Redistilled Liquid Smoke from Oil-Palm Shells and Its Application as Natural Rubber Coagulant

REDISTILLED LIQUID SMOKE FROM OIL-PALM SHELLS
AND ITS APPLICATION AS NATURAL
RUBBER COAGULANT

MUHANA NURUL HIDAYAH

DEPARTMENT OF CHEMISTRY
FACULTY OF MATHEMATICS AND NATURAL SCIENCES
BOGOR AGRICULTURAL UNIVERSITY
BOGOR
2014

DECLARATION
I declare that this bachelor thesis entitled “Redistilled Liquid Smoke from
Oil-Palm Shells and Its Application as Natural Rubber Coagulant” is my own
work under direction from committee of supervisors and have not been published
in any form to any university. Information and quotes that were sources from
journals and books have been acknowledged and mentioned where in the bachelor
thesis they appear. All complete references are given at the end of the paper.
I have given the copyright of this paper to Bogor Agricultural University.
Bogor, December 2014

Muhana Nurul Hidayah
Student ID G44100114

ABSTRAK
MUHANA NURUL HIDAYAH. Redistilasi Asap Cair dari Tempurung Kelapa
Sawit dan Aplikasinya sebagai Koagulan Karet Alam. Dibimbing oleh SUMINAR
SETIATI ACHMADI dan ADI CIFRIADI.
Jumlah limbah tempurung kelapa sawit yang setiap tahunnya terus
bertambah akibat peningkatan produksi minyak sawit dapat dimanfaatkan sebagai
bahan baku dalam pembuatan asap cair. Kandungan asam dalam asap cair
berpotensi sebagai koagulan karet alam. Tujuan penelitian ini adalah mendistilasi
ulang asap cair pada suhu 80, 90, and 100 ºC dan menguji sifat koagulasi
redistilat dibandingkan dengan asam format sebagai koagulan komersial. Selama
proses redistilasi di setiap suhu, 2 tampungan redistilat terkumpul. Tampungan
pertama dikumpulkan pada 5 menit pertama dan tampungan kedua dikumpulkan
pada 5 menit berikutnya. Sebanyak 5 L redistilat diperoleh dari tiap tampungan.
Uji sifat fisik pada lembaran karet menunjukkan bahwa redistilat 100 ºC dari
tampungan kedua disarankan untuk digunakan sebagai koagulan karet alam
karena menghasilkan nilai plastisitas Wallace yang memenuhi standar dan
memiliki nilai indeks retensi plastisitas yang memenuhi persyaratan Standar

Nasional Indonesia. Redistilat tidak terbukti dapat mencegah proses pengerasan
karet selama penyimpanan.
Kata kunci: karet alam, koagulasi, redestilasi, tempurung kelapa sawit

ABSTRACT
MUHANA NURUL HIDAYAH. Redistilled Liquid Smoke from Oil-Palm Shells
and Its Application as Natural Rubber Coagulant. Supervised by SUMINAR
SETIATI ACHMADI and ADI CIFRIADI.
Abundant oil-palm shells waste which is generated annually as the result of
the increasing production of palm oil can be utilized as source of liquid smoke.
The acidic property of liquid smoke shows its potency as natural rubber coagulant.
The objectives of this study are to redistill liquid smoke at 80, 90, and 100 ºC and
also to examine the coagulation property of the RLS as compared to formic acid
as a commercial coagulant. During redistillation, two collections of RLS were
obtained from each temperature. The first collection was gathered at the first 5
min and the second one was gathered at the next 5 min. Each collection gave 5 L
of RLS. The physical properties test showed that the RLS 100 ºC from the second
collection was recommended as the natural rubber coagulant. This coagulant
produced Wallace plasticity value that met the the Indonesian standard and high
plasticity retention index value. The assumption of constituents in RLS which can

prevent the storage hardening in rubber was not proven.
Keywords: coagulation, natural rubber, oil-palm shells, redistillation

REDISTILLED LIQUID SMOKE FROM OIL-PALM SHELLS
AND ITS APPLICATION AS NATURAL
RUBBER COAGULANT

MUHANA NURUL HIDAYAH

Bachelor Thesis
in partial fulfillment of the requirements for the degree of
Bachelor of Chemistry
in
the Department of Chemistry

DEPARTMENT OF CHEMISTRY
FACULTY OF MATHEMATICS AND NATURAL SCIENCES
BOGOR AGRICULTURAL UNIVERSITY
BOGOR
2014

Bachelor Thesis Title: Redistilled Liquid Smoke from Oil-Palm Shells and Its
Application as Natural Rubber Coagulant
Name
: Muhana Nurul Hidayah
Student ID
: G44100114

Approved by

Prof Ir Suminar Setiati Achmadi, PhD
First Supervisor

Adi Cifriadi, MSi
Second Supervisor

Acknowledged by

Prof Dr Dra Purwantiningsih Sugita MS
Head of Department

Date of Graduation:

ACKNOWLEDGMENT
Praise to Allah subhanahuwata’ala. The title of this bachelor thesis is
“Redistilled Liquid Smoke from Oil-Palm Shell and Its Application as Natural
Rubber Coagulant”. This scientific paper was written according to the experiment
carried out in February to August 2014 in the Process Laboratory, Center for
Agro-Based Industry, the Organic Chemistry Laboratory, Department of
Chemistry, Bogor Agricultural University (IPB), and the Bogor Research Center
for Rubber Technology.
I sincerely would like to express my gratitude to my supervisors Prof Ir
Suminar Setiati Achmadi, PhD for her suggestions, guidance, and support on
research and Mr. Adi Cifriadi MSi for his helpfulness and guidance throughout
this work. I profoundly thank my parents, Mr. Auzar and Mrs. Rustini, my sister
Fitriana Amani, and my brother Ahmad Ibrahim for unconditional love and
encouragement.
Furthermore, I would like to thank Mr. Bambang Handoko for his advice
and suggesstion, Mr. Kosasih and Mr. Guring Pohan, who kindly helped
redistillation process. Mr. Aos for his help throughout the research in Puslit Karet,

and also thank to Mr. Jaenal for his help in plasticity analysis. I also thank to Mr.
Deni who kindly help tapping the rubber trees. I would like to thank Mrs. Yenni
who provided reagents for this experiment and Mr. Sabur for his advice and help
during my work in Organic Laboratory. Most of all I would like to thank Ihsan
Anggara, partner in liquid smoke research, for his cooperative work, to Krisnawati
for her help during working at Puslit Karet Laboratory. I would like to thank
Mutiara Pratiwi for giving correction to the script and her support, Lesya Agness
and Meira Mawati for their support, Mr. Budi Arifin MSi, Novi Luthfiana Putri
and Vicky Oktriviani for checking the script.
This study is a part of program “Establishing the Indonesian National
Standard for Masoyi Essential Oil and Wood Liquid Smoke Commodities” which
is funded by BOPTN IPB in 2014 and lead by Prof Suminar S Achmadi, PhD.
Bogor, October 2014
Muhana Nurul Hidayah

