SBS/Polyaniline or Carbon Black System: Finding the Optimal Process and Molding Temperatures Through Experimental Design Fernando G. Souza Jr., 1 Bluma G. Soares,* 1 Jose ´ C. Pinto 2 1 Instituto de Macromole ´culas, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, Bl. J, Ilha do Funda ˜o, 21945-970, Rio de Janeiro, RJ, Brasil Fax: (þ55) 21-2562-7207; E-mail: bluma@ima.ufrj.br 2 COPPE, Universidade Federal do Rio de Janeiro, Centro de Tecnologia, Bl. E, Ilha do Funda ˜o, 21945-970, Rio de Janeiro, RJ, Brasil Received: December 1, 2005; Revised: February 1, 2006; Accepted: February 1, 2006; DOI: 10.1002/mame.200500406 Keywords: carbon black; experimental design; mechanical properties; polyaniline; SBS Introduction Conductive composites that are based on styrene-buta- diene-styrene (SBS) triblock copolymers as the insulating matrix are very interesting because it is possible to develop conducting materials with good flexibility and elasticity without using the vulcanization process. Among several conductive additives, carbon black (CB) is one of the most popular because of its good affinity towards unsaturated rubber materials. This affinity generates a reinforcement effect on the mechanical properties of the composite. [1] In addition, this system normally presents a sharp insulator- conductor transition with a relatively small amount of carbon black. Polyaniline is also a very important conductive additive and may impart some characteristics and properties that cannot be achieved with carbon black. For example, their corresponding composites prepared by melt-processing techniques present a light insulator-conductor transition, which can be useful to design materials with controlled conductivity for specific applications. [2] The use of melt- processing techniques for the development of these conducting materials is technologically very attractive and may be performed in these cases, taking the advantage of the SBS matrix processability. [3,4] Recently, this technique was employed to study the effect of polyaniline doped with dodecylbenzene sulfonic acid (Pani.DBSA) on the mechanical and electrical properties of Summary: The optimum mixing and molding conditions for processing of styrene-butadiene-styrene (SBS) triblock copolymer filled with carbon black (CB) or polyaniline doped with dodecylbenzene sulfonic acid (Pani.DBSA) were determined. The mechanical performance of SBS/CB and SBS/Pani.DBSA composites were characterized in terms of strain and stress responses at break condition. In order to reach this goal, two mixed two- and three-level factorial designs were employed. The obtained data show that the molding temperature is the most important parameter to affect the mechanical behavior of the systems. Among the systems analyzed, the SBS/Pani.DBSA blends presented the highest sensitivity to the process and molding conditions. Elongation of composites as a function of molding tempe- rature. Macromol. Mater. Eng. 2006, 291, 463–469 ß 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Full Paper DOI: 10.1002/mame.200500406 463