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Viscoelastic Properties as Functions of the Distribution of Activation Energies

 

作者: W. James Lyons,  

 

期刊: Journal of Applied Physics  (AIP Available online 1953)
卷期: Volume 24, issue 2  

页码: 217-221

 

ISSN:0021-8979

 

年代: 1953

 

DOI:10.1063/1.1721240

 

出版商: AIP

 

数据来源: AIP

 

摘要:

1. Assuming that the elementary molecular deformation process conforms to the Maxwell model, and that the molecular elastic forceGiand viscous force &eegr;iare functions (of unspecified forms) of the free energy of activationF*, the following expressions for the dynamic modulusGdand dynamic viscosity (internal friction) &eegr;dare obtained:Gd=1A0∞&ohgr;2&tgr;i2Gi&phgr;(F*)&ohgr;2&tgr;i2+1dF*,and&eegr;d=1A0∞&eegr;i&phgr;(F*)&ohgr;2&tgr;i2+1dF*,whereA=area of sample, &tgr;i=Gi/&eegr;i, &ohgr;=vibration frequency, and &phgr;(F*)dF*=thenumberof elementary processes having activation energies lying betweenF* andF*+dF*.2. By employing an expression relating the relaxation time &tgr;iwithF* for the elementary process, and adopting the so‐called ``box'' distribution of relaxation times, the following explicit form for the distribution of activation energies is deduced:&phgr;=const(1/kTF*−1/F*2),wherek=Boltzmann's constant andT=absolute temperature. When the box distribution, as represented by this explicit form for &phgr;, is introduced into the foregoing expressions forGdand &eegr;d, the integrated results are found to predict temperature and frequency dependencies which are in gratifying agreement with experiment.

 

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