Dynamic mechanical relaxation in the opaque and transparent poly(4-methyl-1-pentene) films - The glass transition zone

The thermomechanical properties of opaque and transparent polymer films of a solution of poly(4-methyl-1-pentene) (PMP) in cyclohexane and carbon tetr achloride obtained by casting on teflon and glass plates were investigated. The dynamic mechanical thermal analysis was applied in a frequency range f rom 0.01 to 100 Hz. The curves of loss tangent vs. temperature varied depen ding on the sample thermal history. The first part of these curves could re late to the backbone a relaxation into the unperturbed amorphous phase whil e the next relaxation could result from the backbone a relaxation into amor phous phase perturbed by the presence of the crystal domains. The Arrhenius plots of the first relaxation show a-stronger curvature found in each of t he transparent samples indicating strong dependency on specific volume. The second one in the case of transparent films and the first one for opaque s amples might be approximate to straight lines.