Environmentally friendly composite plastic wood material

After many years of researching and manufacturing composite plastic wood material, scientists from the Institute of Tropical Technology under the Vietnam Academy of Science and Technology have been granted by the Intellectual Property Office of Vietnam under the Ministry of Science and Technology patent No. 1-0017173 published on August 25, 2017 for indoor composite plastic wood, and a patent for utility solution No. 2-0001768 published on July 25, 2018 for outdoor composite plastic wood. These composite plastic wood materials are both durable and environmentally friendly.

Composite plastic wood - a synthetic material made from wood pulp, plastic and additives - has both the bearing capacity of natural wood and the plasticity of plastic, which has become the main raw material for many items, such as furniture, flooring, railings, decorative wood, screens, park benches, door and window frames. It has the advantages of flexibility, lower cost than natural wood, and lower cost maintenance costs.

Assoc.Prof.Dr. Nguyen Vu Giang, Institute of Tropical Technology (right), at the composite plastic wood material production line

In 2012, Assoc. Prof. Dr. Nguyen Vu Giang, Deputy Director of the Institute of Tropical Technology, and his colleagues carried out a state-level project (KC.02) on application-oriented science and technology research funded by the Ministry of Science and Technology, on the use of wood pulp milled from waste products of the domestic wood processing and manufacturing industry combined with popular thermoplastic polymers such as PE, PP, PVC, PA and other additives to create a flexible mixture that can be extruded into wood-plastic composite products on an industrial scale.

By using special additives and non-polluting techniques to create a granular third material phase or nanometer-sized film that can bond wood and plastic, the researcher team succeeded in processing wood pulp into a reinforcing material for thermoplastics. The team mixed wood pulp into a TEOS solution to create SiO2 nanoparticles that were able to bind to the -OH group in the wood pulp. When these SiO2 particles adhere to the surface of the wood pulp, they fill in the holes, making the wood pulp covered with the new coat hydrophobic and become more compatible with the plastic surface. The chemicals in the additive will initiate cross-linking reactions, forming a bridge between the plastic base material and the wood pulp.

Composite plastic wood material

The advantage of these nanoparticles or films is to increase the specific surface of the wood pulp in contact with the matrix resin during the melting mixing process, thereby increasing the adhesion to the resin matrix when forming the final product. The mixing technique with high speed up to hundreds of rounds per minute and the frictional heat during rotation causes the wood pulp to spread evenly on the plastic substrate. At the end of this process, the slurry is put into the screw extruder to push the mold, through the water cooling system, and produce the finished wood plastic composite profile.

This process has solved the problem of compatibility between wood pulp and the plastic base, and at the same time introduced a high amount of wood pulp up to 60-70% by weight or more into the product depending on the required quality. This will help reduce the cost of producing materials in Vietnam and give the composite more wood-like properties, balance strength and aesthetics, while still having important plastic properties such as moisture resistance, waterproof and easy to shape. The precious thing about this composite wood material is that after many years of use, the floorboards or door walls made from composite wood materials can be recovered, cleaned, crushed and, using the heat method, returned to the original composite form before re-machining. This helps to reuse materials and minimize waste to the environment.

With the above advantages of wood-plastic composite materials, scientists from the Institute of Tropical Technology have cooperated with domestic enterprises (European Plastics Investment and Development Joint Stock Company -Eurostark) to bring the materials into use. Up to now, wood plastic composite products have been exported to many countries in the Middle East and Europe. Based on the initial success, scientists continue to carry out further studies on high-quality composite materials.

Translated by Phuong Huyen
Link to Vietnamese version

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