Improvement of thermal properties of poly(vinyl chloride) using chemical blending assisted ultrasonic technique

Article abstract of DOI:10.14233/ajchem.2017.20773

The thermal stabilization of poly(vinyl chloride) through blending techniques has been studied. Poly(vinyl chloride) was blended with modified polymer (cellulose acetate-diallyl amine) in different compositions to improve the thermal stability of poly(vinyl chloride). The thermal stability and morphology of the blend films were characterized by scanning electron microscope (SEM) and thermogravimetry. The results revealed that the presence of modified cellulose acetate improved the thermal stability of poly(vinyl chloride). This was attributed to the thermal stable diallylamine moieties among the cellulose acetate chains. The addition of traces of maleimide derivatives to poly(vinyl chloride) prior to the blend process led to an extra thermal stability of the blend film as shown from the values of the initial decomposition temperature (T_o) measured by thermogravimetry.

Full text of DOI:10.14233/ajchem.2017.20773

Asian Journal of Chemistry; Vol. 29, No. 10 (2017), 2285-2288
ASIAN JOURNAL OF CHEMISTRY
https://doi.org/10.14233/ajchem.2017.20773
Improvement of Thermal Properties of Poly(vinyl chloride)
Using Chemical Blending Assisted Ultrasonic Technique
AZZA AL-GHAMDI
Chemistry Department, College of Science, University of Dammam, Dammam, Saudi Arabia
Corresponding author: E-mail: azaalghamdi@uod.edu.sa
Received: 9 May 2017;
Accepted: 30 June 2017;
Published online: 31 August 2017;
AJC-18535
The thermal stabilization of poly(vinyl chloride) through blending techniques has been studied. Poly(vinyl chloride) was blended with
modified polymer (cellulose acetate-diallyl amine) in different compositions to improve the thermal stability of poly(vinyl chloride). The
thermal stability and morphology of the blend films were characterized by scanning electron microscope (SEM) and thermogravimetry.
The results revealed that the presence of modified cellulose acetate improved the thermal stability of poly(vinyl chloride). This was attributed
to the thermal stable diallylamine moieties among the cellulose acetate chains. The addition of traces of maleimide derivatives to poly(vinyl
chloride) prior to the blend process led to an extra thermal stability of the blend film as shown from the values of the initial decomposition
temperature (To) measured by thermogravimetry.
Keywords: Poly(vinyl chloride), Ultrasonic waves, Thermal properties.
INTRODUCTION
EXPERIMENTAL
Poly(vinyl chloride) (PVC) is widely used in plastic appli-
cations due to low cost and ease handling process. The thermal
in-stability during molding and the photo-degradation during
day use are the major problems facing the industrial benefit of
this polymer. Thus, to use PVC to industrial applications, it
should be thermally stabilized to support the polymer during
molding process and against the photo-degradation [1-4].
The heat instability is definitely due the structural defects
formed during polymerization reaction. These defects are
mainly, allylic or tertiary labile chlorine atoms, which cause
the formation of polyenes after losing HCl [5].
Poly(vinyl chloride) (PVC) (suspension), K value 67, from
National (Plastic Company, Sabic), (Kingdom of Saudi
Arabia). Cellulose acetate (CA) was purchased from (Aldrich)
with a degree of polymerization and degree of substitution of
160 and 2.4, respectively.
Aniline was purified by vacuum distillation, 4-chloro aniline
(Acros), 4-bromo aniline (Acros) and maleic anhydride were
recrystallized from acetone. Tetrahydrofuran was obtained
from (Prolabo) (used after distillation in the presence of KOH
pellets). Other reagents and solvents were of analytical grades
and used as received.
The use of stabilizers is either for absorbing the evolved
gas or displacing the labile sites. The commercially used stabilizers
are usually containing heavy metals which are environmentally
rejected. To overcome the accumulation of these heavy metals,
organic based stabilizers were used as additives [6,7] or modi-
fying agents [8,9]. Moreover, polymer blend technique is also
considered as effective and commercial method to stabilize
such a polymer [10-13], these stabilizers are environmentally
accepted [14,15]. The aim of this work is to stabilize poly(vinyl
chloride) by blending it with suitable biodegradable polymers
through their amorphous regions to improve its thermal stability
to enable the adjustment of poly(vinyl chloride) for plastics
applications [16,17].
Thermal characterization: Thermogravimetric analysis
experiments were examined using simultaneous thermal
gravimetric analyzer a Perkin Elmer thermalgravimetric
analyzer (TGA) under nitrogen atmosphere and the heating
rate is10 °C/min.
Morphological surface analysis: Poly(vinyl chloride)
morphology in presence of cellulose acetate, modified cellulose
acetate and additives was examined by emission scanning
electron microscopy (ESEM) using a (FEG-SEM/EDS)or LEO
440ZEISS/LEICA model.
Methods: N-Phenyl maleimide and their derivatives
synthesized in two steps using aniline derivatives and maleic
anhydride.

