Treesearch

Cone calorimeter tests show that backing board materials do not affect the ignition time, initial heat release rate, or the total heat released of combustion for redwood slabs. However, it has been observed that backing board materials alter combustion performance by altering the secondary heat release peak observed when the pyrolysis reaction front nears the unheated side of the wooden slab. This occurs because the presence of backing board materials provides different boundary conditions on the unheated side of the wooden slab. In this paper, a detailed pyrolysis model is used to examine...

Lignins are complex natural polymers resulting from oxidative coupling of, primarily, 4-hydroxyphenylpropanoids. An understanding of their nature is evolving as a result of detailed structural studies, recently aided by the availability of lignin-biosynthetic-pathway mutants and transgenics. The currently accepted theory is that the lignin polymer is formed by combinatorial-like phenolic coupling reactions, via radicals generated by peroxidase-H2O2, under simple chemical control where monolignols react endwise with the growing polymer. As a result, the actual structure of the lignin...

In terms of fibre development in mechanical pulping, most of the energy is spent on the creation of specific surface area. The total surface area created can be divided into two categories: surface area that adds to the unbonded area (optical properties) and surface area that adds to the bonded area (strength properties) of mechanical papers. This paper considers these two types of physical characteristics developed during grinding of Populus species wood. Wood fibre characteristics are used to explain the variation of the development of bonded and unbonded areas. It is shown that the...

High moisture content, flat sawn Japanese cedar (Cryptomeria japonica D. Don) veneer was compressed using a roller press to mechanically remove water. The amount of water removed depended on the amount of compression applied. At 60% compression, 400 kg/m3 of water was removed. The process was not dependent on the size of the wood, the degree of compression, or the feed speed of the specimen. After compression, the remaining water contents were evenly distributed throughout the veneer regardless of the length of the specimen. The specimens did not completely recover to original thickness....

A key to 17 species in the genus Hygrocybe, subgenus Pseudohygrocybe, sections Coccineae and Neohygrocybe sensu Boertmann is provided for the Greater Antilles. Five new species and five taxa that are new reports for the region are described. The new species in section Coccineae are H. pseudoadonis, H. viridiphylla, and H. zonata. The new species in section Neohygrocybe are H. albomarginata and H. ovinoides. The new reports are H. caespitosa, H. coccinea, H. cf. miniata, H. papillata, and H. subovina. Three new combinations are proposed : Hygrocybe mycenoides, H. papillata and H. subovina.

Oriented strandboard (OSB) has gained increased market acceptance as a construction material in almost all geographical areas of Canada and United States. With its growing market, more and more research has been focused on the product’s manufacturing and performance. Commercial OSB products in U.S. and Canada are produced from different manufacturers with different process techniques, which result in different physical properties. The common physical and mechanical properties of OSB include MOR/MOE, Internal Bond (IB), Density and Thickness Swell (TS). A comparative study was conducted to...

Light-induced yellowing has been studied using side-chain ([alpha], [beta], and [gamma]) 13C-enriched DHP (dehydrogenation polymer) and quantitative solution state 13C NMR spectroscopy. The DHP was formed from 13C-enriched coniferin using an enzymatic system consisting of [beta]-glucosidase, glucose oxidase, and peroxidase in a pH 6 buffer solution. The DHP was applied to filter paper, irradiated with UV/VIS light and the photodegraded DHP was extracted and analyzed. The NMR study revealed a drastic decrease in the amount of coniferyl alcohol end groups with the formation of end groups of...

This report describes the results of long-term outdoor exposure on durability of hardwood plywood and the service life of various finishes. Smooth (abrasive-planed) and rough (saw-textured) yellow-poplar (Liriodendron tulipifera L.) and sweetgum (Liquidambar styraciflua L.) plywood panelswere exposed outdoors for 16 years near Madison, Wisconsin. The performance of several finishes was evaluated over a 12-year period, and the panels were evaluated for decay after 16 years. Oil or latex semitransparent stain provided less than 5 years of service life. Nevertheless, the wood showed only...

The intent was to take a "snapshot" census of the mushrooms and other fungi fruiting in Great Smoky Mountains National Park over a short period (July 12-14/2004), and to augment the fungi records for the ATBI.

The objective of this research was to improve the fire-retardant properties of wood in one treatment using a phosphorus pentoxide–amine system. Phosphorus pentoxide and 16 amines including alkyl, halophenyl, and phenyl amines were compounded in N,N-dimethylformamide and the resulting solutions containing phosphoramides were reacted with wood. The characteristics of phosphoramide-reacted wood were analyzed by FTIR, energy-dispersive X-ray analysis, and elemental analysis. Fire retardancy of phosphoramide-reacted woods was evaluated by DSC and thermogravimetric analysis (TGA). DSC demonstrate...