Citation
Penjumras, Patpen
(2018)
Development of antioxidant packaging material based on optimized poly (lactic acid) and cellulose from durian rind biocomposites.
Doctoral thesis, Universiti Putra Malaysia.
Abstract
Durian rinds are the plant waste of durian fruit consumption. Only one-third of
a durian is edible, whereas the seeds and the shell become waste. With
regards to environmental impact, the waste can be converted into value-added
products, such as cellulose, to be used as reinforcement material in
biocomposites. Cellulose is extracted from ground durian rind using
delignification with acidic sodium chlorite, followed by mercerization with
sodium hydroxide. The diameter and aspect ratio of cellulose fibers are in the
range of 100-150 μm and the aspect ratio is in the range of 20-25, which is
higher than the minimum aspect ratio value for good strength transmission for
any reinforcement. A central composite design was employed to determine
the optimum preparation condition of the biocomposites to obtain the highest
tensile strength and impact strength. The selected optimum condition was 35
wt.% cellulose loading at 165°C and 15 minutes of mixing, leading to a
desirability of 94.6%. Under the optimum condition, the tensile strength and
impact strength of the biocomposites were 46.21 MPa and 2.93 kJ/m2,
respectively. The coupling agent 3-aminopropyltriethoxysilane (APS) was
used to modify the surface of cellulose. The result found that silane-treated,
cellulose-reinforced biocomposites offered superior mechanical properties
compared with neat PLA and untreated cellulose-reinforced biocomposites.
The adhesion of cellulose and the PLA matrix was improved by modifying the
cellulose surface, which led to less water absorption into biocomposites. An
antioxidant packaging material was developed using silane-treated durian rind
cellulose reinforced poly(lactic acid) (PLA) biocomposites. The release of BHT
and -tocopherol with 3 wt.% from neat PLA and biocomposites into two food
simulants (50% and 95% ethanol in water) at two temperatures (27°C and
37°C) were monitored. The result found that BHT had a higher release rate than -tocopherol. At higher temperatures, the resulting release rate
increased. Antioxidant was released from neat PLA faster than biocomposites.
BHT released faster into 95% ethanol, while -tocopherol released faster into
50% ethanol. The faster release of antioxidant from each condition contributed
to the inhibition of lipid oxidation, which was indicated by the decrease of
peroxide value (PV) and thiobarbituric acid reactive substance (TBARS). It can
be summarized that BHT had higher effectiveness as an antioxidant in active
packaging application for edible oil. This study concluded that durian rind cellulose
can be successfully used as a reinforcing material for poly(lactic acid) biocomposites.
Its application, with the addition of antioxidants was seen to be an effective active
packaging for the protection of edible oil from oxidation.
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