Surface modification of poly (lactic acid) film by low-temperature plasma-graft ammonia onto poly (lactic acid) film

In order to study whether the ammonia-plasma can modify the poly (lactic acid) (PLA) film surfaces and what chemical reactions occur on the film surfaces during the ammonia-plasma treatment, surface modification of PLA film by ammonia-plasma was investigated by using contact angle measurements and XPS spectra. The experimental results show that groups of -NH-CO-, C-N and -NH3+ can be grafted onto the surface of the PLA film by low-temperature plasma. The content of nitrogen element which is grafted onto the surface of the PLA film increases from 3.2% to 5.2% when the treating time prolongs from 5 min to 20 min (P=80 W): while the contact angle changes with the various content of hydrophilic group of -NH3+ grafted onto the surface of PLA film.