TABLE OF CONTENT
LIST OF TABLES
LIST OF FIGURES
LIST OF APPENDICES
INTRODUCTION

METHODS
Redistillation of Liquid Smoke
Characterization of RLS
Coagulation of Natural Rubber
Physical Property Testing of Sheet Rubber
RESULTS AND DISCUSSION
Redistilled Liquid Smoke
Chemical Constituents in The RLS
Coagulation of Natural Rubber
Physical Properties of Sheets Rubber
CONCLUSIONS
REFERENCES
APPENDICES
BIOGRAPHY

vi
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2

2
2
3
3
5
5
6
9
10
14
14
17
33

LIST OF TABLES
1 pH and total acid content of RLS and CLS
2 Volume of coagulant and serum separation
3 SNI 06-1903-2000 for Standard Indonesian Rubber 3L

6

9
10

LIST OF FIGURES
1 Color of the crude liquid smoke (CLS, a) and the redistilled liquid
smoke (RLS, b)
2 Chemical constituents in RLS 80 ºC; the first collection area ( ), and
the second collection area ( )
3 Chemical constituents in RLS 90 ºC; the first collection area ( ), and
the second collection area ( )
4 Chemical constituents in RLS 100 ºC; the first collection area ( ) and
( ) the second collection area
5 Chemical constituents in CLS
6 The comparation of acetic acid ( ) and phenol ( ) area between first
(a) and second (b) collection of RLS
7 Sheet rubber coagulated by using formic acid 1% (a), RLS 90 ºC (b),
CLS (c)
8 Effect of coagulants on initial plasticity of sheet rubber
9 PRI values on rubber sheet using different coagulants
10 Nitrogen content on rubber sheet using different coagulants

11 Volatile matter on rubber sheet using different coagulants
12 Accelerated storage hardening values on rubber sheet

5
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7
8
8
9
10
11
11
12
13
14

LIST OF APPENDICES
1
2
3

4
5
6
7
8
9
10
11
12
13
14
15

Total acid content
GC-MS result of RLS 80 ºC from the first collection
GC-MS result of RLS 80 ºC from the second collection
GC-MS result of RLS 90 ºC from the first collection
GC-MS result of RLS 90 ºC from the second collection
GC-MS result of RLS 100 ºC from the first collection
GC-MS result of RLS 100 ºC from the second collection
GC-MS result of CLS
Sheet rubbers that were coagulated by formic acid, RLS, and CLS
Wallace plasticity (Po) and plasticity retention index (PRI)
Statistical analysis for Wallace plasticity (Po)
Statistical analysis for plasticity retention index (PRI)
Nitrogen content
Statistical analysis for nitrogen content
Volatile matter content

16
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18
19
20
21
22
23
24
25
26
27
28
29
30

16 Statistical analysis for volatile matter content
17 Accelerated storage hardening content

31
32

INTRODUCTION
Indonesia is one of the world’s largest producers and exporters of palm oil,
producing over 18 million tons of palm oil, annually. Global demand for palm oil
is expected to grow further in the future; palm oil offers promising economic
prospects for Indonesia (World Growth 2011). According to Directorate General
Estate Crop, Ministry of Agriculture (2010), oil palm plantation in Indonesia
cover approximately 8.4 million hectares in 2010 and this area is expected to
increase to 13 million hectares by 2020. Despite the significant benefit, oil palm
mill also generates wastes, among them are empty fruit bunches (EFB), mesocarp
fruit fibers (MF), palm oil mill effluent (POME), and oil-palm shells (Sulaiman et
al. 2010). Currently, in some plantations EFB and POME are used as fertilizer for
plantation, while fibers and shells are burnt to generate fuel to produce power for
the mill operations. However, burning the bio-wastes contributes to air pollution
(Hayashi 2007).
One of the strategic ways to utilize oil-palm shells is by converting it into
liquid smoke. The pyrolysis of lignocelullosic materials produces liquid smoke or
also known as wood vinegar. The liquid smoke is generally dark brown in color,
viscous, and composed of a very complex mixture of oxygenated hydrocarbons.
The dominant constituents in liquid smoke based on their functional groups are
carboxylic acids, phenols, and carbonyls (Ramakrishnan and Moeller 2002;
Ratanapisit et al. 2009).
Indonesia also has the largest area of rubber plantation in the world which is
dominated by smallholders which make up for 84.5% of 3.2 million hectare of
cultivated land (Setiawan and Andoko 2005). Hence, rubber is a potential
commodity that plays important role in economic growth. Natural rubber (Havea
brasiliensis) can be processed into primary rubber product such as sheet rubber
through coagulation by acid, then followed by certain processes to produce
various final rubber products (White and De 2001). Formic acid is one of
available coagulants recommended by the prevailing regulation (BSN 2000).
Beside formic acid, acetic acid is also recommended as coagulant. Both are
preferred due to their volatile nature and being noncorrosive (White and De 2001).
Asni et al. (2012) reported various coagulants which are commonly used, but not
really recommended for natural rubber coagulation, i.e. sulfuric acid, phosphate
fertilizer, and alum. Those coagulants are known to cause low quality of natural
rubber products and result in lower price of the final products.
Acid content in liquid smoke is potential to be utilized as natural rubber
coagulant. The predominant acid in liquid smoke derived from oil-palm shells is
acetic acid (Achmadi et al. 2013). Utilization of liquid smoke as natural rubber
coagulant as reported by Baimark et al. (2008) indicates that raw and tar-extracted
liquid smoke prepared from Eucalyptus globulus can be used as coagulant for
natural rubber. According to Prasertsit et al. (2011), crude coconut shell liquid
smoke improves the physical properties of sheet rubber and can prevent fungal
growth on sheet rubber due to phenolics and acetic acid contents.
Acid as a part of complex mixture in liquid smoke should be purified to
enhance its function as natural rubber coagulant. One of the available ways to
purify liquid smoke is redistillation (Darmaji 2002). In this study, the liquid

2
smoke was redistilled at 80, 90, and 100 ºC. At those temperatures more acids
content can be obtained. The coagulation property of the redistilled liquid smoke
(RLS), crude liquid smoke (CLS), and formic acid were examined.

METHODS
The experiment was done in 5 steps, starting with redistillation of CLS;
characterization of the redistillate which consists of pH measurement, total acid
content; and identification of chemical constituents using gas chromatographymass spectrometer (GC-MS) instrument; coagulation of natural rubber; and finally
physical properties test for the rubber sheets.
CLS was obtained from PT Global Deorub Industry, located in Palembang,
and was redistilled using a concentration boule type TA62D in the Laboratory of
Process, available in the Center for Agro-Based Industry (BBIA), Cikaret, Bogor.
The temperature of redistillation was 80, 90, and 100 ºC. Chemical constituents in
RLS were identified using GC-MS instrument in the Center for Forensic
Laboratory (Puslabfor), Police Head quarters (Mabes Polri), Jakarta. RLS, CLS,
and formic acid were individually used to coagulate natural rubber latex. The latex
was tapped from rubber plantation owned by the Center for Plantation
Biotechnology Research (BPBP) in Ciomas, Bogor. Physical properties
determination of rubber sheet were the Wallace plasticity, plasticity retention
index, nitrogen content, accelerated storage hardening test, and volatile matter.
Statistical analysis was done using SPSS 16.0 for Windows.

