Introduction: In the field of orthotics, more precisely in the field of orthopaedic insoles, we use various natural as well as artificial materials. The choice of material is based on different properties of the material, such as: the angle, colour, roughness, hardness, tensile strength, zeta potential and density. The choice of material depends on the needs of the patient. Purpose: Determine the superficial and mechanical properties of foamed and un-foamed polymers, which are widely used in the orthotics and prosthetics. Methods: We used six different materials, exactly four foamed polymers: foamed polyethylene, Poliform, Nora (EVA), a pressed cork and two unpadded polymers: polyethylene and polypropylene. All materials were defined as limit angle, colour values, tensile strength, hardness, zeta potential and roughness. By measuring the boundary angle on the surface, we determined the hydrophobicity or hydrophilicity of the materials. For colour values the CIE parameters L*, a* and b* were determined. Measured Young's modulus, tensile strength, elongation and plasticity of materials. Hardness was determined by methods Shore A. Surface topographies were also measured and Ra (arithmetic mean roughness) and Rq (square mean roughness) were determined. The magnitude of the zeta potential was measured by measuring the flow potential. Each material was calibrated several times, and then the mean value and standard deviation were calculated. Results: The most hydrophobic material is closed cell PE. Polyform and foam PE are the most colourful materials. Nora and cork approach the colour of tanned and brown skin, while the colour PE and PP correspond to the colour of the normal skin type. Polyform and PEfoam match the brighter colour of the skin. Tensile strength and hardness were highest in PE and PP. The biggest negative charge was PE. Roughness was most pronounced in PEfoam. However, the lowest roughness was in PP. Discussion and conclusion: We found that foam materials and solid materials differ from each other in terms of mechanical properties. In general, it could be said that the chosen PE is harder compared to the selected PP sample, more hydrophobic, with higher tensile strength, more negatively charged and has lowest roughness. Among the group of foamed polymers, however, PEfoam differed greatly.
|
