Synthesis and properties of castor oil based plasticizers

Article abstract of DOI:10.1039/c8ra10288k

A series of environment-friendly plasticizers has been synthesized from castor oil through a mild esterification/epoxidation reaction. The modified epoxy acetylated castor oil (EACO) can plastify poly(vinyl chloride) (PVC) efficiently, even better than the commercial plasticizers dioctyl terephthalate (DOTP) and epoxidized soybean oil (ESO), in terms of in tensile strength, migration stability, solvent extraction stability and thermal stability. Specifically, the tensile strength and elongation at break of a PVC sample plastified by epoxy acetylated castor oil (EACO) were 18.5 and 10.0% higher than that of DOTP, and 13.9 and 23.8% higher than that of ESO, respectively. Volatility, migration, solvent extraction and thermal stability tests indicated that the presence of carbon-carbon double bonds and hydroxy groups reduce the compatibility of a plasticizer with PVC while the presence of epoxy groups and ester bonds can improve the plasticizing effect of the plasticizer on PVC. In addition, alkyl groups can improve the plasticizing effect on PVC while benzene rings increase the rigidity of the PVC. The design strategy based on castor oil highlights a sustainable avenue for preparing cost-effective and high-efficiency plasticizers.

Full text of DOI:10.1039/c8ra10288k

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Synthesis and properties of castor oil based
plasticizers
Cite this: RSC Adv., 2019, 9, 10049
a
b
a
a
a
a
*
Qinghe Fu, Yilang Long, Yingyun Gao, Yuan Ling, Hao Qian, Fang Wang
ab
*
and Xinbao Zhu
A series of environment-friendly plasticizers has been synthesized from castor oil through a mild
esterification/epoxidation reaction. The modified epoxy acetylated castor oil (EACO) can plastify
poly(vinyl chloride) (PVC) efficiently, even better than the commercial plasticizers dioctyl terephthalate
(DOTP) and epoxidized soybean oil (ESO), in terms of in tensile strength, migration stability, solvent
extraction stability and thermal stability. Specifically, the tensile strength and elongation at break of
a PVC sample plastified by epoxy acetylated castor oil (EACO) were 18.5 and 10.0% higher than that of
DOTP, and 13.9 and 23.8% higher than that of ESO, respectively. Volatility, migration, solvent extraction
and thermal stability tests indicated that the presence of carbon–carbon double bonds and hydroxy
groups reduce the compatibility of a plasticizer with PVC while the presence of epoxy groups and ester
bonds can improve the plasticizing effect of the plasticizer on PVC. In addition, alkyl groups can improve
the plasticizing effect on PVC while benzene rings increase the rigidity of the PVC. The design strategy
based on castor oil highlights a sustainable avenue for preparing cost-effective and high-efficiency
plasticizers.
Received 15th December 2018
Accepted 18th March 2019
DOI: 10.1039/c8ra10288k
rsc.li/rsc-advances
a role as stabilizer.10 When heated, PVC undergoes autocatalytic
dehydrochlorination, whereas the epoxide group can scavenge
Introduction
the produced HCl which would have been constantly generated
by a free radical reaction from PVC through induced catalytic
degradation.11 Currently, an epoxy fatty acid multi-ester,12 dimer
acid ester13 and fatty acid glycidyl ester14 are also used as plas-
ticizers in PVC. However, most of these plasticizers, which are
based on vegetable oils still have a problem in terms of their
also being edible food ingredients.