Redistillation of Liquid Smoke
Approximately 60 L of CLS from oil-palm shells was filtered and was
divided into 3 separate containers. CLS was redistilled using a concentration
boule type TA62D at 80, 90, and 100 ºC. RLS were collected in separate closed
containers. The collection of RLS was repeated twice. The first collection was
done at the first 5 min and the second was done for the next 5 min. Each
collection was 5 L of RLS (modification of Achmadi et al. 2013).

Characterization of RLS
Measurement of pH
The pH of RLS was measured by calibrated pH meter using buffer solution
of pH 4 and 7. Fifty mL of RLS was measured for its pH.
Total Acid Content (AOAC 2005)
About 5 mL RLS was added to 100 mL of distilled water; followed by 3
drops of phenolphthalein. The mixture was titrated with 0.1 N NaOH solution
until the color of solution turned into soft pink. The measurement was repeated 3
times for each RLS. H3BO3 was used to standardize the NaOH.

3

GC-MS Analysis (Achmadi et al. 2013)
Chemical constituents in RLS were identified using a gas chromatography
(GC-17A Shimadzu) mass spectrometry (MS QP 5050A) instrument. The GC-MS
was equipped with 60-meter HP5 column. Detector temperature was at 250, 280,
290 ºC, respectively. Helium was used as carrier gas with flow rate of 23.7 mL
min-1 at 17.56 psi pressure. The injected volume of RLS was 1 µL.

Coagulation of Natural Rubber
Fresh natural rubber was tapped and collected in a container that has been
filled with ammonia to preserve the field latex for the transportation to the
laboratory. The amount of ammonia that should be added has to be precalculated
properly; the dose of ammonia used was determined as 0.05%. The field latex was
filtered and the dry rubber content (DRC) of latex was determined. Subsequently,
the field latex was diluted with water until DRC of latex reached 20%. Fifteen
beaker glasses were prepared and each beaker was filled with approximately 300
mL of latex. Coagulants that used in the experiment were 1% formic acid as the
standard coagulant for natural rubber (Cecil and Mitchell 2005), 25% RLS 80, 90,
100 ºC, and 25% CLS, respectively. Each coagulant treatment was performed in
triplicates.
The coagulant was added to beaker glass dropwise until pH of the latex
reached 5.0. The pH value was checked using universal pH paper. The amount of
coagulant added to gain the favorable pH was then used as the standard to
coagulate the other replicates. The field latex formed coagulum as the result of
coagulation. The coagulum was left for about 19 hours to complete the
coagulation. Serum separation was observed, then the coagulum was compressed
between 2 rolls, washed with water, and it turned into sheet rubber. Sheet rubber
was air-dried for 1 hour and followed by oven-drying for 11 hours at 50−60 ºC
(modification of Baimark et al. 2008). Physical properties of sheet rubber were
determined according to Indonesia National Standard (SNI) 06-1903-2000,
including Wallace plasticity, plasticity retention index, nitrogen content,
accelerated storage hardening test (ASHT), and volatile matter.

Physical Property Testing of Sheet Rubber
Wallace Plasticity and Plasticity Retention Index (SNI 06-1903-2000)
Test portion of about 15−25 g from the homogenized sample was taken and
it was passed at maximum 3 times between mill rolls at room temperature with
adjusted rolls so that the final the sheet thickness was approximately 1.6−1.8 mm.
The process was repeated if the sheets thickness did not met the requirement. The
sheet was doubled and the two halves were pressed lightly together. Six test
specimens from the doubled sheet were formed with the Wallace punch and their
thickness were measured until six test pellets were obtained with thickness of
3.2˗3.6 mm (precision was 0.01 mm) and diameter of ±13 mm. These specimens
were divided into 2 sets of 3 randomly. One set for plasticity tests before aging

4
and the other for testing after aging for 30 min at 140 ºC. After that, the testpieces were removed from the oven. Then, they were allowed to cool down to
room temperature.
Two pieces of tissue paper were placed between the heated platens and the
thickness measuring device was set to zero when the platens are closed. A pellet
was inserted at room temperature between the two pieces of tissue paper and the
whole assembly was placed centrally between the heated platens. The machine
lever was put into operation after 15 seconds conditioning period; the timing
device automatically releases the force 100 N to compress the specimen. This load
period will automatically adjust, exactly in 15 seconds duration. The final
thickness was expressed in units equivalent to 0.01 mm, remains locked after the
15-s period on the dial micrometer until the operation handle was moved to open
the instrument. The measured thickness was recorded from the dial micrometer.
That process was repeated for each specimen, both aged and in original condition.
The plasticity in original condition is called initial plasticity (Po) or also
known as Wallace plasticity. Plasticity retention index (PRI) can be calculated by
the percentage ratio between aged plasticity (Pa) and Po.
Nitrogen Content (SNI 06-1903-2000)
About 0.3 g sample of the homogenized sheet rubber was weighed
accurately and was placed in a Kjeldahl flask. Approximately 1.95 g catalyst
mixture and 9 mL of concentrated H2SO4 were added. The flask was heated until
the solution turned into clear green color (or colorless) and there was no yellow
color appears, and then it cooled, and transferred to distillation apparatus. The
flask was rinsed with 30 mL distilled water and 30 mL of 3% boric acid solution
and 2−3 drops of indicator (mixture of methylene blue and methyl red) were
added into the distillate container.
67% NaOH solution (30 mL) was added to the steam distillation apparatus,
and the funnel was washed with 30 mL distilled water. The distillation was run to
collect distillate of 100 to 200 mL. The distillate was titrated with 0.2 N H2SO4.
The endpoint was confirmed when the color of the solution changed from green to
red-purple. A blank test was performed in the same manner.
Accelerated Storage Hardening Test (SNI 06-1903-2000)
Sample preparation of accelerated storage hardening (ASH) test was similar
to that for the PRI test. The speciments were prepared until 6 test pellets were
obtained with thickness of 3.2−3.6 mm (precision was 0.01 mm) and diameter of
±13 mm. Weighing bottle and the pellets should be clean and dry. The 6 test
pellets were divided into 2 groups (test pellets number 1 and 2). 6−8 g of
phosphorus pentaoxide (P2O5) and test pellets number 2 were put into the
weighing bottle and were arranged so that each of the test pellets were apart from
each other.
Silicon grease was spread on the weighing bottle cap. The weighing bottle
was heated in an oven at 60 ± 1 ºC for 24 ± 1 hour. After 30 min, the bottle was
checked as it should be airtight; the time was recorded afterward. Plasticity of test
pellets number 1 (Po) and number 2 (PH) were measured, and the difference
between the plasticity values was presented as the ASH value.

