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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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Formato: | Online Artículo Texto |
Lenguaje: | English |
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[Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology
1976
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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. |
format | Online Article Text |
id | pubmed-5293352 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 1976 |
publisher | [Gaithersburg, MD] : U.S. Dept. of Commerce, National Institute of Standards and Technology |
record_format | MEDLINE/PubMed |
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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