Cellulose nanofibers from oil palm mesocarp fiber and their utilization as reinforcement material in low density polyethylene composites
Oil palm mesocarp fiber (OPMF) is made up of mainly cellulose, making it a potentially raw material for microfibrillated cellulose (MFC) and cellulose nanofiber (CNF) production. MFC and CNF properties may be influenced by their production method; it is therefore in this study three different...
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| Format: | Thesis |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/77050/1/IPTPH%202018%207%20-%20IR.pdf |
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| Summary: | Oil palm mesocarp fiber (OPMF) is made up of mainly cellulose, making it a
potentially raw material for microfibrillated cellulose (MFC) and cellulose nanofiber
(CNF) production. MFC and CNF properties may be influenced by their production
method; it is therefore in this study three different methods were used for the
production of MFC and CNF from OPMF: electrospinning, ultrasonication and high
pressure homogenization. In electrospinning, cellulose concentration and ionic
liquid formulation affected the cellulose solubility, and viscosity; which influenced
the properties of the MFC produced. The best MFC was formed when 6% (w/v)
OPMF-cellulose was dissolved in ([EMIM]Cl:([C10MIM][Cl]):DMF; whereby MFC
with average diameter of 200 to 500 nm, crystallinity of 57% and Td50% at 348 °C
was obtained. By using electrospinning, nano-sized fiber (< 100nm) was not
obtained, hence, ultrasonication and high pressure homogenization were
conducted. Ultrasonication at 125 W and 36 kHz for 9 hours produced mixture of
MFC and CNF with non-homogeneous diameter size between 40 – 200 nm,
having crystallinity index and Td50% of 41% and 338 C, respectively. Meanwhile,
high pressure homogenizationconducted at 50 MPa for 30 passes with cellulose
concentration of 0.2% (w/v) resulted in CNF with diameter of 80 – 100 nm,
crystallinity index of 62% and Td50% at 353 C. The CNF obtained from high
pressure homogenization method was then used as reinforcement material for low
density polyethylene (LDPE) composites production. Effect of melt compounding
methods on the mechanical properties of nano-sized fiber composites was
determined. Composites consisted of low density polyethylene (LDPE), maleic anhydride-grafted PE (PEgMA) and CNF at formulations of 97/3/0.5–5 (wt/wt/wt),
respectively, were prepared by twin screw extrusion and internal melt blending
processes. Morphology of the composites as revealed by SEM-EDS and X-CT
scan showed that the twin screw extrusion process permitted homogeneous
dispersion of CNF, thus led to an increment of up to 195% in flexural strength
compared to neat LDPE. In contrast, the composites prepared by internal meltblending
method showed an agglomeration and heterogeneous dispersion of CNF
within LDPE matrix, caused the composites to have lower tensile strength and
flexural strength compared to those prepared by twin screw extrusion. CNF-based
composites preparation method can be shortened by introducing simultaneous
nanofibrillation and melt compounding using one unit operation. Herewith, a onepot
process was conducted by using an extruder with specially designed twin
screw. FE-SEM micrograph exhibited that the resultant LDPE/CNF composites
had CNF with average diameter of 80 – 100 nm. These composites prepared by
one-pot process had similar properties with those prepared in conventional twopot
process, with the advantage of having higher productivity – by almost doubled.
A two-step in one unit operation (2-in-1) would be an ideal process for composites
making as this method may improve productivity, reduce downtime in between the
two steps, could contribute to a lower capital and processing costs, and may have
lower energy consumption. The one-pot process also meets most of the Green
Chemistry Principles; suggesting the method as a sustainable and greener method
for polymer composites production. |
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