טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentMironi-Harpaz Iris
SubjectComposite Systems Based on Thermosetting Polyesters and
Nano-Layered Clay Filler
DepartmentDepartment of Chemical Engineering
Supervisor Professor Emeritus Moshe Narkis


Abstract

Polymer nanocomposites comprising extremely low clay contents exhibit significantly enhanced properties when compared to neat polymers or conventional composites. Through this research, an understanding of the factors affecting the structuring processes involved in the formation of nanocomposite systems based on thermosetting unsaturated-polyester (UP) matrices and layered-silicates (clay) is proposed, and the materials-processing-structure-performance interrelations are established.

Studying of styrene-containing-UP/clay nanocomposites prepared by various mixing processes using several organically modified clay types shows that incorporation of some of these clay types results in high levels of intercalation, its extent depending mainly on the specific clay treatment. Introducing several clay types into styrene-free-UP through various mixing processes and durations was investigated. Inducing high shear levels for prolonged times on styrene-free-UP/octadecylamine (ODA) treated clay nanocomposites promotes the intercalation and exfoliation of the silicate layers. The high shear level effects are achieved by vigorous mechanical mixing and intensified by using large amounts of clay and appropriate matrix viscosity. A novel approach to intrinsically crosslinking of styrene-free-UP into a thermoset matrix in the presence of a free-radical-forming-initiator was established. Implementation of this approach on styrene-free-UP/clay systems results in the formation of thermoset nanocomposites. The final nanostructure of the thermoset nanocomposites is controlled by the initial processing conditions, peroxide concentration and catalyzing effect of the ODA treatment. When the silicate nanolayer separation level is high, it dominates the effects of clay content, peroxide content and plasticization by clay treatment in determining the thermoset nanocomposite’s properties. Thus, the right choice of materials and processing conditions allows tailoring of the UP/clay nanostructure, affecting the resulting nanocomposites’ performance.