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Journal of Advanced Research in Applied Sciences and Engineering Technology 48, Issue 2 (2025) 1-9
1
Journal of Advanced Research in Applied
Sciences and Engineering Technology
Journal homepage:
https://semarakilmu.com.my/journals/index.php/applied_sciences_eng_tech/index
ISSN: 2462-1943
Properties of Key Lime Essential Oil Blend into Polylactide
Acid/Polyethylene Glycol Film Composite
Muhammad Hanif Izzat Muhammad Zalizan1,*, Nabihah Abdullah1, Rabiatul Manisah Mohamed1,
Yusuf N.N.A.N.2, Masataka Kubo3
1
2
3
Faculty of Engineering Technology, University College TATI, 24000 Kemaman Terengganu, Malaysia
Department of Energy, Minerals and Material Technology, University Malaysia Kelantan, 17600, Jeli, Kelantan, Malaysia
Division of Applied Chemistry, Graduate School of Engineering, Mie University, Tsu, Mie 514-0102, Japan
ARTICLE INFO
ABSTRACT
Article history:
Received 9 June 2023
Received in revised form 27 December 2023
Accepted 15 June 2024
Available online 15 July 2024
Lime essential oil (LEO) has the potential to be incorporated into a film. Biodegradable
polylactic acid (PLA) has shown potential in packaging applications. In this study, Lime
extraction was carried out using a simple distillation method, and solvent casting
methods were used to form the films. FT-IR result shows that the PLA primary
functional group was visible at the frequency region of 495-560 cm-1 and 1740-1750
cm-1. With the addition of polyethylene glycol (PEG) and lime essential oil, the
composite shows improvement in thermal stability. Even after being heated to 500 °C,
none of the three samples completely disintegrated after being given lime essential oil
as an additive.
Keywords:
Polylactide acid composite; key lime
essential oil extraction; PLA thermal
properties
1. Introduction
Lemon, orange, and lime citrus peel are used in industrial production such as pharmaceutical,
food and beverage as stated by Andersen et al., [1]. As a significant processed crop, citrus generates
substantial wastes and products that are rich in various bioactive substances, including pectin, water-
soluble and insoluble antioxidants, and essential oils as mentioned by Barkoula et al., [2]. If citrus
peels are thrown away, they may contribute to environmental problems, most notably water
pollution. This is because citrus peels contain biomaterials such as oil, pectin, and sugar, which
encourage aerobic bacteria to break down biodegradable organic matter into water contaminants
such as carbon dioxide, nitrates, sulphates, and phosphates. Citrus peels are a potential contributor
to environmental problems because of the potential for water pollution, this issues has been pointed
out by Davoodi et al., [3].
Essential oils and volatile oils from a variety of medicinal plants have been utilized to treat cancer,
lung conditions, neurological diseases, and cardiac ailments as health-promoting agents [4]. In
* Corresponding author.
E-mail address: izzatzalizan@gmail.com
https://doi.org/10.37934/araset.48.2.19
Journal of Advanced Research in Applied Sciences and Engineering Technology
Volume 48, Issue 2 (2025) 1-9
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addition, essential oils and the goods that are derived from them can be found in a wide variety of
industries, including but not limited to soaps, cosmetics, aromatherapy, fragrances, phytomedicine,
cleansers, seasonings, meals, agriculture, and drinks [5]. Similarly, like most essential oils, it is
obtained as a byproduct of the juice extraction process using centrifugation, and the resulting oil is
cold pressed [6].
The effects of climate change and the depletion of our planet's natural resources are already
profoundly impacting our daily lives. To protect the environment, scientists are producing
biodegradable and ecologically friendly items [7]. Polylactic acid (PLA) has become the most
extensively used disposable biopolymer in the world because it is biodegradable, has a high level of
biocompatibility, and is transparent. The features of high strength and outstanding processability
make PLA one of the most promising biopolymers. PLA is one of the most promising biodegradable
polymers. As a result, PLA is one of the polymers with the highest level of biodegradability. However,
because of its molecular structure and crystallization, PLA has several obvious drawbacks, some of
which are a high level of brittleness, a low level of melt strength, and a small processing window.
These characteristics combine to significantly restrict its application in a variety of industries [8].
Therefore, many PLA modification studies have been conducted to improve its performance [9].
In this study, PLA was reinforced with Polyethylene Glycol (PEG) to overcome the limitation of PLA.
The key lime essential oil (LEO) was blend into PLA/PEG film to determine the properties of the new
material of composites.
2. Methodology
2.1 Materials
The Key lime that been used in this research was purchased at local super market. The key lime
used was selected in order to make sure the quality of the obtained key lime essential. The solvent
that has been used in this research was chloroform was purchased at Merck KGaA. Polylactic acid
was selected as a polymer in this research was purchased at cardia-bioplastics and polyethylene
glycol was purchased at Sigma-Aldrich.
Tables 1 contain a list of the material specifications used in this research.
