As world markets expand, the need for new materials to satisfy production requirements continues to grow, especially in developing countries. At the same time, high oil prices push up the costs of petroleum derivatives such as polymers, or plastics, used in countless consumer items. One recent and very interesting line of research in the field of materials involves combining natural fibres with thermoplastics. Wood, flax, hemp and jute are just some of the renewable natural materials now showing great promise.
Composite fibre products are not new. The first known composite material was made in Egypt around 3000 years ago when straw was used to reinforce clay walls. In the past decade, findings in the academic world have convinced industrial producers that natural fibres like flax, hemp and jute can be an excellent renewable and sustainable substitute for glass fibres as reinforcement in thermoplastic and thermoset composite materials.
Natural fibres have good intrinsic mechanical properties, low density compared to glass fibres, and they are cheaper. Relevant research publications nearly all show a composite stiffness for flax fibre-reinforced composites close to or even higher than commercial glass ones.
"We need to develop new materials that are cheaper and better. Ideally, such materials should also be recyclable more easily, reducing environmental impacts."
Isokon Plastics Manufacture Ltd., Slovenia
Partners involved in FACTORY ECOPLAST decided to join efforts to develop a palletised compound suitable for injection moulding and extrusion processes, combining two or more material components in such a way that the resulting compound is better than any of the individual components alone.
"We need to develop new materials that are cheaper and better," says FACTORY ECOPLAST coordinator Uros Znidaric of Slovenia's ISOKON. "Ideally, such materials should also be recyclable more easily, reducing environmental impact."
The type and level of filling in reinforced thermoplastics affects their mechanical and thermophysical properties, and governs the method of treating them, their application and cost. Therefore it is of interest to optimise the composition of polymer composite materials to enhance their effect and other special properties.
Project partners looked at compounding conditions, palletising processes, deformation properties, compatibility between natural fibres and thermoplastics, injection moulding parameters and possible applications.
"Once we had enough information about different compound properties, we then focused on product selection," says Znidaric. Final selection was based on key properties, including rigidity, weight and price. The ability to saw and drill the material was also considered, as well as wear and tear on machine equipment used in processing final products.
"The project was very successful," says Znidaric. "We were able to define precise technological parameters for extrusion and an optimal palletising process for making compounds for injection moulding and extrusion. The new materials are suitable for use in the manufacture of a wide variety of products, including vacuum cleaner and lawn mower parts, storage boxes and even golf tees."
Acoustic properties also became a focus of investigation. Znidaric explains, "Although wood is known for its good acoustics and is often used in musical instruments, today a lot of speaker boxes are made of injection-moulded polymers. We wanted to see if our new composite, which contains wood, might display better acoustic properties."
FACTORY ECOPLAST's results show that the wood fibre-filled composites developed under the project are indeed well suited to use in loudspeaker boxes. Znidaric says both damping of sound radiation and sound wave resistance for the material are comparable to those displayed by medium-density fibreboard, one of the most commonly used materials in this application.
"We were able to define precise technological parameters and an optimal palletising process for making compounds for injection moulding and extrusion. The new materials are suitable for use in the manufacture of a wide variety of products."
Isokon Plastics Manufacture Ltd., Slovenia
Further tests of the project's new ‘EUREKA' speaker boxes show a higher frequency acoustic performance on a par with market leaders such as JVC and Nakamichi. The potential for FACTORY ECOPLAST commercialisation in this specific area, say partners, is therefore very high.
More generally, says Znidaric, world markets are becoming increasingly aware of strong public and government support for the use of environmentally friendly materials. "This is just one more reason why we see a high probability of broad commercial success for our products," he says.
"Market studies we performed during the FACTORY ECOPLASTIC preparatory phase showed an enormous increase in the usage of extruded bio-polymer materials in the US market in recent years." Based on these findings, says Znidaric, project partners now believe it is reasonable to expect similar growth intensity for the same materials in Europe.