Thermal Decomposition of PVC Plastisol Foams. Influence of the type of plasticizer

A. Marcilla, A. Zoller and M.I. BeltránDepartment of Chemical Engineering, University of Alicante

P.O.Box 99. E-03080 Alicante, Spain*Corresponding author: e-mail:antonio.marcilla@ua.es, tel.:+349653400-3365

REFERENCES:1. Zoller, A. and Marcilla A., Soft PVC foams. Study of the gelation, fusion and foaming processes.

Part I.:Phthalate ester plasticizers,Journal of Applied Polymer Science, 121,3 (2011) 1495-1505.2. Zoller, A. and Marcilla A., Soft PVC foams. Study of the gelation, fusion and foaming processes.

Part II.:Adipate, Citrate and Other Type of plasticizers,Journal of Applied Polymer Science, In Press (2011)3. A. Marcilla and M. Beltrán, Polymer Degradation and Stability, 53, 261-268 (1996). 4. A. Jiménez, L. Torreand J. M. Kenny, Polymer Degradation and Stability, 73, 447-453 (2001).5. A. Jiménez, J. López, J. Vilaplanaand H. J. Dussel, Journal of Analytical and Applied Pyrolysis, 40-41, 201-215 (1997).6. G. Sivalingam, R. Karthikand G. Madras, Industrial & Engineering Chemistry Research, 42, 3647-3653 (2003). 7. M. Beltrán and A. Marcilla, European Polymer Journal, 33, 1271-1280 (1997).

CONCLUSIONS:

ABSTRACT:

Thermal decomposition of flexible PVC foams prepared with 20 commercial plasticizers has been studied1,2. It has been observed, that the plasticized PVC resin decomposes at lower temperatures, than the pure PVC-VA resin. Moreover, the thermograms show up to 4 weight loss steps3,4.It has been found that the lower the molecular weight of the plasticizer the lower the temperature of the first decomposition process of the resin, consequently the more compatible plasticizers show a destabilizing effect on the resin decomposition.

AzodicarbonamideUnicell D 200 AFoamingAgent

Zinc-oxideZnOCatalyst

Epoxidized Soybean Oil Lankroflex 2307Co-stabilizer

Ca / Zn stabilizerReagens CL 4Stabilizer

DescriptionDescriptionCommercial Commercial NameNameAdditivesAdditives

vinyl chloride-vinyl acetate copolymer with a 4.8 % of vinyl acetate, and a K value of 70, generally applied to prepare plastisols of medium viscosity.

Etinox 400E 400

DescriptionCommercial NameResin

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

RESULTS:

MATERIALS:

METHOD OF SAMPLE PREPARATION:

Twenty 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 one of the studied plasticzers (see Table)• 2 phr of zinc oxide kicker/catalyst

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 foams obtained from plastisols prepared with linear and branched phthalate ester plasticizers

BAYER1.055368MESAMOLLHÉRCULES1.000750H 707HÉRCULES1.000604H 600EASTMAN0.984391EASTMANBASF0.949425DINCHMORFLEX1.050486ATHCMORFLEX1.050402ATBCBASF1.0503300PM 652BASF1.1457000PM 632BASF0.922398DNABASF0.935314DHAEXXON0.991362DIHPBASF1.039278DIBPBASF0.983391DOPPHANCORP0.966447DIDPBASF0.973421DINPBASF1.118222DEPBASF0.953475DUPBASF0.958450NUPBASF0.971418HNUP

ProviderDensity (g/cm3)

Mw (g/mol)

Acronym

Plasticizers:

-0,002

-0,0015

-0,001

-0,0005

050 100 150 200 250 300 350 400 450 500 550

Temperature (ºC)

De

riv

ed

We

igh

t L

os

s (

dm

/dt)

(1

/s)

DEP

HNUP

NUP

DUP

DTG of the foams obtained from plastisols prepared with adipate + citrate and other types ofplasticizers

-0,003

-0,0025

-0,002

-0,0015

-0,001

-0,0005

0

50 100 150 200 250 300 350 400 450 500 550

Temperature (ºC)

Deri

ved

Weig

ht

Lo

ss (

dm

/dt)

(1/s

)

DIBPDIHP

DOPDINP

DIDP

-0,002

-0,0015

-0,001

-0,0005

0

50 100 150 200 250 300 350 400 450 500 550

Temperature (ºC)

De

riv

ed

We

igh

t L

oss (

dm

/dt)

(1/s

)

ATBC

ATHC

DHA

DINA

PM 652

PM 632

-0,002

-0,0015

-0,001

-0,0005

050 100 150 200 250 300 350 400 450 500 550

Temperature (ºC)

Deri

ved

Weig

ht

Lo

ss (

dm

/dt)

(1/s

)

ASE

EHBDC

DINCH

H600

H707

The thermograms obtained clearly show the presence of up to four weight loss steps3,4. The first one corresponds to the evolution of the plasticizer in clear correlation with its corresponding boiling point5. The rest are related with the dehydrochlorination and loss of acetic acid3-6 of the copolymer resin and the products of decomposition of the stabilizer and co-stabilizer, and the last one, at temperatures higher than 400 ºC corresponding to the carbonization of the residue of this first step3,4. It can be observed that the lower the molecular weight of the plasticizer the lower the temperature of the first decomposition process of the resin.

Pure Etinox 400 resin Pure Etinox 400 resin

Pure Etinox 400 resin Pure Etinox 400 resin

•Plasticized PVC resin decomposes at lower temperatures, than the pure PVC-VA resin•Up to 4 weight loss steps can be observed. The sharpest peak can be ascribed to the ZnO/ZnCl2 catalyzed Resin decomposition6, and can be observed in all samples. •The final peak corresponds to the decomposition of the residue from the first decomposition of the resin (i.e.: the loss of HCl and HAc) 3-6, and is highly reduced by almost all plasticizers as compared to that Expected from the resin. DEP and evolves very early in the TG experiment and produces also the largest destabilization effect7 on the resin.•Depending on the molecular weight the plasticizers evolve before or after the resin showing a different destabilization effect. NUP seems not to modify the thermal behavior of the resin (figure 1). •In the series of the branched phthalates (figure 2) the destabilization effect is highly correlated with the Mwof the plasticizer except for the DIDP (the DOP is not an isophthalate).•The citrates and adipates behave in a similar way provoking a destabilization of the resin (figure 3). •The polymeric adipates show the decomposition of the plasticizer at temperatures above the first decomposition of the resin.•The rest of plasticizers show similar effects and again the polymeric ones show the peaks corresponding to plasticizer between those corresponding to the resin (figure 4).