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 tetrachloride obtained by casting on teflon and glass plates were investigated. The dynamic mechanical thermal analysis was applied in a frequency range from 0.01 to 100 Hz. The curves of loss tangent vs. temperature varied depending on the sample thermal history. The first part of these curves could relate to the backbone a relaxation into the unperturbed amorphous phase while the next relaxation could result from the backbone a relaxation into amorphous phase perturbed by the presence of the crystal domains. The Arrhenius plots of the first relaxation show a-stronger curvature found in each of the transparent samples indicating strong dependency on specific volume. The second one in the case of transparent films and the first one for opaque samples might be approximate to straight lines.