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Coated polycarbonate (PC) is a leading engineering thermoplastic used in automotive glazing for replacing laminated glass. Mechanical properties of multi-layer coating systems were investigated using a nano-indenter and the fracture behavior of coating during nano-scratch was studied employing scanning electron and atomic force microscopy. A set of coated samples was prepared, with two layers, namely Layer-1 and Layer-2. Layer-1 was applied directly to the PC substrate and used as adhesion promoter. Layer-2 was prepared with different mechanical properties. Abrasion performance of the coated system was characterized using an ASTM abrasion test methodology. Regression analysis was performed to establish correlation between the mechanical properties of the coating system and its abrasion performance. Fracture behavior of the coating systems and their plausible relationship with abrasion performance was also discussed.

Understanding scratch and mar damage performance of materials is important in the automotive industry. Hence there is need to develop a suitable method to quantify them and relate back to product performance. This paper elucidates a method to quantitatively evaluate mar defects. The method involves marring the surface of a sample with a crockmeter and the damaged surface characterized using a two-camera optical imaging system. These results were then correlated with visual survey results and a transfer function was generated using Design expert DX6net. In the validation stage, a set of newly marred samples were investigated to generate both visual rank and mar index using the transfer functions. Excellent agreement between mar index and visual survey rank reconfirmed the method's effectiveness. Mar performance of different materials (black and high gloss) can be compared using this technique on a 0-100 scale. This method can also be used to characterize polycarbonate glazing surfaces.

Exatec® PC glazing technology team, has developed advanced weathering and abrasion resistant coatings technology that can be applied to protect polycarbonate. It is of particular interest to quantify and understand the factors that determine the surface abrasion performance of coated PC in rear window and backlight applications that have a wiper system. In the present study we describe Exatec's lab scale wiper testing equipment and test protocols. We also describe adaptation of optical imaging system to measure contrast and nano-profiling using nano-indenter, as post wiper surface characterization methods. These methods are more sensitive to fine scratches on glazing surface than standard haze measurement and mechanical profilometry. Three coating systems were investigated; Siloxane wetcoat (A), Siloxane wetcoat (B), and Siloxane wetcoat (B) plus plasma coat (Exatec® E900 coating). The performance comparisons were made using all these surface characterization methods.