Existence of a sharply defined maximum relaxation time for monodisperse polystyrene

Abstract

Measurements of relaxation of stress were carried out in the region of rubbery flow on two samples of polystyrene, A and B. Sample A was prepared by the Szwarc technique which is designed to produce monodisperse polymer. Sample B was prepared by radical-initiated polymerization of styrene carried to low conversions. It was shown by Baysal and Tobolsky2 that the molecular weight distribution under these conditions is given by X ( n ) = np"-'(l -P )~, where X ( n ) is the mole fraction of polymer whose degree of polymerization is n. For this distribution the ratio of

Characterization of stress-strain behavior for binary blends of isotactic polypropylene with ethylene-?-olefin copolymer

“…The relaxation component of E(t), and the relaxation spectra H() was also formulated by means of an analytical technique being referred to as "Procedure X." 24 The present constitutive equation, eq. (6), is applicable only to the sample whose relaxation times are independent of deformation as well as the anharmonicity remains constant during extension at a constant rate of deformation.…”

Prediction of stress-relaxation behavior in high density polyethylene solids

“…3 is shown the linear relaxation modulus E(t) evaluated from the linear dynamic mechanical test. The relaxation component of E(t) and the relaxation spectra H(s) were also formulated by means of an analytical technique being referred to as "Procedure X" 23) . Turning now to the nonlinear constitutive equation (17), we can obtain the solution for W(t) as where the operator of L denotes the Laplace transform.…”

Properties and Morphology of Amorphous Hydrocarbon Block Copolymers

“…Similar experiments were also carried out for a number of triblock copolymers of styrene and a-methylstyrene (19). Maximum relaxation times were determined from the master curves by Procedure X of Tobolsky and Murakami (30). Table 2 shows that the agreement is satisfac tory between the cal culated and experimental values ( 10) .…”