ETCHING RATES OF DIFFERENT POLYMERS IN OXYGEN PLASMA

The etching rates of different polymers in oxygen plasma was compared. The plasma was created in an electrodeless, radiofrequency discharge at a frequency of 27.12 MHz and a power of 200 W. The oxygen pressure was fixed at 75 Pa. The degradation of the polymers by oxidation with plasma particles was monitored by measuring the weight loss of the polymer samples. The samples were weighed just before mounting into the plasma reactor, and then again just after the plasma treatment. The following polymers were used in this study: PET (amorphous and semi-crystalline), PMMA, PS, LDPE, HDPE, PVC and PTFE. The polymer-etching rate was increasing linearly with treatment time. This was explained by the heating of the samples during the plasma treatment. The only exception was the PTFE, where the etching rate was constant. For the PVC polymer extremely high etching rates were observed. However, a characteristic of the PMMA polymer was a very low etching rate at the beginning, which was followed by an exponential increase of the etching rate with treatment time.