Damage Evolution and Fracture Events Sequence Analysis of Core-Shell Nanoparticle Modified Bone Cements by Acoustic Emission Technique.

O.F Pacheco-Salazar,C.R Ríos-Soberanis,L.A Can-Herrera,Shuichi Wakayama,J.M Cervantes-Uc,M.A.A Dzul-Cervantes

doi:10.3390/polym12010208

Abstract

In this research, damage in bone cements that were prepared with core-shell nanoparticles was monitored during four-point bending tests through an analysis of acoustic emission (AE) signals. The core-shell structure consisted of poly(butyl acrylate) (PBA) as rubbery core and methyl methacrylate/styrene copolymer (P(MMA-co-St)) as a glassy shell. Furthermore, different core-shell ratios 20/80, 30/70, 40/60, and 50/50 were prepared and incorporated into the solid phase of the bone cement formulation at 5, 10, and 15 wt %, respectively. The incorporation of a rubbery phase into the bone cement formulation decreased the bending strength and bending modulus. The AE technique revealed that the nanoparticles play an important role on the fracture mechanism of the bone cement, since a higher amount of AE signals (higher amplitude and energy) were obtained from bone cements that were prepared with the nanoparticles in comparison with those without nanoparticles (the reference bone cement). The SEM examination of the fracture surfaces revealed that all of the bone cement formulations exhibited stress whitening, which arises from the development of crazes before the crack propagation. Finally, the use of the AE technique and the fracture surface analysis by SEM enabled insight into the fracture mechanisms that are presented during four-point bending test of the bone cement containing nanoparticles.

Highlights

Acrylic bone cements, which are polymeric materials that are tolerated by the human body, have been employed in clinical applications to fix joint prosthesis, such as the hip and knee
It is noted that the bending strength and bending modulus both decreased when the nanoparticles content increased the bending strength and bending modulus both decreased when the nanoparticles content in the bone cement formulation, whereas the core-shell ratios did not seem to cause a really significant increased in the bone cement formulation, whereas the core-shell ratios did not seem to cause a change in the bending properties
It can be seen that all of the bone cement formulations nanoparticles emitted a higher number of hits during the four-point bending test in comparison to prepared with core-shell nanoparticles emitted a higher number of hits during the four-point those signals that were presented in the reference bone cement. These results suggested that the bending test in comparison to those signals that were presented in the reference bone cement

Summary

Introduction

Acrylic bone cements, which are polymeric materials that are tolerated by the human body, have been employed in clinical applications to fix joint prosthesis, such as the hip and knee. They are mainly used to achieve mechanical stability of the implant and adapt the surface irregularities of the surrounding bone tissue to the surface of the inserted prosthesis [1]. The Acoustic Emission (AE) technique is a nondestructive technique and it would provide insight into the failure mechanisms of the materials This technique is used to alert the system in initial stages of the damage by continuous monitoring through piezoelectric sensors, which integrate on the specimen and receive the high-frequency elastic waves that are produced by the fracture process [5,6]

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