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Thermodynamics of the densification process for polymer glasses

1977; The National Institute of Standards and Technology; Volume: 81A; Issue: 2/3 Linguagem: Inglês

10.6028/jres.081a.018

2376-5704

John E. McKinney, Robert Simha,

Adsorption, diffusion, and thermodynamic properties of materials

A qua ntita tive d esc riptio n is g ive n for the dens ifi cati on process of glasses resulting from g lass [orma ti o n at ele vat ed pressures .Phe nome n olog ica l re lati ons a re de rived, or j us tifie d , whic h al low es tim ati on of th e de ns ifi calion rate K ' (with respect 10 formation pressure ) fro m variolls the rmodynami c q uantiti es a nd glass trans ition be hav ior.In addition, the estimatio n of K ' may be fac ilit a ted by the appl ic a ti on of the hol e theory of S imha and Somcyn s ky.Using these relations K' is estimated , and the results from the d ifferent me thods a re co mpared for data from 23 diffe re nt organi c poly me rs wi th g lass tra ns iti on te mpe ratures rang ing fro m 150 to 455 K. T he a mount of de ns ifi cati on appea rs to be limit ed by the appa re nt convergence o f the glass tempe rature a nd e ffective decompos ition tempe rature wi th in c reas ing pressure .Some estimates of limiting values are presente d. final ly, c hanges of refrac tive index resulting from de ns ification are estima ted from the observed, or predic ted , de nsific atio n ra tes.