The activation of wood fibre for thermoplastic coupling, the reaction of wood with a potential coupling agent

The reaction of pinus sylvestris with an unsaturated aliphatic isocyanate, TMI, was studied. Using six different solvent/swelling systems, the weight percent gains (WPG) of solid wood blocks was investigated. TMI was found to react readily with wood and WPG's of up to 74% were recorded. The modification of the wood improved the dimensional stability, with high anti shrink efficiency (ASE) values up to 90% and low weight losses recorded over two 7 day water soak cycles. This evidence strongly suggests modification of cell wall polymers. The reacted blocks were characterised by FT-IR and the spectra showed good evidence of a reaction between the -NCO and wood -OH with the introduction of a carbonyl group at 1710-1720 cm-1. There was no evidence of polymerisation of TMI, indeed the spectra indicated the continued presence of C=C, possibly 1,1 disubstituted ethylene functionality. The activation energy of the reaction was determined by measuring the WPG at 4 temperatures. This was found to be 54 kJ/mol., comparable to that of butyl-NCO with wood.