5
Volatile Matter (SNI 06-1903-2000)
Sample preparation of volatile matter was similar to that for the PRI test.
About 10 g of sample was cut, weighed, and passed through the mill rolls until its
thickness reached 1.55 mm. Then it was cut until the size was about 2.5 mm × 2.5
mm. The samples were then placed on an preweighed porcelain crucible and was
heated in oven at 100 ± 3 ºC for 3 hours, after being allowed to cool for 30 min,
the samples were weighed.

Statistical Analysis
The observed data on physical properties of rubber sheets were subjected to
analysis of variance (One-Way ANOVA) and if there was any significant
difference, then Duncan multiple range test at α = 0.05 was used to determine the
difference among the treatment means.

RESULTS AND DISCUSSION
Redistilled Liquid Smoke
The CLS turned into clear yellowish (Figure 1) after the redistillation. Dark
color in CLS comes from tar, which is one of the products of the pyrolyzed
lignocellulosics. The temperature of redistillation was set at 80, 90, and 100 ºC,
and as the boiling point of tar is above 300 ºC, this component presumably did not
vapourize, so that it could be separated from the RLS (White and De 2001).
a

b

Figure 1 Color of the crude liquid smoke (CLS, a)
and the redistilled liquid smoke (RLS, b)
The pH value and total acid content of RLS and CLS are shown on Table 1.
The calculation of total acid content is displayed in Appendix 1. The pH of RLS
ranged from 2.26 to 2.57 and pH for CLS was 2.30. The CLS has higher total acid
content than RLS. Total acid content of RLS ranged from 1.77 to 5.43%. Among
the samples, RLS 80 ºC from first collection had the highest total acid content, i.e.
5.43%.

6
Table 1 pH and total acid content of RLS and CLS
Sample code
RLS 80 ºC
RLS 80 ºC
RLS 90 ºC
RLS 90 ºC
RLS 100 ºC
RLS 100 ºC

Collection
1
2
1
2
1
2

pH
2.46
2.26
2.28
2.57
2.49
2.49

Acid content (%)
4.45
5.43
4.34
4.28
1.77
3.81

Acidity of liquid smoke is contributed by acetic acid and other carboxylic
acids. Acetic acid is the main product from pyrolysis of cellulose and
hemicelluloses. The composition of lignocellulosic determines the acid content in
liquid smoke. Kadir et al. (2010) compares CLS from coconut hybrid containing
cellulose and hemicelluloses up to 53.05%. The acid content reachs 12.57%. On
the other hand, with cellulose and hemicellulose content in oil-palm shells of
42.8 % (Shibata et al. 2008), the acid content is only 7.70%.
Achmadi et al. (2013) reported that redistillation of liquid smoke from oilpalm shells at 80±5 ºC, result in pH of 3.2 and total acid of 9.14%. Another
experiment carried out by Irsaluddin (2010) showed that RLS of coconut shells at
111.5, 112.5 and 114.5 ºC resulted in pH ranging from 2.65 to 3.00. The
difference of chemical components in liquid smoke is affected by several factors,
such as composition of biomass, temperature and atmosphere of pyrolysis, rate of
heat transfer, vapor and particle residence time, as well as particle size
(Ramakhrisnan and Moeller 2002).
Redistillation is one of the available ways to purify the original liquid
smoke from undesirable components such as tar and polyaromatic hydrocarbons
(PAH) (Darmaji 2002). This way, the purity of acids as the main component of
liquid smoke to coagulate natural rubber, can be enhanced.

Chemical Constituents in The RLS
The chemical constituents of the RLS as identified by using GC-MS
instruments are displayed in Figure 2, 3, and 4, each for the the first and the
second collection. While, chemical constituents in CLS is displayed in figure 5.
Those chemical constituents were chosen due to their similarities (higher than
90%) with the instrument’s database. The area, retention time, and similarity
percentage of chemical constituents of each RLS can be seen in Appendix 2−7,
and CLS in Appendix 8.
The result showed that predominate constituents of the RLS are phenol and
acetic acid. Ramakhrisnan and Moeller (2002) reported the dominant constituents
in liquid smoke based on their functional group are carboxylic acid, phenol, and
carbonyl. Maga (1988) and Girrard (1992) reported pyrolysis products of
hemicelluloses are furfurals, furans, and furan derivatives, in addition to
carboxylic acids. Pyrolysis products of cellulose are acetic acid and its
homologues and also carbonyl compounds such as acetaldehyde, glyoxal, and
acrolein, while pyrolysis of lignin gives phenol, guaiacol, syringol, and their
homologues.

7
Lignin is the predominant constituent of oil-palm shells which make up for
51.5% (wt), followed by hemicellulose (22.3% wt), and cellulose (20.5% wt)
(Shibata et al. 2008). Oil-palm shell is lignin-rich source, therefore, phenol may
be the main pyrolysis product that predominate the liquid smoke. This fact is in
line with our results, being the phenols and acetic acid predominate. Acids and
phenols also contribute to acidic property of the RLS.
Phenol, 4-ethyl-2-methoxyChemical constituents

Phenol, 2-methoxy-4-methyl-

Phenol, 3,5-dimethylPhenol, 2-methoxyPhenol, 4-methylBenzenemethanol
Phenol, 2-methyl-

Phenol
2-Furancarboxaldehyde, 5-methyl2-Furancarboxaldehyde
Acetic acid
0

5

10

15

20

25

30

35

40

45

Area (%)

Chemical constituents

Figure 2 Chemical constituents in RLS 80 ºC; the first collection area ( ), and
the second collection area ( )
Phenol, 4-ethyl-2-methoxyPhenol, 2-methoxy-4-methylPhenol, 4-methoxy-3-methylPhenol, 3,5-dimethylPhenol, 2-methoxyBenzenemethanol
Phenol, 2-methylPhenol
2-Furancarboxaldehyde, 5-methyl2-Furancarboxaldehyde
Acetic acid
0

5

10

15

20

25

30

35

40

45

Area (%)

Figure 3 Chemical constituents in RLS 90 ºC; the first collection area ( ), and
the second collection area ( )

8

Chemical constituents

Phenol, 4-ethyl-2-methoxyPhenol, 2-methoxy-4-methylPhenol, 2-methoxy
Phenylmethanol
Benzenemethanol
Phenol, 2-methyl-

Phenol
2-Furancarboxaldehyde
Acetic acid
0

20

40

60

Area(%)

Figure 4 Chemical constituents in RLS 100 ºC; the first collection area ( ) and
( ) the second collection area
Phenol, 2,6-dimethoxyChemical constituents

Phenethyl alcohol, o-methoxyPhenol, 2-methoxy-4-methylPhenol, 2-methoxyPhenol, 4-methylPhenol, 2-methyl2-Cyclopenten-1-one, 2-hydroxy-3-m
Phenol
2-Furancarboxaldehyde
Acetic acid
0

5

10

15

20

25

30

35

40 45

Area (%)

Figure 5 Chemical constituents in CLS
In the process of redistillation, RLS was collected twice at each temperature.
The chemical constituents in the first collection is richer that that of the second
collection of RLS 80 ºC and RLS 90 ºC. The opposite happens in RLS 100 ºC,
being the first collection is richer in constituents than that of the second. During
the redestillation, constituents with lower boiling point vapourize first and
followed by that with higher boiling point. Hence, the first collection generally
contains richer chemical constituents.
Figure 6 displayed the relation between the area of acetic acid and phenol
obtained from GC-MS analysis in the first and second collections. The second
collection contains higher concentration acetic acid and phenol than that of the
first collection. Thus, RLS from the second collection was further used as
coagulant in the following step for preparing sheet rubber.

