Thermal scratch healing of poly(methyl methacrylate-co-methacrylate) ionomers neutralized with various cations

The effects of the cation type and under-neutralization on the scratch healing of poly(methyl methacrylate-co-methacrylate) ionomers by heat treatment were investigated as a function of time. The scratch healing efficiency of the ionomer was found to reach 84‒98% within 10 min at a temperature at which log E’ (Pa) = ca. 6.6, regardless of the type of cations of the neutralizing agents or the under-neutralization or the multiplet plasticization. From the results of this study and previous study, it was concluded that a significant level of scratch healing effect without sample deformation could be obtained in a fairly short time at a temperature at which the log E’ (Pa) of the ionomers was maintained at ca. 6.5 ± 0.1, regardless of the polarity of the ionomers, type of neutralizing agents, and degree of under-neutralization of the ionomers. Furthermore, we propose that the above results can be extended to optimal thermal scratch healing conditions for some of amorphous polymers, and are also useful when only small damaged areas of polymer materials are needed to be healed thermally.