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Polymer Diffusion (polymer + diffusion)
Selected AbstractsLiquid-Glassy Polymer Diffusion: Effects of Liquid Molecular Weight and TemperatureMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 10 2007J. Pablo Tomba Abstract We examine mechanistic aspects of the diffusion between a series of liquid polystyrenes (PS) and a glassy poly(phenylene oxide) (PPO) matrix, through the use of confocal Raman microspectroscopy. The results show that the diffusion kinetics has Fickean characteristics, similar to those found in liquid-liquid polymer diffusion. No signatures of the linear regime typical of the case-II diffusion mechanism were found. Overall, these observations are consistent with the claim that case-II is unlikely to occur in liquid-glassy polymer diffusion. [source] Synthesis of an alkali-swellable emulsion and its effect on the rate of polymer diffusion in poly(vinyl acetate-butyl acrylate) latex filmsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2005Jung Kwon Oh Abstract We describe the synthesis and characterization of a weakly cross-linked poly(methacrylic acid- co -ethyl acrylate) alkali-swellable emulsion (ASE), as well as an investigation of its influence on the rate of polymer diffusion in latex films. The films examined were formed from poly(vinyl acetate- co -butyl acrylate) latex particles containing a small amount of acrylic acid as a comonomer. Polymer diffusion rates were monitored by the energy transfer technique. We found that the presence of the ASE component, either in the acid form or fully neutralized by ammonia or sodium hydroxide, had very little effect on the polymer diffusion rate. However, in the presence of 2 wt % NH4 -ASE, there was a small but significant increase in the polymer diffusion rate. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5632,5642, 2005 [source] Epoxy-functionalized, low-glass-transition-temperature latex.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2002Abstract This article describes the results of experiments examining the competition between the polymer diffusion rate and the crosslinking rate in low-glass-transition-temperature, epoxy-containing latex films in the presence of a diamine. We examined films formed from donor- and acceptor-labeled poly(butyl acrylate- co -methyl methacrylate- co -glycidyl methacrylate) copolymer latex and studied the influence of several parameters on the growth rate of gel content and the rate of polymer diffusion. These factors include the molecular weight of the latex polymer, the presence or absence of a diamine crosslinking agent, and the cure protocol. The results were compared to the predictions of a recent theory of the competition between crosslinking and polymer diffusion across interfaces. In the initially formed films, polymer diffusion occurs more rapidly than the chemical reaction rate. Therefore, these films fall into the fast-diffusion category of this model. In our system (unlike in the model), the latex polymer has a broad distribution of molecular weights and a distribution of diffusivities. The shortest chains contribute to the early time diffusion that we measure. At later stages of our experiment, slower diffusing species contribute to the signal that we measure. The diffusion time decreases substantially, and we observe a crossover to a regime in which the chemical reaction dominates. The increases in chain branching and gel formation bring polymer diffusion to a halt. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4098,4116, 2002 [source] Liquid-Glassy Polymer Diffusion: Effects of Liquid Molecular Weight and TemperatureMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 10 2007J. Pablo Tomba Abstract We examine mechanistic aspects of the diffusion between a series of liquid polystyrenes (PS) and a glassy poly(phenylene oxide) (PPO) matrix, through the use of confocal Raman microspectroscopy. The results show that the diffusion kinetics has Fickean characteristics, similar to those found in liquid-liquid polymer diffusion. No signatures of the linear regime typical of the case-II diffusion mechanism were found. Overall, these observations are consistent with the claim that case-II is unlikely to occur in liquid-glassy polymer diffusion. [source] Diffusion Kinetics at Liquid-Glassy Polymer InterphasesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 8 2005Luis Arzondo Abstract Summary: We explored the diffusion mechanisms in a series of liquid/glassy polymer interphases. The diffusion experiments were performed in a unique way: the temperature range studied encompassed the glass transition temperature (Tg) of the glassy matrices. We observed that the diffusion behavior of the liquid polymer was remarkably continuous when passing through the matrix Tg, and that the diffusion modes at the liquid/glassy interphases were very similar to those observed in liquid/liquid polymer diffusion. Diffusion profiles of liquid PS in glassy PPO obtained by confocal Raman spectroscopy. The sample was held at 160,°C for the times indicated in the plot. [source] | ||||||||||