9
a

b

50

40

Area (%)

Area (%)

50
30
20

40
30
20

10

10

0

0
80
90
100
Temperature of redistillation
(ºC)

80

90

100

Temperature of redistillation
(ºC)

Figure 6 The comparation of acetic acid ( ) and phenol ( ) area between first
(a) and second (b) collection of RLS
Chemical constituents in the second collection of RLS 80 °C that were
similar to RLS 90 °C. There are 9 constituents in RLS 80 °C and RLS 90 °C.
While, RLS 100 ºC has less constituents (8 constituents). Benzenemethanol only
appears in RLS 80 °C and RLS 100 °C, 2-furancarboxaldehyde, 5-methylappears in RLS 80 °C and RLS 90 °C and phenol, 4-methyl only appears in RLS
90 ºC.

Coagulation of Natural Rubber
Table 2 shows the volume of coagulant that was properly added to obtain
the optimum pH for coagulation. Formic acid 1% as standard had the lowest
volume needed with 17 mL, while among RLS, the RLS 80 ºC had the lowest
volume needed with 19 mL. Normal coagulation was carried out by acidifying
latex from approximately neutral to pH 4.7−5.1. The volume of each coagulant
needed to reach that pH was different for each treatment.
Table 2 Volume of coagulant and serum separation
Volume of coagulant
Coagulants
Serum colour
(mL)
Formic acid
17
Not sufficiently clear
RLS 80 ºC
19
Not sufficiently clear
RLS 90 ºC
22
Serum did not separate
RLS 100 ºC
30
Serum did not separate
CLS
20
Not sufficiently clear
Natural rubber or latex is a colloidal system of rubber globules suspended in
aqueous serum and surrounded by a protective layer of protein and phospholipids.
Negative charge which is present on the protective layer stabilizes the latex.
Coagulation is achieved by neutralizing the negative charge on the rubber particle
so that they coalesce. Formic acid is preferred as coagulant based on its volatile
nature and non-corrosive characteristic. Besides formic acid, acetic acid is also

10
recommended to be used as coagulant (White and De 2001). Acetic acid and
phenol that are predominant constituents in RLS contribute in natural rubber
coagulation.
The concentration of RLS for coagulation used in this experiment was much
higher than that of the formic acid due to several chemical constituents that affect
the acidity of coagulant. In this experiment, 25% of RLS was used; on the other
hand, only 1% formic acid was used.
The objective of diluting latex before coagulation is to produce a liquid with
a standard DRC 15−20% (Cecil and Mitchell 2005). In the experiment, the latex
was diluted until the DRC reached 20%. It is desirable to coagulate latex with the
maximum DRC and to make a sheet as large and as thin as possible. Coagulum
made with maximum DRC will not be easy to deform during handling in sheeting
machines. After coagulation, the coagulum should be completely uniform, with
the correct texture, plasticity, and density. This will ensure the best results on
machining and drying. The residual serum should be clear (Kurian and Peter
2002; Cecil and Mitchell 2005). In the experiment, complete serum separation
was not observed.
Figure 7 shows sheet rubber which were coagulated with formic acid 1%,
RLS 90 ºC, and CLS. Appendix 9 provide photos of all sheets rubber coagulated
by using formic acid 1%, RLS 80 ºC, RLS 90 ºC, RLS 100 ºC, and CLS.
a

b

c

Figure 7 Sheet rubber coagulated by using formic acid 1% (a), RLS 90 ºC (b),
CLS (c)

Physical Properties of Sheets Rubber
Table 3 shows the parameters in Indonesia National Standard (SNI) 061903-2000 for Standard Indonesian Rubber (SIR) 3L, one of the rubber qualities
that was produced by latex. Those parameters were used as standard for physical
property testing of sheet rubber that was coagulated by using RLS.
Table 3SNI 06-1903-2000 for Standard Indonesian Rubber 3L
Parameter
Unit
Limit
Wallace plastisity
Min 30
Plasticity retention index
Min 75
Nitrogen content
%(wt)
Max 0.60
Volatile matter
%(wt)
Max 0.80
Wallace Plasticity
According to SNI 06-1903-2000 for SIR 3L, minimum value of Wallace
plasticity (Po) or also known as initial plasticity on rubber is 30. Po analysis

11

Po

showed that only RLS 100 ºC and CLS as coagulant that fulfilled the requirement.
Figure 8 shows that the highest Po was obtained by using RLS 100 ºC and CLS,
then followed by RLS 80 ºC, 90 ºC, and formic acid 1%.
33
32
31
30
29
28
27
26
25

SNI
Limit

FA 1%

RLS 80 ºC

RLS 90 ºC RLS 100 ºC

CLS

Coagulants

Figure 8 Effect of coagulants on initial plasticity of sheet rubber
The analysis of variance figured that coagulants gave significant difference
on Po values. Duncan test revealed that RLS 100 ºC and CLS had high influence
on Po compare to other coagulants. The data of Po measurement can be seen on
Appendix 10, while statistical analysis for Po in the Appendix 11.

PRI (%)

Plasticity Retention Index
Minimum value of PRI on rubber is 75 according to SNI 06-1903-2000 for
SIR 3L. Figure 9 shows that the highest PRI value was obtained by using formic
acid 1% as coagulant, while other coagulants had slightly similar PRI value. All
coagulants produced PRI that fulfilled the SNI requirement.
130
120
110
100
90
80
70
60

SNI
Limit
FA 1%

RLS 80 ºC

RLS 90 ºC

RLS 100 ºC

CLS

Coagulants

Figure 9 PRI values on rubber sheet using different coagulants
The data for PRI measurement is shown in Appendix 10 and the statistical
analysis in Appendix 12. The analysis of variance showed that the coagulant gave
significant difference on the PRI value. According to Duncan test, formic acid 1%
exhibited high effect on PRI test as compared to other coagulants. Following

12
formic acid, RLS 100 ºC was the second best coagulant that produced high PRI
value.
According to Baimark et al. (2008), PRI value of sheet rubber that was
coagulated by raw wood vinegar or CLS of Eucalyptus globulus, tar-extracted
CLS, formic acid, and acetic acid were 95.40, 104.70, 90.30, and 104.60,
respectively. In the experiment, the PRI value of sheet rubber coagulated by
formic acid, RLS 80 ºC, RLS 90 ºC, RLS 100 ºC, and CLS were 119.03, 99.43,
102.37, 104.43, and 99.47, respectively.
High PRI values are generally associated with rubbers that possess good
resistance to thermal oxidative breakdown. Both Po and PRI are basic parameters
to determine the quality of sheet rubber. According to Po test, RLS 100 ºC and
CLS fulfilled SNI requirement, while in PRI test, formic acid had the highest PRI
value and the followed by RLS 100 ºC. This result indicated that RLS 100 ºC gave
a good performance to coagulate natural rubber compared to other RLS.
Nitrogen Content
According to SNI 06-1903-2000 for SIR 3L, nitrogen content in rubber
should not exceed 0.60%. All coagulants produced nitrogen content lower than
0.60%. Figure 10 shows that RLS 80 ºC had the highest nitrogen content
compared to other coagulants. The data of nitrogen measurement can be seen in
Appendix 13. The analysis of variance showed that coagulants also gave
significant difference on nitrogen content. Duncan test revealed that RLS 80 ºC
gave high influence on nitrogen content as compared to other coagulants.
Statistical analysis of nitrogen content is shown in Appendix 14.

