Treesearch

Aspen (Populus gradidentata) and loblolly pine (Pinus taeda) flakes were prepared with tangential-grain and radial-grain faces on a laboratory disk flaker. These were gently dried in a steam-heated rotary drum dryer. Approximately 1 week after drying, surface wettability was measured on a large sample of flakes using an aqueous dye solution. Three replicate boards of each combination of flake species and face grain were then fabricated. Each of the three replicate boards was made with a different adhesive resin. The three adhesives were urea-formaldehyde, phenolic, and neat isocyanate. The...

This report lists wood-based panel industry plant locations, production capacities, timber inventories, and wood costs for 24 U.S. states. Industry sectors covered include medium-density fiberboard, particleboard, softwood plywood, and oriented strandboard. Maps of major forest producing states show plant locations and the underlying density of timber stocking by county. The study relates physical measures of timber availability to market measures of timber scarcity and draws inferences about the potential of selected states to increase timber output at their present rate of forest...

As part of a continuing cooperative research between the Midwest Roadside Safety Facility (MwRSF); the USDA Forest Service, Forest Products Laboratory (FPL); and the Federal Highway Administration (FHWA), several crashworthy wood bridge railings and approach railing transitions have been adapted for use on concrete bridge decks. These railings meet testing and evaluation criteria outlined in National Cooperative Research Program (NCHRP) Report 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features, and include a glued-laminated timber (glulam) rail, with and...

Fungal decay of wood in service results in billions of dollars (U.S.) in losses annually. Recent environmental restrictions, both U.S. and international, are limiting and eliminating the use of broad-spectrum, heavy metal biocides for wood preservation. Restrictions result primarily from problems with disposal. New wood preservatives need to be developed and tested which specifically target key elements in the sequence of fungal decay mechanisms. Our laboratory has been experimenting with chemicals which inhibit pectin hydrolysis during incipient brown-rot and white-rot decay in southern...

Removal of stickie contaminants is currently a major focus of paper recycling research. Medium consistency alkaline repulping followed by pressure screening has proven to be effective for stickie removal. There is, however, an alternate method that is equally effective and more environmentally benign. This study compares the effectiveness of this alternative method, neutral enzymatic repulping, with conventional alkaline repulping for contaminant removal from a controlled office paper furnish spiked with typical pressure-sensitive adhesives. Neutral repulping on a pilot scale was performed...

Wind pressures can play an important role in the wetting of exterior walls (driving rain). In response, the rain screen concept, including compartmentalization and air spaces, has been developed to provide pressure equalization and limit water entry into the wall. However, conventional construction such as wood lap siding has not been evaluated as to its ability to function as a rain screen. As part of a two-year project assessing the performance of hardboard lap siding, we measured air pressure differences across the siding over extended periods of time in two single-story wood-frame...

Xylanases reduce kappa and release UV- and visibly absorptive materials from kraft pulps. The extents of these actions depend on the origin and processing of the pulp, access of enzymes to the substrate, and the natures of the enzymes. Hexeneuronic acid (HexA) is a component of kraft pulp xylans that accounts for a fraction of the kappa content. It absorbs strongly in the UV region (235 nm), and its release can be used to monitor xylanase activity. This report shows that HexA release correlates closely with release of xylooligo-saccharides, but not with the reduction in kappa.

The following results are preliminary, but show some basic information that will be used in an attempt to model pulp molded structures so that by measuring several basic fundamental properties of a fiber furnish and specifying process conditions, a molded structure could be designed for a particular performance need.

The steam injection schedule best suited for dimensionally stabilizing a flake mat is one in which steam treatment is initiated before the press is closed and is continued at least until the mat attains target thickness. Experiments showed that resinless mats treated with 20 sec of steam at 600 kPa had maximum thickness swelling of 205% compared to 350% for resinless mats pressed in a conventional fashion. Reductions in thickness swelling were proportional to steam duration and pressure. Mats treated with 20 sec of steam at 1.950 kPa had only one-tenth the thickness swelling measured in...

Four new species of Alboleptonia are described from Puerto Rico and new distribution records for Alboleptonia are noted for Puerto Rico and St. John, U.S. Virgin Islands. Information from examination of the type collections of Alboleptonia aripoana, A. cyathiformis, and A. hyalodepas is discussed. Clarification of conflicting reports in the literature concerning the application of A. hyalodepas is presented and a lectotype is designated. Two new combinations are also made for Entoloma minutoalbum and E. talisporum. A key to the taxa of Alboleptonia occurring in and around the Caribbean...