Resouce: DesignNews
Researchers in Malaysia have developed a bio-based composite material by substituting coconut fibers for traditional ceramic fibers in biocomposite tiles. The natural fibers improve the strength and stiffness of the composite materials and also reduce their weight.

The low density, high cellulose content, and abundance of coconut shell fibers, make them popular in Southeast Asia and other areas for a number of rope, fiber, and textile applications. Other advantages of using the fibers of coconut coir include its toughness, low density, low cost, and biodegradability. Several different types of biocomposites already exist, including those composed of biodegradable plant-based or animal-based natural fibers, such as flax, jute, silk, or wool.
Professor Suhaimi Muhammed of the Universiti Teknologi Mara (UiTM) Pahang in Malaysia and his colleagues Amran Shafie and Noorshashillawati Azura Mohammad from the faculty of applied sciences took long fiber bundles of coconut coir derived from coconut husks and combined them with fiberglass. Then they bonded the resulting composite further with a gel coat of acrylic resin.

When this biocomposite material was tested for dimensional stability, it exhibited very low water absorption rates of less than 3 percent and low thickness swelling of less than 1 percent. These results lead Suhaimi's team to suggest that plant-based fibers may be used as reinforcement in a composite system to improve the properties and performance of polymer matrix resins. The improved strength and stiffness, in addition to the lower weight, of natural fibers can make the composite tiles useful in vehicle plates, some industrial applications, and for walls and floors in construction.

Another result was a manufacturing method for producing the tiles that the team expects will benefit small-scale entrepreneurs as well as coconut growers. The researchers developed a portable biocomposite press that will let entrepreneurs invent and create their own biocomposite materials.

In a second, apparently unrelated study at UiTM's Shah Alam campus, Mohd Iqbal Misnon and his collaborators in the departments of textile technology and biocomposite technology tested hybrid composites made of rubberwood, coconut shell, and woven cotton or polyester textile fabrics. Their intent was to find out how reinforcement provided by textile fabrics affects biocomposites.

Several different hybrid composites were created, with two, three, or four layers of cotton or polyester fabric. The control samples were unreinforced hybrid composites. The team conducted flexural strength, impact strength, water absorption, and thickness swelling tests.

The flexural strength and flexural modulus of fabric-reinforced hybrid composites improved compared to the control sample. The flexural modulus of composites reinforced with four layers of fabric tended to decrease slightly. Fabric also delivered better impact damage tolerance, which increased with layer count.

Since the polyester fabric did not adhere well to the rubberwood and coconut shell mixture, it was not as strong as the cotton fabric-reinforced versions. The researchers said that, if its adherence was improved, the polyester hybrid composite's flexural strength and impact properties would likely improve.

The hybrid composites reinforced with cotton had better flexural but lower-impact strength than the polyester-reinforced composites. Composites reinforced with both fabric types had lower water absorption and higher values of thickness swelling than the control sample.
 



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