Viscosity measurement of Xanthan\u2013Poly(vinyl alcohol) mixture and its effect on the mechanical properties of the hydrogel for 3D modeling

Yasutomo Shimizu,Kazue Kurihara,Makoto Ohta,Motohiro Kasuya,Hiroshi Yoshida,Tadao Matsunaga,Yoichi Haga,Tadao Tanabe

doi:10.1038/s41598-018-34986-4

Abstract

Biomodels made of poly(vinyl alcohol) (PVA) are demanded because they can represent the geometries and mechanical properties of human tissues realistically. Injecting and molding, commonly used in three-dimensional (3D) modeling, help to represent the blood vessels accurately. However, these techniques sometimes require higher pressures than the upper pressure limit of the dispensers for pouring in high viscosity materials; the material viscosity should therefore be lower. Moreover, the mechanical properties of the biomodels should be reproduced. This study proposes a PVA solution through the addition of xanthan gum (XG) for 3D modeling, which lowers liquid viscosity while maintaining the mechanical properties of biomodels. XG is known to facilitate the achievement of non-Newtonian fluidity; however, the effects of XG on a PVA solution and PVA hydrogel (PVA-H) are not confirmed. The viscosity measurement using 15 wt% PVA with XG solution (PVA/XG) shows that it will provide easier pouring than 17 wt% PVA solution. The tensile test using the PVA-H of PVA(15 wt%)/XG(0.2 wt%) reveals that the gel is comparable in Young’s modulus to 17 wt% PVA-H. X-ray diffraction shows the crystalline structures of the PVA/XG gel and PVA-H are identical. Thus, this PVA/XG would be useful for fabricating biomodels using injection molding techniques.

Highlights

Painting, dip-coating, and injection molding are common methods to fabricate biomodels[3]
We compare the shearing viscosities in 15 wt% poly(vinyl alcohol) (PVA) solutions made with various xanthan gum (XG) concentrations with that in 17 wt% PVA solution that is usually prepared for vessel biomodels
The viscosity of solution (a) at 50 s−1 and 300 s−1 was 27.9 Pa·s and 6.0 Pa·s higher, respectively, than that of solution (i). These results indicate that XG works as a viscous agent in the PVA solution and that including XG greatly affects the viscosity at a low shear rate, especially below 50 s−1

Summary

Introduction

Dip-coating, and injection molding are common methods to fabricate biomodels[3]. Painting and dip-coating are usually necessary to control the wall thickness of the model. Such control is important in fabrication, it is difficult to do so accurately. The range of PVA-H stiffness in vessel models should be constant even if the viscosity of the PVA solution is decreased because the PVA-H mechanical properties play a very important role in biomodels. We compare the shearing viscosities in 15 wt% PVA solutions made with various XG concentrations with that in 17 wt% PVA solution that is usually prepared for vessel biomodels. We use X-ray diffraction (XRD) to reveal the crystal structure of each PVA-H specimen to discuss the relationship between solution viscosity and Young’s modulus

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Discussion

Conclusion