BASF (Ludwigshafen, Germany) has already built somewhat of a reputation in developing low-warpage injection molding grades based on a blend of polybutylene terephthalate (PBT) and acrylonitrile-styrene-acrylate (ASA). Take, for example, Ultradur S4090 GM13, a PBT/ASA reinforced with minerals and glass fibers that displays a shrinkage ratio of 0.70/0.80. Moving one step beyond, the new grade—Ultradur S4090 GM11—boasts a ratio of 0.95/1.0 as measured by the ISO 294 standard.
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