Hollow glass microspheres have been used as low-density fillers for various kinds of polymeric compounds since the mid-1960s. For the first 20 years after their introduction, hollow glass microspheres weren’t strong enough to survive the high shear forces and high pressures involved in plastics compounding and injection molding.
Hollow glass microsphere, has the highest compressive strength in the world for such a product. It also has the highest strength-to-density ratio of any glass or other microsphere in the marketplace. Made from soda/lime borosilicate, it can withstand injection molding pressures up to around 30,000 psi.
Relative to earlier glass microspheres, the improved mechanical properties imparted by hollow glass microsphere include better impact strength and elongation, prevention of scratch or stress whitening, tighter tolerances for small parts, and improved surface finish on the end product due to better packing. Greater crush strength means there is much less breakage of the hollow glass microspheres during extrusion or injection molding.
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