Publications Details
The use of neutron reflectivity to study degradative processes at an epoxy/solid interface
Neutron reflection is used to examine the structure of an epoxy near an interface. Variations in both the density and the crosslink density within the interphase region are examined. The density is increased near the interface relative to that in the bulk of the film, but the crosslink density over the same region is reduced relative to that in the bulk of the film. These observations are interpreted via packing of the resin oligamers next to the wall, which leads to an increased density and also inhibits the crosslinking reaction. The effect is more pronounced the more slowly the resin is cured. Significant variations in reflectivity are observed with thermal cycling, which indicate an increase in the size of the interfacial layer of excess toluene. However, data for samples with greater number of thermal cycles are required to determine the relation of this effect to the fracture process.