SNI
Limit

Figure 10 Nitrogen content on rubber sheet using different coagulants
Volatile Matter
SNI 06-1903-2000 for SIR 3L states that volatile matter in rubber should
not exceed 0.80%. Figure 11 shows that all coagulants produced volatile matter
content lower than 0.80%. Volatile matter measurement is shown in Appendix 15.
The analysis of variance showed that coagulants gave no significant difference on
the volatile matter (Appendix 16).

13

SNI
Limit

Figure 11 Volatile matter on rubber sheet using different coagulants
Volatile matter test was done to confirm whether high PRI values related to
incomplete drying process. If the drying was not complete, the heat on PRI test
would be used to vaporize the water instead of oxidizing the rubber. Thus, the
result of PRI test would not represent the actual resistance of rubber toward
thermal oxidation. In the experiment, all coagulants produced volatile matter
values that were below 0.80%, which means that the drying process was complete
and high PRI value does not relate to incomplete drying process.
Accelerated Storage Hardening Test
Stabilization of viscosity is commonly evaluated by accelerated storage
hardening (ASH) test. The increase on initial plasticity should be less than eight.
Figure 12 shows that all coagulants produced ASH value higher than eight. ASH
measurement is shown in Appendix 17. Natural rubber undergoes hardening
during storage, especially under low humidity. The increase of viscosity is caused
by crosslinking reaction involving the randomly distributed carbonyl groups on
the rubber molecules. Amnuaypornsri et al. (2009) reports that interaction of fatty
acid ester group in phospholipids at chain ends of rubber molecules is responsible
for the formation of crosslinking during storage. It was assumed that there are
RLS constituents preventing the storage hardening. The assumption was not
proved in this experiment; the ASH values produced by applying RLS exceed 8
magnitudes.

ASHT value

14
70
60
50
40
30
20
10
0

SNI
Limit
FA 1% RLS 80 ºC RLS 90 ºC RLS 100
ºC
Coagulants

CLS

Figure 12 Accelerated storage hardening values on rubber sheet

CONCLUSIONS
The result showed that RLS 100 ºC from the second collection was
recommended as natural rubber coagulant, as this coagulant produced Wallace
plasticity that meet the standard and high plasticity retention index value. The
assumption of constituents in RLS that can prevent the storage hardening in
rubber was not proved. For further research, it is recommended to study more
about the redistillation to enhance the acid content recovery, i.e by prolonging the
holding temperature of redistillation. In this research, only one concentration of
coagulant that was used. It is also recommended to vary the coagulant
concentration and to do water content to calculate the concentration of acid
constituents in RLS.

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redistilled liquid smoke of oil-palm shells and its application as fish
preservatives. J Appl Sci. 13(3):401-408. doi:10.3923/jas.2013.401-408.
Amnuaypornsri S, Nimpalboon A, Sakdapipanich J. 2009. Role of phospolipid on
gel formation and physical properties of NR during accelerated storage.
KGK·März. 88-92.
[AOAC] Association of Official Analytical Chemist. 2005. Official Methods of
Analysis. 18th Ed. Washington DC (US): AOAC.
Asni N, Firdaus, Endrizal. 2012. Identifikasi dan analisa mutu lateks asalan (slab)
di provinsi Jambi. Jambi (ID): BPTP Jambi.
Baimark Y, Threeprom J, Dumrongchi N, Srisuwun Y, Kotsaeng N. 2008.
Utilization of wood vinegars as sustainable coagulating and antifungal
agents in the production of natural rubber sheets. J Environ Sci Technol.
1(4):157-163.

15
[BSN] Badan Standardisasi Nasional. 2000. SNI 06-1903-2000. Standard
Indonesian Rubber (SIR). Jakarta (ID): BSN.
Cecil J, Mitchell P. 2005. Processing of Natural Rubber FAO [Internet].
[downloaded 2014 Feb 16th]. Available at: http://ecoport.org/ep?SearchType
= earticleView&earticleId=644&page=-2.
Darmaji P. 2002. Optimasi permunian asap cair dengan metoda redestilasi. J
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Directorate General Estate Crop, Ministry of Agriculture. 2010. Agricultural
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Girrard JP. 1992. Smoking in Technology of Meat and Meat Products. New York
(US): Ellis Harwood.
Hayashi K. 2007. Environmental impact of palm oil industry in Indonesia. In:
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ISETS07 [Internet]. [Time and place of meeting are unknown]. Nagoya (JP):
Nagoya University. p 646-65; [downloaded 2014 Nov 26th]. Available at:
www.esi.nagoya-u.ac.jp/h/isets07/Contents/Session05/1003Hayashi.pdf.
Irsaluddin. 2010. Kajian teknik penyulingan ulang (redistilasi) untuk
meningkatkan mutu asap cair [skripsi]. Bogor (ID): Institut Pertanian Bogor.
Kadir S, Darmadji P, Hidayat C, Supriyadi. 2010. Fraksinasi dan identifikasi
senyawa volatil pada asap cair tempurung kelapa hibrida. Agritech.
30(2):57-67.
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Dehli (IN): New India Pub.
Maga JA. 1988. Smoke in Food Processing. Boca Raton (US): CRC Pr.
Prasertsit K, Rattanawa N, Ratanapisit J. 2011. Effect of wood vinegar as an
additive for natural rubber products. Songklanakarin J Sci Technol.
33(4):425-430.
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Fuel Chem Division Preprint. 47(1):366-367.
Ratanapisit J, Apiraksakul S, Rerngnarong A, Chungsiriporn J, Bunyakorn C.
2009. Preliminary evaluation of production and characterization of wood
vinegar from rubberwood. Songklanakarin J Sci Technol. 31(3):343-349.
Setiawan DH, Andoko A. 2005. Petunjuk Lengkap Budidaya Karet. Jakarta (ID):
Agromedia Pustaka.
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chemical composition of the oil palm (Elaeis guineensis). J Jpn Inst Energy.
87(5):383-388.
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and it wastes. J Phys Sci. 21(1):67-77.
White JR, De SK. 2001. Rubber Technologist’s Handbook. Shawbury (UK):
Rapra Technology.
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(ID): World Growth.

