Walter Federle received the 2017 Adhesion Society Distinguished Paper Award presented at the 2017 Annual Meeting of the Adhesion Society for the paper "Running with Sticky Feet: Biomechanics of Insect Adhesion". In his paper, Walter described adaptations of insects, spiders and vertebrates to climb on the surfaces of plants using specialised adhesive structures. Animals can rapidly switch between firm adhesion and detachment during locomotion. This control is achieved by shear forces so that adhesive pads stick firmly when pulled towards the body, but detach when pushed. We found that the pads’ shear force dependence cannot be explained by classic peeling theory or changes in contact area, but by the adhesion-enhancing effects of sliding. An extreme case of rapid adhesion control occurs in insects that are able to jump from smooth surfaces (but with adhesion switched on for pushing). Many plant surfaces are slippery for insects via micro-rough wax crystals or lubricating fluid films. Some insects in turn have evolved striking counter-adaptations for climbing safely on these plants. Studying the function of biological adhesives may provide important insights for the design of novel biomimetic adhesives.
Jonathan Seppala received the 2017 Adhesion Society Distinguished Paper Award presented at the 2017 Annual Meeting of the Adhesion Society for the paper Polymer Physics of Material Extrusion Additive Manufacturing Processes. In his paper, Jonathan describes the process-performance relationship in material extrusion additive manufacturing. Thermography and rheology are used to capture the thermally driven welding process and mode III fracture is used to capture the weld performance. The non-isothermal and highly dynamic process is recast as isothermal weld time and weld strength, allowing direct comparison between different extrusion conditions and comparison to isothermal polymer-polymer welding. The technique provides a method for understanding the basic polymer physics controlling weld formation in the material extrusion process.