MIDDLEBURY, Conn. (May 8)—Crompton Corp.'s polymer business registered a 7-percent rise in operating earnings in the first quarter, despite a drop in EPDM rubber sales. The Crompton polymer unit posted operating profits of $9.3 million, as increased unit volumes of other products more than offset reduced selling prices and higher raw material costs in the EPDM business, the company said. EPDM sales by Crompton's Uniroyal Chemical unit fell 8 percent in the quarter, in part due to lower selling prices resulting from industry overcapacity. By contrast, urethane polymer sales were up 11 percent on increased demand and favorable currency translations, Crompton said. At Crompton's polymer additives business, rubber additives sales rose 3 percent as increased demand and favorable currency trends outweighed the impact of lower selling prices. Operating profit for the polymer additives business as a whole rose 16 percent. Higher unit volumes and lower manufacturing costs more than offset higher raw material costs and lower selling prices, Crompton said.