Poly(vinyl chloride) (PVC) is currently one of the largest
produced synthetic resin products in the world. Adding an
appropriate amount of plasticizer to PVC resin can improve the
processibility, plasticity, exibility, stretchability etc. Dioctyl
phthalate (DOP), as the most applied typical plasticizer, has
been widely used to plastify PVC for decades. Considering the
direct and indirect threat of phthalate plasticizers for human
health as well as the environment,1–3 dioctyl terephthalate
(DOTP) is gradually replacing DOP as the main plasticizer in
PVC. However, DOTP is still produced from petrochemical
resources, hence nding cheap, environmentally friendly, and
renewable alternative raw materials has become an urgent issue
to relieve the crisis arising from fossil fuel depletion and envi-
ronmental hazards. Vegetable oils have been increasingly used
in the eld of plasticizers because of their wide distribution,
non-toxicity, low price, environmentally friendly properties and
renewable nature.4
Castor oil, a land-grown oil, is an inedible oil and a highly
renewable resource for many chemical industries, and is mainly
produced in Asia and Africa. Castor oil molecules contain
hydroxy groups, carbon–carbon double bonds and ester bonds,
which can be undergo epoxidation, sulfonation, halogenation,
esterication, hydrolysis and other reactions to produce
different varieties of plasticizers. For example, epoxidized
methyl acetoricinoleate is a common castor oil based plasticizer
with high epoxy value and good thermal stability,15 but a large
amount of glycerol is produced during its preparation, which
represents excess capacity. Two types of epoxy acetyl castor oil
polyol ester plasticizers were synthesized by Jia et al. and had
better plasticizing effect than DOP and ESO,16 but the tensile
strength of the PVC blends was much lower than that from ESO,
which makes its replacing of soybean oil impractical. A castor
oil-based diglycidyl ester plasticizer (C26-DGE) was prepared by
Chen et al.17 with ricinoleic acid as raw material and results
showed that the plasticizer endowed the PVC matrix with
enhanced compatibility and exibility. Besides, a series of
Plasticizers prepared from vegetable oils mainly include
epoxy vegetable oils,5–8 and epoxidized fatty acid esters.9 In these
types of plasticizers, the presence of the epoxy group makes the
plasticizers have a better plasticizing effect on PVC and plays
aCollege of Chemical Engineering, Nanjing Forestry University, Nanjing 210037,
China. E-mail: zhuxinbao@njfu.com.cn
bAnhui Engineering Research Center of Epoxy Resin and Additives, Huangshan 245900,
China
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phosphorus-containing ame retardant plasticizers based on mL) and cation exchange resin catalyst (4.7 g) were added, aer
castor oil as a secondary plasticizer were synthesized and the that 30% hydrogen peroxide (39.7 g) was added dropwise to the
results showed that the material added plasticizers had reaction mixture over 2 h and then stirred for 5 h. Then the
improved tensile strength, with good heat insulation and ame reaction mixture was ltered to recycle the cation exchange
retardant properties, but the elongation at break was resin, and the remaining uid was washed to pH ¼ 7 with
decreased.18–21
sodium carbonate solution and distilled water. Then the water
Our team has conducted a substantial amount of work on and solvent were removed by vacuum distillation.
the synthesis of plasticizers, especially in clean production
processes.22–24 In this study, we synthesized ve environment-
friendly plasticizers derived from castor oil through mild
esterication/epoxidation reactions. The synthetic plasticizers
were added to PVC (along with a heat stabilizer), and the
properties were investigated and compared to the commercial
plasticizers DOTP and ESO. We compared the effects of epoxy
groups and carbon–carbon double bonds, ester groups and
hydroxyl groups, and alkyl and benzene rings on plasticizing
Synthesis of benzoyl castor oil (BCO)
Castor oil (93.4 g), benzoyl chloride (38.0 g), calcium oxide (10.6
g) and toluene (100 mL) were added to a 500 mL four-necked
ask and were stirred at 110 ꢀC for 3 h. Then the reaction
mixture was washed to pH ¼ 7 with sodium hydroxide solution
and distilled water. Then the water and solvent were removed by
vacuum distillation.
PVC to attempt to nd an environment-friendly plasticizer with
good plasticity ability using a simple synthesis method. We
expect more competitive results compared with traditional
plasticizers to lead the way towards green and sustainable
routes for PVC application.
Synthesis of epoxy benzoyl castor oil (EBCO)
BCO (121.5 g), acetic acid (18.0 g), toluene (100 mL) and cation
exchange resin catalyst (4.7 g) were added to a 500 mL four-
necked ask and were heated and 30% hydrogen peroxide
(39.7 g) was added dropwise to the reaction mixture over 2 h and
stirred at 60 ꢀC for 5 h. Then the reaction mixture was ltered to
recycle the cation exchange resin, and the remaining uid was
washed to pH ¼ 7 with sodium carbonate solution and distilled
water. Then the water and toluene were removed by vacuum
distillation.
Experimental section
Materials
Hydrogen peroxide, acetic anhydride, benzoyl chloride, acetic
acid, calcium oxide, toluene, sodium hydroxide, sodium
carbonate, hydrochloric acid and acetone were provided by
Nanjing Chemical Reagent Co., Ltd. (China); castor oil and the
cation exchange resin were provided by Anhui Xinyuan Chem-
ical Co., Ltd. (China).
