Skip to content
Licensed Unlicensed Requires Authentication Published by De Gruyter April 13, 2018

Modelling the Thermal Degradation and Stabilisation of PVC in a Torque Rheometer

Reinhard Heinrich Fechter, Carl Sandrock and Frederick Johannes Willem Jacobus Labuschagne ORCID logo


A novel method for simulating the torque and temperature curves from a torque rheometer thermal stability test on poly(vinyl chloride) (PVC) was developed. A mathematical model was proposed which combines the chemical kinetics involved in the thermal degradation and stabilisation process of PVC with heat transfer and viscosity relationships within the torque rheometer. The model coefficients were fitted to data obtained from previous experiments with a program written in the Python programming language using the Levenberg-Marquardt Algorithm (LMA) with multiple starts. The mathematical model fits the torque rheometer data successfully depending on the characteristics of the torque curve. The model fit is successful when the torque curve follows the expected behaviour. An unsuccessful model fit occurs when the torque curve deviates from the expected shape in a very specific way. In the degradation phase the torque curve increases to a local maximum, decreases to a local minimum and then increases again. The exact reason for the dip in torque is unknown.


[1] Gupta S, Dd A, Banerjee S. Thermal stabilization of poly(vinyl chloride) by hydrotalcites zeolites, and conventional stabilizers. J Vinyl Add Technol [Internet]. 2009 ;15(3):164–70 .10.1002/vnl.20196Search in Google Scholar

[2] Braun D. Poly(vinyl chloride) on the way from the 19th century to the 21st century. J Polymer Sci: Part A: Polymer Chem. 2004;42:578–86.10.1002/pola.10906Search in Google Scholar

[3] Bacaloglu R, Fisch M. Degradation and stabilization of poly (vinyl chloride). V. Reaction mechanism of poly(vinyl chloride) degradation. Polymer Degrad Stabili [Internet]. 1995 ;47(1):33–57 .10.1016/0141-3910(94)00086-NSearch in Google Scholar

[4] Wilkes CE, Summers JW, Daniels CA. PVC handbook. 1st ed. Munich: Hanser; 2005.Search in Google Scholar

[5] Wypych G. PVC degradation & stabilization. 2nd ed. Toronto: ChemTec; 2008.Search in Google Scholar

[6] Bacaloglu R, Fisch MH. Thermal Degradation and Stabilisation of PVC. Munich: Hanser; 2000.Search in Google Scholar

[7] Forano T, Hibino T, Leroux F, Taviot-Gueho C. Layered double hydroxides. In: Bergaya F, Bkg T, Lagaly G, editor(s). Handbok of clay science. Amsterdam: Elsevier Ltd, 2006:1021–70.10.1016/S1572-4352(05)01039-1Search in Google Scholar

[8] Lin Y, Wang J, Dg E, Li D. Layered and intercalated hydrotalcite-like materials as thermal stabilizers in PVC resin. J Phys Chem Solids [Internet]. 2006 ;67(5–6):998–1001 .10.1016/j.jpcs.2006.01.016Search in Google Scholar

[9] van der ven L, Van Gemert M, Batenburg L, Keern J, Gielgens L, Koster T, et al. On the action of hydrotalcite-like clay materials as stabilizers in polyvinylchloride. Appl Clay Sci. 2000;17:25–34.10.1016/S0169-1317(00)00002-8Search in Google Scholar

[10] Labuschagne FJWJJ, Molefe DM, Focke WW, Westhuizen I, van der Wright HC, Royeppen MD. Heat stabilising flexible PVC with layered double hydroxide derivatives. Polymer Degrad Stabili [Internet]. 2015 ;113:46–54 .10.1016/j.polymdegradstab.2015.01.016Search in Google Scholar

[11] Liu S, Zhang P, Yan K, Zhang Y, Ye Y, Chen X. Sb-intercalated layered double hydroxides–poly(vinyl chloride) nanocomposites: preparation, characterization, and thermal stability. J Appl Polym Sci. 2015 ;132(39). DOI: 10.1002/app.42524 .Search in Google Scholar

[12] Yan J, Yang Z. Intercalated hydrotalcite-like materials and their application as thermal stabilizers in poly(vinyl chloride). J Appl Polym Sci. 2017 ;134(22). DOI: 10.1002/app.44896 .Search in Google Scholar

[13] Yi S, Yang Z, Wang S-W, Liu D, Wang S-Q, Liu Q, et al. Effects of MgAlCe-CO3 layered double hydroxides on the thermal stability of PVC resin. J Appl Polym Sci. 2010 ;119. DOI: 10.1002/app.32807 .Search in Google Scholar

[14] Wang X, Zhang Q. Effect of hydrotalcite on the thermal stability, mechanical properties, rheology and flame retardance of poly(vinyl chloride). Polym Int. 2004;53:698–707.10.1002/pi.1482Search in Google Scholar

[15] Yang H, Yang Z. The effect of sodium stearate-modified hydrocalumite on the thermal stability of poly(vinyl chloride). J Appl Polym Sci. 2017 ;135(4). DOI: 10.1002/app.45758 .Search in Google Scholar

[16] Ari GA. Using a torque rheometer to characterize flow in poly(vinyl chloride) composites. New York: Plastics Research Online, 2010.Search in Google Scholar

[17] Jin G, Zhao X, Wang M. Evaluation of rheological measurement of polymer blends melts in torque rheometer. Adv Mat Res. 2011 ;314–116:1424–29.10.4028/ in Google Scholar

[18] Jazi S, Esfahany M, Bagheri R. Investigation of the addition of nano-CaCO3 at dry mixing or onset of fusion on the dispersion, torque, and mechanical properties of compounded PVC. J Vinyl Additive Technol. 2012;18:153–60.10.1002/vnl.20317Search in Google Scholar

[19] Saeb M, Moghri M, Khonakdar H, Wagenknecht U, Heinrich G. Fusion level optimization of rigid PVC nanocompounds by using response surface methodology. J Vinyl Additive Technol. 2013;19(3):168–76.10.1002/vnl.21324Search in Google Scholar

[20] Levenberg K. A method for the solution of certain non-linear problems in least squares. Q Appl Math [Internet]. 1944 ;2(2):164–68 .10.1090/qam/10666Search in Google Scholar

[21] Marquardt DW. An algorithm for least-squares estimation of nonlinear parameters. J Soc Ind Appl Math [Internet]. 1963 ;11(2):431–41 .10.1137/0111030Search in Google Scholar

[22] Kluyver T, Ragan-Kelley B, Perez F, Granger B, Bussonnier M, Frederic J, et al. Jupyter notebooks—a publishing format for reproducible computational workflows. In: Loizides F, Schmidt B, editor(s). Positioning and power in academic publishing: players, agents and agendas. Amsterdam: IOS Press, 2016.Search in Google Scholar

Received: 2017-06-08
Revised: 2018-02-12
Accepted: 2018-02-14
Published Online: 2018-04-13

© 2018 Walter de Gruyter GmbH, Berlin/Boston