16
Appendix 1 Total acid content
Volume of NaOH (mL)
Samples
Collection
Acid content (%w/v)
1
2
3
RLS 80 ºC
1
7.75
7.75
7.80
4.45
RLS 80 ºC
2
9.50
9.50
9.50
5.43
RLS 90 ºC
1
7.60
7.60
7.60
4.34
RLS 90 ºC
2
7.50
7.50
7.50
4.28
RLS 100 ºC
1
3.10
3.10
3.10
1.77
RLS 100 ºC
2
6.70
6.65
6.65
3.81
CLS
13.50 13.50 13.45
7.70
Calculation:
N NaOH= 0.0952 N
Volume of sample = 1.00 mL
Molecular weight (gram/mol)= 60
% Total acid content=

V NaOH ×N NaOH ×60×100%
1000 ×V sample
7.75 mL ×0.0952 N×60×100%

=
1000 ×1.00 mL
= 4.43%
4.43%+4.43%+4.48%
Average of total acid content =
3
= 4.45%

pH
2.46
2.26
2.28
2.57
2.49
2.49
2.30

17
Appendix 2 GC-MS result of RLS 80 ºC from the first collection
A b u n d a n c e
T IC : F R A K S I 1 _ 8 0 .D
2 e + 0 7

1 .8 e + 0 7

1 .6 e + 0 7
6 .3 9
1 .4 e + 0 7

1 .2 e + 0 7

1 e + 0 7
4 .1 7
8 0 0 0 0 0 0
7 .4 6
6 0 0 0 0 0 0

5 .1 5

4 0 0 0 0 0 0
8 .4 6

3 .9 3
4 .3 6

2 0 0 0 0 0 0

1 .0 0

2 .0 0

3 .0 0

3 .8 9

4 4. 7. 89 8

4 .0 0

5 .0 0

7 .0 9
7 .3 1
5 . 7 36 . 2 2
6 .6 2
6 .0 0

7 .0 0

9 .2 8
8 . 08 3. 3 3
8 .0 0

9 .0 0

1 0 .0 0

T im e - - >

Chemical constituents
Acetic acid
2-Furancarboxaldehyde
2-Furancarboxaldehyde, 5-methylPhenol
Phenol, 2-methylPhenol, 4-methylPhenol, 2-methoxyPhenol, 3,5-dimethylPhenol, 2-methoxy-4-methylPhenol, 4-ethyl-2-methoxy-

Retention time
(min)
4.16
5.15
6.22
6.39
7.09
7.31
7.46
8.03
8.46
9.28

Area
(%)
28.92
8.39
0.49
34.23
1.95
1.16
8.63
0.46
3.90
2.29

Similarity

(%)
91
91
91
94
97
97
97
97
95
95

18
Appendix 3 GC-MS result of RLS 80 ºC from the second collection
A b u n d a n c e
T IC : F R A K S I 2 _ 8 0 .D
2 e +0 7

1 .8 e + 0 7

1 .6 e + 0 7
6 .3 9
1 .4 e + 0 7

1 .2 e + 0 7
4 .1 9

1 e +0 7

8 0 0 0 0 0 0

6 0 0 0 0 0 0
7 .4 6
4 0 0 0 0 0 0
4 .3 7 5 .1 6

2 0 0 0 0 0 0

33 ..89 94
1 .0 0

2 .0 0

3 .0 0

4 .0 0

4 .8 0
5 .0 0

8 .4 6
5 .7 6
6 .0 0

7 .1 0
7 .3 1
7 .0 0

9 .2 8
8 .0 0

9 .0 0

1 0 .0 0

T im e - - >

Chemical constituents
Acetic acid
2-Furancarboxaldehyde
2-Furancarboxaldehyde, 5-methylPhenol
Phenol, 2-methylBenzenemethanol
Phenol, 2-methoxyPhenol, 2-methoxy-4-methylPhenol, 4-ethyl-2-methoxy-

Retention time
(min)
4.19
5.16
6.22
6.40
7.09
7.31
7.46
8.46
9.28

Area
(%)
38.17
3.91
0.27
36.34
1.53
1.26
7.08
2.80
1.33

Similarity
(%)
91
91
91
94
97
97
97
95
94

19
Appendix 4 GC-MS result of RLS 90 ºC from the first collection
A b u n d a n c e
T IC : F R A K S I 1 _ 9 0 .D
2 e + 0 7
1 .9 e + 0 7
1 .8 e + 0 7
1 .7 e + 0 7
1 .6 e + 0 7
1 .5 e + 0 7
6 .3 9

1 .4 e + 0 7
1 .3 e + 0 7
1 .2 e + 0 7
1 .1 e + 0 7
1 e + 0 7
9 0 0 0 0 0 0

4 .1 8

8 0 0 0 0 0 0
7 0 0 0 0 0 0

7 .4 6

6 0 0 0 0 0 0
5 0 0 0 0 0 0

5 .1 6

4 0 0 0 0 0 0
3 .9 4

3 0 0 0 0 0 0

8 .4 6
4 .3 7

2 0 0 0 0 0 0
1 0 0 0 0 0 0
1 .0 0

2 .0 0

3 .0 0

3 .8 9

4 4 . 8. 8 0 9

4 .0 0

5 .0 0

5 . 7 56 . 2 2
6 .0 0

7 .1 0
7 .3 1
7 .0 0

9 .2 8
8 .3 3
8 .0 0

9 .0 0

1 0 .0 0

T im e - - >

Chemical constituents
Acetic acid
2-Furancarboxaldehyde
2-Furancarboxaldehyde, 5-methylPhenol
Phenol, 2-methylBenzenemethanol
Phenol, 2-methoxyPhenol, 3,5-dimethylPhenol, 4-methoxy-3-methylPhenol, 2-methoxy-4-methylPhenol, 4-ethyl-2-methoxy-

Retention time
(min)
4.18
5.16
6.22
6.37
7.09
7.31
7.46
8.03
8.33
8.46
9.28

Area
(%)
30.42
8.38
0.46
38.60
1.89
1.08
8.18
0.39
0.36
3.41
1.98

Similarity

(%)
91
91
91
91
97
97
97
97
90
95
94

20
Appendix 5 GC-MS result of RLS 90 ºC from the second collection
A b u n d a n c e
T IC : F R A K S I 2 _ 9 0 .D
2 e + 0 7

1 .8 e + 0 7

1 .6 e + 0 7

1 .4 e + 0 7

6 .3 9

1 .2 e + 0 7

1 e + 0 7
4 .1 9
8 0 0 0 0 0 0

6 0 0 0 0 0 0
7 .4 6
4 0 0 0 0 0 0
5 .1 5
2 0 0 0 0 0 0

4 .3 8
3 .9 3
1 .0 0

2 .0 0

3 .0 0

4 .0 0

8 .4 6

4 .8 1
5 .0 0

5 .7 4
6 .0 0

7 .0 9
7 .3 1
7 .0 0

9 .2 8
8 .0 0

9 .0 0

1 0 .0 0

T im e - - >

Chemical constituents
Acetic acid
2-Furancarboxaldehyde
2-Furancarboxaldehyde, 5-methylPhenol
Phenol, 2-methylPhenol, 4-methylPhenol, 2-methoxyPhenol, 2-methoxy-4-methylPhenol, 4-ethyl-2-methoxy-

