Polyurethanes play a major role in today’s modern materials such as in composite wood, which is a combination of synthetic and natural materials. Polyurethane-based binders, typically used both with wood and rubber, are used in composite wood products to permanently glue organic materials into oriented strand board, medium-density fiberboard, long strand lumber, and even strawboard and particleboard.

What Is Oriented Strand Board?

Oriented Strand Board, also referred to as OSB, is manufactured from fast-growing trees such as the aspen poplar, southern yellow pine, mixed hardwoods and other suitable species. OSB is frequently made by coating wood chips (known as strands) with MDI, then arranging consecutive strand layers roughly perpendicular to each other, and finally pressing the strands under high temperature and high pressure to form boards. These bonds form a chemical matrix that serves to glue the strands together. The perpendicular orientation of the wood strands imparts strength properties to the panels. OSB panels measure 4’x8’ with thickness typically ¼” to 23/32”. OSB is widely used in residential construction for sheathing and flooring, as the web material for wood I-joists, and in the production of structural insulated panels (SIPs).

What Is Medium-Density Fiberboard?

Medium-Density Fiberboard, also referred to as MDF, is widely used in the manufacture of furniture, cabinets, door parts, moldings, millwork and laminate flooring. MDF panels are manufactured in a variety of dimensions and densities, providing the opportunity to design the end product with the specific MDF needed.

As with other composite wood products, MDF typically consists of cellulosic fibers combined with a synthetic resin or other suitable bonding system and joined together under heat and pressure. Additives may be introduced during manufacturing to impart additional characteristics. The surface of MDF is flat, smooth, uniform, dense and free of knots and grain patterns, all of which make finishing operations easier and more consistent. The homogeneous density profile of MDF allows intricate and precise machining and finishing techniques for superior finished products. Trim waste is significantly reduced when using MDF compared to other substrates. Stability and strength are important assets of MDF, and it holds precise tolerances in accurately cut parts.

What Is Long Strand Lumber?

Long Strand Lumber (LSL), also known as Oriented Strand Lumber (OSL), is similar to OSB, except for the following important differences. The strands used in LSL are longer than those used in OSB. Also, all of the strands are arranged parallel to each other, so that the product is very strong along its length. LSL is much thicker than OSB because its intended use is to serve as a substitute for dimension lumber. It is suitable to use in place of 2”x4” studs in residential construction applications. Another major use is the flange portions of wooden I-joist beams.

What is ParticleBoard?

Particleboard, also known as chipboard, is an engineered wood product manufactured from wood chips, sawmill shavings, or even sawdust, and MDI, which is pressed and extruded. Particle board is denser and more uniform than conventional wood and plywood and is substituted for them when strength and appearance is more important. Different grades of particleboard have different densities, with higher density connoting greater strength and greater resistance to failure of screw fasteners.  Particle geometry, MDI levels, and manufacturing processes may be modified for products with multiple end uses.  Furthermore, additives can be utilized to give greater dimensional stability, fire and moisture resistance, and other properties.

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