丙烯酸聚氨酯涂料成膜过程(Ⅱ)模型及模拟

将双组分丙烯酸聚氨酯涂料体系按二元聚合物-溶剂体系进行简化处理建立了涂膜中溶剂组分的连续性方程、涂膜厚度的时间依赖性方程及其边界条件和初始条件,并采用有限元技术求出了本模型方程组的解.模拟结果表明,一些实际测得的宏观实验数据与模型预测结果非常吻合,而且模型预测还能够较好地解释涂膜干燥过程中表层较内部干燥快所形成的结皮现象.     

含氟聚合物及其涂料

200903006 快速干燥的含氟聚合物分散体涂料组合物;200903007 热稳定的氟聚合物组合物;200903008 涂料组合物及其涂膜的形成     

改性不饱和聚酯亮光清漆的研究

针对不饱和聚酯亮光清漆易产生针孔及柔韧性差的弊病,采用聚氨酯加成物对其进行改性,形成互穿聚合物网络结构。通过协同效应,加快涂料干燥速度,提高涂膜的综合性能。     

水性聚合物及其涂料的现代分析测试技术

对涂料各项宏观性能的测试及对涂料在微观层次上的分析技术,构成了涂料科学的一个重要组成部分.本文从水性聚合物及其涂料的原材料分析、涂料剖析、涂膜形成过程分析、涂膜结构与形貌分析等方面讨论了现代分析技术在水性聚合物及其涂料分析测试中的应用.     

丙烯酸聚氨酯涂料成膜过程(Ⅰ)溶剂扩散系数的估算

采用傅里叶变换红外光谱（FTIR）测定了不同时间下丙烯酸聚氨酯涂料体系成膜聚合物的固化度及固化反应速率常数,并将该体系按二元聚合物-溶剂体系进行简化处理,在Vrentas-Duda自由体积理论模型的基础上,利用Di-Benedetto方程关联了溶剂的扩散系数与涂膜的固化度,建立了涂膜中溶剂扩散系数的预测模型.结果表明,本涂膜体系中溶剂扩散系数是溶剂浓度、干燥时间的函数.     

第七章 流平剂

一、前言任何涂料施工后,都有流动及干燥过程,然后逐渐形成平整、光滑、均匀的涂膜。涂膜能否达到平整、光滑的特性,称为流平性。在涂料施工过程中,刷涂时出现刷痕,喷涂时出现桔皮,辊涂时产生辊痕,而且在干燥     

涂膜干燥时间测定技术及其应用

涂膜的干燥往往需要一定的时间，才能保证最终形成固体涂膜的质量，因而，干燥时间的测定是涂料常规性物理检验的一个重要方面。作者介绍了国内外一些常用的涂膜干燥时间的测定方法及测定仪器。     

溶胶-凝胶法制备二氧化硅无机膜工艺研究

通过实验考察了在用溶胶-凝胶法制备二氧化硅无机膜的过程中涂膜温度、干燥条件及浸没时间对膜性能的影响。结果表明,控制适宜的涂膜温度、干燥环境和涂膜时间可以提高膜的性能。     

浅谈聚合物水泥防水涂料的机理、性能及其测试

在现代建筑中,渗漏现象一直没有找到较好的解决办法,导致不论是在建筑过程中,还是人们日后在使用过程中都造成了一定的麻烦,也造成了巨大的损失。为了防止这一现象的发生,利用聚合物水泥防水材料就显得尤为必要。聚合物水泥防水材料指的是由水性聚合物分散体和水泥以及其他辅助材料的双组份防水涂料,搅拌成均匀的浆料,这样的材料在干燥后就能形成防水涂膜,这种材料兼具了二者的优点,既能像水泥一样,保证很高的强度而且黏性较高,还能兼具聚合物涂膜防水性好的特点,并且没有毒害。完美地防止渗漏带来的损失。本文根据这一材料的组成和成膜机理,对影响其性能的因素进行分析,并且简要介绍了使用注意事项和环保性能。希望可以为建筑行业的发展做到一点贡献。     

