SANS studies on the relaxation of an amorphous polymer melt is reported. Just after the uniaxial elongation the chains deform affinely. Shortly thereafter the SANS results give evidence of chain contraction. Some randomization is observed long before the reptation time is reached.

AbstractA large number of specially prepared model networks with different types of network defects have been produced since de Gennes proposed the reptation motion for linear chains. The viscoelastic properties of these model networks show clearly that branched chains and dangling chains are the cause of the gradual and extremely slow relaxations in lightly crosslinked networks. These experimental results have been followed by theoretical developments that point towards a complete molecular theory for the non‐equilibrium properties of lightly crosslinked networks. It is proposed that the presence of dangling chains in endlinked networks may be revealed by measurements of the viscoelastic properties of such networks near the transition zone.

Journal of Polymer Science: Polymer Physics EditionVolume 15, Issue 4 p. 761-763 Note Entanglement networks of 1,2-polybutadiene crosslinked in states of equibiaxial extension Ole Kramer, Ole Kramer Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, DenmarkSearch for more papers by this authorJohn D. Ferry, John D. Ferry Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706Search for more papers by this author Ole Kramer, Ole Kramer Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, DenmarkSearch for more papers by this authorJohn D. Ferry, John D. Ferry Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706Search for more papers by this author First published: April 1977 https://doi.org/10.1002/pol.1977.180150416Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume15, Issue4April 1977Pages 761-763 RelatedInformation

Abstract This paper gives the results of a recalculation of the data in Paper I of this series, with an expression for strain energy which is a special case of the Mooney-Rivlin theory, instead of the ideal theory based on Gaussian networks. It was shown in Paper I that the apparent concentration of elastically effective network strands terminated by entanglements, νN, can be estimated by crosslinking linear polymers in states of strain. The maximum value of νN found by this method was about one-half the value obtained from viscoelastic measurements in the rubbery plateau zone, νc=2.5×10−4 mol cm−3. The low value of νN was primarily attributed to the crosslinking temperature being too far (12°) above the glass-transition temperature, Tg. Crosslinking temperatures closer to Tg give values of νN close to νc, as will be shown in Paper III of this series. In addition, it was found that these networks behave slightly differently from the predictions of the ideal Gaussian composite network theory: ideal Gaussian composite networks are isotropic relative to the state of ease whereas these networks exhibit anisotropy of equilibrium swelling, relative to the state of ease, in n-heptane; and νN, instead of being a constant, was found to decrease with increasing extension ratio during crosslinking, λ0. The latter result is illustrated in Figure 1 for irradiation times from 3 to 5 h; here, νN is plotted against the extension ratio, λs, in the state of ease in which the retractive force of the entanglement network and the compressive force of the crosslink network are equal and opposite in direction. The experimental points can be fitted rather well by a curve (not the one shown) with the functional form of a constant divided by λs, like the C2 term in the Mooney-Rivlin equation.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEntanglement Networks of 1,2-Polybutadiene Cross-Linked in States of Strain. II. Application of the Mooney-Rivlin Equation to Networks Cross-Linked at O°Ole Kramer and John D. FerryCite this: Macromolecules 1975, 8, 1, 87–89Publication Date (Print):January 1, 1975Publication History Published online1 May 2002Published inissue 1 January 1975https://pubs.acs.org/doi/10.1021/ma60043a023https://doi.org/10.1021/ma60043a023research-articleACS PublicationsRequest reuse permissionsArticle Views119Altmetric-Citations15LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

The storage and loss shear moduli (G', G″) of human fibrin clots have been measured in small oscillating deformations over a frequency range of 0.01 to 160 Hz with the modified Birnboim transducer apparatus. Most clots were prepared by the action of thrombin on purified fibrinogen, under various conditions of pH and ionic strength to produce networks ranging from coarse to fine structure; some were liaated by fibrinoligase. The fine, unligated clot showed very little mechanical loss or frequency dependence of G' over the experimental frequency range, though loss mechanisms evidently appear at higher frequencies; G' was proportional to the 1.5 power of fibrin concentration. The coarse, unligated clot showed a slight increase of G' with frequency, reflecting some relaxation mechanisms with time constants whose reciprocals lie in the experimental frequency range. Ligation did not greatly affect the magnitude of G'. However, clots prepared by dilution of solutions of fibrin monomer in 1 M sodium bromide had smaller moduli by a factor of ten than corresponding clots prepared by the action of thrombin of fibrinogen. Oscillatory measurements in the Birnboim apparatus with closed-end (annular pumping) geometry revealed a low-frequency anomaly which was shown to be due to permeation of fluid through the clot structure, and from these measurements the Darcy constants for coarse clots were calculated. From the Darcy constants, the average thicknesses of the fibrous elements of the structures were estimated to be from 300 to 700 A.