Progress in Engineering Application and Technology Vol. 3 No.

1 (2022) 756–768
© Universiti Tun Hussein Onn Malaysia Publisher’s Office

PEAT
Homepage: http://publisher.uthm.edu.my/periodicals/index.php/peat
e-ISSN : 2773-5303

Evaluation of Virgin and Recycled LDPE Plastic

Bags Manufactured using Film Blowing Machine
Kong Pei Yee1, Yong Tze Mi1*, Mazlan Zakaria2, Kang Chee
Hwang2
1
Department of Mechanical Engineering Technology, Faculty of Engineering
Technology, Universiti Tun Hussein Onn Malaysia, 84600 Pagoh, Johor,
MALAYSIA
2
No 22, Jalan Kota Murni, Taman Perindustrian Kota Murni, Off Jalan Minyak Beku,
83000 Batu Pahat, Johor, MALAYSIA

*Corresponding Author Designation

DOI: https://doi.org/10.30880/peat.2022.03.01.075
Received 17 January 2022; Accepted 11 April 2022; Available online 25 June 2022

Abstract: Plastic is a versatile material that can be shaped and molded, making it a
popular choice for a wide range of items. As a result, the demand for and
manufacturing plastic bags is gradually increasing. Every year, it is estimated that
trillions of plastic bags are used as carrying bags all over the world. Film blowing
extrusion is the most common method for producing plastic films, particularly in the
packaging industry. The raw material used was Low Density Polyethylene (LDPE).
Thus, in this study the mechanical properties of plastic bags are evaluated by using
thickness measurement, density test, tensile test, tearing test and oxygen permeability
test and and make comparison between Wahdah Plastics Industry Sdn. Bhd. and
commercial plastic bags samples. The samples will undergo a few tests according to
the American Standard Testing Method (ASTM) includes thickness measurement
(ASTM D6988-13), tearing test (ASTM D689-03), tensile test (ASTM D882),
oxygen permeability test (ASTM D1434-82) and density test. The results have shown
that plastic sample A which is virgin LDPE from Wahdah Plastic Industries is best
overall for the tensile and tearing test. In the tensile test, the most ductile sample is
sample A at the cross direction. The tearing strength after divided by thickness of
sample A is the highest which showed it needs more strength to tear the plastic film
and withstand high tearing resistance. This sample tends to float on the water and is
better for the environment since it is easy to be removed when it floats on the water.
Overall, sample A which is virgin LDPE from Wahdah Plastic Industries showed the
best performance in thickness, density, tensile, tearing strength and oxygen
permeability test which achieved desired quality of plastic bag to sell on the market.

Keywords: Low Density Polyethylene (LDPE), Plastic, Recycled, Virgin

1. Introduction

*Corresponding author: tmyong@uthm.edu.my

2022 UTHM Publisher. All right reserved.
penerbit.uthm.edu.my/periodicals/index.php/peat
Yee et al., Progress in Engineering Application and Technology Vol. 3 No. 1 (2022) p. 756-768

