title: A tribo-mechanical analysis of PVA-based building-blocks for implementation in a 2-layered skin model.
abstract: Poly(vinyl) alcohol hydrogel (PVA) is a well-known polymer widely used in the medical field due to its biocompatibility properties and easy manufacturing. In this work, the tribo-mechanical properties of PVA-based blocks are studied to evaluate their suitability as a part of a structure simulating the length scale dependence of human skin. Thus, blocks of pure PVA and PVA mixed with Cellulose (PVA-Cel) were synthesised via freezing/thawing cycles and their mechanical properties were determined by Dynamic Mechanical Analysis (DMA) and creep tests. The dynamic tests addressed to elastic moduli between 38 and 50kPa for the PVA and PVA-Cel, respectively. The fitting of the creep compliance tests in the SLS model confirmed the viscoelastic behaviour of the samples with retardation times of 23 and 16 seconds for the PVA and PVA-Cel, respectively. Micro indentation tests were also achieved and the results indicated elastic moduli in the same range of the dynamic tests. Specifically, values between 45-55 and 56-81kPa were obtained for the PVA and PVA-Cel samples, respectively. The tribological results indicated values of 0.55 at low forces for the PVA decreasing to 0.13 at higher forces. The PVA-Cel blocks showed lower friction even at low forces with values between 0.2 and 0.07. The implementation of these building blocks in the design of a 2-layered skin model (2LSM) is also presented in this work. The 2LSM was stamped with four different textures and their surface properties were evaluated. The hydration of the 2LSM was also evaluated with a corneometer and the results indicated a gradient of hydration comparable to the human skin.
authors.affiliation: Surface Technology and Tribology Group, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands. Electronic address: m.moraleshurtado@utwente.nl.
authors.forename: M
authors.initials: M
authors.lastname: Morales Hurtado
authors.affiliation: Surface Technology and Tribology Group, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands.
authors.forename: E G
authors.initials: EG
authors.lastname: de Vries
authors.affiliation: Surface Technology and Tribology Group, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands; Advanced lubricating Materials Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Haike Road 100, Pudong, Shanghai, China.
authors.forename: X
authors.initials: X
authors.lastname: Zeng
authors.affiliation: Surface Technology and Tribology Group, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands; TU Delft, Faculty of Civil Engineering and Geosciences, Stevinweg 1, 2628 CN Delft, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: van der Heide
mesh_terms: D001672:Biocompatible Materials; D055119:Elastic Modulus; D017276:Friction; D006801:Humans; D020100:Hydrogels; D011142:Polyvinyl Alcohol; D017768:Skin, Artificial; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D020100:Hydrogels; D011142:Polyvinyl Alcohol
keywords: 2-Layered Skin Model; PVA hydrogel; Skin tribology; Tribo-mechanical properties