Preparation of plasticized PVC samples
The PVC, plasticizer and heat stabilizer were mixed in the ratio
of 50 : 25 : 1. The mixture was blended for 7 min at 170 ꢀC using
a HAAKE PolyLab OS torque rheometer, and then placed in
a at-panel curing machine and pressed for 4 min at 170 ꢀC and
2 min at room temperature. The PVC blends were labeled as
PVC-DOTP (PVC/DOTP), PVC-ESO (PVC/ESO), PVC-ECO (PVC/
ECO), PVC-ACO (PVC/ACO), PVC-EACO (PVC/EACO), PVC-BCO
(PVC/BCO) and PVC-EBCO (PVC/EBCO).
Synthesis of epoxy castor oil (ECO)
Castor oil (93.4 g), acetic acid (18.0 g), toluene (100 mL) and
cation exchange resin catalyst (4.7 g) were added to a 500 mL
four-necked ask equipped with a stirrer, a thermometer,
a constant pressure funnel and a ball condenser, 30% hydrogen
peroxide (39.7 g) was dropwise added in the reaction mixture
over 2 h and stirred at 60 ꢀC for 5 h. Then the reaction mixture
was ltered to recycle the cation exchange resin, and the
remaining uid was washed to pH ¼ 7 with sodium carbonate
solution and distilled water. Then the water and solvent were
removed by vacuum distillation. Scheme 1 shows the synthesis
routes of all products.
Characterizations and measurements
FT-IR spectra were recorded on a Nicolet FTIR-360 (Nicolet
Instrument Corp., USA) Fourier transform infrared spectro-
photometer. The spectra was acquired in the range of 400 to
4000 cmꢁ1
.
1H NMR spectra were recorded by using an AVANE400
(Bruker Company, Switzerland) with deuterated chloroform as
a solvent.
Synthesis of acetylated castor oil (ACO)
Castor oil (93.4 g) and acetic anhydride (27.5 g) were added to
ꢀ
a 500 mL four-necked ask, and were stirred at 140 C for 2 h.
Tensile strength and elongation at break of all PVC samples
were determined according to the GB/T 1040.1-2006 (China)
under ambient conditions by using an E43.104 Universal
Testing Machine (MTS Instrument Corp., China).
The volatility stability tests were determined by GB/T 3830-
Then the reaction mixture was washed to pH ¼ 7 with sodium
carbonate solution and distilled water. Then the water was
removed by vacuum distillation.
Synthesis of epoxy acetylated castor oil (EACO)
2008, PVC samples were cut into 50 mm ꢂ 50 mm squares,
ꢀ
Castor oil (93.4 g) and acetic anhydride (27.5 g) were added to placed in an oven for 24 h at 80 C, and then cooled to room
ꢀ
a 500 mL four-necked ask and were stirred at 140 C for 2 h. temperature in a desiccator. The mass changes were measured
Then the reaction mixture was cooled to 60 ꢀC, and toluene (100 by weighing before and aer heating. The volatility rate was
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Scheme 1 Synthesis of ECO, ACO, EACO, BCO and EBCO.
calculated as the ratio of the evaporated and the initial
plasticizer.
Results and discussion
FTIR and NMR characterization of the synthesized plasticizers
Migration stability tests were determined according to the
ISO 176-2005, PVC samples were cut into 50 mm ꢂ 50 mm
squares, and covered with activated carbon on both sides.
The FT-IR spectra of CO, ECO, ACO, EACO, BCO and EBCO are
shown in Fig. 1. Compared to CO and ECO, the hydroxy group
signal at 3400 cmꢁ1 almost disappeared in the spectra of ACO,
EACO, BCO and EBCO, which indicated that acylation reaction
occurred. The epoxy group at 1068 cmꢁ1 appeared in the FT-IR
of ECO, EACO and EBCO, while the carbon–carbon double
bonds of CO, ACO and BCO at around 3010 cmꢁ1 disappeared,
which demonstrated that the carbon–carbon double bonds
have been converted into epoxy groups.
ꢀ
Samples were placed in an oven for 24 h at 20 and 70 C, and
weight loss was measured before and aer heating.
The solvent extraction stability tests were determined
according to the GB/T3830-2008, PVC samples with 50 mm ꢂ
50 mm shape were immersed in ve different solvents (distilled
water, 30% (w/w) acetic acid, 30% (w/w) sodium hydroxide, 50%
(w/w) ethanol and cyclohexane) for 24 h at room temperature.
ꢀ
Subsequently, samples were placed in an oven for 8 h at 50 C
and cooled to room temperature in a desiccator. The mass rate
changes were measured before and aer these processes.
