Friction in Magnetic Tapes III: Role of Chemical Properties

Abstract

Whenever there are changes in surface chemistry of the magnetic tape caused by various tribological or environmental parameters, such as humidity and temperature, they may significanty increase the adhesive interaction between the magnetic tape and the drive components. Exposure to high humidity at elevated temperatures for extended periods can result in the hydrolytic degradation of the tape-binder system. The products of hydrolytic degradation have lower molecular weight and may be tacky in nature. Changes in the binder can be monitored by measuring molecular weight, extractable binder-to-lubricant ratio, and modulus of elasticity. A chemically stable binder system minimizes the risk of high friction. In the case of tapes tested at low humidity, the frictional behavior shows little dependence on the chemistry of the binder and primarily on the thermomechanical response of the magnetic coating. It is also noted that in most commercial tapes, the friction is high when measured at high humidities (above 60 percent RH).