Microwave absorber based on biocomposites derived from agricultural wastes with reinforcement of poly lactic acid
The development of new microwave absorber (MA) materials has been motivated by an increasing ecological and environmental consciousness. Biocomposites is natural fibre-reinforced polymers has low density and biodegradable nature obtain from natural fibers which are cheap, continuous supply, ea...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/97780/1/FK%202021%2070%20UPMIR.pdf http://psasir.upm.edu.my/id/eprint/97780/ |
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| Summary: | The development of new microwave absorber (MA) materials has been motivated
by an increasing ecological and environmental consciousness. Biocomposites is
natural fibre-reinforced polymers has low density and biodegradable nature obtain
from natural fibers which are cheap, continuous supply, easy and safe handling. The
idea of this research is to develop a MA from biocomposite derived from oil palm
fronds (OPF), empty fruit bunch (EFB), pineapple leaf fiber (PALF) and
strengthened with poly-lactic acid (PLA). The fibers samples are prepared in 0.3 mm
particle size, meanwhile the polymer and biocomposites are in ring shaped forms
using mix and blend process and injection moulding. Their dielectric constant, (ɛ')
and loss tangent, (tan ) are extracted using open ended coaxial probe and S-parameter Reflection measurements. OPF, EFB and PALF show ’with 1.92, 1.88
and 2.04 respectively and tan with 0.105, 0.096 and 0.102 respectively. PLA ’ and
tan is about 1.99 0.25 and 0.044 0.02 respectively in the X band. Each type of
biocomposite mixture of fiber and PLA composition (wt%) namely OPFPLA,
EFBPLA, and PALFPLA prepared in 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt%
fiber loadings. The optimum ’ and tan for each biocomposite is 2.718 and 0.165
at fo = 8.6 GHz for OPFPLA5050 with 50 wt% OPF and 50 wt% PLA, meanwhile
2.079 and 0.168 at fo = 8.8 GHz for EFBPLA5050 with 10 wt% EFB and 90 wt%
PLA and 2.23 and 0.09 at fo = 8.4 GHz for PALFPLA with 50 wt% PALF and 50
wt% PLA. The MA performance is observe from CST simulation, where S11 and S21
parameters are the key factors of MA absorption rates (AR), fractional bandwidth
(FBW) and its thickness, d is used to determine the new formulation of figure of
merit (FOM) for the percentage of wave absorption per unit milimeter (mm).
OPFPLA5050 MA with d = 9 mm resonates at 8.6 GHz show the optimum
performance with AR of 40.9%, FBW of 31.2% and the FOM is 4.5% per unit mm
using normal incident in TE and TM polarization. When incident wave transmitted
in variation angles of , the AR and FBW increase as increases until 45o
in TE and TM polarization. Then, OPFPLA5050 MA is fabricated using 30 x 30 x 1 cm3 mould
and hot press machine. It is measured using free space and bistatic reflection
methods. The results shows OPFPLA5050 MA with d = 10 mm resonates at 8.17
GHz with AR is 35.9%, FBW is 7.42 % and FOM is 3.6% per unit mm. Due to
fabrication error, the MA thickness is different form the simulation although their
plots show same trends except for the shifted resonant frequency. A fine-tune
simulation shows that the fabricated MA consider to have ’ = 2.46 and tan = 0.12
and frequency at 8.17 GHz where the corresponding AR is 32%, FBW is 26.8% and
FOM is 3.2% per unit mm which is close to the fabricated results. Then, a similar
trend observed with the simulations when varies from 0o
in 45o
in TE and TM
polarization. Therefore, these findings on natural fiber reinforced PLA
biocomposites have significant implications in the application of microwave
absorber. The unique composition between oil palm frond fibers and PLA
demonstrates promising wave absorption for further exploration as alternative
material in future research. |
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