[Chemical degradation of 15 composites--an SEM study]

SEM-micrographs of 15 untreated composites that were laid in 96% ethanol were investigated. The surface of untreated samples show different fissures and cracks. Under the influence of alcohol the fissures become wider, the bond between fillers and unfilled resin enlarges, and the filling particles become prominent or fall out. Fine-grained hybrid composites with an unfilled resin densely compacted with microfillers, are least prone to degradation.