Dr Bart Hallmark is currently a lecturer at CEB, but he also did his doctoral and postdoctoral research here between 2002 and 2008 with Prof. Malcolm Mackley. Together, they developed a simple and exciting new plastic processing technology that produced a novel material, Microcapillary Film (MCF). MCF is a flat extrusion-processed, flexible, plastic film containing an array of microcapillaries that run along its entire length. The precision-engineered capillaries are effectively uniform and can range between 30 microns and 1 millimetre in diameter depending on processing conditions and die design. It was thought that MCF had many potential application areas, so two patent applications were filed via Cambridge Enterprise covering different aspects of the process and products (including U.S. Pat. # 8641946). After lengthy examination processes, both patents were finally granted. Dr Margaret Wilkinson, technology manager at Cambridge Enterprise, and Malcolm were both instrumental in then negotiating three manufacturing licenses that were sold to companies for MCF production.
One of the licensees was Dow Chemicals; they have now greatly extended the MCF development work and upped the ante by creating their own patent-applied-for film die that allows coextrusion of a second polymer into the microchannels. At the Society of Plastics Engineers’ recent ANTEC conference in Orlando, FL, Dow associate research scientist Wenyi Huang presented the "Effect of Rheology on the Morphology of Coextruded Microcapillary Films", showing how different viscosities and different processing conditions affect microcapillary structure and describing some of the unique films that can be made.
Huang’s paper doesn’t say what the benefits of microcapillary film might be, but two recent Dow patent applications give clues. Depending on processing parameters and what resin or other material is pumped into the microcapillaries, they could be used as heat transfer devices providing heating and cooling or as a novel means of strengthening thin films.