The ability of waterborne coatings to adhere to polypropylene-based substrates is a challenge in the automotive industry. This thesis seeks to explore novel methods to improve the adhesion and provide coated substrates of an industrial standard. Two methods are explored, whereby a physical entanglement method is found to be unsuccessful but a chemical bonding method is found to give patentable results. It is found that the UV curing of carbene precursors as candidate adhesion promoters, gives an adhesive force which is comparable to the industrial state of the art method, flaming. Initially, the UV energy initiates CH insertion reactions, which covalently graft the adhesion promoter to the polypropylene surface. Secondly, the hydrophilic functional groups of the adhesion promoter adhere to the waterborne basecoat, thus optimal adhesion is achieved. Statistical modelling of the results reveals that the adhesive strength depends on the UV intensity, the adhesion promoter concentration and functional group type. To explore the industrial applicability, the safety and stability during storage and the aesthetics of the adhesion promoters were investigated. This research is the first step to developing a formulation that is able to replace the current flaming method.
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