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A forced torsional oscillator for dynamic mechanical measurements
Author(s) -
Davis William M.,
Macosko Christopher W.
Publication year - 1977
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.760170106
Subject(s) - torsion pendulum clock , polycarbonate , materials science , torsion (gastropod) , glass transition , dimensionless quantity , phase transition , arrhenius equation , composite material , thermodynamics , analytical chemistry (journal) , polymer , physics , chemistry , kinetics , classical mechanics , medicine , surgery , quantum mechanics , chromatography
A forced torsional oscillator (FTO) for measuring dynamic properties from 0.01 to 30 Hz and −190 to +250°C is described. It uses a digital transfer function analyzer to determine G ′ and G ″ directly. Errors such as clamping corrections, phase angle resolution, and instrument phase shift are evaluated. FTO measurements vs temperature on polymethylmethacrylate (PMMA) and polycarbonate compare well with free torsion pendulum data. Measurements on a silicone liquid vs frequency compare well to eccentric rotating disks data. The frequency sensitivity of the dynamic mechanical response of PMMA and polycarbonate is evaluated at 0.1, 1 and 10 Hz. The frequency dependence of the transitions is fit to an Arrhenius relation and activation energies calculated. A dimensionless transition temperature shift, Δ T *, giving the shift for a one decade frequency change divided by the temperature, is found to be approximately 0.01 for the glass transition and 0.07 for several secondary transitions in glassy polymers.