Experimental and Computational Thermal Modeling of In Vitro Pin-on-Disk Tests of Ultra High Molecular Weight Polyethylene

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Kathleen A. Lewicki ◽  
Douglas W. Van Citters
Keyword(s):  
Molecular Weight ◽  
Coefficient Of Friction ◽  
Bovine Serum ◽  
Temperature Increase ◽  
Frictional Heating ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Frictional Heat ◽  
Bulk Temperature ◽  
Gravimetric Analysis

Frictional heating occurring during pin-on-flat tribotesting of ultrahigh molecular weight polyethylene (UHMWPE) pins was measured and modeled. A full factorial experiment was conducted to determine if testing parameters can produce sufficient frictional heat to alter tribological properties of the bovine serum used as lubricant in the system. Temperature of the surrounding bovine serum was monitored during tribotests using varying pin sizes and sliding speeds to determine typical temperature rises due to frictional heating. This work examined two sliding speeds (40 mm/s and 80 mm/s) and two pin diameters (6.35 mm and 9.5 mm) at a single static load. Gravimetric analysis for wear determination and coefficient of friction measurement were performed for each test. Results showed that frictional heating increased the bulk temperature of the surrounding serum and correlated to sliding speed and average coefficient of friction. No correlation was seen at this temperature range between serum temperature rise and wear rate, providing evidence that the tested parameters are acceptable for tribotesting of UHMWPE. A computational model was developed to predict bulk serum temperature increase. This model closely predicted the temperature increase to within 2 °C, which is sufficient accuracy for identifying if bovine serum protein precipitation is likely during tribotesting. This work serves as an initial estimate and prediction for appropriate testing parameters based on lubricant responses to frictional heating.

In Vitro Study Bioactivity of HA/UHMWPE Nanocomposites

2007 ◽  
Vol 342-343 ◽  
pp. 701-704
Author(s):  
Li Ming Fang ◽  
Yang Leng ◽  
Ping Gao
Keyword(s):  
Molecular Weight ◽  
Calcium Phosphate ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
In Vitro Study ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Octacalcium Phosphate ◽  
Tof Sims ◽  
Ultrahigh Molecular Weight

Bioactivity of hydroxyapatite reinforced ultrahigh molecular weight polyethylene (HA/UHMWPE) nanocomposites with HA volume content of 10~50 % was evaluated by simulated body fluid (SBF) immersion. The effect of HA content on the capability for calcium phosphate (Ca- P) induction was studied. It was found that Ca-P deposition covered the whole surface of the composite with 30 vol. % of HA after immersion for 1 day and the layer grew to around 10 0m thick in one-week immersion, while there was few nucleus formed for composites with HA content lower than 30 vol. % after one-week immersion. The Ca-P structure was identified as octacalcium phosphate (OCP) by SEM, TEM, and ToF-SIMS.

scholarly journals Porous Ultrahigh Molecular Weight Polyethylene/Functionalized Activated Nanocarbon Composites with Improved Biocompatibility

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6065
Author(s):  
Wangxi Fan ◽  
Xiuqin Fu ◽  
Zefang Li ◽  
Junfei Ou ◽  
Zhou Yang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
Tensile Strength ◽  
Wear Resistance ◽  
Biomedical Applications ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
In Vitro Experiments ◽  
Ultrahigh Molecular Weight ◽  
Uhmwpe Composite

Ultrahigh molecular weight polyethylene (UHMWPE) materials have been prevalent joint replacement materials for more than 45 years because of their excellent biocompatibility and wear resistance. In this study, functionalized activated nanocarbon (FANC) was prepared by grafting maleic anhydride polyethylene onto acid-treated activated nanocarbon. A novel porous UHMWPE composite was prepared by incorporating the appropriate amount of FANC and pore-forming agents during the hot-pressing process for medical UHMWPE powder. The experimental results showed that the best prepared porous UHMWPE/FANC exhibited appropriate tensile strength, porosity, and excellent hydrophilicity, with a contact angle of 65.9°. In vitro experiments showed that the porous UHMWPE/FANC had excellent biocompatibility, which is due to its porous structure and hydrophilicity caused by FANC. This study demonstrates the potential viability for our porous UHMWPE/FANC to be used as cartilage replacement material for biomedical applications.

