The Influence of Filler Loading on Mechanical Properties of Rice Husk Reinforced High Density Polyethylene

The aim of this project was to investigate the influence of varying filler loading on
composite mechanical properties. The filler used in this research was rice husk and the
matrix was high density polyethylene (HOPE). The particle size of the filler was 0.5
mm. Particulate size of' rice husks were compounded together with the matrix polymer
and moulded into dog-bone shaped specimens using an injection moulding machine. In
the sample preparation, rice husks were prepared using four different filler loadings
which were 0, 5, 10 and 15 wt.%. The effect of the coupling agent on the mechanical
properties was also investigated by incorporating 2% maleated polyethylene (MAPE) at
three different filler loadings which were 5, 10 and 15 wt. %. From the microstructure
observation, the surface characteristic of filler was changed when it has been dried in an
oven during filler preparation process. After the drying process, the surface of rice husk
appeared to be smoother than before the drying process and the ridges were less visible
from the surface. Results obtained from tensile test showed that tensile strengths of the
composites decreased with increasing filler loading. With the addition of
compatibilizing agent, tensile strength of the composites was improved as much as 14%
as filler was incorporated into the matrix at 5 wt.%. For the flexural strength, it was
observed that flexural strength increases gradually with increase in filler loading.
Flexural strength decreased by 16 % as 5 % filler loading added to the composite.
However the flexural strength of the composites increased gradually as filler content
increased to I() and 15 wt. %. Microstructural observation of the tensile fractured
surfaces of samples without added compatibilizing agent showed poor compatibility of
the filler-matrix as evidenced by filler debonding and pull-out. in the case of the
composites with compatibilizing agent, the interfacial bonding between the filler and the
matrix polymer was stronger, resulting in fracture at the filler itself and not at the
interface.