Stabilizing Effect of Biobased Additives on the Thermal Degradation of PVC T.O. Egbuchunam 1, a , F.E. Okieimen 2, b and D. Balköse 3, c 1 Department of Chemistry, Federal University of Petroleum Resources, PMB 1221, Effurun, Delta State, Nigeria 2 University of Benin, Centre for Biomaterials Research, Benin City, Nigeria 3 Department of Chemical Engineering, Izmir Institute of Technology, Urla-Izmir, Turkey ( a tessychunam@yahoo.com ), b fexokieimen@yahoo.com , c devrimbalkose@iyte.edu.tr [Received 14 August 2009, accepted 18 January 2010] Keywords: Biobased additives, PVC, Thermal stabilization Abstract: Novel biobased additives prepared from rubber seed oil were evaluated as thermal stabilizer for PVC. Divalent metal (barium and cadmium) soaps of rubber seed oil were prepared by metathesis in aqueous alcohol and characterized by thermal methods (differential scanning calorimetry and thermogravimetry). The stabilizing effect of the soaps and their admixtures on the thermal degradation of PVC powder and plasticized PVC was examined by dynamic thermogravimetry and dehydrochlorination studies at 160 o C using the Thermomat equipment. The metal soaps showed multiple decomposition endotherms but were generally stable (with weight loss less than 5%) within the temperature range (180 – 220 o C) frequently used in the processing of PVC. Using the Broido model, values of apparent activation energy of decomposition of between 50 and 200 kJmol -1 were obtained for the soaps. The biobased additives were found to be relatively effective in stabilizing PVC in powder and plasticized forms against thermal degradation. Using inhibition/retardation time, temperature of incipient decomposition, and temperature at which various extents of decomposition was attained as indices of thermal stabilization, the results from this study indicate a potential for the application of the biobased additives as thermal stabilizer for PVC in rigid and flexible formulations. Introduction Poly (vinyl chloride) (PVC) is a commonly used material employed for a wide range of applications, mainly due to its relative low cost and high versatility. Plasticized PVC (P-PVC) is a soft material widely used in industry for flexible applications. This is based on the combination of a PVC resin and a plasticizer agent to form a PVC paste or liquid plastisol which can be converted into a solid plastisol by controlled heating through a curing process [1]. On account of the low thermal stability of PVC at the molecular level, it has become the practice to process the polymer in the presence of heat stabilizing additives. For example, thermal stabilizers based on compounds with chemicals (lead, tin, barium, calcium or zinc), have been employed for decades to improve its stability during processing. The thermal degradation and stabilization of PVC has been studied extensively [2 – 10] because of its important practical/technological and scientific implication on the production and use of the polymer. Most of these investigations have been based on measurement of rates of evolution of gaseous products, thermogravimetry and analytical characterization of the residue of degradation. However, technical evaluation of candidate additive as thermal stabilizer for PVC is comparative rather than absolute measurement. It should therefore be possible to develop and/or adopt simple and reliable tools/equipment and/or indices for polymer International Journal of Engineering Research in Africa Online: 2010-02-15 ISSN: 1663-4144, Vol. 1, pp 47-56 doi:10.4028/www.scientific.net/JERA.1.47 © 2010 Trans Tech Publications, Switzerland All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, www.ttp.net. (#72456274, İzmir Yüksek Teknoloji Enstitüsü ( Izmir Institute of Technology), Urla - Izmir, Turkey-12/12/16,12:34:49)