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Title: How far can a rubber molecule stretch before breaking? Ab initio study of tensile elasticity and failure in single-molecule polyisoprene

Abstract

We present ab initio calculations of the internal C-C bond dissociation curve for single molecules of (cis 1,4) polyisoprene, polybutadiene, and polyethylene, all of comparable length. We define 'bond rupture' as that point on the reaction coordinate where the unrestricted Kohn-Sham, or diradical, solution falls below the restricted, or closed-shell, solution. Using this well-defined though crude approximation, we find that rupture occurs at a tensile force of 6.8 nN for poly isoprene and 7.2 nN for polybutadiene. Their respective rupture strains are 45% and 42%. Our calculations show that the energy density vs. extension is not sensitive to the length of the molecule, i.e., it is essentially independent of the number of isoprene units contained. These relatively large rupture strains have important implications for understanding the failure mechanism in rubber, and imply that purely enthalpic chain stretching must commence well before tensile failure occurs.

Authors:
 [1]
  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
962252
Report Number(s):
LA-UR-08-05597; LA-UR-08-5597
Journal ID: ISSN 0032-3861; POLMAG; TRN: US0903410
DOE Contract Number:  
AC52-06NA25396
Resource Type:
Journal Article
Journal Name:
Polymer
Additional Journal Information:
Journal Name: Polymer; Journal ID: ISSN 0032-3861
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; DISSOCIATION; ELASTICITY; ENERGY DENSITY; ISOPRENE; POLYISOPRENE; RUBBERS; RUPTURES; STRAINS

Citation Formats

Hanson, David E. How far can a rubber molecule stretch before breaking? Ab initio study of tensile elasticity and failure in single-molecule polyisoprene. United States: N. p., 2008. Web.
Hanson, David E. How far can a rubber molecule stretch before breaking? Ab initio study of tensile elasticity and failure in single-molecule polyisoprene. United States.
Hanson, David E. 2008. "How far can a rubber molecule stretch before breaking? Ab initio study of tensile elasticity and failure in single-molecule polyisoprene". United States. https://www.osti.gov/servlets/purl/962252.
@article{osti_962252,
title = {How far can a rubber molecule stretch before breaking? Ab initio study of tensile elasticity and failure in single-molecule polyisoprene},
author = {Hanson, David E},
abstractNote = {We present ab initio calculations of the internal C-C bond dissociation curve for single molecules of (cis 1,4) polyisoprene, polybutadiene, and polyethylene, all of comparable length. We define 'bond rupture' as that point on the reaction coordinate where the unrestricted Kohn-Sham, or diradical, solution falls below the restricted, or closed-shell, solution. Using this well-defined though crude approximation, we find that rupture occurs at a tensile force of 6.8 nN for poly isoprene and 7.2 nN for polybutadiene. Their respective rupture strains are 45% and 42%. Our calculations show that the energy density vs. extension is not sensitive to the length of the molecule, i.e., it is essentially independent of the number of isoprene units contained. These relatively large rupture strains have important implications for understanding the failure mechanism in rubber, and imply that purely enthalpic chain stretching must commence well before tensile failure occurs.},
doi = {},
url = {https://www.osti.gov/biblio/962252}, journal = {Polymer},
issn = {0032-3861},
number = ,
volume = ,
place = {United States},
year = {Tue Jan 01 00:00:00 EST 2008},
month = {Tue Jan 01 00:00:00 EST 2008}
}