A Statistical Approach of Morphological and chemical Data to determine their influence on adhesion properties
Résumé
Metallization of polymers surfaces are introduced in many industrial applications. Polypropylene is a semi-crystalline thermoplastic material, has many advantages: it is cheap, non-toxic and odorless, highly resistant to fatigue and bending, very dense, chemically inert, sterilizable and recyclable. However, bonding and plating of many polymers present a problem due to the low surface energy. It is well known that surface roughness enhances wetting and adherence properties. Many studies have been carried out to produce a roughness increase. Among the different techniques used to change the surface roughness, femtosecond laser may be a promising option. One of its advantages is the possibility to generate three-dimensional structures defined by modified surface, ablation depth and shape of the impact. In this work, the laser treatment was used to obtain different surface morphologies. The following laser process conditions were varied: power density, number of pulse, and the distance between the impacts. 3D morphological parameters were measured with an optical profiler: macroscopic resulting parameters (depth, diameter, ablation volume, modified surface and non-modified surface) and microscopic resulting parameters (roughness parameters: Sa, Sq, Sku ...) and chemical properties (wettability, surface energy). The wettability behavior was quantified by contact angle measurements between a deposed liquid drop and different surfaces. The adhesion of metallic coatings on polymers was measurement with pull test. The adhesion behavior of treated surfaces according to the morphological parameters was investigated by the statistical analysis technique to determine the influence respectively of macroscopic, microscopic, or chemical properties.