Abstract
dc:description.abstractThe effect of water absorption in epoxide adhesives, both in bulk and joint forms, was examined. Boiling-water immersion was found to be a suitable technique to accelerate water diffusion in bulk epoxides. The boiling-water diffusion was found to be Fickian in epoxides except for the DOM system’, water-vapour diffusion at 25°C was found to be Fickian. To study accurately the effect of water absorption (liquid and vapour) on the mechanical properties of bulk epoxides, a new method of specimen preparation was developed. Water absorption in epoxides was found to involve two processes, namely plasticization and cross linking; the predominant effect depends on the particular system. Water absorption in epoxides was found to seriously depress the glass transition temperature (Tg), which explains the reason for the deterioration in the mechanical properties. A manual torsional pendulum was used to measure the Tg values. In a later stage, an automatic torsional pendulum was constructed to obtain accurate and reproducible results. The effect of water on the mechanical and thermal properties was found to be reversible, suggesting plasticisation was involved and not hydrolysis of chemical bonds. Exposing epoxide-clad aluminium joints to high humidity (100% R.H. at 50°C), caused degradation in joint strengths. From theoretical analysis of fractional water concentration in joints and the observed failure modes of joints, the mechanism of strength loss is believed to be related to the water plasticization of the adhesive. However, above a critical water concentration, interfacial degradation due to water accumulation induces further strength loss.
Degree
thesis:*- Name dc:type.qualificationname
- PhD
- Level dc:type.qualificationlevel
- Doctoral
- Grantor dc:publisher.institution
- De Montfort University
- Year dc:date.issued
- 1979
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- SHALASH, RIADTH JASIM ABBAS