The document studies the thermal decomposition of pre-cured polyvinyl chloride-vinyl acetate (PVC-VA) plastisols and foams with varying concentrations of plasticizers. Thermogravimetric analysis (TGA) shows that the plasticizer concentration influences decomposition behavior. Plastisols containing more of the lower molecular weight plasticizer diethyl phthalate (DEP) decompose at lower temperatures. TGA also indicates that plasticizer is lost during curing, more so without a blowing agent. The first peak in derivative thermogravimetry (DTG) curves corresponds to DEP evolution, while the second involves the higher molecular weight plasticizer and resin decomposition.

1. THERMAL DECOMPOSITION OF PRE-CURED PVC-VA PLASTISOLS
AND FOAMS. INFLUENCE OF THE PLASTICIZER CONCENTRATION
A. Zoller and A. Marcilla
Department of Chemical Engineering, University of Alicante
P.O.Box 99. E-03080 Alicante, Spain
*Corresponding author: e-mail:agnes.zoller@ua.es, tel.:+349653400-2386
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Part III.: Mixed Phthalate ester plasticizers,Journal of Applied Polymer Science, Accepted for publication 2011.
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[4.] A. Jiménez, L. Torreand J. M. Kenny, Polymer Degradation and Stability, 2001. 73: p. 447-453.
[5.] Rodolfo, A. and L.H. Innocentini Mei, Journal of Applied Polymer Science, 2010. 118(5): p. 2613-2623.
[6.] G. Sivalingam, R. Karthikand G. Madras, Industrial & Engineering Chemistry Research, 2003. 42: p.3647-3653.
[7.] Wu, C.-H., et al., The Canadian Journal of Chemical Engineering, 1994. 72(4): p. 644-650.
CONCLUSIONS:
The influence of the concentration of the plasticizer on the thermal decomposition of pre-cured
plastisols and flexible foams of PVC-VA prepared with mixtures of two commercial plasticizers has
been studied1. A series of PVC-VA plastisols were prepared by mixing 100 phr of the ETINOX 400 a
poly vinyl chloride-vinyl acetate copolymer, 100 phr of a mixture of DEP (diethyl phthalate) and DIDP
(di-isodecyl phthalate) of DEP concentration of 0, 25, 50 75 and 100%, respectively. The plastisols
were cured in an open mould at 180ºC during 10 min. Plastisols containing chemical blowing agent
produce foams during this curing process. Pre-cured samples and foams have been studied by TGA2.
The first peak observed in the DTG curves corresponds to the evolution of the DEP, whereas the
second peak corresponds to the overlapping of the evolution of the DIDP and the first step of
decomposition of the resin. Strong interactions between the different components of the formulations
are evident, and the presence of ZnO catalyzes the resin decomposition. It has been also observed
that these plastisols suffer plasticizer loss by evaporation during curing. Depending on the plasticizer
mixture, each plastisol looses different amount of plasticizer. Finally, it can be deduced that TGA
measurements are relevant to follow the thermal transitions of such pastes and allow a better
interpretation of the results obtained, as well as the curing and foaming behavior and foam quality.
Plasticizers Abbreviation Commercial
Name
Density
(g/cm3)
Molecular
Weight (g/mol)
Diethyl
Phthalate
DEP Palatinol A 1.118 222
Diisodecyl
Phthalate
DIDP Palatinol DIDP 0.966 447
AdditivesAdditives Commercial NameCommercial Name DescriptionDescription
Stabilizer Reagens CL 4 Ca / Zn stabilizer
Co-stabilizer Lankroflex 2307 Epoxidized Soybean Oil (ESBO)
Catalyst ZnO Zinc-oxide
Foaming Agent Unicell D 200 A Azodicarbonamide (ADC)
Resin Commercial Name Description K value
E 400 Etinox 400 vinyl chloride-vinyl acetate copolymer
with a 4.8 % of vinyl acetate, generally
used to prepare plastisols of medium
viscosity.
70
MEASUREMENT CONDITIONS:
• Approximately 6 mg of sample
• TGA in a nitrogen atmosphere (50 mL/min)
• heating rates of 5 K/min from room temperature to 873 K
• Termobalance METTLER TOLEDO, model TGA/SDTA851e/SF/1100
• continuous on-line records of weight loss and temperature
• TGA and DTG curves
RESULTS1:
MATERIALS:
Formulation Resin
Etinox 400
(Phr)
Plasticizer I.
DEP
(Phr)
Plasticizer
II. DIDP
(Phr)
Stabilizer
CL4
(Phr)
Co-stab.
ESBO
(Phr)
Catalyst
ZnO
(Phr)
CBA
ADC
(Phr)
100 DEP 100 100 0 2 6 2 2
75 DEP 100 75 25 2 6 2 2
50 DEP 100 50 50 2 6 2 2
25 DEP 100 25 75 2 6 2 2
0 DEP 100 0 100 2 6 2 2
METHOD OF SAMPLE PREPARATION:
Five PVC plastisols were prepared by mixing
• 100 phr (parts per hundred resin) of the ETINOX 400 PVC resin
• 2 phr of Reagens CL4 commercial Zn/Ca-stearate stabilizer
• 6 phr of Lankroflex 2307 epoxidized soybean oil co-stabilizer
• 100 phr of a mixture of DEP and DIDP of DEP concentration of 0, 25, 50
75 and 100%, respectively.
