Friction properties of PVA-H/steel ball contact under water lubrication conditions

An in vitro biomodel with mechanical properties similar to those of human soft tissues is useful to learn skills for clinical practice of medical doctors or dentists (for instance for suturing oral mucosa). Poly (vinyl alcohol) hydrogel (PVA-H) with good mechanical strength and low surface friction has potential for use in such a biomodel for surgical trainings. The friction properties of biomodels and medical devices are an important factor for reproducing the natural feel of human soft tissue. However, while the low surface friction of PVA-Hs is well known, the effects of PVA factors such as concentration, polymerization, and saponification on the friction properties have not been clarified. In this study, five kinds of PVA-H samples with different properties were prepared, and ball-on-disk friction tests were carried out using a stainless steel ball, the same material as that of a surgical scalpel blade. Furthermore, the contact areas between the PVA-H sample and the ball were evaluated by measurement of the contact radii. Results showed that the friction coefficients of various PVA-Hs varied despite their similar contact areas.