Table 1.

Conditions and acid number results of thermal degradation procedure on PS0 flakes.

Sample	Acid Number (mg KOH/g)	Process Conditions
PS0	22.0	N/A
PS1	39.0	60 °C, O3/O2, 20 h
PS2	33.7	80 °C, O3/O2, 20 h
PS3	29.5	100 °C, O3/O2, 20 h
PS4	23.6	180 °C, O3/O2, 20 h