Analysis of butyl acrylate diffusion in a glassy polystyrene matrix to predict gradient structure

To be able to control composition structure in gradient polymers prepared by sequential polymerization, diffusion phenomena has to be considered, particularly for the first 100% weight increment in a glassy polymer matrix. With that purpose, an analytical model to predict diffusion in that region has been developed for amorphous polymers. The inclusion of a relaxation time to estimate surface concentration changes during sorption led to diffusion coefficients one order of magnitude higher than Fickian coefficients. However, adding a volume increment term to account for polymer swelling, diffusion coefficients went up to 48 times the Fickian values. Experimentally, butyl acrylate with a small amount of photosensitizer was diffused into a slightly crosslinked polystyrene slab matrix at different temperatures in the glassy region. After fixing the gradient composition by photopolymerization, chemical structures throughout the slab were determined by FTIR. The proposed model was confronted with experimental sorption showing a close fit at the different temperatures in the region of interest. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1343–1348, 2001     

填料对紫外光固化环氧丙烯酸酯体系阻光效应的影响

在UV(紫外光)固化EA(环氧丙烯酸酯)体系中分别加入SiO2(二氧化硅)、滑石粉、CaCO3(碳酸钙)或TiO2(钛白粉)填料,配制不同的填充EA体系。采用UV-vis(紫外-可见分光光度)法、FT-IR(红外光谱)法和凝胶含量等评价了不同填充EA体系的UV固化特性,并探讨了填料类型、粒径和含量对不同填料阻光效应的影响。试验结果表明:四种填料的阻光效应为TiO2>CaCO3>滑石粉>SiO2;当填料粒径为1~10μm时,粒径5μm填料的阻光效应相对最小;填料含量越多,阻光效应越大,但10%SiO2填充EA体系的凝胶含量仍高达96%。     

Thermogravimetric profile of decomposition of acrylate systems based on bornyl acrylate monomers

This study deals with the thermal decomposition of the homopolymers of isobornyl acrylate (IBOA) and bornyl acrylate (BOA), and their relationship with polymers that contain IBOA as a reactive diluent. We have examined the profile, the mechanism and the energetics of the thermal decomposition reaction(s) and found a stereochemical dependence in the decomposition process.     

溶剂型丙烯酸酯压敏胶基质对贴片黏附性的影响

考察了不同的丙烯酸酯压敏胶(PSA)型号、溶剂系统组成及含量、高分子添加剂类型及含量等对PSA基质黏附性的影响。通过测定180°剥离强度和持粘力探讨了干燥条件对基质黏附性的影响,并对各因素进行优化筛选。结果表明:Duro-Tak87-2677的180°剥离强度为0.88kN/m,持粘力为50h,适合作为丙烯酸酯PSA的基质;当组合溶剂中V(异丙醇)∶V(正庚烷)∶V(乙酸乙酯)=37∶37∶21、m(水)∶m(乙醇)∶m(组合溶剂)=10∶7∶(67～70)时,PSA基质的溶剂系统为均一体系;当w(RLPO)=5%、干燥温度为80℃和干燥时间为15min时,丙烯酸酯PSA基质的180°剥离强度为0.1～0.6kN/m,持粘力9h,黏附性较好。     

Mutual diffusion and phase equilibrium in copolymers of nonyl acrylate and acrylic acid–diglycidyl ether of bisphenol A systems

The influence of the composition of statistical copolymers of nonyl acrylate with acrylic acid on the rate of mass transfer and phase equilibrium in solutions with diglycidyl ether of bisphenol A was studied. For these systems, the data on concentration dependencies of mutual diffusion coefficients and phase diagrams were obtained. The results were interpreted on the basis of the assumption about the effect of the effective concentration of nodes of the network of hydrogen bonds on the mutual diffusion and phase equilibrium. The dependencies of the mutual diffusion coefficients on the content of acrylic acid in the copolymers are described in terms of the free volume theory. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2353–2356, 1999     

Usefulness of solute elution from frozen matrix for freeze-concentration technique

A novel freeze-concentration method was proposed to use solute elution from a frozen matrix as a concentrating operation. A batch crystallizer was made up to freeze solution with a jacket cooler, and a rod heater was set at the centre of the crystallizer in order to make the solution contact with the frozen zone. Commercial apple juice was employed as a model liquid food, and the concentration behavior was investigated with the present apparatus. It was found that the concentration clearly increased with time, and the concentrate was recovered at desirable level if the temperature of the jacket and the heater were properly selected. In fact almost all the solute could be recovered from the original apple juice. The present method would mainly be governed by the solute elution from a frozen phase to a liquid phase, therefore, would not require complicated operation.     

