Termite resistance

In the list of homeowners problems, termites rate ranks very high. According to the Boston Globe, which in turn refers to Bay Colony Home Inspections, between 20 and 25% of the homes sold in most areas of New England have termites or have had them in the past. Toward the South of the United States problem is higher. And, of course, termites not just live around the house. In many cases, termites eat as much as 80% and more of all the structural components of a house, including its deck, if it has one. According to Home Inspection data, in 70% of the above cases the termites have been treated and returned. 

There are several main types of termites. Some of them require elevated moisture content, such as dampwood termites (Fig. 1.37). Some live deep inside wood, such as drywood termites (Fig. 1.38). Some live in colonies in the ground and build tunnels, using wood as their food (Fig. 1.39). These pictures were provided with permission by Specialty Termite, Inc. (Pleasanton, CA). 

WPC materials are commonly very resistant to termites. Despite that wood fibers are not completely—as a rule—encapsulated into the plastic matrix, and form a sort of continuing chains across WPC materials (unless the ratio of plastic to fiber is really high, more than 80%), termites cannot get into the plastic matrix. At best, termites can only slightly trim cellulose fiber at the WPC surface. 

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Kumar and Agarwal (1983) modified wood with thioacetic acid in the vapour phase, which results in hydrogen sulphide being generated as the by-product. The decay and termite resistance of the wood was determined. The thioacetic acid modified wood exhibited... 

Imamura, Y. Nishimoto, K., Yoshida, Y., Kawai, S., Sato, T. and Nakaji, M. (1986). Production technology for acetylated low-density particleboard II. Decay and termite resistance. Wood... 

Yusuf, S., Takahashi, M. and Imamura, Y. (1989). Particleboard from acetylated albizzia particles. III. Enhancement of decay resistance, termite resistance, and weathering properties through acetylation. Mokuzai Gakkaishi, 35(7), 633-639. 

The use of PVC wood, which includes PVC foam and PVC/wood flour composite, as an alternative to wood and wood-like products is discussed. Compared with traditional products, the PVC wood is shown to exhibit improved termite resistance and weathering resistance, lower moisture absorption and ease of installation. It is demonstrated that PVC wood can be nailed, screwed, sawed, cut and bonded like wood by conventional tools without any special skills being required. The bending strength of PVC wood is lower, but it can still be used for... 

The decay resistance of FA-treated wood to a white-rot fungus Coriolus versicolor) is remarkable, but not to a brown-rot fungus (Tyromycespalustris) (33). Meanwhile, the termite resistance is enhanced regardless of wood species and the method of treatment (33). 

It is well known that acetylation results in an increase of density as well as an improvement of dimensional stability and decay resistance [1,2,50]. Also, termite resistance [48,50], electric insulation [50,52], and acoustic properties [50,53] are improved. ASE effectiveness caused by acetylation is due mainly to chemical blocking of the hydroxyl groups [2]. 

The molecular weight of PF resin affected termite resistance less clearly than decay resistance, but resins with up to 621 Mn gave better termite resistance than larger molecular weight resins. Although total elimination of termite attack was not achieved by any PF resin treatment, activities of termites fed on the treated wood declined at a greater rate than that of starved termites. At 10% of WPG, all treated blocks caused a 100% mortality of termites after 6 or 7 weeks feeding. 

Here are few examples of termite resistance ratings, showed in the respective company records ... 

One can see that commercial WPG deck boards are dramatically more termite resistant than wood lumber. 

Termite resistance, 33 Termites, 33 Dampwood, 33 Drywood, 33 Subterranean, 33 Terpenes, 75, 94 Terpolymer, 80... 

A number of bisnaphthoquinones from the genera and Diospyros (Ebenaceae) (Fig. 6.6) have antifungal, antibacterial, and termite-resistant properties. Scrapings of wood are used in African folk medicine for the treatment of leprosy, and the ichthyotoxic properties of the bark of some species are used for capture of fish. One of these compounds, diosindigo A (53), is blue and responsible for the blue color of the heartwood of some Diospyros species (Fig. 6.6) (Leistner, 1985). 

Termite resistance test - weight loss (%) (ASTM D 3345) <1.5... 

M. Deka, C.N. Saikia, and K. K. Baruah, Studies on thermal degradation and termite resistant properties of chemically modified wood. Bioresour. Technol. 84,151-157 (2002). 

The natural resins present in native guayule have been extensively studied and include mono-, sesqui-, di-, and triterpene groups, as well as other secondary metabolites (108). Unfractionated guayule resin has shown considerable promise in the areas of wood preservation (in marine and terrestrial environments) (129) and insect antifeedents (termite resistance) (130-132). These resins also show promise as a biobased renewable replacement for petroleum-based monomers and oligomers in adhesives and coatings. Additional profitable uses for the resins include a natural, low toxicity replacement for creosote in wood treatment and for prevention of termite attack. Resin/lignin products, such as additives for phenol formaldehyde resins, may also prove possible. 

Sandermann W, Dietrichs H H 1957 Investigations on termite-resistant wood. Holz Roh-Werkst 15 281-297... 

Wolcott G N 1951 The termite resistance of pinosylvin and other new insecticides. J Econ En-tomol 44 263-264... 

To develop wood with high function and remarkable properties such as dimensional stability, termite resistance, anti-microbial property, photostabihty and fire-resistance, we have tried to prepare inorganic composites ofwood without losing characteristic properties of the wood as seen in its porous structure. In spite ofthe same inorganic substances used, the observed properties are different if inorganic substances are distributed differently in the wood cells. 

Williams, R.M.C. (1973). Evaluation of field and laboratory methods for testing termite resistance of timber and building materials in Ghana, with relative biological studies. Tropical Test Bull. 3. Center for Overseas Pest Research, London, pp 8-64. 

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