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Modulus of Natural Rubber Cross-Linked by Dicumyl Peroxide III. Some Molecular Interpretations, Possible Refinements of Theory, and Conclusions

The shear modulus G = 5.925 × 10(−)(3)(fp − 0.45)T+G* (Part I), its energy component G* = 0.0684 (fp − 0.45)+ 2.70 (Part II), and the number of effective suh-chains per unit volume v(e)= (G – G*)/RT are given detailed molecular consideration. G is given in Mdyn cm(−2) for rubber cross-linked by addi...

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Autor principal: Wood, Lawrence A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: [Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology 1976
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5293352/
https://www.ncbi.nlm.nih.gov/pubmed/32196273
http://dx.doi.org/10.6028/jres.080A.051
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author Wood, Lawrence A.
author_facet Wood, Lawrence A.
author_sort Wood, Lawrence A.
collection PubMed
description The shear modulus G = 5.925 × 10(−)(3)(fp − 0.45)T+G* (Part I), its energy component G* = 0.0684 (fp − 0.45)+ 2.70 (Part II), and the number of effective suh-chains per unit volume v(e)= (G – G*)/RT are given detailed molecular consideration. G is given in Mdyn cm(−2) for rubber cross-linked by adding p parts of dicumyl peroxide per hundred of rubber, and heating until a fraction f of the peroxide is decomposed. v(e) is found to be approximately twice the density of cross-links, after a correction for impurities and chain ends is made. It can not be computed as G/RT since only the entropy component of modulus is related to v(e). The sub-chains for the most highly cross-linked rubbers studied had a molecular weight of about 575 g mol(−1), corresponding to about 8 isoprene units. The modulus corresponding to no added cross-links is not zero. It is determined chiefiy by the energy component of the modulus; it does not arise from entanglements. The “front factor” is found to be unity. An extensive literature survey yields values of the quantity RTΨ(v(2)), where Ψ (v(2)) is the Flory- Rehner equation function of v(2), the equilibrium volume fraction obtained by swelling the cross-linked rubber. RTψ (v(2)) is found to be greater than G – G* but not as large as G itself.
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spelling pubmed-52933522020-03-18 Modulus of Natural Rubber Cross-Linked by Dicumyl Peroxide III. Some Molecular Interpretations, Possible Refinements of Theory, and Conclusions Wood, Lawrence A. J Res Natl Bur Stand A Phys Chem Article The shear modulus G = 5.925 × 10(−)(3)(fp − 0.45)T+G* (Part I), its energy component G* = 0.0684 (fp − 0.45)+ 2.70 (Part II), and the number of effective suh-chains per unit volume v(e)= (G – G*)/RT are given detailed molecular consideration. G is given in Mdyn cm(−2) for rubber cross-linked by adding p parts of dicumyl peroxide per hundred of rubber, and heating until a fraction f of the peroxide is decomposed. v(e) is found to be approximately twice the density of cross-links, after a correction for impurities and chain ends is made. It can not be computed as G/RT since only the entropy component of modulus is related to v(e). The sub-chains for the most highly cross-linked rubbers studied had a molecular weight of about 575 g mol(−1), corresponding to about 8 isoprene units. The modulus corresponding to no added cross-links is not zero. It is determined chiefiy by the energy component of the modulus; it does not arise from entanglements. The “front factor” is found to be unity. An extensive literature survey yields values of the quantity RTΨ(v(2)), where Ψ (v(2)) is the Flory- Rehner equation function of v(2), the equilibrium volume fraction obtained by swelling the cross-linked rubber. RTψ (v(2)) is found to be greater than G – G* but not as large as G itself. [Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology 1976 1976-06-01 /pmc/articles/PMC5293352/ /pubmed/32196273 http://dx.doi.org/10.6028/jres.080A.051 Text en https://creativecommons.org/publicdomain/zero/1.0/ The Journal of Research of the National Bureau of Standards Section A is a publication of the U.S. Government. The papers are in the public domain and are not subject to copyright in the United States. Articles from J Res may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright.
spellingShingle Article
Wood, Lawrence A.
Modulus of Natural Rubber Cross-Linked by Dicumyl Peroxide III. Some Molecular Interpretations, Possible Refinements of Theory, and Conclusions
title Modulus of Natural Rubber Cross-Linked by Dicumyl Peroxide III. Some Molecular Interpretations, Possible Refinements of Theory, and Conclusions
title_full Modulus of Natural Rubber Cross-Linked by Dicumyl Peroxide III. Some Molecular Interpretations, Possible Refinements of Theory, and Conclusions
title_fullStr Modulus of Natural Rubber Cross-Linked by Dicumyl Peroxide III. Some Molecular Interpretations, Possible Refinements of Theory, and Conclusions
title_full_unstemmed Modulus of Natural Rubber Cross-Linked by Dicumyl Peroxide III. Some Molecular Interpretations, Possible Refinements of Theory, and Conclusions
title_short Modulus of Natural Rubber Cross-Linked by Dicumyl Peroxide III. Some Molecular Interpretations, Possible Refinements of Theory, and Conclusions
title_sort modulus of natural rubber cross-linked by dicumyl peroxide iii. some molecular interpretations, possible refinements of theory, and conclusions
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5293352/
https://www.ncbi.nlm.nih.gov/pubmed/32196273
http://dx.doi.org/10.6028/jres.080A.051
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