New TP body panel alloys.
Two new families of thermoplastic alloys, known as Sabre and Prevail, engineered for automotive body panel applications, were introduced by Dow Plastics, Midland, Mich. As reported earlier this year, these new resins are identified as "second-generation blends" designed for specific car platforms now being developed (see PT, Jan. '91, p. 89).
R.D. Albert, v.p. of Dow's Automotive Materials Group, says the two new alloy families will complement Dow's existing Pulse B250 resin line, which is being used in the door panels for the new Saturn car (see PT, Oct '90, p. 103). Compared with Pulse, Sabre is designed for enhanced solvent resistance while maintaining dimensional stability for applications such as fenders and quarter panels. It also is aimed at power tools and lawn/garden equipment. Prevail is formulated as a lower modulus, flexible material for bumper fascia and rocker panels, with other potential uses in hard-sided luggage and furniture armrests.
Sabre is a family of three polycarbonate/PET and PC/PBT alloys, making use of a proprietary thermoplastic compatibilizing agent and impact modifier. Prevail is based on TP urethane, the initial grades being TPU/ABS alloys. Unlike Sabre, Prevail does not make use of a discrete compatabilizer; rather, the two alloy partners are specially designed and formulated upstream to be compatible with one another, as Dow is basic to both resin technologies, according to James E. Schwartz, technical manager.
Both Sabre and Prevail provide a "Class-A" surface and require no primer or adhesion promoters for painting operations. Like Pulse, they have a max. paint temperature limit of 260 F. The new materials, offered in neat and mineral-filled grades, are designed for injection molding.
An unfilled grade of Sabre has an HDT of 264-270 F (at 66 psi), ultimate elongation of 135%, flex modulus of 305,000 psi, tensile modulus of 265,000 psi, and notched Izod impact of 13.3 ft-lb/in. at 73 F and 3.6 ft-lb/in at -20 F. Prices run $2 to $2.50/lb.
Prevail has an HDT of 197 F (annealed at 66 psi), Vicat temperature of 214 F, ultimate elongation of 200%, flex modulus of 100,000 psi, tensile strength of 3600 psi, notched Izod impact of 14 ft-lb/in. at -20 F (no break at 73 F), and Shore D hardness of 67. Price is $1.90/lb.
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|Title Annotation:||Dow Plastics' Sabre and Prevail - thermoplastic alloys for car bodies|
|Date:||Apr 1, 1991|
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