FINE-TUNING ATMOSPHERIC PLASMA TO IMPROVE THE BONDABILITY AND COATABILITY OF PLASTICS IN MODERN AND CONTEMPORARY ART AND DESIGN
BY ANNA COMIOTTO
This paper reports on the further development of a plasma pen, designed for small-scale improvements of the bondability and coatability of non-polar plastics used in modern and contemporary art and design. With regard to conservation and restoration applications the plasma pen was successfully fine-tuned for effecting a minimal thermal load during pre-treating thermoplastic polymer surfaces. The effectiveness of this temperature-tuned plasma for enhancing the bondability of poly(ethylene) [PE] and poly(propylene) [PP] has been proved by testing the tensile shear strength of untreated and plasma pre-treated adhesive joints. With regard to improving the adhesion of retouchings, changes in the coatability of PP, PE and poly(styrene) [PS] were quantified by performing pull-off tests. Through plasma pre-treatment the breaking strength of all tested adhesive joints were signifi- cantly enhanced and the application of mechanical resilient water-based and water-removable gouache retouchings became feasible. Furthermore, by testing adhesive joints two and a half years after pre-treating and bonding, results can be taken as an indication that the effected adhesion improvements are long lasting. As is well known, surface oxidation initiated by free radicals is an essential chemical mechanism during plasma pre-treatment. First results of long-term monitoring changes in oxidation sta- bility, performed on untreated and plasma treated PE-LD, will be presented.