AI Article Synopsis
- The engineering polymer polyacetal has a history of use in medical devices like knee replacements and shows potential for hip resurfacing applications.
- Testing involved five grades of polyacetal immersed in saline at 37 degrees Celsius for up to six months.
- While ultimate tensile strengths remained stable, significant reductions in Young's modulus were observed after one month, suggesting that polyacetal could still be effective for load-bearing orthopedic applications despite some mechanical property changes.
Article Abstract
The engineering polymer polyacetal (also known as polyoxymethylene) has a long history of clinical use including in the femoral component of the Freeman all-polymer knee replacement. The polymer is a promising material for novel applications including the femoral component of hip resurfacing prostheses. However, no work following the effect on mechanical properties of extended immersion in the physiological environment has been reported. Samples of five grades of polyacetal were obtained and tested on an MTS Bionix 858 at 37 degrees C in physiological saline. Three groups of specimens were tested: "as received"; immersed in Ringer's solution at 37 degrees C for one month; immersed in Ringer's solution at 37 degrees C for six months'. While there were negligible reductions in the ultimate tensile strengths, the Young's moduli of all polymer grades showed significant reductions (p < 0.01) of up to 19.5% following one months' immersion. There were negligible changes in ultimate tensile strength and stiffness between one and six months' immersion, however some polymers showed a small, but significant (p < 0.05) increase in stiffness. The percentage elongation and true stress for plastic instability showed negligible changes following immersion for one and six months'. These results encourage the use of polyacetal in load-bearing orthopaedic applications.
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| http://dx.doi.org/10.1023/a:1012815822323 | DOI Listing |
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