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Asian J. Chem.
Preparation of N-phenyl maleimide: Aniline (0.1 mol)
Thermogravimetry (TG): Another example for the assis-
tance of ultrasonic waves is their effect on the thermal stability
of the blend film. It was clearly found that the ultrasonic waves
assisted the homogeneity of the blend film since the thermal
stability of the blend films prepared in ultrasonic bath exhibited
higher thermal stability than that prepared without ultrasonic
waves. Fig. 3 and Table-1 showed To value (initial decompo-
sition temperature) of the blend films. The results revealed
that the films prepared using ultrasonic waves which showed
homogeneous feature exhibited higher value (To = 217 °C) as
compared to those showing limited homogeneity and exhi-
biting lower value (To = 200 °C). This might be attributed to
the help of ultrasonic waves on providing better distribution
of both polymers through their amorphous regions.
and maleic anhydride (0.1 mol) were dissolved in 50 mL
chloroform. The reaction was stirred for 3 h at room tempe-
rature (20-25 °C). The solid maleaimic acid derivatives were
filtered and dried.
The maleamic acid was allowed to cyclodehydrated by
using acetic anhydride and fused sodium acetate. The solution
was stirred for 0.5 h at 80 °C. The prepared produced is
precipitated in ice, filtered and washed by water. The product
was then crystallized by ethanol [6] (Fig. 1).
Preparation of modified cellulose acetate: Cellulose
acetate modified by diallylamine was prepared by adding
diallylamine to a solution of cellulose acetate in cyclohexanone
according to the method described by Abdel-Naby et al. [18].
The modification reaction occurs in ultrasonic bath of power
1050 W for 2 h at 60 °C.
TABLE-1
EFFECT OF ULTRASONIC WAVES ON THE THERMAL
STABILITY BLEND FILM (70:30) (PVC:CA) IN PRESENCE
AND ABSENCE OF MODIFIED CELLULOSE ACETATE (CA)
Preparation of blend film: The PVC compounding (PVC
+ 0.02 % N-phenyl maleimide derivatives) sample solution is
blended with cellulose acetate or modified cellulose acetate
solution in an ultrasonic bath for certain interval of time till
homo-geneous solution is obtained. The casting technique is
used to obtain the blend film after the evaporation of the solvent
at room temperature.
Ultrasonic
waves exposure
To
(°C)
Total weight loss
(%) at 500 °C
Blend films
Poly(vinyl chloride)
Cellulose acetate
[PVC-CA]
0
0
0
2
2
180
260
200
217
240
88.7
89.3
84.4
83.7
82.7
[PVC-CA]
[PVC-(CA/DAA)]
RESULTS AND DISCUSSION
Effect of ultrasonic waves on homogeneity of the blend
films: Ultrasonic waves are known to possess the ability to initiate
chemical reaction in solution [19] as they provide fast particles
motion. They enhanced the interaction between the two polymers
and thus improved the homogeneity of the film (Fig. 2). The
morphology of (70:30) [PVC/(CA-DAA)] blend film showed
very limited homogeneity feature (b). However, the use of ultra-
sonic bath during the blending process improved the homogeneity
of the blend film as seen from the morphology feature (c).
Comparing the thermogravimetry of (PVC-CA), it
was found that To value increased with the using modified
cellulose acetate (CA/DAA) as compared with free cellulose
acetate (Fig. 3). This is attributed to the increase in the crystalline
regions provided by modified cellulose acetate polymeric
matrix [18].
The [PVC-(CA/DAA)] (70:30) blend film exhibited the
highest thermal stability as shown from the highest value of
(To = 240 °C).
O
O
O
(CH3CO)2O
CH3COONa
HC
C
HN
R
N
O
R
Chloroform
(0-5 C)
O
NH2
R
CH
°
(70-80
30 min
°C)
COOH
N-(aryl)maleamic acid
N-(RPh)M
O
N-(aryl)maleimide
N-(RPh)M
R: H, Br, Cl
Fig. 1. Preparation of N-phenyl malemide [Ref. 6]
Fig. 2. ESEM of (a) PVC, (b) (70:30) [PVC-(CA/DAA)] prepared in water bath and (c) (70:30) [PVC-(CA/DAA)] Prepared in ultrasonic
bath for 2 h

