Surface modification on thermoplastic olefins by low-temperature cascade arc discharge-air plasmas for enhanced adhesion with primer

Abstract

Improvement of primer adhesion to thermoplastic olefins (TPOs) by surface modification with a low-temperature cascade arc discharge-air plasmas was investigated. Air plasma with a low-temperature cascade arc plasma torch can be used for improving the primer adhesion to TPOs. Tape-adhesion tests (ASTM 3359-92a method) demonstrated this improvement with a rating of “0” for untreated TPOs and “5” for air plasma-modified TPOs at certain plasma conditions even for aging at 60 °C and 80% relative humidity for 5 days. The adhesion to primer for the soft and flexible kind of TPOs (ETA-3041c and ETA-3101) was easily enhanced. The adhesion to primer for the hard and brittle TPOs (ETA-3183) needs to optimize the plasma conditions to pass the wet-adhesion test using air plasmas. To relate the surface characteristics of air plasma-modified TPOs to adhesion performance with primer, the wettability and polarity of TPOs were evaluated by the contact-angle measurements of primer and deionized water to TPOs. TPO surface morphology was evaluated using scanning electron microscopy. The surface composition was characterized with electron spectroscopy for chemical analysis. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 623–637, 2002; DOI 10.1002/polb.10122