WPC - Durable and dashing alliance of wood and plastic
Wood-plastic composites (WPCs) are continuing to drive growth in wood replacement applications due to their aesthetic and low maintenance properties. The global wood plastic composite market size was estimated at USD 4.01 billion in 2017 and it is expected to witness significant growth over the coming 5 years owing to the fluctuating petrochemical prices and intensified environmental concerns. Wood processing and plastic manufacturers are expected to shift towards wood plastic composite manufacturing owing to similar manufacturing technology, as well lower production cost. Furthermore, plastic manufacturers are expected to shift more rapidly owing to technical know-how.
WPCs are increasingly employed both as interior and exterior building materials. For these applications, the materials have to exhibit multifunctional characteristics such as a combination of exceptional mechanical properties and flame retardancy, which can be achieved with the addition of specific additives during composite processing.
Wood fibers, polymers and additives
Wood plastic composite is a hybrid material composed of natural wood and plastic fiber. Saw dust from fiber fillers like pulp, peanut hulls, and bamboo are mixed with new or waste plastic powder, from materials such as polyethylene, polyvinyl chloride, polypropylene, and acrylonitrile butadiene styrene. Wood fibers (or wood flour) are used as reinforcing fillers in amounts generally ranging from 50 to 80 % whereas polymer materials function as binders. Once the materials are mixed together to achieve a relatively thick consistency, they are extruded or molded.
Additives, such as colorants, reinforcing agents, and lubricants can be added to achieve a higher level of specification for the intended product’s use. Because of the composite’s unique composition, wood plastic composite can be manipulated to assume a wide array of shapes and dimensions, including arched and bent shapes. As a result of their high cellulose content, wood plastic composites can be treated in a similar fashion as wood, but they are also moisture- and rot-resistant.
Wood plastic composite (WPC) that consists of polyethylene (PE) and wood sawdust is primarily used in building and structural components. WPC comprised of wood sawdust and polypropylene (PP), on the other hand, is more commonly used for automotive and consumer products. Wood sawdust and polyvinyl chloride (PVC) create a WPC that is typically found in window manufacturing, as well as certain decking applications. The combination acrylonitrile butadiene styrene (ABS) and wood sawdust produces a WPC that can be used in varying applications.
Material selection depends in large part upon the manufacturer’s preference, and is based on the general properties of each component as well as availability. Maple, oak, and pine are common types of sawdust, and tend to be relatively low-cost to obtain.
Recyclability, thermal stability and stiffness
WPC assumes many of the same characteristics of wood thanks to the high cellulose content from the wood. Therefore it can be subjected to the same processes, including planning, drilling, and sanding. Nails, screws, and other fasteners often achieve greater hold when used with WPC than with lumber, which results in WPC’s ability to use smaller fasteners to hold more. Additionally, WPC offers superior water resistance when compared to basic wood with minimal expansion. The lack of moisture present within WPC also results in resistance to decay. The ability of WPC to perform in high temperature environments is also better than that of wood. They are frequently used as a replacement for tropical timber on account of their longevity, thereby contributing to the preservation of ecologically important tropical forests.
Additives for improved performance
To achieve the varying characteristics listed above, the manner in which the wood is processed and interfacial adhesion must be controlled. The difference between the surface energy of the wood and the matrix of the plastic polymer determines the final physical properties of the composite, often requiring the addition of a coupling agent to enable strong interfacial adhesion. Coupling agents encourage dissimilar materials (such as plastic and wood) to form an alloy. Compatibilization can also be used, a process by which wetting is achieved within the mixture. There are several manners in which coupling and compatibilization can take place, including the modification of the fiber or polymer and the addition of coupling agents. Depending on the type of wood and plastic involved, different coupling agents and compatibilizers may be appropriate.
Algol Chemicals portfolio contains a wide variety of additives to enhance processing conditions and improve performance of the final product. If you’re searching for antioxidants, flame retardants, lubricants & waxes, modifiers, pigments, titanium dioxide, uv-absorbers or -stabilizers for WPC applications, please do not hesitate to contact us.