Biological, Mechanical, and Thermal Properties of Compressed-Wood Polymer Composite (CWPC) Pretreated with Boric Acid

Compressed-wood polymer composite (CWPC) was prepared by in situ polymerization of vinyl monomers, styrene (ST), methylmethacrylate (MMA), and their combination (50:50, v/v) under hot-compression of treated sapwood of Japanese cedar (Cryptomeria japonica D. Don.) to a dry set of 50 and 70% of original radial dimension. Boric acid (BA) was impregnated into wood at 1.00% aqueous solution concentration prior to monomer treatment. CWPC with and without BA-pretreatment was tested in terms of biological resistance and mechanical and thermal properties.Boric acid pretreatment imparted CWPC total resistance against decay test fungi Tyromycespalustris and Coriolus versicolor, representing brown- and white-rot fungi, respectively. CWPC showed remarkable resistance against Formosan subterranean termite Coptotermes formosanus, and BA-pretreatment contributed to a total inactivation of termite activity. Surface hardness of CWPC was superior to wood polymer composite (WPC) obtained at the same polymerization temperature and time by a conventional heat process in an oven without compression. Modulus of elasticity and rupture were also considerably improved with this newly introduced in situ polymerization process, suggesting the great potential of CWPC for exterior use. Thermal analysis revealed a reducing effect of boron on heat release of CWPC during combustion

The Effect of Heat Treatment on the Pull-off Strength of Optionally Varnished Surfaces of Five Wood Materials

This study investigated the effects of heat treatment, following optional treatment with synthetic, water-based, and alkyd varnishes, on the pull-off strength of wooden materials sampled from oriental beech (Fagus orientalis L.), oak (Quercus petraea Liebl.), black poplar (Populus nigra L.), pine (Pinus sylvestris L.), and fir (Abies bornmulleriana M.). The test samples were subjected to heat treatment at temperatures of 165 °C and 175 °C for periods of 2 and 4 h with a total of 4 variations. With respect to the wood type, the samples of beech wood yielded the highest results for pull-off strength, while fir wood yielded the lowest. With respect to the varnish types, the highest pull-off strength was found in the samples of synthetic varnished beech (5,452 with a 37.2% improvement) at 175 °C heat treatment for 4 h, while the lowest results were obtained in the samples of fir (0.991 with a 48.5% decrease) at 175 °C heat treatment for 4 h. In conclusion, heat treatment significantly decreased the pull-off strength of the woods

The Effect of Heat Treatment on the Pull-off Strength of Optionally Varnished Surfaces of Five Wood Materials

This study investigated the effects of heat treatment, following optional treatment with synthetic, water-based, and alkyd varnishes, on the pull-off strength of wooden materials sampled from oriental beech (Fagus orientalis L.), oak (Quercus petraea Liebl.), black poplar (Populus nigra L.), pine (Pinus sylvestris L.), and fir (Abies bornmulleriana M.). The test samples were subjected to heat treatment at temperatures of 165 degrees C and 175 degrees C for periods of 2 and 4 h with a total of 4 variations. With respect to the wood type, the samples of beech wood yielded the highest results for pull-off strength, while fir wood yielded the lowest. With respect to the varnish types, the highest pull-off strength was found in the samples of synthetic varnished beech (5,452 with a 37.2\% improvement) at 175 degrees C heat treatment for 4 h, while the lowest results were obtained in the samples of fir (0.991 with a 48.5\% decrease) at 175 degrees C heat treatment for 4 h. In conclusion, heat treatment significantly decreased the pull-off strength of the woods