By David Reed, UT EditorCranston, Rhode Island-Mearthane Products Corp., a custom formulator of castable thermoset polyurethane elastomers, has improved one of its key proprietary formulations.A new grade of its Durethane C material with improved electrostatic dissipation properties, is now available, and eliminates damaging electrostatic discharges in relevant products such as rollers in electronic equipment. It can be made as machinable solid elastomers or as foam, a 22 Aug Mearthane press announcement said."We have continuously advanced both the range and quality of conductivity customisation by exploring different additives and processes," said Albert Chiang, vice president of research and development at Mearthane, in the statement. Durethane C has two main attributes, the statement explains: it helps dissipate triboelectricity (generated by friction) in printers, copiers and other paper-handling devices; but it also is used in to supply specific charge densities in applications such as developer rollers in laser printers, which use electrostatic charges to control the amount of toner particles transferred to the paper during printing.The new Durethane C grades offer volume resistivity in solid form from E5 to E10 ohm-cm at hardnesses from Shore 5A to 70D; or in open- or closed-cell foams from E7 to E10 ohm-cm at hardnesses of Shore 1-90A, Mearthane says. These various grades contain from 0.01 to 10 percent by weight of additives, the firm added. They are available as sheets, rollers, bars, rods and tubes.Traditional materials use coatings or carbon fibres alone or in combination with metal powders to control the charges, but Mearthane claims its Durethane C uses conductive additives which alter the molecular form of the polyurethanes and so is less sensitive to changes in temperature and humidity."