室温交联型双组分丙烯酸系共聚物乳液研究

用马来酸酐和乙二胺合成了含有双键的伯胺化合物(UPA)，并将其与丙烯酸酯进行乳液共聚合制成了双组分室温固化涂料的第一组分。论文研究了乳化剂种类和UPA用量对聚合稳定性的影响。将乙二醇二缩水甘油醚乳化形成水乳液，作为水乳型涂料的第二组分。将两种乳液复合后在室温下干燥成膜，通过对聚合物涂膜的DSC测试表明，双组分体系在成膜过程中发生了交联反应，而未加环氧化合物的单组分聚合物乳液成膜时则不发生交联。论文还研究了UPA含量对涂膜拉伸强度的影响。     

Mechanism of bubble formation in the drying of polymer films

A common problem in making thin polymer films by solution processing is the undesirable formation of bubbles during the drying process. These bubbles appear well below the boiling point of the solvent. Experience indicates, however, that the degassing of the polymer solutions reduces bubble formation, indicating a relationship with the presence of air. This work is based on a hypothesis that if the solubility of air in the polymer solution increases with solvent concentration, then the solution can become supersaturated with air as the concentration of the solvent is reduced during the drying process. To test this hypothesis the system poly(vinyl acetate)‐toluene‐nitrogen was chosen. Previously published data on the solubility and diffusion of nitrogen in the polymer‐solvent system were used. Different diffusion models based on the friction coefficients and free‐volume model were then used to correlate the diffusivity data so that the diffusion behavior of the ternary system can be predicted over a broad range of conditions. Finally, the thermodynamic and diffusivity correlations were incorporated into a multicomponent drying model which included main and cross‐diffusion terms to predict saturation behavior in the polymer solution during the drying process. The model without the cross‐diffusion terms represents the ideal system in which the diffusion of one component does not affect the diffusion of others. The drying model did not predict supersaturation of nitrogen when cross‐diffusion terms were neglected. Supersaturation of nitrogen was predicted, however, when the cross‐diffusion terms are included. Therefore, the cross‐diffusion terms in the mass transfer model are essential for the development of nitrogen supersaturation. Also different diffusion models based on the friction coefficients led to qualitatively similar predictions for the supersaturation of nitrogen. The simulation's results supported our experimental observations regarding bubble formation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

COMPUTER-AIDED ESTIMATION OF ACETONE, METHYL ACETATE, AND CHLOROFORM DIFFUSION COEFFICIENTS IN POLY(VINYL ACETATE)

The diffusion coefficients of acetone, methyl acetate, and chloroform in amorphous poly(vinyl acetate) are estimated using the solvent evaporation method. The evaporation process from polymer solutions, cast in the form of thin films, is studied as a numerical experiment. The process is modeled as a coupled heat and mass transfer problem with a moving boundary. Lattice fluid (LF) thermodynamics is used to describe polymer-solvent system volumetric properties and to derive appropriate expressions for solvents' chemical potentials. The resulting nonlinear system of governing equations is solved with the Galerkin finite element method. The estimated diffusion coefficients are in satisfactory agreement with reported data.     

Measurements and predictive modeling of water diffusion coefficients in bovine serum albumin/polymer blends for biosensors

The knowledge of mass transport parameters in polymer/protein blend films is of substantial interest for the preparation of glucose biosensor test strips where drying and rehydration need to be controlled. In this study, the diffusion of water in bovine serum albumin (BSA) and poly(vinylpyrrolidone) (PVP) films and blends of BSA with PVP and polyvinylalcohol is investigated and the applicability of predictive models for the diffusion coefficient in mixtures is explored. Water concentration profiles are measured with Raman spectroscopy during drying experiments under controlled conditions. Concentration‐dependent diffusion coefficients of water in the films are then determined by fitting simulated drying curves to measured data. Comparison of the resulting diffusion coefficients in the blends with a predictive logarithmic model shows good agreement. The application of such predictive models could greatly facilitate the development of polymer/protein blends in the future. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45368.     

Computer-aided estimation of acetone,methyl acetate,and chloroform diffusion coefficients in poly(vinyl acetate)

The diffusion coefficients of acetone, methyl acetate, and chloroform in amorphous poly(vinyl acetate) are estimated using the solvent evaporation method. The evaporation process from polymer solutions, cast in the form of thin films, is studied as a numerical experiment. The process is modeled as a coupled heat and mass transfer problem with a moving boundary. Lattice fluid (LF) thermodynamics is used to describe polymer-solvent system volumetric properties and to derive appropriate expressions for solvents' chemical potentials. The resulting nonlinear system of governing equations is solved with the Galerkin finite element method. The estimated diffusion coefficients are in satisfactory agreement with reported data.     

