Micromechanics of oil palm mesocarp fibres and biocomposites
Investigation was conducted on non-linear mechanical behaviour of oil palm mesocarp fibres (OPMF) and their biocomposites, with focus on the interface of the fibres (filler) and matrix. Viscoelastic with damage was observed from tensile tests conducted under cyclic mode, as reported from the u...
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| Format: | Thesis |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/75820/1/FK%202018%2066%20IR.pdf |
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| Summary: | Investigation was conducted on non-linear mechanical behaviour of oil palm
mesocarp fibres (OPMF) and their biocomposites, with focus on the interface
of the fibres (filler) and matrix. Viscoelastic with damage was observed from
tensile tests conducted under cyclic mode, as reported from the unloadingreloading
results of the cyclic tests at larger deformations (2 and 3mm
deformation). This behaviour was related to the lignocellulosic components of
the fibres, as well as geometry of the fibres consisting of silica bodies and
cellular structure. On the other hand, mechanical tests comparison of the
processed fibres mentioned before with fresh mesocarp fibres showed
different viscoelastic behaviour of the latter fibres, which was due to moisture
within the fibres containing palm oil, as well as the effect of oil palm
processing that altered the processed fibres. The tests results were modelled
through a viscoelastic model available in finite element software, Abaqus,
which consisted of hyperelastic model with Prony series and a stress softening
function. Good agreement was reported from the fitting of the model to the
mechanical tests results, highlighting the viscoelastic behaviour of oil palm
fibres. Emphasis was then given to the effect of silica bodies towards integrity
of the oil palm fibres, where a cohesive zone modelling (CZM) was included
to model the interface between silica bodies and fibres. The results showed
minimal effect of silica bodies towards integrity of the fibres as a whole, which
was due to the silica bodies were only partly embedded on the outer surface
of the fibres. The fibres were then used for biocomposites development as
filler, and LLDPE was used as matrix. The interface between the filler and matrix was improved using anhydrate (maleic anhydride and itaconic
anhdride). In addition to the interface improvement using chemical method
(anhydrate to strengthen the filler-matrix interface), it is hypothesised that the
geometric effect of the fibres consisting of silica bodies on the surface can also
improve the filler-matrix interface. Therefore, the fibres were not chemically
treated (with alkali or acid as conducted before in previous literatures) to
preserve the silica bodies and fibres integrity. Improvement of the
biocomposites with both anhydrate and silica bodies was reported from a
series of experiments, namely mechanical tests, FTIR, and microscopy
analyses. In particular, SEM image showed that silica bodies left craters after
being pull during tensile testing, suggesting that the silica bodies prevent
sliding between the filler-matrix interface. Likewise, evidence of OH bond
between the silica bodies and matrix was shown, similar to the filler-matrix
improvement due to addition of anhydrate. Biocomposites finite element
model geometry was generated using Digimat software, but the modelling
analysis was terminated before any results can be obtained. The results from
both mechanical behaviour of fibres and biocomposites interface highlighted
that oil palm mesocarp fibres behaved as a viscoelastic material with damage
due to deformation, and the fibres used for biocomposites application can be
obtained directly without chemical treatment. |
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