MIDLAND, Mich. (Oct. 9)—Dow Chemical Co. and Mitsui Chemical Inc. have formed a joint development program under which Mitsui will develop markets in Japan for Dow´s ethylene styrene interpolymers. Based on the coplolymerization of ethylene, styrene and potentially other monomers, ESI boasts properties such as stress relaxation and high mineral filler loading capacity that will contribute to new applications, Dow said. Tokyo-based Mitsui is a producer of base chemicals, industrial chemicals, polymers, functional materials, performance materials and fine chemicals. Its 1999 consolidated sales were $8.1 billion. Dow, a Midland-based maker of chemicals, elastomer and agricultural products for a number of markets, recently began operations at a 50-million-pound-per-year ESI plant in Sarnia, Ontario, Canada. The joint program will help accelerate both global market demand and product development for the material, Dow said.