Adding long-glass-reinforced ETPU to ABS is said to be a cost-effective way to increase strength, stiffness, and toughness. Dow Plastics, Midland, Mich., is touting compounds of its Isoplast engineering thermoplastic urethane (ETPU) as "vitamins" for pumping up ABS properties. Dow says the blends can closely match glass-reinforced nylon in both cost and structural performance. But amorphous ABS/ETPU blends are said to be more dimensionally stable than crystalline nylons, and their properties do not change with moisture content.
Blending long-glass Isoplast pellets about 0.5-in. long with ABS allows the ETPU to act as a coupling agent between the glass and ABS. Shrinkage of the blends barely changes over a range of long-glass-fiber (LGF) contents from 12% to 60%. Thus, you can try out different blend ratios without having to recut the tool.
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