Dynamic glass transition above the cooperativity onset in poly(n-octyl methacrylate)

Experimental heat capacity, dielectric, and shear spectroscopy data are reported on the alpha beta splitting region of poly(n-octyl methacrylate). New facets of a major difference between the high-temperature alpha relaxation at frequencies above the alpha beta splitting region and the ordinary alpha relaxation below are obtained: An alpha cooperativity onset in the splitting region and dominance of Rouse-Zimm-like modes R for the alpha relaxation. The alpha and alpha relaxations are not related by temperature-time superposition.