pentene)

Sorption and volume dilation isotherms of semicrystalline poly(4-methyl-1-pentene) (PMP) were measured using CO₂ and C₃H₈ as penetrants, which have sieving diameters of 3.3 and 4.3 Å, respectively. On the other hand, the PMP crystal has a void width of approximately 4 Å as estimated by X-ray diffraction, so it was anticipated that CO₂ would be able to sorb into the PMP crystal while C₃H₈ would not. The data show that C₃H₈ has a constant partial molar volume of approximately 87 cc/mol, just above the value reported in other rubbery polymers, and are consistent with the hypothesis that the C₃H₈ molecules are too large to sorb into the PMP crystals. The partial molar volume of CO₂ was found to be 39 cc/mol for CO₂ weight fractions of up to 0.03. Since the typical partial molar volume of CO₂ in rubbery materials is 46 cc/mol, the lower values in this study were attributed to CO₂ sorption into crystalline regions of the polymer, which provided no dilation. Application of a two-phase model using the assumption of Henry's law sorption showed that apparently all C₃H₈ sorption was occurring in the amorphous region but approximately 16% of CO₂ sorption occurred in the crystalline regions. © 1996 John Wiley & Sons, Inc.     

Small-angle X-ray scattering of isotactic poly(4-methyl-1-pentene)

Although the crystalline phase of poly(4-methyl-1-pentene) (P4MP) is less dense than the amorphous phase, the density difference is very small at room temperature. This makes it difficult to study the fine structure of P4MP by small-angle x-ray scattering (SAXS). It has therefore not been clear whether a so-called superlattice, or long-spacing structure, is formed in P4MP as in other synthetic polymers. However, it is found that raising the temperature increases the density difference sufficiently to make SAXS study feasible, and the existence of the long-spacing structure of P4MP is indicated. Annealing studies reveal two characteristic temperatures of 170 and 200°C: above 170°C the long-spacing structure is formed with an abrupt increase of crystallinity, and at 200°C the structure is further developed.     

Preparation and properties of polyesters and copolyesters based on 4-methyl-2,4-bis (p-hydroxyphenyl)-1-pentene

4-Methyl-2,4-bis (p-hydroxyphenyl)-1-pentene (MBHPP) was prepared from thermal cracking of bisphenol A (BPA). Unsaturated polyesters were synthesized from the polycondensation of MBHPP with diacid chlorides. Three synthetic routes—solution, interfacial, and melt polycondensation—were employed. MBHPP-polyesters with higher molecular weights were obtained by the interfacial polycondensation reaction. During the preparation of MBHPP-polysters, the products usually contain some insoluble gel, which is probably caused by the crosslinking reaction of the vinyl groups of MBHPP in the aqueous NaOH. Thus, a modified interfacial polycondensation method was proposed, in which both of the bisphenol MBHPP and diacid chloride were dissolved in organic phase and then the solution was stirred with an aqueous NaOH solution to promote the polycondensation. This method reduced the time of MBHPP present in the alkali and produced polymers with higher inherent viscosity and lower gel fraction. The effects of some variables, such as the nature of porganic solvents and phase transfer agents and the concentration of reactants, on the modified interfacial polycondensation of MBHPP with the mixture of equal parts of isophthaloyl and terephthaloyl chloride [IPC/TPC (50/50)] were investigated in some detail. Copolyesters of mixed bisphenols of BPA/MBHPP with IPC/TPC (50/50) were also prepared and characterized.     

FTIR and FT Raman spectra and analysis of poly(4-methyl-1-pentene)

Poly(4-methyl-1-pentene) is the most widely used polymer in industry and medical products. Fourier transform infrared and Raman Spectra of poly(4-methyl-1-pentene) have been recorded in the range of 4000-400 and 4000-100 cm(-1), respectively. In the present investigation a detailed assignments of the observed fundamental bands of poly(4-methyl-1-pentene) has been analyzed in terms of peak positions and relative intensities. With the hope of providing more and effective information on the fundamental vibrations, a normal coordinate analysis has also been performed on poly(4-methyl-1-pentene) by assuming Cs symmetry. The simple general valence force field (SGVFF) method has been employed in normal coordinate analysis and the potential energy distribution (PED) has been calculated for each fundamental vibration. The PED contribution corresponding to each of the observed frequencies shows the reliability and accuracy of spectral analysis. The validity of the SGVFF method as a practical tool for complete analysis of vibrational spectra, for poly(4-methyl-1-pentene) is confirmed in the present work.     

聚-N-异丙基丙烯酰胺的制备及应用进展

聚(N-异丙基丙烯酰胺)(PNIPAM)是一种温敏性高分子聚合物,在最低临界溶解温度(LCST)处会发生构象转变。对PNIPAM加以改性,可拓宽温敏性聚合物材料的研究领域,使其在药物负载运输、基因传递、化学分析和表面浸润性等领域发挥更大的应用价值。本文对PNIPAM的活性自由基聚合方法及其应用进展进行了综述,并展望了其发展前景。     

Equibiaxial deformation of poly(4-methyl-1-pentene) by a forging process

Poly(4-methyl-1-pentene) (PMP) has been uniaxially compressed by a forging (equibiaxial) process. The rheology of the process has been examined for this semicrystalline polyolefin, melting point about 235°C. The yield energy, area under the compressive stress-strain curve up to the yield point, as a function of temperature was found to consist of two linear components of different slope. These two linear relations arise from the glassy and crystalline phases of PMP. The intercept temperature (T_i) at zero yield energy for the glassy phase has been evaluated. The attainable maximum compression ratio without sample rupture (CR_max) increased steadily on increasing forging temperature above T_i, and below T_m. In this range, the crystalline relaxation temperature (T_c), evaluated from an Arrhenius plot of yield stress was 160°C. Above T_c, a CR_max of 240 was reached. This value is five times higher than that attained for isotactic polypropylene (i-PP). However, the draw efficiency evaluated by elastic recovery in the plane direction of PMP (0.76) is lower than for i-PP (0.97). Differential scanning calorimetry analyses showed that the melting peak became a complex doublet on increasing compression ratio ( > 100). The drawing and stress-strain behavior of PMP are compared with i-PP. © 1994 John Wiley & Sons, Inc.