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This paper describes a novel measuring system for investigating the influence of pressure and temperature on the mechanical properties of time-dependent polymer materials. The system can measure the volume and the shear relaxation moduli of solid polymer specimens simultaneously subjected to temperatures from j50 to +120-C with a precision of T0.01-C, and pressures from atmospheric to 500 MPa with a precision of T0.1 MPa. The paper demonstrates the measuring capabilities of the apparatus. For poly(vinyl) acetate (PVAc) are presented sample measurements of the shear relaxation modulus as function of time, pressure and temperature; specific volume; the bulk creep compliance; the coefficient of thermal expansion; the bulk modulus; and the pressure drop experiments which simulate conditions to which a material is exposed during the injection molding process. The shear moduli may be measured in the range from 1 to 4,000 MPa with the relative error of 3%.The error of volumetric measurements is 0.05%, which corresponds to 0.00005 cm 3 /g. In all cases results are shown as measured, no additional smoothing or filtering was employed.

Abstraet. The proton motion in bulk and highly drawn fiber polyamide-6 has been studied by field cycling relaxometry and proton line shape measurements. The dips in the T~ dispersion allowed for the determination of the ~4N quadrupole coupling tensor. The fact that only one set of Z4N nuclear quadrupole resonance lines has been found shows that all N-H groups in nylon-6 are H-bonded. A striking difference in the main line width transition and the low-frequency molecular dynamics has been observed between a slowly cooled "bulk'" polyamide-6 sample and a rapidly cooled and highly drawn "fiber" sample by wide line proton nuclear magnetic resonance line shape and spin-lattice relaxation time measurements. This result is consistent with the picture that shearing melt processing procedures, such as spinning, plant stable and long-lived crystallization nuclei into the amorphous phase which impose additional motional constraints on the surroundings and inhibit the self-diffusion process.

The sorption behavior of two highly swelling "rubbery" polymers, natural rubber and polyethylene, has been studied. The polymers are in many aspects very different. Yet, when the solute mass uptake, in this case limonene, is plotted as a function of the square root of time, both polymers show similar "sigmoidal"-types of curves. This triggered the research to determine what mechanisms were responsible for the observed similarities and if the degree in sigmoidal behavior and swelling anisotropy could be easily assessed explicitly by any mechanical parameter. It was found that their degrees of swelling anisotropy, described by a solute-surface-concentration relaxation time, could be explained by their relative bulk moduli. It was assumed that the ratio in bulk modulus at zero pressure, determined from compression measurements, could represent the ratio in expansion bulk modulus during swelling. However, the prediction in swelling anisotropy during sorption using the ratio in bulk modulus was slightly less successful when the swelling anisotropy was quantified as the relative ratio of sheet thickness to cross-sectional area side length. It should be noted that the ratio in uniaxial tensile modulus between polyethylene and natural rubber was several orders of magnitude higher than their ratio in swelling anisotropy. The natural rubber sheet became saddle-shaped during limonene sorption and collapsed into a flat shape when the saturation concentration was approached. During desorption, the sheet went from flat to cup-shaped and then flat again at the end of desorption. The saddle and cup shapes occurred in both square and round sheets. These shapes are believed to be a consequence of buckling and deformation due to instabilities in the stress state of the sheet. This was, in turn, explained by the normally existing local variation in cross-link density.

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