The dynamic mechanical analyses were performed via
a DMTA Q800 (TA Instruments, US) using rectangular samples
of geometry 35 mm (L) ꢂ 12.5 mm (W) ꢂ 3.2 mm (T). The
oscillatory frequency of the dynamic tests werꢁe1 1 Hz. The
temperature was raised at a rate of 3 ꢀC min
to +120 C.
from ꢁ60
ꢀ
The thermal ability of PVC blends was characterized in
a DTG-60AH TGA thermal analysis instruments set-up (Netzsch
Instrument Crop., Germany) inꢀ an N2 atmosphere (50
mL minꢁ1) at a heating rate of 10 C minꢁ1. 5 mg of samples
were placed into platinum pans and scanned from 30 to 600 ꢀC.
The fracture surface morphology of the PVC blends aer
tensile fracture were analysed by a Hitachi S-4800 (Hitachi,
Japan) scanning electron microscope (SEM) operated at 1 kV.
Fig. 1 FT-IR spectra of CO and the synthesized plasticizers.
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1
Fig. 2 shows the H NMR spectra of CO, ECO, ACO, EACO, lower elongation compared with the other six samples. Aer
BCO and EBCO. Compared to the CO 1H NMR spectra, the acetylation or benzoylation of hydroxy groups and subsequent
proton signals in the 5.45–5.55 ppm region of ECO, EACO and epoxidation, there is an obvious increase in tensile strength
EBCO spectra associated with carbon–carbon double bond and elongation of PVC-EACO and PVC-EBCO, which indicated
bands were weakened, and signals in the 2.95–3.15 ppm region that the hydroxy group can reduce the compatibility of plas-
of ECO, EACO and EBCO spectra associated with epoxy groups ticizers with PVC.15 Compared to PVC-ACO and PVC-BCO,
bands indicated that during the epoxidation reaction, most of PVC-EACO and PVC-EBCO displayed superior tensile
the carbon–carbon double bonds have been converted. The strength and break elongation, which can be attributed to
signals in the 2.01 ppm region of ACO and EACO spectra are that the epoxidation of carbon–carbon double bonds
associated with shied methyl hydrogens of the acetyl group, so enhanced the plasticizer so as to be compatible with PVC.25,26
verifying the acetylation reaction. Also, the proton signals in the The tensile strength and elongation at break of PVC-EACO
7.45–7.55 and 8.1 ppm region of BCO and EBCO spectra asso- were 18.5 and 10.0% higher than PVC-DOTP, and 13.9 and
ciated with benzene revealed that the hydroxy group of castor oil 23.8% higher than PVC-ESO, respectively, demonstrating that
was acylated with benzoyl chloride.
the plasticizing effect of EACO on PVC is more efficient than
that of DOTP and ESO. This may be because EACO has more
epoxy groups than DOTP and more ester bonds than ESO,
which can obviously increase the compatibility of plasticizers
and PVC.14 PVC-EBCO showed the highest tensile strength
Tensile test
The results of tensile strength and elongation at break are
presented in Fig. 3. PVC-ECO shows a lower tensile strength and
Fig. 2 1H NMR spectrum of (a) CO, (b) ECO, (c) ACO, (d) EACO, (e) BCO and (f) EBCO. Note: ‘
functional group as the first molecular chain in their respective chemical structures.
’ represents the same structure and
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Fig. 3 Tensile properties of the PVC blends.
compared with the other six samples and lower elongation
than PVC-DOTP, PVC-ESO, PVC-ACO and PVC-EACO, which
meant that the rigid benzene ring on the plasticizer structure
can improve the tensile strength of the blend and reduce the
uidity of the plasticizer in PVC.27Plasticizer EBCO can thus
be used in materials requiring high rigidity.
Migration stability test
The migration stability of the different plasticizers in the PVC
blends is shown in Fig. 5. At 20 ꢀC, the weight loss of all samples
is small, on account of the low molecular mobility at low
ꢀ
temperature. At 70 C, the trend is similar to that of volatility
stability. The results further illustrate that the hydroxy group
reduced the compatibility of plasticizers with PVC while the
epoxy group could improve the volatility and migration stability
of the plasticizer.
