Papers by Author: Mikko Karttunen

Abstract: The thermal stability of polypropylene (PP) based cellular electromechanical films was improved by compounding PP with thermally more durable cyclo olefin copolymer (COC) and polyhedral oligomeric silsesquioxane (POSS) nanochemical. The cast films were biaxially oriented in laboratory scale and then expanded by a gas diffusion expansion method, which increased the pore size inside the cellular film structure and the thickness of the film. The cellular films were then electrostatically charged by a contact charging method and metallized by gold sputtering. The samples were aged at 85°C showing that the d33 signal decreased from the original value, but remained at high level; more than 120 pC/N even after two weeks of ageing.

Abstract: The properties of polymeric materials have been enhanced by developing nanocomposites in several projects at the Technical Research Centre of Finland VTT. The improvement of conductivity, dielectric, mechanical properties and the thermal stability of polymer materials opens new application potential in electronic industry. In this paper the results of several projects are presented. By applying nano-POSS particles in polypropylene and epoxy the break down voltage was increased by 10 - 20%. The use of carbon nanotubes in polyaniline enhanced the conductivity by two decades compared to the commercially available polymers.