Temperature-dependent decaying mechanism of BOPET corona films

BOPET corona films undergo a decrease in surface energy with time, a so called decaying effect, which has become a serious and widely known problem which prohibits their downstream industrial applications and needs to be carefully understood. Herein, the decaying behaviors and dynamics of decaying BOPET corona films in hot air were studied carefully by measuring water contact angle and surface tension and variable angle XPS. It was found that the molecular mechanism for the decaying effect involves migration of polar groups from the surface to the interior, and the decaying process is highly dependent on temperature. In addition, it was also found that such a temperature-dependent decay process is related to the glass transition of BOPET, and the glass transition temperature (T_g) can be predicted through analysis of the dynamics.