Experimental Study On Factors Influencing Adhesion Properties Of Flexible Material Surface

After the evolutionary selection of the survival of the fittest during the past billions of years,many organisms have evolved special adhesion structure to adapt to the living environment so that they can climb on different rough surfaces.Inspired by polygonal pillars on the toe pads of tree frogs and newts,many scholars have committed to imitate these amazing microstructures and applied them to the surface of special materials to improve friction and adhesion properties.In this paper,a hydrophilic flexible material was selected to study the influence of its’ adhesive performance by surface roughness and hexagonal microstructures.First of all,cast polyurethane elastomer(CPUE)was selected as the hydrophilic flexible material,the two stages microstructure transfer process was adopted to fabricate textures on the CPUE surface.Secondly,some mechanical and physical properties,related to the friction and adhesion performance of CPUE,were tested.Then,all adhesion experiments were performed by a self-made adhesion tester,and the change rules of adhesion force was investigated by varying the probe roughness and hexagonal microstructures on CPUE surface.Finally,the paper analyzed the mechanisms of these change rules from the aspects of micro-textures of two surfaces,the deformation of CPUE,drainage capacity of channels,etc.In total,the paper provides reference for improving the surface adhesion characteristic and promoting the application of CPUE.The main conclusions of the paper are shown as follows:(1)The static contact angle of the smooth CPUE material surface is about 70°.Compared to hydrophobic PDMS,the wettability of CPUE surface is more similar to the animals toe pads.(2)According to the surface micro-morphology,the contact between rough probes and textured CPUE specimen can be considered as the contact between rough probe surfaces and many small rough hexagonal surfaces.If the roughness of these two surfaces are similar to each other,the “resonance effect” will form and the adhesion force could reach a maximum.Otherwise,the adhesion force of textured CPUE specimen would be weakened by the roughness of probes.(3)Compared with hexagonal pits,the surface with hexagonal pillars has drainage capacity.Single sizes of interconnected channels(hexagonal pillars)have effect on adhesion performance.Compared with single sizes,the effect on adhesion force by coupling sizes is more comprehensive and significant.