Coextruding sheet with alternating microlayers of solid and foamed plastic reduces foam cell size dramatically without increasing the density. Alternating layers also allow the sheet to be made thinner without sacrificing tensile strength. Those are two conclusions of joint R&D by Dow Chemical Co., Midland, Mich., and Case Western Reserve University, Cleveland. Sheet structures made using a series of layer multipliers in the feedblock have cell sizes of 100 microns with 32 layers and cells as small as 10 microns with 64 layers. Depending on the resin used, microlayered foam/solid sheet can resemble cork in compressive strength and can be stiff for thermoformed packaging or soft and elastomeric for fabric replacement. The researchers have made coextrusions 0.5 to 4 mm thick and up to 600 mm wide. Materials include foamed and solid PE and foamed PP with solid PE. Work is continuing on systems with improved barrier properties. Dow: (979) 238-4246 . www.dowplastics.com.
The Dow Chemical Company
2301 Brazosport Blvd.
Freeport, TX 77541
Phone: 979-238-4246 Fax: 979-238-0019