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.
Type and extent of biodeterioration occurring on eastern spruce trees, Picea spp., infested by spruce budworm Choristoneura fumiferana (Clem.), and its effect on the value of timber as raw material for lumber and compoition board production was investigated in New Brunswick and Nova Scotia. Moderately defoliated, severely defoliated and dead (standing) trees were examined and compared with normal trees. The results indicated that the loss in wood quality due to fungal decay and insect damage on defoliated trees was not substantial and could be ignored in the use of the wood as raw material for the products mentioned above. Dead trees were found to be deteriorated to a considerable extent, mainly as a result of fungal decay, especially on the butt ends, and contained moisture in most parts to a level considered favorable for fungal decay. Decay and insect damage present on dead trees did not affect the lumber processing rate. Lower lumber recovery, however, and especially downgrading, resulted in a 21% loss of the value of lumber recovered. Particle boards and waferboards produced from the roundwood from dead trees (6-foot bolts, 7 to 13 feet from the ground) were excellent in quality and equal to those produced from unattacked or defoliated trees. A storage study was initiated near Fredericton, N.B. Six-foot long bolts from dead, defoliated and normal trees, with and without bark, will be monitored and examined for the rate and causes of deterioration during storage.
Elimination of saw kerf through the compression slicing process has initiated research into the optimization of the compression slicing parameters. Five of these parameters have been selected for study in the 1979-1980 federal fiscal year, through a contract given to Forintek Canada Corp. by Environment Canada. These parameters are the following: 1) Find an alternative to tires or pads for lateral pressuriza tion, 2) Study knife profile to reduce checking damage, 3) Study knife tensioning to reduce checking damage, 4) Study methods of reducing knife friction, 5) Study the dustribution of stresses in the knife when tensioning and slicing. Following is a detailed description of the work done during the 1979-1980 federal fiscal year on each of these compression slicing parameters.
Overall properties of poplar waferboard can be considerably upgraded by the massive use of an inexpensive resin binder derived form ammonium-based spent sulphite liquor (SSL). Further improvement on waferboard quality can be achieved by the combination of higher resin content and thinner wafers. Low-density waferboard also can be produced to meet CSA 0188 requirements by using aligned wafers. This inexpensive SSL binder, however, requires a longer press time and prefers a higher platen temperature to cure. A new waferboard plant, designed and built to fully exploit both technical and economical advantages of this binder system, would be ideal. For some existing waferboard plants it may be necessary to slightly modify their production line in order to adopt this new binder system. Great savings on resin cost can be realized by substituting the expensive petrochemical-based phenolic resin with the renewable and inexpensive sulphite liquor binder. Economically and technically speaking it is entirely possible to produce a new type of better waferboard at a lower cost.