By Liz White, UT staffMidland, Michigan-Dow Chemical Co. has increased prices for various propylene glycols from 1 Sept. The increase, effective in the Americas and the Caribbean, is $0.05 per pound on: • propylene glycol industrial grade;• propylene glycol USP/EP grade;• dipropylene glycol regular grade; • dipropylene glycol LO+ grade; • tripropylene glycol; and • tripropylene glycol acrylate grade. "