Plastic bags seem to have always been a part of our lives. Markets, grocery shops, and other retail
establishments frequently utilize plastic bags. Plastic bags are used approximately 1 trillion times per
year, owing to their durability and low cost. When shopping at markets or grocery stores, 96.00 % of
shoppers use plastic bags, 2.00 % use paper-based bags, and only 2.00 % use reusable bags [1]. Plastic
waste is easily dispersed, permanent, noticeable, and an essentially accumulated waste material due to
the same characteristics that make it a flexible packaging material, durable, lightweight, and high
strength. Plastic bag, on the other hand, is mostly non-biodegradable and if they are not properly handled,
it will pollute the atmosphere and living organisms [1].
Plastic pollution has already established itself as a major problem. Plastic littering not only causes
substantial discomfort to people of the impacted towns and suburbs, but it also harms bodies of water,
forests, and the ecosystem in general. Various systems have previously been devised and used for the
disposal of plastic utensils, windows, and other solid things. Plastic bags, on the other hand, have
received insufficient attention [2]. This environmental problem has now caught the interest of
governments all over the world, including Malaysia. The government has made numerous attempts to
protect the environment from damage. Earth Hour, Go Green, and 3R (reuse, reduce and recycle). Each
of these initiatives takes a different approach to raise public awareness. As a result, the Malaysian
government has launched a "No Plastic Bag" initiative as part of its recycling campaign. Many
businesses have contributed to the success of the "No Plastic Bag" movement by collaborating with the
government.
In this project, the plastic film provided from Wahdah Plastics Industries Sdn. Bhd. will be
undergone testing and be evaluated together with the plastic film bought from internet. Using recycled
plastics can reduce natural gas and oil exploration, mining, and transportation, dramatically minimizing
environmental consequences [3]. The machines used for testing are in Makmal Sistem Pengujian,
UTHM Campus Pagoh and is specially designed for the testing for plastic. To improve the recycled
plastic bag’s quality, tests will be conducted to evaluate the mechanical properties of plastic films
produced from the trial formulas according to the American Standard Testing Method (ASTM). ASTM
includes thickness measurement (ASTM D6988-13), density test, tearing test (ASTM D1922), tensile
test (ASTM D882) and oxygen permeability test (ASTM D1434).
Wahdah Plastics Industries Sdn. Bhd. is classified as Plastic Injection Moulding Manufacturers and
Plastic Products. This industry’s costumer is the majority from the furniture industry and fishery
industry. The main focus of this project is the evaluation of virgin and recycled LDPE plastic bags
produced from Wahdah Plastics Industries Sdn. Bhd. With testing the plastic films manufactured,
Wahdah Plastics Industries will have better knowledge of the performance of their products in the
market.
The study aims to evaluate the mechanical properties of plastic bags by using thickness
measurement, density test, tensile test, tearing test and oxygen permeability test and and make
comparison between Wahdah Plastics Industry Sdn. Bhd. and commercial plastic bags samples.
1.1 Plastic bag usage in Malaysia
Malaysia launched the No Plastic Bag Day campaign in 2011 to discourage people from using
plastic bags. Plastic bags are widely used as shopping bags in the world. However, their widespread use
generates a significant amount of plastic waste. Plastic waste takes a long time to decompose, leading
to air, water, and soil pollution [4]. A study was carried out mentioned that out of 192 coastal nations,
Malaysia is the seventh greatest supplier of mismanaged plastic trash. According to this report, Malaysia
produced 0.94 million tonnes of poorly managed plastic trash, with 0.14 to 0.37 million tonnes
potentially pouring into the oceans in 2010. Plastics account for 13.00 % of Malaysia’s solid waste,
with 55.00 % of that being mismanaged [5].

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2. Materials and Methods

This section will discuss and focus on the framework used to complete this project. The methods
start with the sample collection from Wahdah Plastics Industries Sdn. Bhd., followed by the purchasing
of plastic from the market and ending with the data analysis of the plastics bags produced. The project
will end with the reporting to Wahdah Plastics Industries Sdn. Bhd. Besides, this section also will
explain about material and methods that were used in the five tests.
2.1 Material selection
In this project, virgin and recycled LDPE plastic samples were collected from Wahdah Plastics
Industries Sdn. Bhd. Also, samples that were bought from the internet are selected and purchased to
undergo several testings and to make a comparison.
2.1.1 Sample collection from Wahdah Plastics Industries Sdn.Bhd.
The plastic film provided from Wahdah Plastics Industries Sdn. Bhd. is virgin and recycled LDPE
when collected the plastic sample from the factory. Therefore, the plastic film is decided to LDPE
plastic type in this project, thus another virgin and recycled plastic film are bought from the market to
make a comparison. Figure 1 and Figure 2 show the virgin and recycled LDPE plastic samples collected
from Wahdah Plastic Industries.

Figure 1: Virgin LDPE plastic sample Figure 2: Recycled LDPE plastic sample

2.1.2 Sample bought from internet

Other than sample collection from Wahdah Plastic Industries, another commercial virgin and
recycled plastic films also purchased. Figure 3 shows the commercial virgin LDPE plastic sample while
Figure 4 shows recycled LDPE plastic sample. These plastic films are then undergoing the same testing
with the plastic films collected from Wahdah Plastic Industries.

