Wood flakes

Woodell s scale Wooden barrels Wooden matches Wood fiberboards Wood fillers Wood finishing Wood flake boards Wood flour... 

Reconstituted Wood Products. This category includes three general varieties wood flake board, particle board, and wood fiberboard. The manufacturiag processes are similar for all these products except for the size of the wood particles that are glued together. 

Wood FIa.ke Boards. This category covers a range of products depending on the size and orientation of the wood flakes used. The earliest product was made in the 1950s using low density wood species, such as aspen and pine, with the flakes bonded together with phenoHc resins. Today there are two types of flake board, waferboard and oriented strand board (OSB). 

Rowell, R.M., Tillman, A.-M. and Simonson, R. (1986d). Vapor phase acetylation of southern pine, Douglas-fir, and aspen wood flakes. Journal of Wood Chemistry and Technology, 6(3), 449 71. 

When using furfuryl alcohol and wood flakes treated with NG(5%)+02 internal bonds were significantly increased in products having densities (0.7U and 0,76) similar to those of the bagasse... 

Wood particles used for the outer layers were comprised of that fraction of Pallmann milled particles which passed a 10-mesh screen and were retained on a 16-mesh screen with random lengths to 1/2-inch. Wood flakes which remained on a 10-mesh screen and between 0.008 and 0.012-inch thick, with random lengths to 3/4-inch and random width to 1/4-inch were used as core in the three-layer board. 

The thermal properties of composite boards were the subject of a recent report by Place and Maloney (58). Thermal conductivity tests were made on three-layer boards with surfaces of white pine wood flakes and cores of either Douglas-fir or grand fir bark. Density was varied at 34, 42, and 52 pounds per cubic foot. The composite boards containing bark proved to be better insulators than wood particleboard of comparable density. Douglas-fir bark cores had lower thermal conductivity than did grand fir. 

Wood flakes have been reacted with BO/triethylamine [44]. Flakes modified to 20% WG gave a flakeboard that absorbed 25% less water and had reduced thickness swelling up to 50% as compared to an untreated flakeboard. Similarly, wood particles were treated with PO prior to board manufacture [45]. PO-treated boards showed excellent decay resistance. 

Rowell et al. [44] prepared flakeboards from acetylated wood flakes. Their water absorption was 50% less and thickness swelling was reduced 85%. There was an 85% reduction in thickness swelling when the boards were subjected to 90% relative humidity over a period of 20 days. 

In terms of the performance of coatings, the developed system proved to be comparable to phenol-formaldehyde. The board appeared to be less susceptible to fungal decay in preliminary studies, as compared to phenol-formaldehyde board, but had high mold susceptibility. According to ASTM 631 72 corrosion test, the board was initially highly corrosive to metals but after 16 d the corrosiveness dropped and was only slightly higher than that of untreated wood flakes (102). 

Figure 11 Fracture surface of Southern pine flakeboard showing unfractured fillet of phenol-formaldehyde adhesive (A) original surface of wood flake (B) adhesive fillet (C) fragment of SI layer of secondary wall from second wood flake.

Brady and Kamke [26] investigated the penetration of PF resins into thin wood flakes using fluorescence microscopy and showed that resin penetration was influenced rather by the natural variability of the wood material than by pressing conditions. Also, it was about three times greater in Douglas Fir earlywood than in latewood. Cell wall fractures enhanced penetration by providing additional paths for hydrodynamic flow. 

Johnson and Kamke [15] used three PF resins with different degrees of conden-sahon in order to investigate the penetration behavior into the cell lumens and also the big vessels of hardwood (yellow poplar). The higher the molar mass, the less was the penetration into the wood flakes. Adhesive penetration into hardwood is likely to be dominated by flow into vessel elements. 

Wood chips, wood fibers, wood flakes, and similar wood-based starting materials, in combination with snitable inor nic binders, are widely used in the produetion of reinforced eementitious eomposites, sueh as wood ehip cement boards (also ealled cement-bound wood ehip boards). 

Particleboard (constructed from wood flakes, shavings or splinters)... 

MDI is mostly used in polyurethane chemistry. About 80% of MDI is used to make polyurethane foams, both flexible and rigid. Half of all the foam produced with MDI is rigid foam. This rigid foam is used in the insulation, construction, refrigeration, and packaging industries. Also, MDI is used in the production of spandex fibers. MDI is used as a wood binder and in foundry cores. The binding of wood flakes into oriented strandboard is replacing plywood in construction. 

Examples of PE-containing composites are hydroxyapatite-filled PE composites, HDPE/wood flonr or ElDPE/wood flake, UHMWPE/gold, HDPE/layered silicate nanocomposites, and nanocomposites comprising HDPE, organically modified clay, and maleated PE. 

P. W. Balasuriya, L. Ye, and Y. -W. Mai. Mechanical properties of wood flake-polyethylene composites. Part I effects of processing methods and matrix melt flowbehavior. Composites Part A. 32 (5), 619-629 (2001). 

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