MICRODISTRIBUTION AND RETENTION OF CHLOROPICRIN IN WOOD (DOUGLAS-FIR).

摘要

Quantitative and qualitative information on the retention of chlorinated residues in chloropicrin treated wood is lacking. Retention of chloropicrin and its chemical breakdown products in wood, and the effects of chloropicrin treatment of wood on invading decay fungi are explored in this thesis.; Chlorinated residues in amounts up to 1.5% (w/w, as determined by neutron activation analysis) were present in Douglas-fir wood exposed to chloropicrin vapors for 240 days. These residues could not be totally removed by aeration, acetone extraction, heating, or high vacuum treatment. Lesser amounts of chlorinated residues were detected in wood exposed to chloropicrin for shorter periods of time or treated with smaller quantities of the chemical. Analysis of vapors desorbed from chloropicrin-treated wood suggests that chemically unaltered chloropicrin can be retained by wood up to 4 years after treatment. Decreased retention of chlorinated residues in treated wood with brown rot decay suggests that hydrogen bonding and van der Waals forces are responsible, at least in part, for this retention.; Wood does not swell when treated with chloropicrin. Although a monomolecular layer of chloropicrin may hydrogen bond to wood at some sites, lack of swelling indicates that chloropicrin molecules are retained by forces weaker than the hydrogen bonds which hold the lignocellulose matrix of wood together.; Covalent linkages may also form between chloropicrin, or chlorinated breakdown products of chloropicrin, and wood. Energy dispersive X-ray analysis showed that chloropicrin residues were present in greater concentrations in areas of the wood rich in lignin or extractives. Covalent linkages between chloropicrin breakdown products and vanillin were detected in mass spectrographic analyses of chloropicrin/vanillin mixtures. Thin layer chromatography of extracts from chloropicrin treated wood indicated that chloropicrin may be bonding to dihydroquercetin (a phenolic wood extractive) and to other extractives in wood.; Microscopic observation of Douglas-fir wood exposed under severe laboratory decay conditions to Poria carbonica (a brown rot fungus), and to Ganoderma applanatum (a white rot fungus), showed that these fungi will attack chloropicrin treated wood, producing bore holes and erosion of cell lumen surfaces similar to that observed in untreated wood. Lysis and vacuolation of the fungal hyphae, particularly of G. applanatum, indicates that chloropicrin has an inhibitory effect on fungi in wood.