Using mixture experimental design to study the effect of multifunctional acrylate monomers on UV cured epoxy acrylate resins

An epoxy acrylate resin was synthesized and the resin was used along with different multifunctional acrylate monomers, i.e. trimethylol propane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), 1,6-hexanedioldiacrylate (HDDA). The effect of the chemical structure of the monomers on some of the physical–mechanical properties of the resins and their cured films, such as viscosity, T_g, hardness and scratch resistance was studied. To minimize the number of experiments, mixture method was used as an appropriate tool for experimental design.     

双级孔材料内组分有效扩散系数的理论计算

双级孔材料中扩散与吸附现象广泛存在于化工过程中,准确预测其传递性质对指导过程设计具有重要意义。从最小尺度的孔隙开始采用体积平均方法推导出一个扩散型方程,并且得到该孔隙尺度下有效扩散系数的表达式。然后以此扩散方程为基础逐级扩大孔隙尺度,直至获得最大尺度孔隙中对应的扩散型方程及其对应的有效扩散系数的理论表达式。基于此,推导出一个扩散型方程描述双级孔材料内的组分扩散与吸附过程。孔隙结构、扩散速率、吸附强度的影响由有效扩散系数衡量。将上述理论模型与孔尺度模拟方法结合,对多孔圆柱阵列内的扩散吸附过程进行预测,预测结果与文献报道的直接数值模拟的结果吻合。结果表明:体积平均理论以及推导得到的封闭方程可用于预测双级孔材料内组分的有效扩散系数,为理解孔隙结构对有效扩散系数的影响以及调控相关过程性能提供了新的方法。     

Optimization of diffusion systems

The limiting performance of diffusion systems that convert mechanical work into separation work and extract work in systems with inhomogeneous compositions are studied. Diffusion engines with periodic and constant contact between the working body and sources are discussed.     

Effects of matrix moisture on gas diffusion and flow in coal

Gas production from coal is a complex process whereby gas, initially adsorbed in the coal matrix, desorbs and diffuses through the matrix into the cleat and eventually flows through the cleat system into a production well or a drainage borehole. Hence, the gas production rate is mainly controlled by the gas diffusivity in the matrix and gas permeability in the cleat system. Moisture in the coal matrix has significant impact on gas adsorption capacity and would also play a key role in desorption and migration of gas. However, how moisture affects gas desorption and diffusion in the coal matrix is still poorly understood. In this work, experimental study is performed to investigate effects of moisture on gas sorption rate for an Australian coal. Coal seam gases, CH₄ and CO₂, are used in the study. The experimental results show that moisture content in the matrix has significant impact on the gas sorption rate and the impact of moisture content on the diffusion rate is stronger for CH₄ than CO₂. Moreover, the impact of moisture on gas diffusivity in pores with different size is different, suggested from the modelling results using the bidisperse approach. Furthermore, moisture in coal matrix would cause coal swelling/shrinkage and mechanical properties change that could impact on coal permeability under reservoir conditions. Experimental measurements of coal matrix swelling and Young’s modulus on the same coal sample show that matrix moisture content has significant impact on those properties and may have significant implications on coalbed methane recovery and CO₂ storage in coal.     

丙烯酸酯压敏胶基贴片制备工艺中的质量控制

以丙烯酸酯PSA(压敏胶)和乳癖消浸膏共混作为药用PSA基质,考察了载药量、过程水的加入量、环境湿度、存放时间和制备工艺等因素对PSA基质的黏附性、抗老化性能和药物释放度等影响。结果表明:药用PSA基质中,当w(中药浸膏)≈38%(相对于基质总量而言)、w(水)=8%～10%(相对于基质总量而言)且贴片密封保存时,压敏胶基质的抗老化性能得到明显提高,其180°剥离强度为0.1～0.6kN/m,持粘力超过6h,并保持良好的稳定性;以50r/min左右的搅拌速率制取的PSA基质,其贴片的芍药苷12h释放度为83.61%(相对于芍药苷总量而言);当贴片存放时间超过60d时,药物释放度基本趋于稳定。     

The effect of mixing on the paired dimerisations of methyl acrylate and diethyl malonate

The paired dimerisations of methyl acrylate and diethyl malonate have been carried out in a pump cell, a capillary gap cell, a parallel plate cell and a trickle tower cell, and the distributions of products related to the environments in the cells. It is clear that good dispersion of malonate anions is essential for high selectivity, but that too high a dispersion rate leads to loss of current efficiency through the parasitic iodine cycle.     

Influence of ultrasound on diffusion through skin/leather matrix

Leather is a unique porous material, which is composed of a three-dimensional weave of tanned collagen fibre bundles. Collagen is a fibrous protein well organized in the formation of skin as building block. This paper studies the use of ultrasound in improving the diffusion process through porous skin/leather matrix. A diffusion model for leather processing has been proposed taking into account of pore characteristics in leather. Dye diffusion experiments have been carried out with leather and powdered leather to show the influence of ultrasound under two different diffusion conditions. Apparent diffusion coefficient (D) of dye through leather matrix has been calculated from the experimental dye uptake data. The results indicate that the use of ultrasound could achieve, 16.2 and 8.56 times improvement in D value for leather at 50 °C and 30 °C, respectively as compared to 2.99 and 1.55 times for powdered leather. Scanning electron microscopy (SEM) analysis of leather has also been performed which shows that fibre structure and morphology are not affected by the use of ultrasound. This study throws some light on enhanced transport through porous materials of complex nature such as skin/leather using ultrasound.     

