Treesearch

Three types of adhesives, urea-formaldehyde (UF) resin, phenol-formaldehyde (PF) resin, and polymeric methylene bis(phenyl isocyanate) (pMDI), were used for investigating the effect of pressing variables on volatile organic compound (VOC) emissions. The variables examined included press temperature and time, mat moisture content and resin content, and board density. The VOCs emitted during particleboard hot-pressing with Southern Pine furnish were collected with two scrubbers filled with water and methylene chloride, respectively. The water solution of emissions trapped in the first...

Alkyd-, oil-modified-latex-, and latex-based finishes were applied to severely weathered western redcedar and redwood boards that did not have any surface treatment to ameliorate the weathered surface prior to painting. Six finishes were evaluated annually for 11 years for cracking, flaking, erosion, mildew growth, discoloration, and general appearance. Low-solids- content latex finishes that contained about 10% raw linseed oil and 11% acrylic resin (i.e., the oil-modified latex finishes) performed better on badly weathered wood than did the alkyd and the other latex finish, even after 11...

Sustainable development has become the umbrella objective for forest management in many countries of the world, and managers are increasingly faced with the challenges of balancing environmental and economic health in their forest management and resource utilization decisions. It can no longer be assumed that abundant raw materials are available simply for the taking. As we enter the next century, a key question is where will we find the wood needed for shelter, fuel, transportation needs, and a host of other durable and nondurable goods? Wood will continue to be a staple of human society...

An experimental study was conducted to evaluate the residual shear capacity of large Douglas-fir timbers used in a military facility in Ardeen Hills, MN. A S-point and 4-point bending test was used to determine the effects of checks and splits on the shear strength capacity. Experimental results are compared to past shear and flexural studies.

This guide was prepared to assist inspectors in the use of stress wave timing instruments and the various methods of locating and defining areas of decay in timber bridge members. The first two sections provide (a) background information regarding conventional methods to locate and measure decay in timber bridges and (b) the principles of stress wave nondestructive testing and its measurement techniques. The last section is a detailed description of how to apply the field use of stress wave nondestructive testing methods. A sample field data acquisition form and additional reference...

Our understanding of the molecular architecture of intact, native plant cell walls is very limited. Traditional methods of investigation disturb the tissue to varying degrees and conclusions based on these methods may be intimately related to the technique used. A promising new technique to study native-state organization is polarized Raman spectroscopy. In this present work the macromolecular orientation and compositional variability for both cellulose and lignin in latewood cell walls of loblolly pine tracheids were investigated using Raman spectroscopy. This study has provided direct...

Fire safety is an important concern in all types of construction. The high level of national concern for fire safety is reflected in limitations and design requirements in building codes. These code requirements are discussed in the context of fire safety design and evaluation in the initial section of this chapter. Since basic data on fire behavior of wood products are needed to evaluate fire safety for wood construction, the second major section of this chapter covers fire performance characteristics of wood products. The chapter concludes with a discussion of flame-retardant treatments...

Glued structural members are manufactured in a variety of configurations. Structural composite lumber (SCL) products consist of small pieces of wood glued together into sizes common for solid-sawn lumber. Glued-laminated timber (glulam) is an engineered stress-rated product that consists of two or more layers of lumber in which the grain of all layers is oriented parallel to the length of the lumber. Glued structural members also include lumber that is glued to panel products, such as box beams and I- eams, and structural sandwich construction.

Our understanding of the diversity of native celluloses has been limited by the fact that studies of their structures have sought to establish ideal crystal lattice forms for the native state. Departures from ideal structures in the native state are viewed as defects in the ideal lattice. In most instances real celluloses have been regarded as departing from the ideal structures primarily with respect to the degree of disorder. The disorder is considered as imparting an amorphous character to part of the cellulose and methods are sought to quantify the bamorphousc fraction. In contrast,...

Hydrolysis of bordered and pinoid pits may be a key event during colonization of wood by decay fungi. Although pits are numerous, studies of pectin-hydrolyzing enzymes in wood decay fungi are scarce, probably because of the relatively low content (less than 4 %) of pectin in wood and because of the primary focus on understanding the degradation of lignified components. Endopolygalacturonase (endo- PG) activity was estimated by cup-plate assay and viscosity reduction of pectin from liquid cultures of fifteen brown-rot and eight white-rot basidiomycetous fungi using sodium polypectate as the...