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Stress‐Strain isotherms for stereoirregular and stereoblock cis‐trans polybutadienes
Author(s) -
Sharaf M. A.,
Mark J. E.,
Gunesin B.,
Julemont M.,
Teyssié P.
Publication year - 1986
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760260208
Subject(s) - polybutadiene , materials science , crystallization , polymer , elastomer , solvent , polymer chemistry , elongation , stress (linguistics) , strain (injury) , thermodynamics , composite material , copolymer , ultimate tensile strength , organic chemistry , chemistry , physics , linguistics , philosophy , medicine
Gamma radiation and high‐energy electrons were used to crosslink two types of polybutadiene (PBD), the first having random cis‐trans‐vinyl contents and the second consisting primarily of blocks of cis units and blocks of trans. The resulting elastomers were studied in elongation in the unswollen stale, generally at 5°C, and in swelling equilibrium in a thermodynamically good solvent. Stress‐strain isotherms obtained for the random‐PBD networks did not show upturns in the reduced stress [ f *] at high elongations, which is consistent with their non‐crystallizability. The stereoblock polymers were found to be crystalline, with melting points ranging from 14 to 65°C. Attempts to achieve strain‐induced crystallization in the stereoblock networks by judicious choice of temperature were unsuccessful as judged by the absence of any significant upturns in [ f *]. Values of the elasticity constants 2 C 1 and 2 C 2 , and the molecular weight between crosslinks were similar to those obtained from the linear portions of the isotherms previously reported for high‐cis and high‐trans PBD, which readily undergo strain‐induced crystallization.