Analysis of wood polymer composites by two-stage pyrolysis–GC/MS

Wood polymer composites (WPC) of several wood types (spruce, beech), chemically modified wood (acetylated, propionated), and different polymers (polyethylene, polypropylene, polyvinylchloride, melamine resin) were prepared and analyzed by a two-stage pyrolysis process. Pyrolysis temperatures and times were varied to separate wood and polymer matrix and obtain at first a chromatogram only of the woody material and in the second stage a profile of the synthetic polymer. Using this two-stage approach simplifies the chromatograms compared to a single high temperature pyrolysis and thus makes identification of components easy. Optimum conditions for polyolefins were found to be a prepyrolysis step at 550 °C, 10 s followed by pyrolysis at 700 °C, 10 s, which also worked very well for all other polymers. The method was successfully applied to elucidate the composition of five commercial WPCs.