The effects of nitrogen plasma on the adhesion of thermoplastic olefin elastomer (TPO) are studied with attenuated total reflection infrared spectroscopy (ATR), the lap shear test, and the contact angle measurement. The plasma is applied after the TPO is dip-coated with acrylic acid (AA), mixed with benzophenone (BP), benzoyl peroxide, and 2,2-azoisobutyronitrile initiators. ATR spectra confirm the presence of grafted AA on TPO, with the amount depending on the exposure time and the initiator used. The total surface energy and the polar component of the grafted TPO increase while the lap shear strength (LSS) decreases with exposure time, and all these also vary with the initiator. The plasma treatment and the grafted AA improve the LSS of the TPO. The greatest LSS is obtained from the specimen grafted with AA and BP. The nature of the reacted surface layer has a significant effect on the adhesion strength of the TPO.
Hong, Shinn-Gwo, Chi-An Ho
Macromol. Mater. Eng.