共查询到19条相似文献，搜索用时 46 毫秒
1.
溶剂在高分子膜中吸收和解吸的传递机理非常复杂,对其传递过程的研究有助于膜分离过程的开发、膜材料的选择。本文对溶剂在高分子膜中传递现象研究的进展作简要介绍。 相似文献
2.
3.
4.
基于双方式吸收的基本概念,并假设气体在膜中的溶解过程类似于在溶液中的溶解过程,得出了用于描述气体在玻璃态高分子膜中吸收过程的普遍化双方式吸收模型.该模型考虑了气体分子与膜之间的相互作用,并认为主要是溶解浓度影响了溶解度系数. 相似文献
5.
高分子膜（纤维）蠕变仪研制及其应用夏波拉杨秀英李青山王士威＊周伟＊＊（齐齐哈尔哈轻工学院高分子教研室１６１００６）０前言蠕变是指在恒定温度和恒定应力作用下，材料的形变随时间而发展的现象，是高聚物静态粘弹性的表现。特别是高分子膜和初生纤维在受外力作用时... 相似文献
6.
7.
8.
本文作者以醋酸纤维素类高分子膜提纯和浓缩活性染料获得成功。文中介绍了该技术的工艺流程、提纯浓缩效果以及对膜最佳操作条件的探索等情况。 相似文献
9.
采用石英弹簧称重法测定了乙醇在几种聚氨酯（PU）／乙烯基酯树脂互穿网络（IPN）中的吸收动力学数据，用蠕变传递模型对实验数据进行关联，并对IPN的微观结构进行了分析。结果表明：乙醇在PU／含促羟基的乙烯基酯树脂（CBIPN）膜和PU／正丁醇接枝乙烯基酯树脂（HBIPN）膜中的D远大于在PU膜和PU／不含仲羟基的乙烯基酯树脂（PIPN）膜中的D，关联得到的CBIPN和HBIPN膜的杨氏模糊也远大于纯PU和PIPN膜，与其它实验结果相吻合，说明在网络间引入化学键或氢键作用能有效地改善聚氨酯／乙烯基酯树脂互穿网络的相容性，从而提高材料的力学性能 相似文献
10.
11.
Closed-form solutions of the non-steady state diffusion equation with constant transport coefficients are presented. The diffusion coefficient is assumed to be finite, but the surface emission coefficient can be either finite or infinite. Mathematical conditions are established for the transport coefficients to be constant. When these conditions are met, the transport coefficients can then be easily evaluated. Diffusion test data can be compared against these conditions to determine whether or not the transport coefficients are constant. Desorption test data of northern red oak indicate that initial moisture content in wood and equilibrium moisture content in the environment are closely related to the constancy of the transport coefficients. 相似文献
12.
ABSTRACT Closed-form solutions of the non-steady state diffusion equation with constant transport coefficients are presented. The diffusion coefficient is assumed to be finite, but the surface emission coefficient can be either finite or infinite. Mathematical conditions are established for the transport coefficients to be constant. When these conditions are met, the transport coefficients can then be easily evaluated. Diffusion test data can be compared against these conditions to determine whether or not the transport coefficients are constant. Desorption test data of northern red oak indicate that initial moisture content in wood and equilibrium moisture content in the environment are closely related to the constancy of the transport coefficients. 相似文献
13.
ABSTRACT This naver analvzes the surface emission coefficient corresponding to anv diffusion coefficient expressed as an exponential function of the concentration diffusing substance in capillary porous solids. Theoretical equations for surface emission coefficient for both sorption and desorption are presented. Procedures to derive the diffusion coefficient and to verify the corresponding surface emission coefficient are made using experimental sorption data of aspen (Populur sp.) wood. It is of interest to note that the theoretical models for diffusion and surface emission coefficients can be established and/or evaluated using the same set of experimental dara. 相似文献
14.
15.
Molecular transport of aromatic hydrocarbons through crosslinked SBR has been carried out in the temperature range (25–65°C). SBR has been vulcanized by four different vulcanizing techniques viz., conventional, efficient, dicumyl peroxide and a mixture consisting of sulfur and peroxide. SBR vulcanized with EV system showed highest solvent uptake tendency and that vulcanized with peroxide showed the lowest. The influence of penetrant size on sorption behaviour of SBR has been examined. The thermodynamic constants such as standard entropy, standard enthalpy and first-order kinetic rate constant have been evaluated. A correlation between theoretical and experimental sorption results was evaluated. The polymer—solvent interaction parameter (χ) was also computed from the diffusion data. 相似文献
16.
