Since 2002, an unusual die has been pelletizing PLA biopolymer at NatureWorks LLC, Minnetonka, Minn. It was publically discussed for the first time by Coperion Werner & Pfleiderer, Ramsey, N.J., at Plastics Technology's Bioplastics Processing Conference last month in Charlotte, N.C. The die has a heating channel between every row of die holes-instead of every two rows-for greater heat control. It also uses a rectangular heating slot to increase surface area and heating efficiency because PLA's viscosity is 50 times more temperature-sensitive than that of polyolefins, Coperion notes. Improved wear protection comes from brazing the tungsten carbide die-hole cylinders to each other instead of to the chrome die surface. The latter creates a site for corrosion, Coperion says. Tel: (201) 327-6300 . www.coperion.com

Coperion Corp.
663 E Crescent Ave. Ramsey, NJ 07446
Phone (201) 327-6300 Fax (201) 825-6491