The 21 polymeric materials reviewed are selected as representative of those useful for large scale damping applications, and for which there are available wide frequency and temperature ranges of relevant experimental data given by values of complex shear compliance, J* = J' - iJ ", and shear modulus, G* = G' + G " = 1/J*. For effective damping high energy loss in the damping material is needed as measured by the loss tangent, J " /J' = G " /G', together with values of mechanical impedance that match the vibration source impedance. Brief summaries listing some of these damping parameters are given for the 21 systems divided into seven groups as follows: 1. Polyisobutylene, 2. Plasticized polyvinyl chloride (10, 40, 60% polyvinylchloride), 3. Butadiene-acrylonitrile-copolymer (0, 15.6, 26.9, 35.0% carbon black), 4. Polybutadiene(0, .04, .2% curing agent), 5. Natural and synthetic rubber tire stocks ( effects of rayon, nylon cord), 6. Plasticized polyvinyl acetate (50, 100% polyvinyl acetate), 7. Polyethylene (3 molecular weight distributions). Numerical values of complex shear compliance, modulus, and loss tangent chiefly at frequencies from 25 to 5000 Hz in a temperature range from -50 to 150 degreesC have been transferred in ASCII format to a computer disk for convenient access in damping design applications. Measurements on combinations of plasticized polyvinyl chloride compositions are used to demonstrate the use of varying polymer concentrations in blended and/or laminated composites to give "smart" damping materials with large loss tangents over extended frequency and temperature ranges.

Journal of Polymer Science Part B: Polymer PhysicsVolume 37, Issue 7 p. 621-622 Special Section: Historical Notes in Polymer Physics Temperature dependence of viscoelastic properties: The Fitzgerald apparatus and the WLF equation † John D. Ferry, John D. Ferry University of Wisconsin, Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706-1396Search for more papers by this author John D. Ferry, John D. Ferry University of Wisconsin, Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706-1396Search for more papers by this author First published: 01 March 1999 https://doi.org/10.1002/(SICI)1099-0488(19990401)37:7<621::AID-POLB4>3.0.CO;2-CCitations: 4 † Portions of this note were published in a somewhat longer paper, Ferry, J. D., J Soc Rubber Ind Japan 1997, 70(11), 651–656. AboutPDF 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 Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume37, Issue71 April 1999Pages 621-622 RelatedInformation

The frequency dependences of the storage and loss shear moduli, G' and G'', of dilute solutions of highly purified xanthan polysaccharide were measured at 20.0-degrees-C using the Birnboim-Schrag multiple-lumped resonator. The frequency range was 150-8000 Hz and the concentration range was 0.1-0.4 g/l. Three solvents were used, one of which contained 75% by weight glycerol to increase the solution viscosity. Measurements of oscillatory flow birefringence were also made in one solvent over the frequency range from 1-630 Hz and agreed well with the viscoelastic data in the range of overlap. The intrinsic viscosity in both water and 25%/75% water/glycerol (with 0.085 mol/l sodium chloride) was determined as 5200 ml/g. The frequency dependences of G' and G'', extrapolated to infinite dilution, could be fitted to a hybrid model for semiflexible rods which was modified to take into account a moderate degree of molecular weight distribution (M(w)/M(n) = 1.4). From the experimental data the persistence length of the native xanthan was estimated at 500-800 nm and Young's modulus of the rod, modeled as a homogeneous body, was calculated to be about 2 X 10(9) dyn/cm2.

Early events in the development of understanding the dynamics of configurational changes in macromolecules and their relation to physical properties (viscoelasticity, dielectric dispersion, and diffusion) are reviewed. The period covered is generally from 1930 (when polymers were first accepted as genuine molecules) to about 1970, though there are a few references to earlier and later contributions. Emphasis is given to early work that is less familiar to contemporary investigators and is seldom if ever cited in the current literature.