Volatility stability test
The volatility stability of all plasticizers was investigated, and
the results are shown in Fig. 4. PVC-ECO shows the highest
volatility, which proved that the plasticizer ECO exhibited worst
compatibility towards PVC owing to the presence of the hydroxyl
group. The lower mass change of PVC-EACO and PVC-EBCO
when compared to PVC-ACO and PVC-BCO indicated that the
epoxide functional groups of EACO and EBCO play a more
signicant role than the double bonds of ACO and BCO. Addi-
tionally, the mass change of PVC lms plastied by acetylation-
modied plasticizers is less than that upon benzoylation
modication, which illustrated that alkyl groups can increase
the compatibility of plasticizers and PVC more than benzene
rings.
Migration stability test
The solvent extraction stability of the different plasticizers in
PVC blends is shown in Fig. 6. The weight loss of PVC blends is
strongly affected by the strength of the interactions between the
plasticizers and the polymer chain.28 PVC-ECO, PVC-ACO and
PVC-BCO show higher dissolution rate than PVC-DOTP, PVC-
ESO and PVC-EACO in distilled water, 30% (w/w) acetic acid,
30% (w/w) sodium hydroxide and 50% (w/w) ethanol, which
indicate that the hydroxy group and the double bonds have
a negative effect on the interactions between the plasticizers
Fig. 4 Volatility properties of the PVC blends.
Fig. 5 Migration stabilities of the PVC blends.
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Fig. 6 Solvent extraction stabilities of the PVC blends.
and PVC, which made more plasticizer transfer to the solvent PVC-BCO and PVC-EBCO showed only one tan d peak, and the
from PVC. However, in cyclohexane, PVC-ESO, PVC-ECO, PVC- Tg values were 35.2, 39.8, 70.2, 35.7, 76.9 and 60.1 ꢀC respec-
EACO and PVC-EBCO have a lower extraction rate than the tively, indicating that the six plasticizers were compatible with
other three samples, which may be because the epoxy group is PVC, while ECO was not, with two tan d peaks at ꢁ34.8 and
a polar group, and has a stronger interaction with the polar 86.4 ꢀC in PVC-ECO. PVC-EACO and PVC-EBCO show a lower Tg
parts of the PVC molecules, which reduces the plasticizer value than PVC-ACO and PVC-EBCO respectively, which
dissolution rate.27 Moreover, PVC-EBCO presents a higher demonstrates that the epoxy groups can make the molecule
dissolution rate compared with PVC-EACO, even though EBCO more polar, and hydrogen bonds formed between the molecular
has no hydroxy groups or carbon–carbon double bonds. chains can ultimately increase the viscous activity of the
However, the non-polar benzene rings of EBCO serve to weaken mixture.30
the attractive forces between the plasticizer and PVC chains,
thus increasing the free volume and imparting exibility to the
polymer.29 On the whole, PVC-EACO had better solvent extrac-
Thermogravimetric analysis
The TGA of PVC plasticized with different plasticizers is pre-
sented in Fig. 10. From the TGA curves of PVC blends, it can be
tion stability than PVC-DOTP and PVC-ESO, which signies that
EACO has higher potential application value in food packing
and medical devices.
Dynamic mechanical property test
According to Fig. 7, the storage modulus of PVC-EACO is higher
than that of PVC-DOTP and PVC-ESO, which indicated that PVC-
EACO has a higher elasticity. At the same time, the acetylation
and epoxidation modied PVC test pieces had higher storage
modulus than for benzoylation and non-epoxidation samples,
demonstrating that the alkyl and epoxy groups enhance the PVC
elasticity compared to the benzene ring and carbon–carbon
double bonds.
The loss modulus (Fig. 8), which represents the amount of
energy lost by viscous deformation of the material, is charac-
terized by a peak value as well as the curve of the damping factor
(tan d, Fig. 9), and generally the peak value of T is taken as the
glass transition temperature. In most cases, a narrow tan d peak
and single Tg of the polymer composite indicate excellent
homogeneity.26 PVC-DOTP, PVC-ESO, PVC-ACO, PVC-EACO, Fig. 7 Storage modulus of the PVC blends.
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Fig. 10 TGA curves of the PVC blends.
Fig. 8 Loss modulus of the PVC blends.
ECO, EACO and EBCO were higher than those with DOTP, ACO
and BCO, which proves that epoxy groups can absorb hydrogen
chloride degraded by light and heat, preventing the contin-
uous decomposition of PVC and prolonging the lifetime of
PVC.31,32 In addition, the TP2 values of PVC-ACO and PVC-BCO
are lower than those of PVC-EACO and PVC-EBCO, which may
be because the double bonds in ACO and BCO reduced the
thermal stability. The char residue of PVC plasticized with
DOTP is higher than that of the other plasticizers, indicating
that ESO, ECO, ACO, EACO, BCO and EBCO could decrease the
char residue of PVC blends more than DOTP. From these data,
we could conclude that the castor oil based plasticizers could
improve the thermal stability and reduce the amount of char
residue of PVC blends.
