Various Kraft lignin binder formulations with phenolic resins were developed and tested in terms of application, curing requirements and product performance. The two most promising glues were selected and this report presents their evaluation as binder for laminated lumber. For the first time, a rapid method of curing lignin adhesives in laminated lumber was developed using the residual heat from pre-heated wood. The study has confirmed that rapid lamination of lumber using low cost lignin binder is possible. Further study for rapid methods of pre-heating the laminae and application of the binder is required. The development of a faster curing low cost binder would be the best improvement to the process.
A heat -pipe heat exchanger was used to recover exhaust heat from the ventilation system of a 4 Mbf capacity research dry-kiln. Heat exchanger effectiveness ranged from 76 to 90 percent for sensible heat transfer under winter operations. Total heat effectiveness ranged from 9.2 to 21.4 percent. Energy savings for spruce-pine-fir studs and 1-inch hard maple was 7.4 and 3.8 percent respectively, which would result in estimated payback periods of 0.6 years for spruce-pine-fir and 1.7 years for 1-inch maple applied to an industrial drying operation.
Reinforced particleboards were made at several panel densities and with several resin treatments of the fibreglass reinforcing scrims. It was the inclusion of fibreglass scrims that dramatically increased the strength and stiffness of particleboards especially when the overall panel density was above 0.7 gm/cc. Of the various locations tested, reinforcement at the extreme surfaces was found to be the best. Treatment of the fibreglass with phenolic resins produced some improvement in wood-fibreglass bonding, however the addition of a coupling agent significantly improved the fibreglass fixation.
Aligned waferboard panels were prepared, the mean and the standard deviation of measured angles of aligned face wafers were carefully determined. The importance of orientation angle and angle distribution was demonstrated for board properties such as modulus of rupture and module of elasticity. Linear and non-linear regression models were studied and a number of prediction equations in terms of strength properties were tested and reported.
The relationship of press closing time, strength properties and density profile of thick waferboard panels to mat moisture content was demonstrated in this study. Lower mat moisture contents were found to increase press clothing time but permit faster binder curing. When the distribution of mat moisture was higher in the face layers, shorter press times were achievable and a significant densification of the panel was observed.
Overall properties of poplar waferboard can be considerably upgraded by the massive use of an inexpensive resin binder derived from ammonium-based 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 exising 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.