Polymer Testing 20 (2001) 607–614 www.elsevier.nl/locate/polytest Material Properties Comparison of cetyltrimethylammonium maleate and sulphenamide as an accelerator in carbon black filled natural rubber compounds Hanafi Ismail * , Z. Ahmad, Z.A. Mohd Ishak School of Industrial Technology, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia Received 12 January 2000; accepted 28 November 2000 Abstract The effects of using cetyltrimethylammonium maleate (CTMAM) and N-cyclohexyl-2-benzothiazole-2-sulphenamide (CBS) as an accelerator in carbon black filled natural rubber compounds were studied. Results show that curing time, t 90 and scorch time, t 2 are faster for CTMAM compared to CBS. CTMAM can function in its own right as an accelerator for sulphur vulcanization without the presence of zinc oxide and stearic acid as activators. The use of CTMAM without the presence of zinc oxide and stearic acid not only gave good tensile and tear strengths, tensile modulus, rebound resilience and hardness but was better compared to the use of commercial CBS.  2001 Elsevier Science Ltd. All rights reserved. Keywords: Cetyltrimethylammonium maleate; Accelerator; Carbon black; Natural rubber; Curing characteristics; Mechanical properties 1. Introduction In our previous works [1,2], the preparation and appli- cation of a quaternary ammonium surfactant, ie. cetyltri- methylammonium maleate having the formula; in the carbon black filled natural rubber compounds were reported. The incorporation of cetyltrimetylammonium maleate (CTMAM) in natural rubber compounds gave * Corresponding author. Tel.: +60-4-657-7888 x2214; fax: +60-4-657-3678. E-mail address: ihanafi@usm.my (H. Ismail). 0142-9418/01/$ - see front matter  2001 Elsevier Science Ltd. All rights reserved. PII:S0142-9418(00)00082-9 better mechanical properties viz. tensile strength, tensile modulus (modulus at 100% elongation, M100 and 300% elongation, M300), tear strength and hardness. The enhancement of these properties was attributed to the improvement of filler dispersion in the rubber com- pounds and better crosslink density due to the incorpor- ation of CTMAM. Results also indicated that CTMAM can function as an accelerator. In this study the acceleration effect of CTMAM on curing characteristics and mechanical properties of car- bon black filled natural rubber compounds was compared with a commercial available accelerator, ie. N- cyclohexy1-2-benzothiazole-2-sulphenamide (CBS). The effect of zinc oxide (ZnO) and stearic acid concentration on curing characteristics and mechanical properties of the sulfur/CTMAM curing system was also evaluated. 2. Experimental 2.1. Compounding ingredients and formulations The formulations used in this work are given in Tables 1 and 2. Natural Rubber (SMR L) was obtained from the