Figure 3: Commercial virgin LDPE plastic sample Figure 4: Commercial recycled LDPE plastic
sample

2.2 Product testing

2.2.1 Thickness measurement
According to ASTM D6988-13, Standard Guide for Determination of Thickness of Plastic Film
Test Specimens, this guide is intended to provide advice and best practices for determining precise
dimensions when they are required for the calculation of physical unit attributes. This guide covers the
determination of the thickness of plastic films where the thickness is used directly in determining the
results of tests. According to ASTM D6988-03, a square shape film will be cut which is 10.00 cm ×

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10.00 cm and a total of 20 pieces of specimen with 5 pieces each for the 4 different types of plastic film
and every specimen will be marked for identification. Precision micrometer TMI 49-61 is used for
thickness measurement.
2.2.2 Density test
The mass density of an object, also known as density, is the mass divided by the volume of the
thing. The Greek letter rho (ρ) is used to denote density, which is determined using the density formula:
𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚
𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 = Eq. 1
𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣

The piece of the plastic specimen was cut into a given size that is the same as the thickness test,
which is 10cm × 10cm and being weighed by using a weighing machine. A total of 20 specimens was
needed for 4 different types of plastic film. 5 measurements on each specimen were required to be tested.
The volume of the plastic film then is calculated from the thickness of the film multiplied by its area
which is length multiplied by width, as shown in equation 2. To calculate the density of the plastic film,
the measured mass was divided by the measured volume according to the equation shown above.
𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉 = 𝑡𝑡ℎ𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖 𝑥𝑥 (𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙ℎ 𝑥𝑥 𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤ℎ) Eq. 2
2.2.3 Tensile test
Tensile test was done according to the Standard Test Method for Tensile Properties of Thin Plastic
Sheeting (ASTM D882), the method's properties are useful for identifying and characterization of
materials for control and specification purposes. Tensile test was carried out using the hot tact tester. A
trial test was performed to determine the elongation of the specimen. According to Thin Plastic Sheeting
(ASTM D882), 10 specimens were to be tested from each sample, where 5 were used for machine
direction and cross direction respectively. The sample preparation for the test was cut into each strip
15mm wide while the length of the specimen is 160 mm and it must be cut in one stroke condition. The
area and reduced area after the tensile test of plastic are measured and calculated. Then, engineering
stress and true stress are calculated and compared based on the results.
2.2.4 Tearing test
According to Standard Test Method for Propagation Tear Resistance of Plastic Film and Thin
Sheeting by Pendulum Method (ASTM D1922), this test method is useful for comparing the tearing
resistance of different plastic films and thin sheeting. The machine used to conduct the tearing test is
Elmendorf Tearing Tester GT-7055-AD. In this tearing test, a total of 20 specimens from 4 different
plastic films was cut to form a rectangle shape 76mm in length and 63 mm in width according to ASTM
D1922. The gram force is a non-SI metric unit for force. Gram-force can be abbreviated as gf and Gram-
force is a unit of force equal to the force needed to move one gram of mass at a rate of 9.80665 meters
per second squared. The results were then recorded and be collected on the tearing tester. The tearing
force is determined using the equation:
1 𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 (𝑔𝑔𝑔𝑔) = 9.81 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 (𝑚𝑚𝑚𝑚) Eq. 3
2.2.5 Oxygen permeability test
Based on the Standard Test Method for Determining Gas Permeability Characteristics of Plastic
Film and Sheeting (ASTM D1434-82), this test method covers the estimation of the steady-state rate of
transmission of gas through plastics in the form of film, sheeting, laminates, and plastic-coated papers
or fabrics. Oxygen Transmission Rate (OTR) is the measurement of the amount of oxygen gas that
passes through a substance over a given time. The samples that are going to undergo the oxygen
transmission test are placed in a room with controlled temperature and humidity for not less than 48
hours according to ASTM D1434-82. This can ensure the plastic film samples are at the steady state

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rate at which the oxygen gas permeates through a film at specified conditions like temperature and
relative humidity. Figure 3 shows the oxygen permeability tester in Makmal Sistem Pengujian, UTHM.
The size of the film sample was cut into 12.50 cm x 12.50 cm for the oxygen permeability test based
on the template shown in Figure 6. Thickness for each sample is required before the oxygen
permeability test started and the unit for thickness is in 𝜇𝜇𝜇𝜇. Before the oxygen permeability test started,
the machine will need 1 hour for conditioning. 4 cycles are required for the testing process and 3 times
of the zeroing process.

Figure 5: Oxygen permeability tester Figure 6: Size template

3. Results and Discussion

The results based on the data obtained from the varying test which are thickness measurement,
density test, tensile test, tearing test and oxygen permeability test with the observation on the product
has been discussed.
3.1 Relative observation between plastic samples
The samples used in this research include virgin and recycled LDPE. Here the observation of
samples used was discussed including the colour, transparency, roughness compared to one another.

