New Insights into the Effects of Physical Aging on Glass Transition of Polystyrene by FTIR

Abstract

A new method to detect the glass transition was used to investigate the effects of physical aging on the glass transition of polystyrene by Fourier transform infrared (FTIR) spectroscopy. The results showed that the onset point of the glass transition shifted to higher temperature with aging, but the end point didn't change. It was demonstrated that this method was of great use in determining the glass transition temperature of aged polymeric samples. For each aged sample, the four bands assigned to the vibrational modes of the main chain groups and the side groups of polystyrene showed the same transition regions, indicating that the main chain and the side groups were aging synchronously. The rates of increase of the relative peak areas for the four investigated bands during the glass transition decreased with aging with the increased rates of the relative peak areas for the two bands assigned to side group decreasing less than those of main chain, which seemed to indicate the dominance of the side group in aging process.

Study on O-Terphenyl/Polystyrene Blends: How Plasticizer Affects the Glass Transition of Polystyrene?

“…1. [17] We ascribed these step-like increases of peak areas in the glass transition region to the dipole moment change caused by chain motion. [17] Since the rate of increase of the peak area (see details in ref.…”

“…[17] We ascribed these step-like increases of peak areas in the glass transition region to the dipole moment change caused by chain motion. [17] Since the rate of increase of the peak area (see details in ref. [17]) is not of concern here, the peak areas for the four bands were normalized for clarity in this paper.…”

“…[17] Since the rate of increase of the peak area (see details in ref. [17]) is not of concern here, the peak areas for the four bands were normalized for clarity in this paper.…”

“…In our earlier study, [17] a new method to determine T g by FTIR was found, and used to study the effect of physical aging on the glass transition of PS. In contrast with the previous works by other authors in which the glass transition of a polymer was detected by FTIR, [18,19] four conformation insensitive bands in the spectrum of PS were investigated and the peak areas were calculated.…”

“…(b) Heat capacity of PS vs. temperature derived from DSC measurement [17]. Heating curves of pure OTP and PS plasticized by 1, 4, 7, and 10 wt% OTP.…”