Extraction and characterization of cellulose nanocrystals from tea leaf waste fibers as a filler in poly(lactic acid) bio-nanocomposites
Poly(lactic acid) (PLA) is known to be a very useful material in replacing the petrochemical-based polymer in the packaging sector due to its biodegradability and good mechanical characteristics. Despite the impressive behaviors of PLA, the low brittleness of itself has limited the usage of this...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/83538/1/FS%202018%2096%20-%20IR.pdf |
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| Summary: | Poly(lactic acid) (PLA) is known to be a very useful material in replacing the
petrochemical-based polymer in the packaging sector due to its biodegradability and
good mechanical characteristics. Despite the impressive behaviors of PLA, the low
brittleness of itself has limited the usage of this material. Thus, cellulose nanocrystals
(CNCs) was extracted from tea leaf wastes fibers (TLWF) to incorporate into PLA,
enhancing the performance of polymer nanocomposites while keeping the environment
safe.
This research was conducted to explore the utilization of TLWF as a source for the
production of CNCs and its uses as a filler on PLA. TLWF was first treated with
alkaline, followed by bleaching before being hydrolyzed with concentrated sulfuric
acid. The materials attained after each step of treatments were characterized. From
Fourier transform infrared spectroscopy (FTIR), the peak at 1716 represents C=O
stretching disappeared in the spectra after the alkaline and bleaching treatments
indicated that hemicellulose and lignin were almost discarded from the fiber. The
reduction intensity of the absorption band at 1236 cm−1which accredited to the C–O
stretching vibration of the lignin and xylan occurred due to the decreasing of lignin and
a small hemicellulose contents from TLWF. Meanwhile, the thermal stability of CNCs
was decreased due to the replacement of hydroxyl groups by sulfate groups during
hydrolysis. The scanning electron microscopy (SEM) showed the defibrillation of
fibers occurred after the treatments, increasing the susceptibility of fiber for acid
hydrolysis. The crystallinity index of fiber also increased from 41.5% to 83.1% and
from transmission electron microscopy (TEM), the rod-like shaped CNCs with an
average diameter of 7.97 ± 1.09 nm was revealed.
Then, the resultant CNCs were used as filler in PLA bio-nanocomposites via solvent
casting method. The different contents of CNCs between 0.5 to 5 wt % were filled. The
mechanical properties of films were analyzed through the tensile properties. The
optimum value of tensile strength and modulus was achieved when 2.0 wt % of CNCs
content was incorporated into the matrix. As a conclusion, CNCs can be produced from
TLWF and can be used as a filler for PLA at the 2.0 wt % of CNCs loading. |
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