An Experimental Method for Determining Poisson’s Ratio of Elastomers

Rightmire, G. K.

doi:10.1115/1.3451416

Cited by 14 publications

(1 citation statement)

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“…calcium formal fixative in preparation for subsequent A value for Poisson's ratio of 0.5 was used for the elastohistology. Osteochondral plugs were decalcified using mers [43]. Values of 62.7 GPa and 0.2 were used as the Decalcifier I (Surgipath, Richmond, Illinois), dehymodulus of elasticity and Poisson's ratio respectively for drated in a tissue processor ( Tissue-TekA VIP, Miles glass [44].…”

Section: Introductionmentioning

confidence: 99%

Effect of phospholipidic boundary lubrication in rigid and compliant hemiarthroplasty models

Foy

Williams²,

Powell

et al. 1999

Proc Inst Mech Eng H

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Hemiarthroplasty may benefit from materials which produce lower friction and improved boundary lubrication protection during start-up conditions. The purpose of this study was to evaluate the effect of phospholipidic boundary lubrication in both rigid and compliant hemiarthroplasty. An in vitro model was designed to dissociate the relative contribution of implant material compliance and the presence of phospholipid to the overall friction of a hemiarthroplasty contact using bovine articular cartilage. Normal bovine articular cartilage was articulated against four flat materials using reciprocating motion: (a) borosilicate glass: (b) borosilicate glass coated with dipalmitoylphosphatidylcholine (DPPC); (c) polyurethane (PU) elastomer (Tecoflex SG93A, a medical-grade aliphatic thermoplastic PU, Thermedics Incorporated. Woburn, Massachusetts); and (d) surface-coated PU (Tecoflex SG93A substrate coated with lipid-attracting copolymer poly[methacryloyloxyethyl phosphorylcholine (MPC)-co-butyl methacrylate (BMA)]. Tests were conducted in physiologically simulated tribological conditions for a non-conformal point contact. Friction and lubrication analysis was performed using both static and kinetic coefficients of friction mu measured for each group as a function of time for a sliding distance of up to 60 m. Results showed that the inclusion of supplemental phospholipid, DPPC, on a rigid substrate significantly decreased mu in comparison with the control (cartilage-glass). Additionally, removal of phospholipid components from the articular cartilage surface produced a significantly greater start-up mu in comparison with normal cartilage at the test onset. The use of a material with a lower modulus resulted in lower mu for the entire duration of the test. Polyurethane elastomer coated with the lipid-attracting copolymer, poly(MPC-co-BMA), resulted in the lowest frictional response. As seen in this study, the improvement of low-modulus hemiarthroplasty may involve the optimization of chemical modification and incorporation of lipid-attracting MPC copolymers onto compliant materials. However, further tests are warranted to determine whether lipid-attracting MPC copolymers perform as well during long-time, in vivo wear studies.

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Section: Introductionmentioning

confidence: 99%