The resistance of wood chemically modified with isocyanates - Part 1. Brown rot, white rot and acid chlorite delignification

This study was to assess the bioprotectant performance of chemical modifica tion with three different isocyanates (n-butyl, hexyl and 1,6-diisocyanatoh exane, BuNCO, HeNCO and HDI respectively) in Corsican pine (Pinus nigra Sch neid) sapwood. Wood-isocyanate bond formation was verified by the increase in sample weight, volume and by infra-red spectroscopy. Basidiomycete (Coniophora puteana, Gloeophyllum trabeum, Coriolus versicolo r, Pycnoporus sanguineus) decay tests demonstrated protection by chemical m odification. The relationships of fungal species, weight percent gain (WPG) , and decay induced weight loss were examined. One of the brown rot fungi, C. puteana, showed higher threshold protection values than the other fungi tested and the diisocyanate showed better performance. Chemical characteristics of the sound and brown rotted wood (C. puteana) ha ve been examined using sulphuric acid and sodium chlorite procedures to cla rify the principles which govern isocyanate modifications and restrict fung al decay. These demonstrated that appreciable wood protection against C. pu teana only occurred when the holocellulose fraction showed substantial chan ges due to chemical modification.