A rheological test to characterize the melt in various vinyl coating resins in a flooring wear layer formulation shows that the surface quality (absence of orange‐peel) of the resilient foamed flooring is associated with the viscoelastic nature of the wear layer resin during the cure cycle: Resins with high molecular weight of a sufficiently high melt viscosity showed no entrapment of air bubbles or tendency to orange‐peel, while resins with low melt viscosity produced very severe orange‐peel. Orange‐peel is independent of the type of foam resin used. For a given formulation, the proper selection of wear layer resin or resin mixtures that will develop the desired hot melt strength to contain the gases given off by the decomposition of the blowing agent, will help to alleviate or minimize orange‐peel.

A stress is applied to the end of a semi-infinite, inhomogeneous, “standard” viscoelastic rod. The rod is initially unstressed and at rest. The applied stress is uniformly distributed over the end, and it is oscillatory in time. The propagation of small-amplitude, one-dimensional, longitudinal waves is studied. A formal asymptotic expansion of the solution is obtained. A partial justification of the method for homogeneous rods is given. The leading term in the expansion represents a modulated, oscillating, progressive wave that propagates with variable velocity. The modulation depends on the elastic and viscous moduli. The velocity depends only on the elastic moduli. The Maxwell rod is studied as a limiting case of the standard rod. Application of the method to finite rods is discussed.

The effect of the sample extrusion temperature between 160° and 180°C on the elongational flow properties of a low molecular weight suspension PVC (unplasticized) has been studied with the Rheometrics Extensional Rheometer. The results of both the tensile creep measurements at a constant stress of 24 KPa and the stretching experiment at a constant strain rate of 0.01 sec−1 indicated the existence of a rheological transition at 185°C marked by the dual valued flow activation energy and also by the temperature dependence of the tensile stress‐strain curves. Increasing extrusion temperature increased both the flow activation energy and the extensional viscosity below the transition temperature.