Analysis of the four parameter linear viscoelastic model on prosthetic nucleus and the influence of manufacture on parameters of this model / 生物医学工程学杂志

The purpose of this study is to characterize the stress relax properties of PVA-H prosthetic nucleus via the four-parameter linear viscoelastic model and to analyze the influence of swelling ratio and initial PVA content upon the properties of dissipating compressive stress. The four-parameter linear viscoelastic model can simulate the viscoelastic property of prosthetic nucleus well (corr > 0.99) and be more effective than the three parameter linear viscoelastic model. From the parameters of this model we have obtained the following results: the prosthetic nucleus of higher water content can dissipate compressive stress more quickly than that of lower water content can do, but the quantity of stress relax can not be influenced by water content; the higher the initial PVA content,the slower and smaller the dissipation of compressive stress;the relax time of prosthetic nucleus is similar to that of human nucleus.

Swelling characterization of poly (vinyl alcohol) hydrogel for prosthetic intervertebral disc nucleus / 生物医学工程学杂志

In this study the poly(vinyl alcohol)(PVA) hydrogel elastomer was prepared by freezing-thawing method. The influences of percentage of poly (vinyl alcohol) in hydrogel, pH of solution and swelling temperature upon the swelling characteristic of PVA-hydrogel prosthetic nucleus material were studied. Its micropores were observed using SEM, and the swelling dynamics was further discussed. The experimental results showed that the poly (vinyl alcohol) hydrogel was a kind of network with a lot of micropores, the pore size was related with the PVA content. The maximum swelling ratio decreases when the percentage of PVA in hydrogel, the pH of solution and the swelling temperature were enhanced. The swelling process was described by the equation of swelling dynamics equation. The swelling rate was greatly influenced by the PVA content, the pH of solution and the dimension of hydrogel sample.

Development of artificial disc nucleus materials (semicrystalline polyvinyl alcohol hydrogel elastomers) / 生物医学工程学杂志

For the purpose of developing of disc nucleus replacement (semicrystalline PVA hydrogel elastomers) and explorating the possibility of clinical application, in this study,the aqueous PVA solution froze at -20 degrees C for 6-12 h, and then thawed at room temperature for 1-2 h. The same process was repeated 1-3 times. After the specimen was dehydrated in vacuum, a kind of artificial disc nucleus materials (semicrystalline PVA hydrogel elastomers ) was formed. DSC and mechanical tests were conducted to investigate the influence of aqueous PVA solution concentration, of dehydrating in vacuum, and of gamma-ray irradiating upon the degree of crystallity and mechanical properties of PVA hydrogel elastomers.