P.M. BRIEFING : Morton Thiokol to Become 2 Firms

Morton Thiokol Inc., manufacturer of the booster rockets that were blamed for the space shuttle Challenger explosion three years ago, will spin off its specialty chemical business from its troubled aerospace operation.

The plan, approved by the board of directors and announced Monday, would split Morton Thiokol into two companies: Thiokol Inc., the aerospace concern, and Morton International Inc., which would include the speciality chemicals, air bags and salt businesses. The transaction is expected to be finalized July 1 pending shareholders’ approval, according to company spokesman Tom Russell.

Under the plan, shareholders would receive a tax-free distribution of a share of Morton International stock for each Morton Thiokol share. The company said it believes the stock of both new companies will qualify for listing on the New York Stock Exchange. Russell said the planned spinoff had nothing to do with the Challenger explosion.