Photooxidation caused an increase in oxygen-containing functional groups for PP-needles c and PP-fibers b , but not PET-fibers b ( . Photooxidation caused a decrease in ice nucleation activity for PP-needles c and PET-fibers b , but not PP-fibers (Table , column 2). We conclude that the decrease in ice nucleation ability caused by photooxidation cannot be explained by just the increase in oxygen-containing functional groups observed with FTIR spectroscopy.