Date of Graduation
Statler College of Engineering and Mineral Resources
Chemical and Biomedical Engineering
Rakesh K. Gupta.
It is well known that layered silicate nanoparticles, when distributed within the matrix of a polymer, can retard the diffusion of small molecules and improve barrier properties. This has been demonstrated in both sorption and permeation experiments in the past. In order to assess the long-term retention of barrier properties of polymer-layered silicate nanocomposites, it becomes important to study their response to various environmental effects.;The main theme of this investigation is to study the effect of several water exposure cycles and exposure coupled with external tensile stress on the barrier properties of various polymers like vinyl ester, polyester and epoxy and their polymer-based nanocomposites. As expected, Montmorillonite clay decreased the diffusivity of moisture in the above polymers and retained its effect during the repeated cycles of sorption and desorption. However, in the presence of clay (5 wt%), diffusivities measured during absorption under external stress were larger than those without stress. SEM analysis on the 5 wt% clay loaded vinyl ester samples subjected to stress-coupled sorption revealed the presence of micro cracks which caused increase in diffusivities.
Burla, Suneetha, "Barrier properties of polymer nanocomposites during cyclic sorption-desorption and stress-coupled sorption experiments" (2006). Graduate Theses, Dissertations, and Problem Reports. 1696.