• 2 phr of zinc oxide kicker/catalyst
Five foams were prepared mixing the same formulation with affitional 2 phr
of azodicarbonide as chemical blowing agent
After mixing, the pastes were subjected to a degassing process for 15 min.
with a maximum vacuum of 1 mbar for air removal.
These plastisols were cured in an open mould at 180ºC during 10 min.
DTG of the 5 foams obtained:
•1st: DEP evolution3
•2nd: DIDP evolution+1st decomposition
step of the resin and HCl + HAc loss
from the VAc4
•3rd:ZnO/ZnCl2 catalyzed resin
decomposition5,6
•4th:final carbonization of the residue
formed in the resin decomposition
process7
The thermal stability of the studied formulations is strongly influenced by the concentration of the plasticizer and
the presence of ZnO. TGA measurements are very convenient and relevant in order to follow the thermal
transitions of such plastisols, as they present a dynamic and complex behavior and allow a quantification of the
amount of plasticizer remaining in a given formulation. Plasticized PVC-VA resin decomposes at lower
temperatures, than the pure PVC-VA resin. Quantification of the peak corresponding to the DEP evolution
reveales that DEP evaporates during the processing.Thus, the final foamed product is less plasticized, than
programmed. Increasing DEP concentration in the formulation leads earlier decomposition of the resin,
consequently showing the destabilization effect of the compatible plasticizer. Moreover modifies the overlapping
of the peaks.The final carbonization of the residue in the last step shows that the foams leave less amount of
PVC residue, than that corresponding the resin in the formulation, thus showing another effect of the plasticizer in
the decomposition of the resin. TGA measurements allowed a better interpretation of the results obtained, since
the nominal and actual plasticizer concentration in a cured plastisol may be different depending on the volatility of
the plasticizer and its concentration, and the process conditions.
0
20
40
60
80
100
200 250 300 350 400 450 500
Molecular Weight (g/mol)
Phrofremainingplasticizer
DTG of the pure DEP and DIDP plasticizers
and the pure resin E400:
Phr of the remaining plasticizer concentration
vs. molecular weight in pre-cured samples:
If considering that DIDP
Plasticizer does not evaporate
DEP Plasticizer lost 25 % of the
initial concentration
Intermediate mixtures loose
plasticizer accordingly
-0,0012
-0,001
-0,0008
-0,0006
-0,0004
-0,0002
0
50 100 150 200 250 300 350 400 450 500 550
Temperature (ºC)
DerivedWeightLoss(dm/dt)(1/s)
The 4 weight loss steps:
1st
2nd
3rd
4th
Etinox 400 resin
100 DEP pre-cured sample has lost
less DEP during the TGA
measurement: The formulation has
lost more plasticizer by evaporation
during the curing than the same
formulation containing ADC.
100 DEP foam has lost more DEP (first
weight loss step larger peak corresponding
to the DEP evolution) during the TGA
measurement, than the pre-cured sample
without containing ADC: During the foaming
process the plastisols containing ADC suffer
less plasticizer evaporation.
Comparison of DTG-s of the 100 DEP foam
and 100 DEP pre-cured plastisol:
ABSTRACT:
-0,0012
-0,001
-0,0008
-0,0006
-0,0004
-0,0002
0
50 100 150 200 250 300 350 400 450 500 550
Temperature (ºC)
DerivedWeightLoss(dm/dt)(1/s)
100 DIDP foam
25 DEP 75 DIDP foam
50 DEP 50 DIDP foam
75 DEP 25 DIDP foam
100 DEP foam
DTG of the pre-cured plastisols:
-0,0020
-0,0015
-0,0010
-0,0005
0,0000
100 150 200 250 300
Temperature (ºC)
DerivedWeightLoss(dm/dt)(1/s)
100 DEP
75 DEP
50 DEP
25 DEP
0 DEP
-0,003
-0,0025
-0,002
-0,0015
-0,001
-0,0005
0
0 100 200 300 400 500 600
Temperature (ºC)
DerivedWeightLoss(dm/dt)(1/s)
DEP Plasticizer
DIDP Plasticizer
E 400
DIDP: 231°C
Etinox 400: 280°C
DEP: 194°C -0,0020
-0,0015
-0,0010
-0,0005
0,0000
-50 50 150 250 350 450 550
Temperature (ºC)
DerivedWeightLoss(dm/dt)(1/s)
100 DEP Foam
100 DEP
REFERENCES:
6th International Symposium on Feedstock Recycling of Polymeric Materials (ISFR2011)
Toledo, Spain, 5 – 7 October 2011