Opening a way to a new hybrid composite, Mohd Iqbal Misnon and collaborators of UiTM Shah Alam, Malaysia tested hybrid composites made of rubberwood, coconut shell and textile fabrics (woven cotton and polyester fabrics).
Each of the hybrid composite fabricated: Cotton fabric reinforced hybrid composite (CtRHC) and Polyester fabric reinforced hybrid composite (PeHC), was reinforced with two, three and four layers cotton or polyester. The control samples were the composite without any textile fabric reinforcement.
Flexural strength, impact strength, water absorption and thickness swelling tests were conducted to determine the mechanical and physical properties of the fabricated hybrid composites respectively.
It was found that the flexural strength of these fabrics reinforced hybrid composites improved as compared to the control sample, which was without textile fabric. The result of flexural modulus of the hybrid composite fabricated demonstrated similar trend with its flexural strength. The flexural modulus of the hybrid composites improved with the presence of textile fabrics. Samples reinforced with textile fabrics exhibited higher values than the control sample. The reinforcement with 4 layers of textile fabric tended to decrease the flexural modulus slightly.
On the other hand, the composite materials have good properties if the substances are strongly bonded with each other. Nevertheless, the polyester fabric does not adhere well with rubberwood and coconut shell mixture. This makes this material system relatively not strong. The delimitation also indicated that the compression load was not effectively transferred from rubberwood and coconut mixture to the polyester fabrics. It is believed that the PeHC sample could have a better flexural strength than CtHC, if the PeHC sample performed good adhesion in their system.
Overall, the cotton and polyester hybrids recorded a higher impact energy than the control sample. The impact load had distributed effectively due to good adhesion between the cotton fabric with the rubberwood and coconut shell particles.
The samples also exhibited better impact damage tolerance. Fibre failure turned smaller as the number of fabric layers increased, indicating that a higher PeHC system can absorb the impact energy.
Again, it is believed that the polyester hybrid composite could have better impact properties if the polyester performs good surface adhesion with the rubber wood and coconut particles. Another factor that contributes to higher impact properties is the properties of polyester fabric itself. Polyester fabric is known to have good elongation between 30 – 40% and this property makes the hybrid composites more ductile and able to withstand impact.
The results of flexural and impact tests showed that the mechanical properties of this new fabricated hybrid composites were better than the control sample.
The cotton fabric reinforced hybrid composite samples had better flexural but lower impact strength in comparison with the polyester reinforced hybrid composites. All newly fabricated hybrid composites also recorded to have a lower water absorption than the control sample.
The cotton hybrid showed lower water absorption than the polyester hybrid due to poor adhesion between polyester and urea formaldehyde. Both types of hybrid composite showed higher values than the control in thickness swelling.
In short, polyester strengthened with particles of rubber wood and coconut shell is stronger than the normal ones.
Mohd Iqbal Misnon
Wan Yunus Wan Ahmad
M.I. Ab Kadir
Department of Textile Technology
Department of Bio-Composite Technology
UiTM Shah Alam