Natural durability and physical properties of particleboard composed of white cypress pine and radiata pine

Phenol-formaldehyde-bonded particleboard was manufactured from blends of non-durable radiata pine (P. radiata) and heartwood of the naturally durable species, white cypress pine (C. glaucophylla). Board specimens were subjected to bioassays using two termite species, M. darwiniensis and C. acinaciformis, and the basidiomycete fungi C. puteana and P. ostreatus, and the durability of specimens was compared with that of commercially manufactured particleboard specimens containing either insecticide or fungicide. Measurements of the physical properties of specimens were also made. The aims were to determine whether the natural durability or physical properties of the boards were modified by the addition of cypress pine and if the durability of boards was comparable to that of boards containing insecticide or fungicide. Particleboard specimens containing cypress pine showed increased durability compared to specimens consisting entirely of radiata pine. There was an inverse relationship between the percentage of cypress pine and mass losses of specimens during the bioassays. Cypress pine specimens, except those consisting entirely of cypress pine, were significantly less resistant to attack by C. acinaciformis than specimens containing insecticide. In contrast, the mass losses of specimens containing 25 percent or more of cypress pine during exposure to M. darwiniensis were not significantly different from those of specimens containing insecticide. Specimens containing 75 percent or more of cypress pine possessed similar decay resistance as specimens containing fungicide. There was an inverse relationship between the percentage of cypress pine and dry modulus of rupture (MOR) and internal bond strength, but specimens containing higher percentages of cypress pine showed less thickness selling and loss of MOR on immersion in water.

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