History of Wood Plastic Composites (WPC)

Wood polymer composites (WPC) are products that have been relatively recently developed. The wood plastic market or wood plastic composites in North America has reached nearly 1 billion dollars in sales. The current market for these products is around 320,000 tons per year (in Europe, in the year 2020), which has developed over approximately 30 years of intense activity. In fact, this product can trace its roots much earlier than these dates. The company that invented and patented the WPC manufacturing process was Covema from Milan in 1960. A few years after the invention of wood plastic, Icma San Giorgio patented the first process of adding wood fibers/wood flour to thermoplastics (WPCs). The Ovattifici Riunitti group produced the 'Woodstock' product for Fiat cars in 1972, and Sonneson AB produced wood fiber floor tiles in Sweden in 1973.

Production Process of Wood Plastic Composites (WPC)

Mixing

The concept of this process is simple. Fine wood powder or biomass from agricultural residues is mixed with thermoplastics such as polyethylene or polypropylene in a large mixer. Thermoplastics can be both virgin and recycled. Polyethylene-based wood plastics are significantly the most common type. Additives such as colorants, coupling agents, UV stabilizers, foaming agents, blowing agents, and lubricants help to adjust the final product for the intended application.

Pressing

Most wood plastics are produced using the pressing process, which employs various types of press machines, including single-screw or twin-screw extruders for the final shaping of the material. Shapes 2, 3, and 4 respectively show samples of WPC products and a flowchart of the typical production process. Other efforts have been made to reduce density, including foaming the core of extruded profiles or designing hollow sections for specific applications. In some manufacturing plants, components are combined and processed in a pelletizing press that produces pellets of the new material. The pellets are then melted and shaped into their final form. Other manufacturers perform this final part in a single step of mixing and pressing. Pressed WPCs are formed into solid and hollow profiles.

Temperature Control

Due to the addition of organic material, wood plastics are usually processed at much lower temperatures than traditional plastics during pressing. Wood plastic composites generally tend to have a lower melting temperature and care must be taken not to exceed their temperature limits. Typically, most wood additives begin to burn at around 400 degrees Fahrenheit. Generally, the higher the ratio of wood to plastic, the lower the melting temperature.

Advantages and Disadvantages of Wood Plastic (WPC)

Wood plastic is widely used in various industries due to its combination of wood and plastic features. These materials have become a popular option in construction and environmental design due to their various advantages. However, like any material, they also have disadvantages that must be considered when selecting and using them in projects.

Advantages

Real wood alternative

Environmental sustainability

Resistance to decay

High moldability

No need for painting

Excellent resistance to weather conditions

Low maintenance

Disadvantages

Vulnerability to UV degradation

Heaviness

Features of Wood Plastic

1. High resistance to weather and moisture

Wood plastic, due to the conditions it undergoes during production, is very resistant to moisture, rain, temperature changes, etc. For this reason, it is the best option for use in outdoor spaces and areas with humid climates.

2. Longer lifespan and durability

Considering that plastic is also used in wood plastic, it is more resistant than natural wood; and it is more resistant to decay, erosion, and damage caused by insects.

3. Aesthetic and natural appearance

Due to the use of a combination of wood and plastic, it has a wood-like appearance and can be used for interior and exterior decoration design.

4. Easy maintenance

Wood plastic is easily cleaned and, unlike natural woods that require more care, it is easier to maintain.

5. Durability against UV rays

Another important feature of wood plastic is its resistance to UV rays, which protects its color and appearance against environmental changes.

Main Differences Between Wood Plastic and Natural Wood

Wood plastic has special differences compared to natural wood, including greater resistance to moisture, decay, and insects, as well as higher durability than natural wood, which makes it an ideal option for use in outdoor spaces and areas with adverse weather conditions. Additionally, it can be noted that wood plastic does not require special maintenance, unlike natural wood, which needs oiling and painting to prevent decay and discoloration.

Applications of Wood Plastic

Construction

Wood plastic is used to produce railings, flooring, etc., in outdoor spaces; also, due to the high resistance of this material, it is a suitable option for landscaping in gardens, villas, etc.

Interior Decoration

Due to the beauty and resistance of wood plastic, it can be used for interior and even exterior design, such as flooring, wall coverings, modern furniture, panels, etc.

Urban Furniture

This material is also used in the construction of urban furniture such as benches, trash cans, fences, and park equipment.

This material can be used for urban furniture such as benches, park equipment, trash cans, etc.

Automotive and Packaging Industry

Due to the specific features of wood plastic, it is used in some industries such as automotive and packaging.

Lifespan of Wood Plastic

According to the Residential Rehabilitation Inspection Guide of the U.S. Department of Housing and Urban Development (HUD) in the year 2000, the lifespan of exterior coverings is as follows:

Aluminum: 20 to 50 years

Wood plastic: 10 to 100 years (highly dependent on weather conditions and maintenance)

Vinyl: 50 years

The high humidity of Florida's climate accelerates the degradation of materials by 2 to 4 times. The accelerated degradation, which is observed near industrial sites, is due to the release of industrial pollutants.

Resistance and Durability of WPC

Wood plastic materials are marketed as products requiring low maintenance and high durability. However, after a decade of outdoor use in the construction industry, questions about their durability have arisen. These questions are based on documented evidence of failures of WPC decking products due to factors such as polymer degradation, wood decay, and susceptibility to fungi, which negatively impact the aesthetic quality of the product.

Industry Response to WPC Issues

The industry has improved WPC formulations to address the problems of first-generation products. Manufacturers have also made significant advancements in providing more reasonable claims and educating consumers about proper care and maintenance of WPC products to preserve the aesthetic quality of the product surface. Research groups around the world are working on a fundamental understanding of WPC durability to help improve or identify new strategies for the protection of WPCs. The durability of WPC will continue to be an important topic in the use of these products in construction and other related applications in this field.

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