Table 1
Material details used in this study
Material
Brand
Key lime
-
Chloroform
Merck KGaA
Polylactic acid
Cardia-bioplastics
Polyethylene glycol
Sigma-Aldrich
2.2 Extraction of Key Lime Essential Oil (LEO)
The oil was extracted from the key lime peels through a simple distillation process. First, the citrus
fruit was peeled and chopped into small pieces. For the extraction, 100 g were measured. The peels
were then added to the round-bottomed boiling flask. In the flask, 250 mL of water was used as the
solvent. The temperature was set to 100 degrees Celsius. As the liquid is heated, vapours with a low
boiling point are produced. The duration of this procedure was three hours. The oil mixture was then
separated using a separating funnel.
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2.3 Gas Chromatography Method
Component PLA/PEG/LEO were determined using gas chromatography. Gas chromatography was
setting accordance to Table 2 below.
Table 2
Gas chromatography setting
Column type
Phenomenex ZB-wax plus; 30m x 0.25mm; 0.25µm
Carrier gas
Helium
Flow
1.0 ml/min
Oven
45 °C,6 min,3 °C /min, 90 °C, 5 °C /min, 180 °C, 16 min
Detector
220
Injector
220
Injection volume
1µL
Split
1:100
Run time
55 min
2.4 Incorporation of Key Lime Essential Oil into PLA/PEG/LEO Film
A solvent casting process was used to prepare a polylactic acid/polyethylene glycol/lime essential
oil film (PLA/PEG/LEO). PLA (1 g) and PEG (0.1 g) were weighted, vigorously dry mixed, and then
added to a glass beaker with 20 mg chloroform and stirred until the polymer dissolved. The essential
oils (5, 15, and 40% w/w of PLA/PEG) were put into the PLA/PEG solutions and blended for an
additional 15 minutes to ensure that the lime essential oils were wholly incorporated into the film
solutions. The resulting mixture was placed onto a (10 cm×1.5 cm) glass petri dish. The chloroform
was evaporated in a fume hood at room temperature. Peeled dried films were removed from the
glass plates and stored at room temperature (25°C) in a desiccator until further usage.
2.5 Thermal Properties
2.5.1 Differential scanning Calorimetry (DSC)
The glass transition and crystallisation were determined using differential scanning calorimetry.
Melting temperatures of PLA/PEG/LEO samples (Perkin-Elmer Diamond DSC). 5 mg samples were
heated at a rate of 5 °C step/min between 30 and 200°C under a constant flow rate of 20 mL/min
nitrogen gas purging through the calorimeter. After 1 minute at 200°C, the sample was cooled to
30°C and then heated to 200°C at the same rate of 5°C /min.
2.5.2 Thermogravimetric analysis (TGA)
The thermal stability of PLA/PEG/LEO samples was studied using a Perkin-Elmer TGA machine and
5-10 mg of samples heated at a rate of 10 °C per minute from room temperature to 500 °C. Each
sample's initial and final degradation temperatures, as well as the accompanying percentage weight
loss, were recorded.
2.5.3 Fourier transform infrared spectroscopy (FT-IR)
Fourier transform infrared spectroscopy of PLA/PEG/LEO film determined their functional group
and carbon structure using Fourier transform infrared spectroscopy (FT-IR). Spectra were collected
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for all the samples by recording 32 scans in % transmission mode in the range of 4000 cm-1 – 400 cm-
1. Peak deconvolutions were performed using Perkin Elmer GRAMS software.
3. Results
3.1 Characterization of Key Lime Essential Oil
Figure 1 shows a chromatogram of the key lime essential oil standard. The graph shows that the
beta-pinene peak occurred at minute 5.08, the limonene peak occurred at minute 8.71, and the
gamma-terpinen peak occurred at minute 10.78. These VOCs were any one of the hundreds of
aromatic chemicals that make up essential oils.
Fig. 1. Gas chromatography of key lime essential oil standard
Figure 2 shows a chromatogram for obtained key lime essential; The graph shows that the peak
of beta-pinene concentration occurred at minute 4.88, the peak of limonene concentration occurred
at minute 8.92, and the peak of gamma-terpinene concentration occurred at minute 10.78. The
findings indicate that the extraction of essential oil was successful because the peaks in Figures 1 and
2 are comparable to one another. Figure 1 and Figure 2 also show that limonene has the higher
concentration compare to the gamma Terpene and beta pinen, this has been proved in previous
study [10,11].
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Fig. 2. Gas chromatography of key lime essential oil
3.2 Fourier Transform Infrared Spectroscopy (FT-IR)
The C-H stretch's distinctive bands, which are between 2877 and 2797 cm-1, are shown in Figure
3. In Figure 3, the carboxylic acid O-H stretch is highly diagnosed at 3318 cm-1, and in Figure 3, it is
highly diagnosed at 3250 cm-1. The characteristic absorption for the C=C stretch occurs at 1637 cm-1
(Figure 3) and 1640-1585 cm-1 (see Figure 3). The characteristic bands depicted in Figure 3 correspond
to the C=O stretch at 1763 cm-1.