Retention time
(min)
4.20
5.16
6.22
6.39
7.09
7.31
7.46
8.45
9.28

Area
(%)
36.81
4.87
0.29
36.70
1.62
1.18
7.24
2.87
1.40

Similarity

(%)
91
91
91
91
97
97
97
95
94

21
Appendix 6 GC-MS result of RLS 100 ºC from the first collection
A b u n d a n c e
T IC : F R A K S I_ 1 (1 0 0 ).D
2 e + 0 7
1 .9 e + 0 7
1 .8 e + 0 7
1 .7 e + 0 7
1 .6 e + 0 7
1 .5 e + 0 7
1 .4 e + 0 7
1 .3 e + 0 7
1 .2 e + 0 7
1 .1 e + 0 7
1 e + 0 7
9 0 0 0 0 0 0
8 0 0 0 0 0 0
7 0 0 0 0 0 0

6 .3 8

6 0 0 0 0 0 0
5 0 0 0 0 0 0

4 .1 3

4 0 0 0 0 0 0
3 0 0 0 0 0 0
2 0 0 0 0 0 0

3 .9 3

1 0 0 0 0 0 0

3 . 8 94 . 3 5
1 .0 0

2 .0 0

3 .0 0

4 .0 0

7 .4 5

5 .1 5
5 .7 3
5 .0 0

6 .0 0

8 .4 6

7 .71 . 03 1
7 .0 0

8 .0 0

9 .2 8

9 .0 0

1 0 .0 0

T im e - - >

Retention time
(min)
Acetic acid
4.13
2-Furancarboxaldehyde
5.15
Phenol
6.37
Phenol, 2-methyl7.09
Phenol, 2-methoxy7.45
Phenol, 2-methoxy-4-methyl8.45
Phenol, 4-ethyl-2-methoxy9.28
Chemical constituents

Area
(%)
38.63
7.35
38.60
1.80
8.04
3.26
2.12

Similarity

(%)
90
90
91
97
97
95
94

22
Appendix 7 GC-MS result of RLS 100 ºC from the second collection
A b u n d a n c e

2 e + 0 7
1 .9 e + 0 7
1 .8 e + 0 7
1 .7 e + 0 7
1 .6 e + 0 7
1 .5 e + 0 7
1 .4 e + 0 7
1 .3 e + 0 7

6 .3 9

1 .2 e + 0 7
1 .1 e + 0 7
1 e + 0 7
4 .2 1

9 0 0 0 0 0 0
8 0 0 0 0 0 0
7 0 0 0 0 0 0
6 0 0 0 0 0 0
5 0 0 0 0 0 0
4 0 0 0 0 0 0

7 .4 6

3 0 0 0 0 0 0
2 0 0 0 0 0 0

4 .4 0

1 0 0 0 0 0 0

3 .9 3
1 .0 0

2 .0 0

3 .0 0

4 .0 0

5 .1 5

8 .4 6
7 .71 . 03 1

4 .8 2
5 .0 0

6 .0 0

7 .0 0

9 .2 8
8 .0 0

9 .0 0

1 0 .0 0

T im e - - >

Chemical constituents
Acetic acid
2-Furancarboxaldehyde
Phenol
Phenol, 2-methylBenzenemethanol
Phenol, 2-methoxy
Phenol, 2-methoxy-4-methylPhenol, 4-ethyl-2-methoxy-

Retention time
(min)
4.21
5.15
6.39
7.09
7.31
7.46
8.46
9.28

Area
(%)
38.63
4.11
37.43
1.51
1.26
6.86
2.68
1.45

Similarity

(%)
91
91
91
97
97
97
95
94

23
Appendix 8 GC-MS result of CLS
Abundance
TIC: SAMPEL.D
7.02
7000000
6000000

4.26
4.64

5000000
4000000
3000000
8.16

2000000
4.49
4.89
5.81

9.16 10.62
7.53
7.75
4.445.37 6.497.29
7.94 9.37
9.98
10.05
5.31 6.42

1000000

2.00

4.00

6.00

8.00

10.00

14.89
12.00

14.00

16.00

18.00

20.00

22.00

Time-->

Chemical constituents
Acetic acid
2-Furancarboxaldehyde
Phenol
2-Cyclopenten-1-one, 2-hydroxy-3-m
Phenol, 2-methylPhenol, 4-methylPhenol, 2-methoxyPhenol, 2-methoxy-4-methyl-

Retention
time (min)
4.64
5.81
7.02
7.53
7.74
7.94
8.16
9.16

Area
(%)
18.60
2.62
40.91
1.02
0.83
0.95
4.02
1.30

Similarity

(%)
91
90
91
96
96
96
97
95

24
Appendix 9 Sheet rubbers that were coagulated by formic acid, RLS, and CLS

Coagulant: Formic acid 1%

Coagulant: RLS 90 °C

Coagulant: CLS

Coagulant: RLS 80 °C

Coagulant: RLS 100 °C

25
Appendix 10 Wallace plasticity (Po) and plasticity retention index (PRI)
Samples
FA
1%
RLS
80 ºC
RLS
90 ºC
RLS
100 ºC
CLS

Speciment thickness
(mm)
Po
27.0
27.0
27.0
28.0
28.0
27.0
28.0
28.5
28.0
28.0
28.0
27.5
29.0
30.0
29.5
29.0
28.5
28.5
27.5
28.0
26.5
27.5
27.0
27.5
28.5
28.0
29.0
30.0
30.0
30.5
30.0
30.0
30.5
30.0
31.0
30.5
31.0
29.5
30.0
30.0
30.0
30.5
30.0
30.5
30.5

Calculation:
PRI = (Pa/Po) × 100
where
Po = plasticity original
Pa = plasticity aged

Speciment thickness
(mm)
Pa
34.0
34.0
33.0
32.5
33.0
32.0
34.0
33.5
33.5
28.0
27.5
27.0
29.0
29.0
28.5
28.5
29.0
29.0
28.0
27.0
26.5
28.5
29.0
28.0
30.0
30.0
29.5
32.0
32.0
32.0
32.0
31.5
30.5
31.0
31.0
30.5
30.5
31.0
30.0
29.0
30.0
29.5
30.0
30.0
29.5

Median
of
Po
27.0
28.0
28.0
28.0
29.5
28.5
27.5
27.5
28.5
30.0
30.0
30.5
30.0
30.0
30.5

Median
of
Pa
34.0
32.5
33.5
27.5
29.0
29.0
27.0
28.5
30.0
32.0
31.5
31.0
30.5
29.5
30.0

PRI
125.9
116.1
119.6
98.2
98.3
101.8
98.2
103.6
105.3
106.7
105.0
101.6
101.7
98.3
98.4

26
Appendix 11 Statistical analysis for Wallace plasticity (Po)
ANOVA
Sum of Squares
Between groups
Within groups
Total
Sig.