(a) (b)

(c) (d)
Figure 7: (a) Virgin LDPE from Wahdah, (b) Recycled LDPE from Wahdah, (c) Commercial virgin
LDPE, (d) Commercial recycled LDPE

For the recycled LDPE sample from Wahdah Plastic Industry shown in Figure 7 (a), the colour is
less white compared to the virgin material. The recycled LDPE is not so transparent as the virgin LDPE.
The surface of the plastic is also less smooth and can feel it is grainy. Different from the recycled LDPE,
the virgin LDPE in Figure 7 (b) has smoother surface. The transparency is also very good.
The virgin LDPE shown in Figure 7 (c) is the commercial plastic bag sample. The colour for this
virgin LDPE plastic is blue therefore not transparent. The surface is smooth we can feel the thickness
is thicker compared to the virgin LDPE plastic manufactured from Wahdah Plastic Industry. The

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commercial recycled LDPE is pink in colour in Figure 7 (d). It has some transparency. This plastic
sample has a smooth surface and does not feel too grainy.

3.2 Tests on LDPE plastic films

The result of thickness measurement, density test, tearing test and tensile test are tabulated and
discussed in the following sections.
3.2.1 Thickness measurement
A precision micrometer is used to conduct the thickness measurement. All specimens were cut into
a square shape with a dimension of 10 𝑐𝑐𝑐𝑐 𝑥𝑥 10 𝑐𝑐𝑐𝑐 according to ASTM D6988-08. Total 5 specimens
were measured for each virgin and recycled LDPE plastic. The plastic sample A, B, C and D was
represented by LDPE plastic bag as shown in Table 1.
Table 1: Description for plastic sample

Sample Description
A Virgin LDPE from Wahdah Plastic Industries
B Recycled LDPE from Wahdah Plastic Industries
C Commercial virgin LDPE
D Commercial recycled LDPE

Table 2: Total average thickness for samples

Sample Thickness of specimen (mm)

A 0.0496 ± 0.001
B 0.0577 ± 0.003
C 0.1165 ± 0.001
D 0.0398 ± 0.001

From the data tabulated from Table 2 which is the total average thickness for samples, the highest
average thickness collected was sample C, that is commercial virgin LDPE plastic sample that is 0.1165
mm while the lowest average thickness is 0.0398 mm which is sample D, commercial recycled LDPE
plastic sample recorded a value of 0.0398 mm.
The parameters used to manufacture virgin and recycled LDPE plastic from Wahdah Plastic
Industry are maintained constant for both plastic films. In this condition, sample A which is recycled
LDPE plastic film is thicker than sample B, which is virgin LDPE plastic. This can be explained based
on the processing method of the material. Recycled plastics may contain a multitude of unintentionally
added chemical additives or contaminants such as pesticide residues, pigments, flame retardants
identification of which alone is challenging and establishing polymer-based toxicological signature
more so [6].
3.2.2 Density test
Table 3 shows the density obtained that includes the data for thickness, area and volume of plastic
film.
Table 3: Density of samples
𝑔𝑔
Sample Thickness (mm) Area (𝑐𝑐𝑐𝑐2 ) Volume (𝑐𝑐𝑐𝑐3 ) Density (𝑐𝑐𝑐𝑐3 )
A 0.00496 100 0.496 1.028
B 0.00577 100 0.577 0.816
C 0.11650 100 1.165 0.953
D 0.03980 100 0.398 0.804

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From Table 3, all the samples have a good density towards water since all the samples have a lower
density than the seawater which is 1.03 𝑔𝑔⁄𝑐𝑐𝑐𝑐3. All four samples will float on the seawater and this will
ease the plastic collection process if all the plastic waste is lighter than seawater's average density [7].
The lower the density of the plastic film sample, the higher the tendency of plastic film to be floating
on the water. Thus, the sea life and quality of aquatic life will be improved by reducing the result of
ingestion, starvation, suffocation, infection and drowning that caused by marine plastic pollution [8].
The low-density property of the four plastic samples is also better for the environment because the
plastics are easy to remove when they float on water. To conclude, sample D has the highest tendency
to be floating on the water as resulting it has the lowest density among the four samples.

