| In spite of having desirable bulk mechanical properties suitable for all engineering applications, polymers and polymer composites are limited for their use in certain areas it is essential to adhesively bond them. This is due to their poor surface adhesion. Hence, they require some kind of surface preparation before they can be bonded. Ultraviolet light treatment has emerged out to be an efficient technique in order to prepare the polymer surfaces for adhesive bonding. It is simple to construct, easy to operate, faster and environmentally benign. The current research involves the use of ultraviolet light from two different sources viz. a lamp and an excimer laser, to treat the polymer surfaces. The polymer composites investigated are polyethylene terepthalate/polypropylene---glass fiber composites. Significant enhancement in surface adhesion was obtained as a result of the ultraviolet light treatment. This is due to a combination of cleaning the surface and functionalizing the surface by the ultraviolet light. To explore the practicality of the ultraviolet light treatment process, automobile engine valve covers from Daimler Chrysler have been UV treated, adhesively bonded and tested. The test results show a tremendous increase in the surface adhesion properties of the valve covers and the failure modes are completely cohesive. Thus this technique has all the potential for being applied in an industrial scale for treating massive and large number of parts that are to be bonded. |