Vol. 29, No. 10 (2017)
Improvement of Thermal Properties of PVC Using Chemical Blending Assisted Ultrasonic Technique 2287
120
However, the PVC compounding is known to contain no
more than 20 % additives to keep the plasticity of the film
unaffected [17,18]. In a trial to give the blend film extra thermal
stability, the PVC is mixed with traces of N-phenyl maleimide
prior to blend it with cellulose acetate.
(f) (70:30) [PVC-BrPhM)/CA]
(e) (70:30) [PVC-ClPhM)/CA]
(b) (PVC)
(a) (CA)
(d) (70:30) [PVC-PhM)/CA]
(c) [PVC-(CA/DAA)] (70:30) sonic
e
f
100
80
60
40
20
0
a
The thermal stability of the thermogravimetry blend films
with (PVC/CA) composition (70:30) in absence and presence
of traces of N-phenyl maleimide derivatives was shown in Fig. 4.
The blend films in presence of halophenylmaleimide derivatives
exhibited highTo values as compared to that in absence maleimide
derivatives or even in presence of unsubstituted N-phenyl male-
imide. This might be attributed to secondary forces provided from
the interaction of halo groups and oxygen atom of the hydroxyl
group of glucopyranose ring of cellulose acetate (Fig. 5).
c
d
b
0
100
200
300 400
Temperature (°C)
500
600
700
120
Fig. 4. Thermogravimetry (TG) of (a) (CA), (b) (PVC), (c) (70:30) [PVC-
(CA/DAA)], (d) (70:30) [(PVC-PhM)/CA], (e) (70:30) [(PVC-
ClPhM)/CA]
100
Fig. 4 and Table-2 revealed that the presence of modified
cellulose acetate gave the extra thermal stability of the film as
shown from the high values of To as compared to the blend
film in presence of unmodified cellulose acetate and 4-bromo-
malimide (To = 230 °C).
e
80
60
40
20
0
a
d
(d) PVC-CA (70:30) sonic
(b) PVC
b
Morphological characterization: The morphology of the
surface of PVC blend films in presence of cellulose acetate
and additives are shown in Fig. 6.
(c) PVC-CA (70:30) without sonic
(a) CA
c
(e) [PVC-(CA/DAA)] (30:70) sonic
Conclusion
0
100
200
300
Temperature (°C)
400
500
600
The PVC blend polymers with cellulose acetate, modified
cellulose acetate and additives have been prepared to improve
the thermal stability of PVC. The thermal stability of blend
Fig. 3. Thermogravimetry (TG) of (a) CA, (b) PVC, (d) (70:30) (PVC-
CA) and (e) (70:30) [PVC-(CA/DAA)] blended with ultrasonic
waves for 2 h, (c) (PVC-CA) blended without ultrasonic waves
CH2 CH CH CH CH2
Cl
CH2 CH CH CH CH2
(a)
Cl
HC
CHCl
CH2 CH CH CH CH2
O
O
N
X
O
O
N
CHCl
Cl
O
O
(a)
+
(b)
N
X
(b)
X
OAc
OAc
O
OAc
AcO
HO
OAc
O
O
O
O
HO
O
O
OH
O
H
AcO
n
OAc
OAc
OAc
X
OAc
electrostatic
force
N
O
O
Cl
CH2 CH CH CH CH2
Fig. 5. Effect of halogen groups in enhancing both the incorporation of N-(4-halo) maleimide molecules into the PVC chains and the compati-
bility of PVC with cellulose acetate chains

2288 Al-Ghamdi
Asian J. Chem.
Fig. 6. ESEM morphology of polymeric films (a) [PVC-PhM/CA], (b) [PVC-4-ClPhM/CA] and (c) [PVC-4-BrPhM/CA]
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(2003);
TABLE-2
THERMAL ANALYSIS OF VARIOUS BLEND FILM (70:30)
(PVC:CA) IN PRESENCE AND ABSENCE OF TRACES OF XPhM
DERIVATIVES PREPARED IN ULTRASONIC BATH FOR 2 h
https://doi.org/10.1016/S0141-3910(03)00194-0.
7. A.Abdel-Naby andA.Al Dossary, J. Vinyl Addit. Technol., 14, 175 (2008);
https://doi.org/10.1002/vnl.20165.
Blend films
To (°C)
180
Total weight loss (%) at 500 °C
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https://doi.org/10.1016/S0141-3910(98)00125-6.
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Environ. Sci., 7, 1 (2011);
PVC
CA
88.7
89.3
90.0
87.7
85.4
85.4
260
[PVC-CA]
217
[PVC-PhM/CA]
[PVC-ClPhM/CA]
[PVC-BrPhM/CA]
213
https://doi.org/10.3844/ajessp.2011.1.14.
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220
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rather than using additives as shown from the higher value of
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The results also revealed that [PVC-(CA/DAA)] blend film
possessed higher To value than that of PVC-phenyl maleimide
derivatives.
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