3.2.3 Tensile test

Table 4 shows the description of plastic samples. The dimension of the specimen used in this test
was 15.000 mm 𝑥𝑥 160.000 mm (width 𝑥𝑥 length). At least 10 specimens, 5 specimens in machine and
cross direction respectively were tested for each sample.
Table 4: Description for plastic sample

Sample Description
A1 Virgin LDPE at machine direction from Wahdah Plastic Industry
A2 Virgin LDPE at cross direction from Wahdah Plastic Industry
B1 Recycled LDPE at machine direction from Wahdah Plastic Industry
B2 Recycled LDPE at cross direction from Wahdah Plastic Industry
C1 Commercial virgin LDPE at machine direction
C2 Commercial virgin LDPE at cross direction
D1 Commercial recycled LDPE at machine direction
D2 Commercial recycled LDPE at cross direction

Figure 8 (a) shows among the specimens for sample A1, four of the plastic films breaks, while only
one does not break.

From Figure 8 (b), we can see that among the specimens A2, only one specimen failed. Four
specimens did not fail after the end of the test. It as expected of the film because B are manufactured
thicker. Two out of five specimens undergo three times necking, while the other three specimens
undergo two times necking. It has better ductility due to long necking and has a strong bonding which
is produced a better strength because it is hard to break. The plastic film with a better ductility exhibited
greater susceptibility to plastic deformation and was easy to neck. This shows that the sample which
experienced a higher number of necking has the higher plasticity. The higher degree of the strength for
virgin LDPE at cross direction led to a higher degree of crystallinity and this will influence the
mechanical properties of the plastic [9].

Figure 8 (c) shows specimens B1 after undergoing tensile test. It is clear to see the plastic specimen
experience whitening after the tensile test. The plastic film needs more force to elongate it thus other
parts of the film will now experience stretching. When force is applied to the plastic film, it can cause
the amorphous sections of the chain to crystalize [10]. When that happens, the way the molecules scatter
light changes causes molecular changes that lead to whitening. It is obvious to observe that all
specimens B2 after undergoing tensile test are all broken down in a shorter time as they do not elongate
more shown in Figure 8 (d). These specimens only experience a little whitening because they are only
being strengthened in a small force which is only 6.60 N of average maximum force and 18.000 mm of
elongation.

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(a) (b)

(c) (d)
Figure 8: Specimen (a) A1, (b) A2, (c) B1 and (d) B2 undergo tensile test

All specimens C1 shown in Figure 9 (a) do not break as they are too thick, but they elongate and
are strengthened until the end during the tensile test and were the longest elongation among the 8
samples which is 457.4 mm. Figure 9 (b) shows specimen C2 experiences three times of necking and
they do not break until the end of the tensile test.

From Figure 9 (c), the 5 specimens for D1 all break into two with an average maximum force of
5.06 N. From Figure 9 (d), the specimens D2 all break into two with an average maximum force of 7.24
N. It required a higher force to break the plastic film in a cross direction compared to in machine
direction.

(a) (b)

(c) (d)
Figure 9: Specimen (a) C1, (b) C2, (c) D1 and (d) D2 undergo tensile test

From Table 5, the most ductile sample in sample A2, which is the virgin LDPE plastic from Wahdah
Plastic Industry at the cross direction, has the highest difference of average engineering and true stress.
In conclusion for the tensile test, four specimens A2 did not fail after the end of the test. Two out of
five specimens undergo three times necking, while the other three specimens undergo two times
necking. It has better ductility due to long necking and has a strong bonding which is produced a better
strength because it is hard to break. The plastic film of specimen A2 with a better ductility exhibited
greater susceptibility to plastic deformation and was easy to neck. This shows that the sample which
experienced a higher number of necking has the higher plasticity.
Table 5: Difference between engineering stress and true stress

Sample Average engineering stress

Average true stress (𝑁𝑁⁄𝑚𝑚𝑚𝑚2 ) Difference (%)
(𝑁𝑁⁄𝑚𝑚𝑚𝑚2 )
A1 14.7446 38.1152 164
A2 11.5753 49.7751 329
B1 11.6118 20.8166 79
B2 7.63030 22.8587 200
C1 11.9371 45.5646 282
C2 15.7173 56.6611 261
D1 8.48240 14.5438 71
D2 12.1340 19.6479 62

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3.2.4 Tearing test

Table 6 is a result after the average tearing strength for each sample is divided by its thickness. This
is to compare based on thickness for each sample as the sample is manufactured from a different factory.