Measurements of small‐angle x‐ray scattering have been made on films prepared from fine and coarse (i.e., formed at high and low, respectively, pH and ionic strength) clots of bovine fibrin by osmotic shrinkage or compression in one dimension. Intensity profiles were obtained with pinhole geometry on films stretched up to a stretch ratio of 1.43. In unstretched coarse films, repeat spacings were seen at about 245, 120, and 77–80 Å. These peaks can probably be identified with the first, second, and third orders of the well‐known fibrin repeat of 225 Å. In unstretched fine films, only the 77–80 Å spacing was seen. In this case, the first two orders may be weak because the half‐staggered arrangement of monomer units giving rise to the 225 Å reflection is not reinforced by lateral aggregation of protofibrils; the third order may be strong since the molecular subdomains appear to divide the repeat roughly into thirds. After stretching, the 77–80 Å spacing persisted in the meridional direction but almost disappeared in the equatorial. Experiments on unstretched films prepared with ancrod substituted for thrombin gave similar results.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTJohn Warren Williams, 1898-1988John D. FerryCite this: Langmuir 1989, 5, 1, 2–3Publication Date (Print):January 1, 1989Publication History Published online1 May 2002Published inissue 1 January 1989https://doi.org/10.1021/la00085a001Request reuse permissionsArticle Views44Altmetric-Citations2LEARN 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 InReddit PDF (1 MB) Get e-Alertsclose Get e-Alerts

The tetrapeptide Gly-Pro-Arg-Pro(GPRP) was introduced by diffusion into fine unligated clots formed from human fibrinogen at pH 8.5 and ionic strength 0.45 by batroxobin (αβ-fibrin) and by thrombin (α-fibrin). The α-fibrin clots were essentially liquefied at GPRP concentrations above 1 m M and αβ-fibrin clots above 15 m M , and the degree of polymerization of the resulting oligomers decreased progressively with increasing GPRP concentration as shown by γ-γ ligation with factor XIIIa and subsequent gel electrophoresis. Much smaller concentrations of GPRP, when introduced into unligated clots by diffusion, were sufficient to modify their mechanical properties profoundly. The shear modulus of elasticity G 25 measured 25 s after imposition of stress fell, for example, by a factor of 0.4 at 0.1 m M GPRP in α-fibrin and at 1.1 m M in αβ-fibrin. The rate of shear creep under constant stress and the proportion of irrecoverable deformation also increased enormously. This behavior, and the corresponding decrease in steady flow viscosity, may be interpreted in terms of competition of GPRP with A sites on the E domains of fibrin monomers for bidning to “a” sites on the D domains, resulting in a moderate increase with increasing GPRP concentration of the average proportion of severed network strands and an enormous increase in the rate at which all strands dissociate and reassociate. Reassociation of severed strands in new configurations is a necessary corollary since the differential modulus or compliance remains constant during creep and creep recovery. The greater susceptibility of α-fibrin clots to interaction with GPRP is attributed to stabilization of contacts between monomer units by Bb associations in αβ-fibrin. Ligated clots, with or without GPRP, exhibited essentially no time-dependent creep and no irrecoverable deformation, corresponding to an absence of any severance of network strands.

Fibrin film is prepared by compaction in one dimension of a fibrin clot (pH 6.3, ionic strength 0.15, fibrin concentration about 0.5%) by expulsion of fluid to reach a fibrin concentration of about 15%. Strips of film, equilibrated in the same buffer with very slowly increasing temperature, shrink in length in a narrow temperature range, as reported in 1962 by Loeb and Scheraga. The transition temperature was found to be 54 +/- 2 degrees C independently of whether the film was unligated or ligated (cross-linked) by Factor XIIIa and whether the film had previously undergone stretching with about 50% stress relaxation at a relative length of 1.23 to 1.44 and subsequent stress-free retraction. The percentage of linear shrinkage in buffer was about 32%. The transition corresponds to that observed calorimetrically by Mihalyi and Donovan in both fibrinogen and fibrin and by Medved' and Privalov in fibrinogen, localized in the D fragment. It is attributed to unfolding of structures in the D domain.

