Degree Type

Dissertation

Date of Award

2013

Degree Name

Doctor of Philosophy

Department

Materials Science and Engineering

First Advisor

Michael R. Kessler

Abstract

A novel bio-renewable thermoset which is synthesized from modified linseed oil (Dilullin) and dicyclopentadiene (DCPD) through ring opening metathesis polymerization (ROMP) method has been characterized and further developed. The fracture toughness of the Dilulin/DCPD copolymer system has been evaluated by essential work of fracture (EWF). Dynamic mechanical analysis (DMA) and scanning electron microcopy (SEM) examinations both demonstrated a reaction-induced phase separation in the copolymers. The correlation between fracture toughness and microphase morphology has been analyzed.

Interfacial adhesion of glass fiber reinforced Dil30DCPD70 (containing 30% Dilulin in weight) composites has been improved with two types of silane coupling agents, monochlorosilane (MCS) and trichlorosilane (TCS). The interfacial shear strength which is evaluated by microbond technique shows significant increases with both silanes. All characterizations of composites made with silane-treated fibers indicate the interfacial adhesion was improved significantly and MCS worked better than TCS due to the simple and reproducible grafting mechanism.

The Dil30DCPD70 copolymer has been applied in pultrusion process for manufacturing glass fiber reinforced composites. A table-top pultrusion machine was built for running those experiments. The resin formulation with the optimum percentage of lubricant and clay and pultrusion processing parameters were investigated based on processing performance. MCS silane was used to modify glass fiber with a simple dipping method. The influences of silane concentration were examined. The optimized silane concentration is 3% and the resulting composites show best results in all characterizations.

The short-term stability of Dil30DCPD70 under UV radiation has been studied with accelerated aging. Time-dependent degradation and surface confined effect have been confirmed by Photoacoustic FTIR and SEM measurements. The presence of unreacted carbon-carbon double bonds after cure is responsible for the relatively fast degradation effect.

Copyright Owner

Hongyu Cui

Language

en

File Format

application/pdf

File Size

126 pages

Share

COinS