After dividing the average tearing strength by thickness, the samples at machine direction which
are samples A1, B1, C1 and D1 have a lower tearing strength than at cross direction which are A2, B2,
C2 and D2 respectively. The tear strength in the machine direction is usually significantly lower than
that in the cross direction. From Table 6, sample A shows that at the cross direction it is 20.00 % stronger
compared to the machine direction, 33.00 % for sample B, 50.00 % for sample C and 24.00 % for
sample D. The mechanical failure of the films is closely related to film orientation. Cracks are easier to
be initiated in machine direction where crystals are aligned, and this shows that the plastic films are
weaker and easier to be torn. In the cross direction, the crystals are bonded, so the strength to tear the
films is higher.

Table 6: Difference between machine direction and cross direction tearing strength

Average tearing Average tearing strength Difference

Sample Thickness
strength (mN) divided by thickness (mN) (%)
A1 0.0496 1640.84 33,081.45
A2 0.0496 8290.76 167,152.42 20
B1 0.0577 2243.02 38,873.83
B2 0.0577 6807.83 117,986.66 33
C1 0.1165 6848.28 58,783.52
C2 0.1165 13564.09 116,429.96 50
D1 0.0398 1259.39 31,642.96
D2 0.0398 5172.95 129,973.62 24

(a) (b)

(c) (d)

(e) (f)

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(g) (h)
Figure 10: Specimen (a) A1, (b) A2, (c) B1, (d) B2, (e) C1, (f) C2, (g) D1 and (h) D2

The virgin LDPE plastic films at the machine direction show a smooth surface at the line of tear
while at the cross direction, the line of tear is rigged. The effect for the machine and cross direction are
the same from specimen A1 to specimen D2 and can be seen from Figure 10.

In conclusion for the tearing test, the virgin LDPE at cross direction collected from Wahdah Plastic
Industries which is sample A2 performed better and stated the highest average tear strength at
167,152.42 mN after being divided by its thickness. A thicker sample will naturally yield better
mechanical properties, but it is also less sustainable as more material is used. Thus, the sample is divided
by its thickness to compare the performance of the samples. The samples at the cross direction show
an obvious tear sign than the sample at the machine direction. This condition happened because the
plastic at cross direction absorbs more energy therefore it needs more strength to let the plastic
completely tear. While the plastic at the machine direction just affected little as the molecule aligns
straight up at this direction, therefore it is more easily to be torn off. Also, the thickness of every
specimen has different values which will affect the tearing strength value. Hence, the tendency to tear
off the plastic film will be more difficult.

3.2.5 Oxygen permeability test

The thickness of each sample is inserted before the oxygen permeability test started therefore the
machine will divide the thickness of the sample out. Table 7 shows the oxygen transmission rate for the
plastic samples.

Table 7: Oxygen transmission rate for each sample

Oxygen transmission rate (𝑐𝑐𝑐𝑐3 ⁄𝑚𝑚2 . 24 ℎ𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜)

Sample
First cycle Second cycle Third cycle Forth cycle Final
A 3853.159 3387.054 3047.281 2834.229 3280.431
B 0.027 1874.199 1239.927 2626.010 1913.379
C 514.540 614.522 864.165 912.238 912.238
D 3634.487 3631.917 3572.434 3614.976 3613.454

It is clear to see the lowest rate is sample C, which is the virgin LDPE from the internet at the rate
of 912.238 𝑐𝑐𝑐𝑐3 ⁄𝑚𝑚2 . 24 ℎ𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜 . For virgin LDPE plastic, the OTR is between 7000 to 8500
𝑐𝑐𝑐𝑐3 ⁄𝑚𝑚2 . 24 ℎ𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜 [10]. Sample A and sample C show a lower rate of OTR compared to the standard
OTR.The graph shown in Figure 25 is acceptable and the final OTR taken for this sample is the average
value from the 4 cycles which is 3280.431 𝑐𝑐𝑐𝑐3 ⁄𝑚𝑚2 . 24 ℎ𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜. Based on Figure 11 (a), the graph
shows that the result for this specimen is not stable, as there is an error during the first cycle.
Furthermore, the graph of OTR shown at cycles 2, 3 and 4 are not stable. This is because the OTR is
not stabilized yet and can be assumed that the graph will become stable after 6 cycles. From Figure 11
(b), the OTR taken is 912.238 𝑐𝑐𝑐𝑐3 ⁄𝑚𝑚2 . 24 ℎ𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜 which is the last cycle for the oxygen permeability
test for sample C. In this situation shown in Figure 11 (c), it can be assumed that after this cycle, the
OTR will become more constant while the graph will be flat after a few more cycles like 6 cycles.
However, this sample recorded the lowest OTR among the four samples and is the best barrier.

