SPECTRAL CURVE-FITTING OF INFRARED-SPECTRA OBTAINED FROM SEMICRYSTALLINE POLYESTER YARNS

Infrared spectra of polymer yarns exhibit a large number of strongly o verlapping peaks. One of the methods to study the physical yarn struct ure quantitatively is to resolve the spectra into separate bell-shaped peaks. Due to the overlapping peak patterns, curve fitting with steep est descent like procedures depend on accurate initial estimates of th e peak parameters. We developed a non-local curve fitting procedure, b ased on a genetic algorithm, which proved to be less sensitive to init ial estimates. The combination of a genetic algorithm with a nonlinear estimator, based on Marquardt's method, gave the best curve fitting r esults.