Microspheres offer an alternative to the foaming of thermoplastic elastomers

Expandable microspheres are used worldwide for a large number of applications of thermoplastics with the goal to reduce the weight of the final product and provide it with a very fine and extremely uniform cell structure. Foaming of thermoplastic elastomers has developed in the past several years into a very important and interesting application for expandable microspheres.
The most versatile of fillers available to composites manufacturers are microspheres (microballoons). Appearing like fine powder, the hollow spheres ranging from 12-300 �m in diameter (a human hair is approximately 75 �m dia), offer a lot of functionality. Integrated into composite parts, they provide a variety of product enhancements and process improvements including low density, improved dimensional stability, increased impact strength, smoother surface finish, greater thermal insulation, easier machine ability, faster cycle times, and cost savings. Composite manufacturers, already adept at making the most of their materials, regularly exploit these benefits as per www.compositesworld.com. Most users focus on one or two attributes of the spheres, but in the composites industry, manufacturers are taking advantage of 6 or 7 attributes of the spheres. The matrix and the microsphere can be tailored to achieve multiple objectives in one part. Microspheres can be used in all standard processing methods for thermoset and thermoplastic composites, including extrusion and injection molding, and have found a range of applications as diverse as simulated wood furniture and lumber, fiberglass-reinforced core materials, automotive brake components and engineered syntactic foams. Each microsphere manufacturer has developed proprietary processes to control a wide range of microsphere variables that include chemical composition, wall thickness and particle size and shape. Each of these variables makes a contribution to one or, more typically, several desirable properties that have made microspheres an effective delivery system for a number of notable benefits. Most of the microspheres commonly used in composites manufacturing are hollow and are made of either glass or plastic.