[Unconverted double bonds and interface phenomena in composite materials]

Analysis of the interfaces and contact surfaces of polymerized composites by infrared spectroscopy showed the amount of unconverted double bonds to be 29% to 48%. This conversion is limited to a surface layer of about 20 microns thickness and usually does not reveal any information on the quality of the bulk material. In depths of more than 60 microns, the amount of unconverted double bonds was 18% to 32%. An influence of polishing could not be proved. Samples containing more than 35% of unconverted double bonds tend to be highly susceptible to discoloration. Removing those layers improves color stability.