Graphene Nanoplatelet-Induced Strengthening of UltraHigh Molecular Weight Polyethylene and Biocompatibility In vitro

2012 ◽  
Vol 4 (4) ◽  
pp. 2234-2241 ◽  
Author(s):  
Debrupa Lahiri ◽  
Rupak Dua ◽  
Cheng Zhang ◽  
Ignacio de Socarraz-Novoa ◽  
Ashwin Bhat ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Graphene Nanoplatelet ◽  
Ultrahigh Molecular Weight

Tribological behavior of an ultrahigh molecular weight polyethylene in lubricated environments

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
O. K. Kahyaoglu ◽  
H Unal ◽  
A Mimaroglu ◽  
S.H. Yetgin
Keyword(s):  
Molecular Weight ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Salt Solution ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Specific Wear Rate ◽  
Distilled Water ◽  
Aisi 304L ◽  
Ultrahigh Molecular Weight ◽  
The Coefficient Of Friction

AbstractThe wear and friction performance of GUR 1020 grade ultrahigh molecular weight polyethylene (UHMWPE) polymer was studied in distilled water, HASS (Hank’s balanced salt solution) and several protein lubrication environments. Wear tests were carried out using polymer pin -on AISI 304L stainless steel disc apparatus. Tests conditions were room temperature, 40N, 80N and 120N applied loads and 0.5 m/s sliding speed. For the range of load and speed value of this work, the coefficient of friction and wear rate for UHMWPE polymer decreases with the increase in applied load values. The coefficient of friction is highest and the specific wear rate values is lowest under HASS +HA solution lubricant. The average specific wear rate values for UHMWPE polymer under distilled water and HASS+HA (Hank’s balanced salt solution with Hyaluronic acid) lubrication conditions are in the order of 9x10-15 m2/N and 3x10-15 m2/N respectively. The wear mechanism includes abrasion and adhesive processes.

The influence of phospholipid concentration in protein-containing lubricants on the wear of ultra-high molecular weight polyethylene in artificial hip joints

2001 ◽  
Vol 215 (2) ◽  
pp. 259-263 ◽  
Author(s):  
J Bell ◽  
J L Tipper ◽  
E Ingham ◽  
M H Stone ◽  
J Fisher
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Phosphatidyl Choline ◽  
Bovine Serum ◽  
Hip Joints ◽  
Wear Rates ◽  
Artificial Hip ◽  
Artificial Hip Joints ◽  
Ultra High Molecular Weight

There is considerable interest in the wear of polyethylene and the resulting wear-debrisinduced osteolysis in artificial hip joints. Proteins play an important role as boundary lubricants in vivo in the pseudosynovial fluid, and these are reproduced in in vitro tests through the use of bovine serum. Little is known, however, about the effect of phospholipid concentrations within proteinaceous solutions on the wear of ultra-high molecular weight polyethylene (UHMWPE). The effects of protein-containing lubricants with 0.05, 0.5 and 5 per cent (w/v) phosphatidyl choline concentrations on the wear of ultra-high molecular weight polyethylene (UHMWPE) were compared with 25 per cent (v/v) bovine serum which had 0.01 per cent (w/v) lipid; the effects were compared in a hip joint simulator with smooth (n = 4) and scratched (n = 3) femoral heads. The control bovine serum lubricant produced UHWMPE wear of 55 and 115mm3/106 cycles on the smooth and rough heads respectively. The increased phospholipid concentration significantly reduced the wear rate. At the higher concentration (5% w/v phosphatidyl choline) the average wear was reduced to less than 2 mm3/106 cycles. Even with the relatively low concentrations of 0.05% w/v phosphatidyl choline the wear was reduced by at least threefold compared with the bovine serum tests for both the smooth and rough femoral heads. There may be considerable differences in the phospholipid concentrations in patients' synovial fluid and this is highly likely to produce considerable variation in wear rates. In vitro, differences in the phospholipid concentration of lubricants may also cause variation in wear rates between different simulator tests.

Influence of gelatin and bovine serum lubricants on ultra-high molecular weight polyethylene wear debris generated in in vitro simulations

2000 ◽  
Vol 214 (5) ◽  
pp. 513-518 ◽  
Author(s):  
J Bell ◽  
A A Besong ◽  
J L Tipper ◽  
E Ingham ◽  
B M Wroblewski ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Bovine Serum ◽  
Wear Debris ◽  
Polyethylene Wear ◽  
In Vitro Tests ◽  
Suitable Alternative ◽  
Boundary Lubricant ◽  
Ultra High Molecular Weight

Ultra-high molecular weight polyethylene (UHMWPE) wear debris induced osteolysis has a major role in the late aseptic loosening and ultimate failure of total hip replacements (THR). Clinically relevant in vitro simulations of wear are essential to predict the osteolytic potential of bearing surfaces in artificial hip joints. Newborn calf or bovine serum has been accepted as a boundary lubricant for such in vitro tests, but its biological stability has been questioned. This study compared the wear factors, number of wear particles and levels of microbial contamination produced in bovine serum and a gelatin-based lubricant. The wear factors produced by the two lubricants were not significantly different, however the wear debris morphology produced was substantially different. The bovine serum became contaminated with micro-organisms within 28 h, whereas the protein-based lubricant remained uncontaminated. The results showed that bovine serum was not a stable boundary lubricant. They also showed that although the wear factors for the two solutions were not significantly different, the protein-based lubricant was not a suitable alternative to bovine serum because the wear debris produced was not clinically relevant.

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