Applied Polymer Symposium No. 27, 193-204 (1975)

A STATISTICAL METHOD FOR DETERMINING THE GLASS

TRANSITION TEMPERATURE FROM DILAOMETRIC DATA

NELSON P. C. CHAO and JOHN A. CUCULO

Department of Textile Chemistry

A. RONALD GALLANT

Department of Statistics

T. WALLER GEORGE

Department of Textile Technology

North Carolina State University,

Raleigh, North Carolina 27607

SYNOPSIS

An objective procedure for estimating the glass transition temperature (T_g) from dilatomctric data is described. The method uses the technique of fitting a segmented linear regression model by least squares. The regression model employed may be specified so as to allow a transition either of the first order in the thermodynamic sense or may be constrained to fit a second order. Methods are given for finding statistical confidence intervals for the estimated glass transition temperature (T_g). Experimental data obtained from PET fiber are used for illustration, these data indicate a preference for the second-order transition model.