Characterization of free volume during vulcanization of styrene butadiene rubber by means of positron annihilation lifetime spectroscopy and dynamic mechanical test

A. J. Marzocca, S. Cerveny, W. Salgueiro, A. Somoza, and L. Gonzalez
Phys. Rev. E 65, 021801 – Published 15 January 2002
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Abstract

An experimental investigation was performed to study the effect on the free volume of the advance of the cross-linking reaction in a copolymer of styrene butadiene rubber by sulfur vulcanization. The dynamic modulus and loss tangent were evaluated over samples cured for different times at 433 K by dynamic mechanical tests over a range of frequencies between 5 and 80 Hz at temperatures between 200 and 300 K. Using the William-Landel-Ferry relationship, master curves were obtained at a reference temperature of 298 K and the coefficients c10 and c20 were evaluated. From these parameters the dependence of the free volume on the cure time is obtained. Positron annihilation lifetime spectroscopy was also used to estimate the size and number density of free volume sites in the material. The spectra were analyzed in terms of continuous distributions of free volume size. The results suggest an increase of the lower free volume size when cross linking takes place. Both techniques give similar results for the dependence of free volume on the time of cure of the polymer.

  • Received 13 December 2000

DOI:https://doi.org/10.1103/PhysRevE.65.021801

©2002 American Physical Society

Authors & Affiliations

A. J. Marzocca1, S. Cerveny1, W. Salgueiro2, A. Somoza2, and L. Gonzalez3

  • 1Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento Física, Laboratorio de Propiertades Mecanicas de Polimeros y Materiales Compuestos, Ciudad Universitaria, Pabellon 1, Buenos Aires (1428), Argentina
  • 2Universidad Nacional del Centro de la Provincia de Buenos Aires, Instituto de Fisica de Materiales de Tandil, Pinto 399, Tandil (7000), ArgentinaComisión de Investigaciones Científicas de la Provincia de Buenos Aires, Argentina
  • 3Instituto de Ciencia y Tecnología de Polímeros (CSIC), Juan de la Cierva 3, 28006, Madrid, Spain

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Vol. 65, Iss. 2 — February 2002

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