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Generally, the lower the OTR, the oxygen barrier-providing layer and the better the barrier. Oxygen
transmission rates through the barrier are critical to measuring and to is the longer a packaging system
will maintain its desired gas composition. Figure 11 (d) shows the best graph after the oxygen
permeability test among the four graphs. It is the most data reliability graph as the OTR from cycle 2 to
cycle 4 are quite constant.

Sample C stated the lowest OTR which is 912.238 𝑐𝑐𝑐𝑐3 ⁄𝑚𝑚2 . 24 ℎ𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜. The thickness of all
samples was divided by the machine therefore the thickness factor is not considered in this situation.
Another factor that causes this is the manufacturing process of the sample. The actual raw material
production and processing will affect the barrier properties. Apart from this, the orientation of the
material also affects and lowers the rate as it aligns the molecular chains and creates a less torturous
path for vapor molecules to pass through.

(a) (b)

(c) (d)
Figure 11: Graph for specimen (a) A, (b) B, (c) C and (d) D
4. Conclusion
In conclusion, based on the analysis of the result obtained from four tests conducted, sample A
which is virgin LDPE from Wahdah Plastic Industries is best overall for tensile and tearing test, and C
is the best in terms of thickness and oxygen permeability. Sample B and sample D which are the
recycled LDPE from two companies are more sustainable in comparison to using virgin material. In
tensile test, sample A at cross direction has better ductility due to long necking and has a strong bonding
which is produced a better strength because it is hard to break. This sample with a better ductility
exhibited greater susceptibility to plastic deformation and was easy to neck. Through the tearing test,
sample A at the cross direction has the highest tear strength which means that the sample was not easy
to be torn and it can withstand high tearing resistance to use as packaging. This shows that sample A
absorbs more energy at cross direction therefore it needs more strength to let the plastic completely tear.
Although the value of the density for sample A is not the lowest among the four samples, this sample
tends to float on the water and is better for the environment since it is easy to be removed when it floats
on the water. Thickness is a manufacture-controlled matter. Through the thickness measurement test,
sample C has the highest value of thickness among all four samples. Based on the oxygen permeability
test, sample C also has a lower oxygen transmission rate compared to other samples. The lower the
OTR, the oxygen barrier-providing layer and the better the barrier. Based on the data analysis and all
the results above, it showed that sample A which is the virgin LDPE plastic sample from Wahdah Plastic

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Industries has the best mechanical properties with its thickness, tensile strength, tearing strength and
oxygen permeability test.
As a recommendation, it is suggested that the four samples in this project can be undergone different
chemical tests to evaluate the properties of plastic samples such as Chemical Compatibility (ASTM
D543). This test covers the evaluation of plastic materials for resistance to chemical reagents, simulating
performance in potential end-use environments. Chemical reagents can include lubricants, cleaning
agents, inks, foods, or anything else that the test material may be expected to encounter. The test
includes provisions for reporting changes in weight, dimensions, appearance and strength properties.
With the addition of chemical tests, it can improve the data quality performed on the plastic. Moreover,
it is recommended that the sample can be run for more cycles for the oxygen permeability test. Sample
B and C are suggested to run longer to get a more reliable and accurate OTR result. The other
recommendation is that the virgin LDPE resins can be manufactured by adding dehydrating agents to
remove the moisture from recycled resin, to make sure there is no water vapour and bubbles during the
process. The adding of dehydrating agent will increase the success probability of producing a more
recyclable plastic film and reduce the cost. Last but not least, the project can be carried out by using
Hyplas film blowing machine in Makmal Mesin Pembungkusan, UTHM Campus Pagoh.
Acknowledgment
The authors would like to thank the Faculty of Engineering Technology, Universiti Tun Hussein
Onn Malaysia and Wahdah Plastic Industries for their support.
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