Adding solid glass spheres to resin formulations as resin extenders reduces shrinkage and improves part flatness as well as lowering moulding and extrusion costs.

Potters Industries has just completed a study of the benefits of using engineered glass microsphere particles. According to William Shaker, Market Development manager of Polymer Additives at Potters Industries, 'One of the major benefits of adding solid glass spheres to resin formulations is reduced manufacturing costs'. ' With resin prices soaring, processors are looking to additives as a way to contain rising costs'.

'By using Spheriglass solid glass microspheres as resin extenders, they can realise substantial cost savings while gaining enhanced physical properties.' Spheriglass glass spheres are performance modifiers engineered to increase the strength of plastics.

High loadings of glass spheres add significantly to the dimensional stability of the finished product by reducing shrinkage and improving part flatness.

For example,' says Shaker, 'Data show that shrinkage of unfilled or glass fiber filled nylon 66 can be cut by 70-80% when 30% glass spheres are used.

And warpage is reduced 95-97% in the same tests.' High loadings can also increase flexural modulus, abrasion resistance, and surface hardness.

Additional benefits include excellent chemical resistance, increased compound flow, and improved compressive strength.

Used in thermoplastics and thermosetting resin systems, Spheriglass glass microspheres offer processing benefits by increasing the flow during extrusion and injection molding.

Microspheres lower the viscosity of most compounded resin systems, acting as miniature ball bearings to improve flow.

'Because flow is improved, very large and thin walled parts can be molded to dimensions,' explains Shaker.

'The spherical shape also yields better stress distribution.

This is important since localised stress within a molded part often leads to premature failure as well as warpage in the finished part.' In contrast to other additives such as fiber glass which have inherent properties that limit their use in certain applications, Spheriglass non-fibrous glass spheres help engineers confront the problems of maintaining dimensional stability, easing plastic flow and lowering molding pressures.

'The cost of glass spheres is less than half that of glass fibers, making them one of the most economical glass products available,' adds Shaker.

Spheriglass solid glass spheres have a density of 2.5g/cc.

They are very strong, with a crush strength of 30,000 lb/in2.

Moh's hardness is 6.0-6.5.

Glass spheres have very low oil absorption, about 18g oil/100g spheres.

And, because the spheres are nonporous, they do not absorb resin in a polymer system.

They are available in two glass compositions: A-glass (soda-lime glass) and E-glass (borosilicate glass).

Potters Industries, a wholly owned subsidiary of PQ Corporation is the world's leading manufacturer of engineered glass materials serving the highway safety, polymer additive, metal finishing, and conductive particle markets.

PQ Corporation recently acquired by JPMorgan Partners, is a leading producer of silicate, zeolite, and other performance materials serving the detergent, pulp and paper, chemical, petroleum, catalyst, water treatment, construction, and beverage markets.