Human fibrinogen (concentration 8.4 mg/mL) was ligated (cross‐linked) with factor XIIIa and dithiothreitol (DTT) at pH 8.5, ionic strength 0.45. With 7.5 μg/mL of factor XIIIa alone, there was almost no γ‐γ ligation, but with 2 m M DTT added, oligomers appeared, and γ‐γ and Aα‐Aα ligation was nearly complete after 3 days. At 38 μg/mL of factor XIIIa, some γ‐γ and Aα‐Aα ligation occurred even without DTT. For fibrinogen concentrations of 4.0 and 8.4 mg/mL, 38 μ/mL factor XIIIa, 2.0 m M DTT, clot‐like gels formed and the shear modulus of elasticity increased slowly over several days to a constant value. The final modulus was similar in magnitude to those of ligated clots of α‐fibrin (clotted by thrombin) and α‐fibrin (clotted by batroxobin) under the same conditions. However, the opacity was somewhat higher; whereas in fine fibrin clots there is minimal lateral association of the protofibrils, in fibrinogen gels at the same pH and ionic strength the protofibrils (which are presumably single chains of fibrinogen monomers joined end to end at their D domains) are evidently associated in bundles (although not to the degree seen in coarse fibrin clots). Creep and creep recovery measurements showed almost perfect elastic behavior, with essentially no creep under stress and complete recovery after removal of stress. The modulus was scarcely affected by introduction of lithium bromide by diffusion to a concentration of 0.6 M , which in unligated fibrin clots causes substantial softening. Whereas in fine fibrin clots (both αβ‐fibrin and α‐fibrin) factor XIIIa causes only γ‐γ ligation, addition of 2 m M DTT produced some α‐α ligation in these also.

Actin is the major protein of eukaryote peripheral cytoplasm where its mechanical effects could determine cell shape and motility. The mechanical properties of purified F-actin, whether it is a viscoelastic fluid or an elastic solid, have been a subject of controversy. Mainstream polymer theory predicts that filaments as long as those found in purified F-actin are so interpenetrated as to appear immobile in measurements over a reasonable time with available instrumentation and that the fluidity of F-actin could only be manifest if the filaments were shortened. We show that the static and dynamic elastic moduli below a critical degree of shear strain are much higher than previously reported, consistent with extreme interpenetration, but that higher strain or treatment with very low concentrations of the F-actin severing protein gelsolin greatly diminish the moduli and cause F-actin to exhibit rheologic behavior expected for independent semidilute rods, and defined by the dimensions of the filaments, including shear rate independent viscosity below a critical shear rate. The findings show that shortening of actin filaments sufficiently to permit reasonable measurements brings out their viscoelastic fluid properties. Since gelsolin shortens F-actin, it is likely that the effect of high strain is also to fragment a population of long actin filaments. We confirmed recent findings that the viscosity of F-actin is inversely proportional to the shear rate, consistent with an indeterminate fluid, but found that gelsolin abolishes this unusual shear rate dependence, indicating that it results from filament disruption during the viscosity measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Fine fibrin clots, prepared at pH 8.5, ionic strength 0.45, with minimal lateral aggregation of protofibrils, and ligated (cross-linked) by factor XIIIa, were subjected to constant static shear strain (γ) with superposed small oscillating strains. The incremental shear modulus (dynamic storage modulus) measured in the oscillating deformations was strain-independent at small static strains (up to about 0.1) and approximately equal to the static modulus. At higher static strains, it increased rapidly, up by a factor of 5 to 8 at γ =0.35. Comparison with earlier data on unligated clots showed that the enhancement of stiffness was independent of ligation except at very high strains. The enhancement is attributed to additional forced contacts between network fibers as the strands are bent and oriented. When the static strain was maintained for up to one day, in a clot ligated by factor XIIIa the enhanced incremental modulus remained constant or decreased slightly, and after removal of stress the clot returned almost to its original shape. This contrasts with the behavior of unligated clots, where most of the enhancement was progressively lost as the incremental modulus fell toward its small-strain value, and there was a substantial permanent deformation after the removal of stress. The latter behavior has been attributed to gradual severance of network strands at high strains, followed by their rejoining in relaxed configurations, but leaving some structural damage that is only very slowly recovered in the resting state. Ligation of protofibrils evidently eliminates the possibility of strand rupture.

