The use of FTIR mapping to assess phase distribution in mixed and recycled WEEE plastics

Attenuated total internal reflection FTIR mapping was used to examine the coarse microscopic two-phase structure seen with some blended and recycled polymers. The blends studied were virgin and recycled ABS, HIPS and polycarbonate, typical of waste electrical and electronic plastics. The method was compared to optical microscopy both before and after etching with chromic acid. It was found that while optical microscopy showed up phase separation on a scale of tens of microns, the FTIR mapping allowed compositional details to be investigated. The phase structure could be quantified by using the standard deviation of band ratios and this correlated well with mechanical performance. The effects of processing method were more significant than whether material was recycled or not. Longer, less intensive processing produced more phase separation than shorter more intensive processing.