Interactions observed during the pyrolysis of binary mixtures of textile polymers

The techniques of differential thermal analysis (DTA), thermogravimetry (TG), large scale pyrolysis (LSP) and hot-stage microscopy (HSM) have been used to determine the pyrolysis behaviour of three binary polymer systems: wool/Terylene, wool/Courtelle and Terylene/Courtelle. Pyrolysis was carried out in a flowing nitrogen atmosphere at a heating rate of approximately 10°C min^?1.Evidence from DTA and TG indicates that the thermal stability of the polyester fibre Terylene is reduced when pyrolysed in the presence of either wool or Courtelle. It is considered that this reduction in thermal stability is the result of chemical interactions between Terylene and degradation products arising from the breakdown of the second polymer present. Unexpectedly high residual yields (at 1213 K) have been observed from LSP experiments on the wool/Courtelle and Terylene/Courtelle systems.HSM observations for these two systems indicate the formation of a coating of the fusing polymer around the non-fusing polymer during pyrolysis. TG studies indicate that this coating of fused polymer may be effective in retaining volatile degradation products from the non-fusing polymer within the solid residue. The eventual chemical bonding of these degradation products into the solid residue thus accounts for the unexpectedly high yields of solid residue observed by LSP.