Clots of human beta-fibrin, in which only (or predominantly) the B fibrinopeptide is released, were formed at 14 degrees C by copperhead venom procoagulant enzyme (CVE or venzyme), at pH 8.5, ionic strength 0.45. The shear modulus of elasticity increased slowly and after several days attained a constant value, which was lower than those of alpha-fibrin or alpha beta-fibrin under the same conditions. Before studying the temperature dependence of elasticity, the CVE was then inhibited by introducing phenyl methyl sulfonyl chloride (PMSF) by diffusion. With increasing temperature, the modulus decreased progressively from 5 degrees C to nearly zero at 35 degrees and was essentially reversible with temperature change; recovery of elasticity after change from 34.5 degrees to 14 degrees required approximately 2 d but was considerably faster than the initial buildup of elasticity by CVE at 14 degrees. Creep and creep recovery measurements on unligated clots showed creep rates and irrecoverable deformation that were similar in magnitude to those of alpha-fibrin clots formed with batroxobin and much larger than those of alpha beta-fibrin clots formed with thrombin, under the same conditions. During creep and creep recovery, the differential modulus or compliance remained constant, showing that there was no permanent structural damage, and if network strands are severed in slow flow, they must rejoin in new configurations. Introduction (by diffusion) of the tetrapeptides Gly-His-Arg-Pro (GHRP) and Gly-Pro-Arg-Pro (GPRP), which resemble the B and A binding sites on the E domain of fibrin respectively, reduced the shear modulus and increased the creep rate of beta-fibrin clots to an extent similar to the effect of GPRP on alpha beta-fibrin, much more than that of GHRP on alpha beta-fibrin, but much less than that of GPRP on a-fibrin. A ligated beta-fibrin clot formed with Factor XIIIa (in which the activating thrombin had been neutralized by hirudin) showed essentially perfect elastic behavior, with no creep and with complete recovery after removal of stress, and was inert to GHRP.

AbstractThe tetrapeptide Gly‐Pro‐Arg‐Pro(GPRP) was introduced by diffusion into fine unligated clots formed from human fibrinogen at pH 8.5 and ionic strength 0.45 by batroxobin (αβ‐fibrin) and by thrombin (α‐fibrin). The α‐fibrin clots were essentially liquefied at GPRP concentrations above 1 mM and αβ‐fibrin clots above 15 mM, and the degree of polymerization of the resulting oligomers decreased progressively with increasing GPRP concentration as shown by γ‐γ ligation with factor XIIIa and subsequent gel electrophoresis. Much smaller concentrations of GPRP, when introduced into unligated clots by diffusion, were sufficient to modify their mechanical properties profoundly. The shear modulus of elasticity G25 measured 25 s after imposition of stress fell, for example, by a factor of 0.4 at 0.1 mM GPRP in α‐fibrin and at 1.1 mM in αβ‐fibrin. The rate of shear creep under constant stress and the proportion of irrecoverable deformation also increased enormously. This behavior, and the corresponding decrease in steady flow viscosity, may be interpreted in terms of competition of GPRP with A sites on the E domains of fibrin monomers for bidning to “a” sites on the D domains, resulting in a moderate increase with increasing GPRP concentration of the average proportion of severed network strands and an enormous increase in the rate at which all strands dissociate and reassociate. Reassociation of severed strands in new configurations is a necessary corollary since the differential modulus or compliance remains constant during creep and creep recovery. The greater susceptibility of α‐fibrin clots to interaction with GPRP is attributed to stabilization of contacts between monomer units by Bb associations in αβ‐fibrin. Ligated clots, with or without GPRP, exhibited essentially no time‐dependent creep and no irrecoverable deformation, corresponding to an absence of any severance of network strands.