Fracture surface morphology analysis
Fig. 9 Loss tangent curves as a function of temperature of the PVC
blends.
The fracture surface morphology of pulled and cut plasticized
PVC blends is shown in Fig. 11. As can be seen, the section
topography of the different PVC blends is quite different. PVC-
DOTP, PVC-ESO, PVC-ACO, PVC-EACO, PVC-BCO and PVC-
EBCO clearly showed numerous small protrusions and non-
retracted laments, which are typical features of ductile
fracture, indicating that the plasticizers have great compati-
bility with PVC and a good plasticizing effect. However, PVC-
seen that all of the PVC blends were thermally stable in
a nitrogen atmosphere below 220 ꢀC and exhibited a two-stage
thermal degradation process above that temperature. The rst
ꢀ
degradation at about 260–350 C corresponds to the elimina-
tion of a large amount of HCl. The second stage at about 440–
480 ꢀC is attributed to the decomposition of the PVC main
chain and plasticizers. The thermal performance data
including the weight loss of 10% (T10%), the weight loss of 50%
(T50%) and the maximum weight-loss temperature rate (TP1
and TP2) are summarized in Table 1. T10%, T50% and TP1 values
of PVC plasticized with ESO, ECO, ACO, EACO, BCO and EBCO
were higher than for DOTP, which may be because compared
to DOTP, the other six plasticizers have more ester bond
structures and epoxy groups, which are associated with higher
thermal stability than the lower-thermally stable chain
segments of DOTP, thereby increasing the thermal stability of
the PVC blends.16 The TP1 values of PVC plasticized with ESO,
Table 1 TGA data of the PVC blends
Samples
T10%/ꢀC
T50%/ꢀC
TP1/ꢀC
TP2/ꢀC
Residue (%)
PVC-DOTP
PVC-ESO
PVC-ECO
PVC-ACO
PVC-EACO
PVC-BCO
PVC-EBCO
264.4
283.1
280.3
268.3
275.7
268.8
274.5
310.1
337.4
340.1
326.9
334.8
322.2
335.2
300.9
310.6
307.9
302.4
309.6
301.7
307.2
465.0
460.8
465.3
459.0
465.5
457.8
466.6
13.16
10.89
11.08
11.83
10.22
11.47
10.74
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Fig. 11 SEM images of (a) PVC-DOTP, (b) PVC-ESO, (c) PVC-ECO, (d) PVC-ACO, (e) PVC-EACO, (f) PVC-BCO and (g) PVC-EBCO.
ECO did not have obvious protrusions and laments, and the
edge of the fracture was very smooth, which indicated that
Acknowledgements
ECO did not show a good plasticizing effect with PVC. The
section topography of PVC-EACO was much more complex
than the others, and protrusions and laments were more
numerous and longer, which indicates that the plasticizer
EACO had the best plasticizing effect, even better than that of
DOTP and ESO.
The authors would like to thank the State Forestry Adminis-
tration 948 project foundation for nancial support under the
Grant No 2015-4-55, China; and the Priority Academic Program
Development of Jiangsu Higher Education Institutions (PAPD),
China. The article is also supported by the Doctorate Fellowship
Foundation of Nanjing Forestry University.
Conclusions
Notes and references
In this study, ve types of environment-friendly material plas-
ticizers based on castor oil were synthesized. The synthetic
plasticizers were added to PVC as the main plasticizer, and the
properties of these PVC blends were investigated and compared
to the commercial plasticizers DOTP and ESO. Tensile proper-
ties showed that the tensile strength and elongation at break of
the PVC sample plastied by EACO were 18.5 and 10.0% higher
than that of DOTP, and 13.9 and 23.8% higher than that of ESO,
respectively. EACO also had generally better volatility, solvent
extraction and migration stability properties than those of
DOTP and ESO, and better than the other four plasticizers
synthesized. All the tests illustrated that compared to hydroxy
groups, carbon–carbon double bonds and phenyl groups, ester
bonds, epoxy groups and alkyl groups can make plasticizers
more compatible with PVC, showing better plasticizing effect
and better thermal stability. Based on the above studies, the
plasticizer EACO based on castor oil shows an excellent
performance, in addition to this, during its synthesis, acetic
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Conflicts of interest
There are no conicts to declare.
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