Fig. 3. FT-IR spectra of key lime essential oil
FT-IR spectroscopy is one of the most sophisticated methods for assessing changes in the
conformations of films. The PLA composite's FT-IR spectra are displayed in Figure 4. FT-IR
spectroscopy is one of the most advanced tools for determining changes in the conformations of
films. According to the report, the primary functional group of PLA appeared in the C=O group-
assigned frequency ranges of 495-560 cm-1 and 1740-1750 cm-1 aligned with previous study[12,13].
From the previous study, when PEG was added to the PLA composite, there was no noticeable change
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at the peaks [14]. Therefore, the similar natural structure of PLA and PEG consists of carbon and
oxygen atoms. This research confirmed that the carbonyl group’s absorption shift peak of PLA and
PEG films moved from 502 cm-1 to 587 cm-1. It demonstrated that PEG has good PLA miscibility, and
low molecular weight PEG enhanced PLA miscibility in line with prior studies [12]. There was a change
in the intensity of the peak at 726 cm-1 after the additional of lime essential oil into the composite
film. This was caused by the C=O group in key lime essential oil (Figure 3) merging with the C=O group
in the composite.
Fig. 4. FT-IR spectra of film
3.3 Differential Scanning Calorimetry (DSC)
DSC thermograms revealed the presence of two distinct thermal transitions: the glass transition,
indicated by the glass transition temperature (Tg), and the crystallization process, characterized by
the crystallization temperature (Tc). By heating the amorphous material, Tg is defined as a physical
change from the way of flexibility to the way of glass Consistent with previous studies [15]. The values
obtained are reported in Table 3. Pure PLA It was discovered that the glass transition temperature
was 41 °C, which is highly comparable to what was stated in the [16] which is at 42.6 °C, and with
addition of PEG increased the composite Tg by about 14°C, which makes Tg for PLA/PEG composite
55°C. The addition of LEO also increased Tg for Composite, which makes Tg for PLA/PEG/5%LEO 59°C,
61°C for PLA/PEG/15%LEO, and Tg for PLA/PEG/40%LEO is 63°C. According to this data, adding PEG
and LEO slightly increases the composite's thermal stability.
Table 3
Data obtained from DSC analysis for PLA composites
Sample
Glass Transition (Tg, °C)
Crystallization Temperature (Tc, °C)
PLA
41
83
PLA/PEG
55
99
PLA/PEG/5% LEO
59
101
PLA/PEG/15% LEO
61
102
PLA/PEG/40% LEO
63
105
Figure 5 also shows that pure PLA began to crystallize at 83°C, and the temperature increased
when pure PLA and PEG were added at 99°C. A similar behaviour also detected by [17]. Crystallization
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also slightly increased when lime essential oil was added to the composite where make Tg for
PLA/PEG/5%LEO is at 101°C, 102°C for PLA/PEG/15%LEO, and 105°C for PLA/PEG/40%LEO. The
findings unequivocally show that increasing PEG and lime content in PLA composite can boost
crystallization temperature.
Fig. 5. DSC thermogram of film
3.4 Thermogravimetric Analysis (TGA)
Thermogravimetric analysis (TGA) measurements were carried out so that an investigation into
the thermal characteristics of the composite could be carried out. As can be seen in Figure 6, the
temperature at which pure PLA begins to decompose is 277°C. After reaching this temperature, the
loss in weight continued, and the final degree temperature for PLA was determined to be 363°C, align
by a previous study [18]. With the addition of PEG in the composite, the composite start decomposing
at 256°C, much lower than pure PLA, and attains a final degree temperature at 448°C, in accordance
with previous study[19,20]. PLA/PEG/5% LEO film shows that the sample start decomposes at 270°C,
whereas PLA/PEG/15% LEO film starts to decompose at 275°C lastly is a composite with higher
additional percentage of lime essential oil start 280°C. According to the findings, the incorporation
of lime essential oil leads to an increase in the temperature of the sample's initial decomposition.
With the addition of lime essential oil, none of the three samples fully decomposed even after being
heated to 500°C.
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Fig. 6. Thermogravimetric of film
4. Conclusions
With a simple distillation method Key lime essential oil was successfully extracted proven by gas
chromatography. PLA was incorporated into composite by casting method and undergo FT-IR to
assessing changes in the conformations of films. There was no noticeable change at the peaks since
PLA and PEG consists of similar natural structure. Glass transition of composite gradually increase
with the addition of PEG and Key lime essential oil. The same thing occurs with crystallization
temperature. For thermal stability, a composite without PEG has higher thermal stability than
composite with PEG.
Acknowledgement
The authors are grateful and would like to express sincerely to the Ministry of Higher Education
(MOHE) of Malaysia for the Fundamental Research Grant Scheme (FRGS/1/2020/TK0/TATI/02/1) and
University College TATI for providing facilities.
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