Kinetics and effect of surfactant and cosurfactant on miniemulsion polymerization of acrylate monomers

The effects of the type and amount of the surfactant and cosurfactant on the miniemulsion polymerization of acrylate monomers were studied, and the comparison of the kinetics between miniemulsion polymerization and conventional emulsion polymerization was discussed in the presence of reactive surfactant allyloxy nonylphenol propyl polyoxyethylene (10), ether sulfate (DNS-86), and reactive cosurfactant stearyl methacrylate (SMA). The results showed that the obtained polyacrylate miniemulsion had a high monomer conversion rate and a low coagulum fraction, which were affected little by the surfactant and cosurfactant type. When the surfactant and cosurfactant amounts were all 2 wt%, the contact angle of the prepared polyacrylate miniemulsion with DNS-86/SMA and the water absorption fraction of the latex film were 39° and 8.3 wt%, respectively. FTIR results confirmed that DNS-86 and SMA took part in the polymerization of acrylate monomers. In the miniemulsion polymerization of acrylate monomers with DNS-86/SMA, monomer droplet nucleation was the main nucleation style.     

丙烯酸酯类反应性微凝胶的制备及其对环氧树脂的增韧作用

采用自稳定分散聚合法,制备了粒径在20nm左右、粒径分布均匀的球形丙烯酸酯类反应性微凝胶;同时研究了其对环氧树脂/间苯二胺(MPDA)体系的增韧效果.结果表明,所制备的丙烯酸酯类反应性微凝胶在室温下呈橡胶态;它是环氧树脂/MPDA体系的一种有效增韧荆,增韧效果受其用量、官能团种类及用量的影响;含有环氧基团的微凝胶颗粒,增韧效果最好,而且提高了环氧树脂的热性能:带有环氧基团的微凝胶颗粒用量越大,或丙烯酸酯类微凝胶中环氧基团的摩尔分数越高,对环氧树脂的增韧效果越好.     

相容性溶质对UASB反应器处理高盐废水效果影响研究

研究复配相容性溶质对UASB反应器厌氧颗粒污泥处理20 g/L高盐废水效果的影响。结果表明,各因素的主次顺序为有机负荷>进水pH>温度>配合比,处理进水COD浓度为2 016 mg/L的20 g/L盐度废水时,最佳反应条件为有机负荷为4 800 mg/(L·d),甜菜碱、海藻糖、谷氨酸、脯氨酸和氯化钾配合比为120∶20∶25∶25∶1,温度为35℃,进水pH为8.6。COD去除率达93.4%,产气量为1.63 L/d。     

水性丙烯酸酯树脂交联体系的研究进展

综述了水性AR(丙烯酸酯树脂)中常用的几种交联体系(包括酮羰基/酰肼基交联体系、氨基树脂/羟基交联体系、氮丙啶类化合物/羧基交联体系、环氧基交联体系、聚碳化二亚胺/羧基交联体系、异氰酸酯类交联体系、硅氧烷基团的水解缩聚交联体系以及环状碳酸酯/胺基交联体系等),并对其交联机制、性能和研究进展进行了介绍。最后对水性AR交联体系的未来发展方向进行了展望。     

Waterborne polyurethane/acrylate: Comparison of hybrid and blend systems

Polyurethane/acrylate hybrid composites in a broad range of composition (10, 30, 50, 70 and 90 wt.% of acrylic content), were obtained by emulsion polymerization of acrylic monomers (methyl methacrylate/n-butyl acrylate/acrylic acid mixture) in the presence of preformed polyurethane chains with polymerizable terminal vinyl groups. Blends with the same acrylic content were also prepared by mixing polyurethane and acrylic dispersions. Samples were characterized by SEC, DLS, FTIR, UV, TEM, AFM, SAXS/WAXS and gel fraction content. Mechanical properties, Buccholz and pencil hardness, surface roughness and water contact angle of films were also determined. The effect of the acrylic content on morphology and film properties was also evaluated. Hybrids are crosslinked systems showing changes in the particle and film morphologies with increasing acrylic content. The properties of hybrid films show a non-linear behavior with the increase of the acrylic component, while physical blends exhibit a gradual behavior from PU to AC. FTIR results indicate better acrylic-polyurethane compatibility in hybrid systems than in physical blends. Hybrid composites with up to 70 wt.% of acrylic component are homogeneous by SAXS. On the other hand, AFM results show that blends are phase segregated systems at all composition levels.