Interfacial Characterization of Multiple Layer Coatings on Thermoplastic Olefins (TPO)

Abstract

AbstractThermoplastic olefins (TPO) have made significant inroads as polymeric materials for interior and exterior automotive parts. Spray applied chlorinated polyolefins (CPO) are often used to improve paint adhesion to the low surface energy TPO substrates. The penetration of the CPO into the substrate is difficult to quantify, but is critical to achieving a good paint/TPO bond. The interphase between each layer in a coated TPO coupon was investigated using a combination of instrumented indentation and confocal Raman microscopy. The degree of CPO interpenetration was Thermoplastic olefins (TPO) have made significant inroads as polymeric materials for interior and exterior automotive parts. Spray applied chlorinated polyolefins (CPO) are often used to improve paint adhesion to the low surface energy TPO substrates. The penetration of the CPO into the substrate is difficult to quantify, but is critical to achieving a good paint/TPO bond. The interphase between each layer in a coated TPO coupon was investigated using a combination of instrumented indentation and confocal Raman microscopy. The degree of CPO interpenetration was altered by using three different CPOs exposed to two different manufacturing methods for the same TPO and base/clear coat system. It was found that the interfaces, CPO/base coat or CPO/TPO, were chemically and mechanically sharp at the 1 μm lateral resolution of both techniques. A gradient in the modulus through the thickness of the clear coat was observed using instrumented indentation.