CONTROL OF CONTACT CHARGE IN POLYMERS WITH IONOMERS

The contact charge developed between powders of a copolymer-ionomer bl end and ferrite beads correlates well with the chemical structure of t he ions. There is a clear correspondence between the sign of the charg e acquired by the blend and the sign of the bonded ion in the ionomer. When both ions are bonded,the charge is small. These charging results support the ion transfer mechanism for charging. The measured charge is less than the value calculated from the total amount:of surface ion s, and there is a small difference in the magnitude of the charge betw een the various ionomer blends. A higher charging capacity is observed with the ionomers with a mobile H+, OTs(-), or I-, while a lower char ging capacity is observed with the pyridinium, Bu(4)N(+), and Na+ ion. This result is attributed to ion pairing which reduces the charging c apacity of the ions. It is proposed that only dissociated ions transfe r across the contact to produce charge. With this model, it is estimat ed that only 10% of the ion pairs in the surface water layer are disso ciated. This indicates that the ion pair dissociation equilibrium cons tant in the surface water layer is lower than in bulk water.