Joining and Characterization of PLA Aluminium Compounds for Industrial Applications

In order to establish new and more ecological materials on the market, extensive basic studies on their properties, correct processing and possible applications are necessary. This study focusses on PLA (polylactic acid), a biobased and biodegradable polymer, which is currently used in small amounts in the packaging industry. New insights on its basic joining properties, especially with metals, are presented to close current knowledge gaps and to facilitate further applications. PLA is potentially a more ecological alternative to many petro-chemical polymers and could become a standard material in long term. Useful applications range from household appliances and electronic items to decorative elements for the automotive industry. Here especially the performance of mixedmaterial connections (plastic and metal) is currently unclear and direct comparisons of joining technologies and material references are hard to find. Thus, PLA and other commercially available thermoplastics (PP, PET) were joined with metals using a range of four different technologies: thermal direct joining with induction or laser heating, adhesive bonding and ultrasonic joining were used. Special attention was also paid to the surface pre-treatment of the metallic joining partner. The connections were analysed destructively and in regard to their fracture behaviour. The results of the investigations show clear and reproducible influences of the pre-treatment-type, the type of heating and the basic properties of the polymers.