Treesearch

As part of an effort to ensure that treated wood products have minimal environmental and handling concerns, an American Wood Preservers Association task force is considering the development of a test to assess the degree of fixation of Waterborne wood preservatives. The proposed test involves removal and leaching of increment cores. This paper describes a laboratory study to determine how parameters such as extraction time, water volume, water temperature; depth of assay zone, and between sample variability might affect the results of such a test for chromated copper arsenate (CCA) treated...

One end of each piece of brick molding (about 35 mm long) was dipped in a water-repellent preservative (WRP). Following the WRP treatment, the sections were divided into two groups and painted with one of two different primers formulated to be typical of factory-applied primers. Each of the primed groups was further divided into four groups to determine the effect of primer weathering on paint service Iife. The primed moldings were exposed without a top coat for about 0,3,6, or 9 months 15 km west of Madison, Wisconsin. Alkyd-oil or acrylic-latex top coats were field-applied and the...

Heat sterilization of wood in various forms is currently receiving attention as a means of killing insects or pathogens to prevent their transfer from one region of the world to another in trade. One concern is the amount of time required to heat wood of various cross-sectional sizes and configurations to a temperature that will kill the insects or pathogens. Estimation of heating time depends on many variables. One estimation method uses heat conduction equations. This report reviews heat conduction equations for round and rectangular cross sections of wood and their validity through...

This paper outlines a methodology to obtain design values for indoor boundary conditions for moisture design calculations for residences. This is part of a larger effort by ASHRAE Standard Project Committee 160P, Design Criteria for Moisture Control in Buildings, to formulate criteria for moisture design loads, analysis techniques, and material and building performance. The standard is being developed to provide a consistent framework for moisture analysis and design. The assumptions for boundary conditions can have a large influence on the results of the moisture design analysis of a...

The Federal Highway Administration (FHWA) set up a validation test to compare the effectiveness of various nondestructive inspection techniques for detecting artificial defects in glulam members. The validation test consisted of a glulam beam fabricated with artificial defects known to FHWA personnel but not originally known to the scientists performing the validation tests. Ultrasonic inspection was effective for identifying voids within the glulam beam. The glulam was inspected across the width and through the depth. The inspections from each direction were combined to accurately detect...

The U.S. has historically been a net importer of wood and paper products. During the 1990’s, the U.S. trade deficit widened, implying an increasing U.S. impact on timber harvests in foreign supply regions. An analysis was made of historical and projected trends in U.S. consumption and trade in terms of the roundwood volume required to make products consumed and traded. Results show that historically, the U.S. has increased its net imports and that the estimated harvest of roundwood overseas to make imports to the U.S. has increased faster than the estimated reductions in overseas harvest...

Computational chemistry methods can be used to explore the theoretical chemistry behind reactive systems, to compare the relative chemical reactivity of different systems, and, by extension, to predict the reactivity of new systems. Ongoing research has focused on the reactivity of a wide variety of phenolic compounds with formaldehyde using semi-empirical and ab initio computational chemistry methods. This research has been expanded to study theoretical transition states formed on reacting phenol with formaldehyde. According to transition state theory, the energy of a transition state is...

The Draft RPA Timber Assessment projects, over the next 50 years, the likelihood of increasing abundance of softwoods in the South and decreasing abundance of hardwoods in the South. These trends in supply, along with projected contributions from the North and West, imply U.S. consumption needs could be met without increasing net product imports and would not increase softwood timber prices over the next 50 years. However, under this scenario, the adequacy of timber supplies depends on 1) continued expansion of softwood plantations with increased management intensity in the South, 2)...

Increased use of pressure sensitive adhesives for labels and stamps has introduced another contaminant into the office paper stream: silicone- coated release liners. This study examines methods and conditions for removal of contaminants, including these liners, from a typical batch of discarded office papers. Removal of contaminants contained in the furnish were compared using alkaline and near neutral pH repulping conditions. Residual contaminants were measured by image analysis, and the number and size of the contaminants were compared on handsheets that were prepared from samples...

Phenolic resins are important adhesives used by the forest products industry. The phenolic compounds in these resins are derived primarily from petrochemical sources. Alternate sources of phenolic compounds include tannins, lignins, biomass pyrolysis products, and coal gasification products. Because of variations in their chemical structures, the reactivities of these phenolic compounds with formaldehyde vary in quite subtle ways. A method is needed for predicting the reactivity of phenolic compounds with formaldehyde in order to allow researchers to efficiently choose those compounds that...