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A critical analysis of the use of sample‐supportive techniques in the measurement of dynamic mechanical relaxation processes
Author(s) -
Neumann R. M.,
Senich G. A.,
Macknight W. J.
Publication year - 1978
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760180804
Subject(s) - materials science , relaxation (psychology) , dynamic mechanical analysis , glass transition , composite material , dissipation factor , braid , dispersion (optics) , spring (device) , thermodynamics , polymer , optics , physics , psychology , social psychology , optoelectronics , dielectric
It is shown that the technique of dynamic spring analysis (DSA) gives rise to a dynamic mechanical loss dispersion well above the glass transition temperature, T g , analogous to the T u process observed in torsional braid analysis. A mechanical model is proposed which explains why any composite sample consisting of an elastic support coupled to a viscous liquid must necessarily produce such a relaxation regardless of whether the liquid is monomeric or polymeric in nature. Loss tangent measurements performed on a series of polystyrenes of varying molecular weight and on glycerol using both DSA and a Rheometrics mechanical spectrometer show that the relaxation observed in DSA is not of molecular origin.