The impact behaviour of epoxy specimens containing 10% by volume of fly‐ash particles with their surface treated for improving or decreasing adhesion is studied. The resulting behavioural patterns are listed and compared to those of composites containing untreated fly‐ash particles and unreinforced (ie neat) epoxy. It was noticed that samples involving adhesion‐increasing (ie acetone and silane) treatments show greater absorption of energy and maximum load compared to untreated samples and those subjected to adhesion‐reducing treatments. Ductility index, however, showed a reversed trend with adhesion‐reducing treatment yielding the highest value. In contrast, the energy absorbed was highest for neat resin and lowest for oil surface bearing ash particulate composites. Scanning electron microscope examination of the failed samples was carried out to obtain information on the fracture features with the aim of correlating microstructure to impact response. Thus, the higher ductility indices cases are shown to be distinct and different from composites containing other surface treatments for fillers. © 2002 Society of Chemical Industry

The impact response of a varying fly ash bearing epoxy system was studied. It is observed that with the increase in filler volume fraction there is a net reduction in the impact strength, fracture area and time to maximum load. The Ductility Index of the system, on the other hand, shows an increase with filler level. From visual observations on the failed samples, analyses of the crack length, shift of crack and point at which the slope of the crack reaches 45°are made. The work clearly shows that a curvilinear path for the crack gives place to straighter ones as the ash content in the matrix increases. Consequently, the crack shift also gets reduced when filler particles are introduced in larger quantities into the resinous system. The SEM pictures unambiguously demonstrate how the initiation, propagation and termination regions have distinct appearances whose features vary with ash content, thereby demonstrating that ash particles do influence the crack at all stages, viz., from its development to final rupture of the test coupon due to impact. The work also throws light on the larger-sized particles playing a role in the furtherance of the crack progression. 

Aim:The aim of the present study was to investigate the effectiveness of the one total-etch self-priming adhesive, one two-step self-etching primer adhesive, and one 'all-in-one' selfetching adhesive system on the adhesion of a resin composite to enamel.