Black liquiors from kraft pulping and as well as a purified kraft lignin were reacted with formaldehyde over the temperature range 30-70C. The activation energy was about 12.9 Kcal per mole. They were also heat treated to "activate" the lignin and some were also reacted with formaldehyde or furfuraldehyde. These treated solutions were then mixed with phenolformaldehyde (PF) resols and used as plywood adhesives. They were first used in suspension at pH 5.3-5.5 with an acid-curing PF resin. This method proved unsatisfactory. When used as solutions mixed with polymethylophenol resols at solids content varying from 40 to 60 per cent of total solids (resol solids plus black liquor solids) and pH about 12.0, good bonding was obtained with either crude or methylolated black liquor or kraft lignin solutions on 3/8 inch (9.6mm) aspen poplar plywood pressed at 350F (177C) fro 5 minutes and 150 per square inch (1034 kPa). Phenolic resin requirements were 40 to 56.5 percent of the amount required when pure PF is used.
Waferboards were made from 5 and 9 year old hybrid poplars, using laboratory prepared wafers. The binder was a powder consisting of a mixture of phenol-formaldehyde (PF) resin and comminuted hybrid poplar bark in equal weights. Only 1.25% PF resin was used based on weight of dry wood. These boards had bending strength and internal bond strength much in excess of the minimum required by Canadian Standards. Another binder was used composed of white spruce tannin, hybrid poplar bark and PF. This amount of PF based on dry wood was 0.5%. this mixture also gave strong boards, both dry and wet, at densities of 42 pounds per cubic foot.
Four-foot hard maple bolts, ranging in diameter from 6 to 16 inches, were produced from pulp wood and sawlogs. The bolts were live-sawn into 1-inch boards to identify the coordinates of each board defect in order to mathematically reconstruct each bolt for simulated sawing. The optimum bolt values were obtained by "computer sawing" the bolt models several times into dimension stock, squares or pallet stock using three sawing patterns; live, around and cant sawing. In the simulated sawing of the actual and theoretical bolts, live sawing consistently resulted in the highest product value. The only exception was for bolts containing a large amount of discoloured wood. In these cases, around and cant sawing performed better than live sawing. In general, liver sawing produced the highest product value for the following reasons; the production of wider boards allows a greater resawing flexibility, fewer saw cuts with less kerf loss and the production of fewer slabs. In-plant studies were conducted to determine the effect of the sawing pattern on productivity. Live sawing increased productivity by 18% for small diameter bolts and up to 30% for larger diameter bolts over the other sawing patterns. While multi-pass systerms may be suitable for the larger, higher quality bolts, it is doubtful that such a system would be viable processing small diameter material down to 6 inches. In processing smaller diameter bolts, it is necessary to have a single-pass system with high productivity to offset the lower quality and value of this material.
Linear programming is a technique used to determine the best (or optimal) solution to a problem where there are a number of competing and usually interrelated choices. The technique requires that each restriction on the problem being modeled be formulated as a linear equation. The model consists of a set of linear equations with more unknowns than equations and thus there are many possible solutions. In order to determine the best of these solutions, it is necessary to decide which criteria will be used to determine the best. Once the criteria (usually maximum profit or minimum cost) is chosen, an equation is set up giving the amount each variable (or activity) contributes to the criteria. The linear program then determines which solution will maximize or minimize this criteria. The LP described in this write up was written to determine the best process and set of process conditions for converting steam exploded Aspen wood into a variety of chemical feedstocks. The LP is designed to maximize profit based on the sales value of the chemicals produced, the cost of raw materials and the processing costs incurred. The model is restricted by the raw material availability, the utility and chemical requirements of each process step, the capacity of each process step and the market requirements for each chemical produced. This report will give a detailed description of the model structure, will discuss the validity of the data used in the model as well as future requirements, will discuss the running of the model on the computer and will discuss analysis of the LP solution.
Wood drying is an essential step in the manufacture of most wood products to minimize the development of defects such as warp and checking. Kiln-drying under controlled conditions of temperature and humidity is the most widely used method for removing moisture from wood and achieving a low, uniform moisture. Many topics relevant to lumber drying are discussed in this manual: wood structure and wood-moisture relationships, drying methods, kiln types and instrumentation, treatment of logs and lumber prior to drying, kiln schedules and drying defects. Graphic data tables dealing with wood properties and wood-moisture relationships at various temperature are provided for hardwoods and softwoods utilized in Eastern Canada.
Reprinted in 1993 - no longer available in print format