T. M. Aminabhavi R. S. Munnolli 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(1):69-77
Results of a study on sorption and diffusion of chlorosulfonated polyethylene geomembrane with methyl benzoate, ethyl benzoate, methyl salicylate, iso-butyl salicylate, phenyl acetate, and diethyl phthalate in the temperature range 25–60°C are presented. A gravimetric sorption method is used to calculate the diffusion and permeation coefficients from the Fickian relationship. The diffusion results are dependent on penetrant–membrane interactions, temperature, and on penetrant concentration. The values of diffusion coefficients range from 0·02 × 10?7 cm2 s?1 for diethyl phthalate at 25°C to 1·81 × 10?7 cm2 s?1 for ethyl benzoate at 60°C. The activation energies for diffusion range from 21 to 50 kJ mol?1. The values of heat of sorption ranged between 2·2 and 6·4 kJ mol?1. Sorption results are also analyzed using a first-order sorption kinetic equation. Experimental results and calculated parameters are used to discuss the transport behavior. None of the esters used have shown any chemical attack toward the geomembrane. 相似文献
17.
Elastometric materials are used as barriers to protect workers against exposure to chemicals. The effectiveness of a polymer as a chemical protective material therefore depends on the rate of the permeation of chemicals through it. The permeation rate depends on the solubility and the diffusion coefficient of chemicals in the materials. The diffusion coefficient itself is a strong function of concentration of the chemicals in the polymeric material. Permeation rates can be measured directly using a permeation cell or they can be calculated from the solubility and the diffusion coefficient data. Sorption/desorption experiments can be used to determine solubility and an expression for the diffusion coefficient in terms of concentration. Experiments were conducted for the sorption and desorption of ethyl acetate in three glove (one butyl and two neoprene materials) and two garment (neoprene and chlorinated polyethylene) materials. The data collected were used to estimate the steady‐state permeation rates of ethyl acetate through the materials. The results of the experiments show that the solubility of ethyl acetate in butyl rubber is 0.795 g/cm3, and the steady‐state permeation rate is 0.32 μg cm−2 s−1. The solubility of the chemical through the three neoprene materials is in the range of 2.25–5.31 g/cm3, and the steady‐state permeation rates vary from 27 to 43 μg cm−2 s−1. The solubility of ethyl acetate in the chlorinated polyethylene is 7.14 g/cm3, and the steady‐state permeation rate is 62.43 μg cm−2 s−1. The experimental method is very simple to use and it requires a small sample of the material (less than 1 cm2) and only a few milliliters of the chemical. Sorption/desorption experiments can also provide information on the amount of additives extracted from an elastomeric material during contact with a chemical. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1265–1272, 2001 相似文献
18.
Sorption and diffusion of some aldehydes and ketones into interpenetrating polymer networks (IPNs) of polyurethane–polystyrene (PU–PS) have been investigated in the temperature interval of 25–60°C. Transport data were found to be affected by the nature of the interacting solvent molecule rather than its size. The diffusion coefficient of ketones range from 9.2 × 10−8 to 645 × 10−8 cm2/s and for aldehyde from 11.5 × 10−8 to 154.5 × 10−8 cm2/s. For all solvents, the polymer remained intact. From the temperature dependence of sorption data, the Arrhenius activation parameter and the thermodynamic parameter, such as entropy and enthalpy for the process of equilibrium sorption, have been estimated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2047–2055, 1998 相似文献
19.
Sorption and diffusion of supercritical carbon dioxide (SCCO2) into polysulfone (PSF) from 313 K and 20 MPa to 333 K and 40 MPa were investigated in this study. A simple gravimetric method was used to measure the mass gain of SCCO2 in PSF, and the Fick's diffusion model was applied to describe the desorption process. The sorption amount, the sorption diffusivity under supercritical states, and the desorption diffusivity at ambient conditions are presented. Comparisons of the sorption amounts and diffusivities of CO2 for polymers of polycarbonate and PSF are discussed according to the interactions between gas and polymers. The morphology change and plasticization effect attributed to gas sorption in PSF were studied. Effects of glass‐transition temperature and yielding stress for PSF and other polymers were used to describe the difference in their diffusivities for the sorption and desorption processes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 474–482, 2004 相似文献