The role of the epoxy resin : curing agent ratio on composite interfacial strength and thermal performance

This paper focuses on analyzing the interfacial and thermal properties of an epoxy resin glass fibre reinforced composite. The interface was studied using the microbond test to investigate interfacial shear strength values while thermo-mechanical analysis and differential scanning calorimetry were used to find variations in the glass transition temperature and coefficient of thermal expansion. For both, the role of the epoxy resin: curing agent ratio was studied to see if it influenced fibre-matrix adhesion and whether it had similar effects on thermal properties. It was found that the epoxy resin: curing agent ratio did indeed influence both interfacial and thermal properties, with maximum performance occurring around the stoichiometric point

The influence of hardener-to-epoxy ratio on the interfacial strength in glass fibre reinforced epoxy composites

This work seeks to develop a better understanding of the influence that the chemistry of an epoxy thermoset system has on the stress-transfer capability of the fibre-matrix interface. We discuss the correlation between the interfacial shear strength (IFSS) and the properties of the matrix such as glass transition temperature (Tg), storage modulus and linear coefficient of thermal expansion (LCTE). The results indicate that each is strongly dependent on the hardener-to-epoxy ratio and it was found that changes in IFSS can be related to changes in the thermomechanical properties of the matrix. From the results presented it is hypothesized that residual radial compressive stresses at the interface are influenced by the chemistry of the matrix system due to the changes in the properties of the matrix. The combination of these residual stresses with static friction may lead to a potential variation of the interfacial stress-transfer capability in glass-fibre reinforced epoxy composites

The influence of temperature and matrix chemistry on interfacial shear strength in glass fibre epoxy composites

The present work focuses on further investigating the influences of the chemistry of an epoxy system and the testing temperature on the stress-transfer capability of the fibre-matrix interface in a glass fibre-reinforced composite. We discuss how the apparent interfacial shear strength (IFSS) is influenced by the hardener-to-epoxy ratio and testing temperature. The results indicated that the IFSS was strongly dependent on both matrix chemistry and testing temperature. It was observed that the IFSS showed a significant inverse dependence on testing temperature, with IFSS dropping as the temperature was increased for all ratios. Notably it was shown that once the testing temperature was raised above the glass transition temperature (Tg) that ratios possessing excess hardener had larger IFSS values. From the results presented it is hypothesized that residual radial compressive stresses at the interface are influenced by the chemistry of the matrix system and relax away at the higher testing temperatures

The dependence of interfacial shear strength on temperature and matrix chemistry in glass fibre epoxy composites

The present work focuses on a fundamental investigation into the influences of the chemistry of epoxy and the testing temperature on the stress-transfer capability of the fibre-matrix interface in a glass fibre reinforced epoxy composite. We discuss how the interfacial shear strength (IFSS) is influenced by the hardener-to-resin ratio, testing temperature and fibre silane coating respectively. It was observed that the IFSS showed a significant inverse dependence on testing temperature for both silanes, with IFSS values dropping as the temperature was increased, for all ratios studied. Notably, it was shown that once the testing temperature was raised above the glass transition temperature that ratios possessing excess amine hardener had larger IFSS values. From the results presented it is hypothesized that residual radial compressive stresses at the interface are influenced by the chemistry of the matrix system and then relax away at the higher testing temperatures

Are silanes the primary driver of interface strength in glass fibre composites? : exploring the relationship of the chemical and physical parameters which control composite interfacial strength

It is probably not an overstatement to say that organosilanes are the most important chemicals used in the glass fibre, and consequently the composites, industry. One of the best-known assertions about silanes is that they promote chemical bonding across the fibre-matrix interface. This concept was fixed in the collective consciousness of the composites community early in its history when developments were focussed strongly on reactive matrices. Indeed, the chemical bridging mindset is strongly entrenched in the interface research community and extends to most other fibre-matrix combinations. However, the development of thermoplastic matrix composites raises questions about the simplistic chemical bridging model of silanes at the interface. A growing number of researchers have also commented on residual stress contributing to the stress transfer capability at the fibre-matrix interface. We will review experimental data on the temperature dependence of the apparent interfacial shear strength (IFSS) in glass fibre-polypropylene and of glass fibre-epoxy composites. This phenomenon is characterised by a large drop in IFSS when the test temperature is raised above the matrix glass transition temperature. These results can be shown to support the hypothesis that the apparent IFSS in composites can be largely explained by residual thermal stresses in the syste

Interfacial Characterization of Natural Fique Fibre/Polypropylene Composites Using Single Fibre Fragmentation Test (SFFT)

The present work focuses on a comprehensive investigation into the fibre-matrix interface of fique fibre-reinforced polypropylene (PP) composites using the single fibre fragmentation test. The objective was to establish the degree of adhesion that exists between fique fibre and PP prior to subsequent surface treatment, which is targeted for a following study

Measurement of the Total Cross Section for the Reaction p + p → p + p + pio

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Siberian Snake and Depolarizing Resonance Studies at the Cooler Ring

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Cooler Target Development

This research was sponsored by the National Science Foundation Grant NSF PHY-931478