Coupling between mass diffusion and film temperature evolution in gravimetric experiments

In gravimetric experiments, the swelling and the drying of polymer films is used to investigate the thermodynamic properties and the mutual diffusion coefficient of polymer/solvent systems. Usually thermodynamic equilibrium at the interface between the film and the solvent vapor and thermal equilibrium between the film and the surroundings are assumed. In this paper we show that the second assumption may fail. Indeed, during a swelling or drying experiment, the temperature of the film surface changes due to the latent heat of vaporization, which induces a variation of the activity. When the corresponding variation of the solvent content is of the same order than the variation due to the sorption experiment and when the thermal time constant is significant compared to the characteristic mass diffusion time, this thermal effect must be taken into account when analyzing sorption data. We evaluate the consequence of this thermal effect on gravimetric experiments and develop a complete model to take this phenomenon into account when analyzing sorption data. As an example, the mutual diffusion coefficient for the system PIB (polyisobutylene)/toluene is estimated for various solvent concentrations at 25 °C.     

DRYING OF POLYMER SOLUTION

Drying process of polymer solution,which i s carryed out industrially by three shapes of the drying material,is investigated comprehensively. The three shapes are slab as various polymer films by film casting dryer, cylinder as various synthetic. fibers by solution spinning and sphere (drop) as particle or povder of various food materials and polymers by spray drying. These are analysed basically in common manner by silnul tanews solution of diffusion equations and heat balance equations with activity and concentration dependent diffusion coefficient of polymer-solvent system. The conceptions concerning the     

Prediction of diffusion in a ternary solvent–solvent–polymer blend by means of binary diffusion data: Comparison of experimental data and simulative results

Multicomponent diffusion of solvents in polymeric systems is not completely understood, despite many scientific contributions to the topic. Literature scarcely offers measurement data on diffusion for model validation in such systems. In this work, the ternary systems consisting of poly(vinyl acetate) and the solvents toluene and methanol was investigated experimentally and numerically. By means of inverse micro Raman spectroscopy (IMRS) concentration gradients in drying thin films have been measured. Initial composition of the samples has been varied systematically in order to detect mutual influence of the solvents' diffusive behavior. It was shown that the mobility of the different species is increased in the presence of other solvents as predicted by theory. This experimental data is provided for model validation. A new expression to calculate the diffusion coefficients in ternary mixtures is proposed which only requires binary data. This expression is tested by means of a model‐based simulation to predict the drying of ternary polymer solutions in terms of concentration profiles and residual solvent content. The results are in very good agreement with the experiments. Cross terms diffusion coefficients and thermodynamic factors were not found to be necessary for a satisfying prediction. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43899.     

DRYING OF POLYMER SOLUTION

ABSTRACT

Drying process of polymer solution,which i s carryed out industrially by three shapes of the drying material,is investigated comprehensively. The three shapes are slab as various polymer films by film casting dryer, cylinder as various synthetic. fibers by solution spinning and sphere (drop) as particle or povder of various food materials and polymers by spray drying. These are analysed basically in common manner by silnul tanews solution of diffusion equations and heat balance equations with activity and concentration dependent diffusion coefficient of polymer-solvent system. The conceptions concerning the     

Drying of glassy polymer varnishes: A quartz resonator study

We report on desorption measurements on polymeric thin films coated onto quartz crystal resonators. Due to the high sensitivity of quartz crystal microbalances, the experiments can be performed on very thin films, which have small diffusion time constants even in the glassy state. When drying is performed slowly enough, diffusion equilibrium can be maintained through the whole process of desorption, including the glassy domain. From these quasi-stationary pressure ramps, we derived the solvent chemical potential as a function of polymer volume fraction μ(ϕ). The results fit well to a model recently proposed by Leibler and Sekimoto.¹ In addition, we have derived the mutual diffusion coefficient D(ϕ) from pressure step experiments. We observe a strong decrease of D(ϕ) for high polymer concentrations typical of hypodiffusive systems like polymers. We investigated the drying of an industrial varnish that is a blend of 2 copolymers as well as the drying of its components separately. Both the solvent chemical potential μ(ϕ) and the mutual diffusion coefficient D(ϕ) of the blend interpolate between the respective quantities of the components. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2235–2246, 1998