Ultra high molecular weight polyethylene based nano-composite in medical application: thermal, mechanical and tribological properties before and after aging and gama irradiation

• Introduction: Osteolysis due the wear particles release at implant surfaces is one of the most important reasons for the failure of the polymer on metal implant devices in hip and knee prosthesis. Today the polymer on Metal/cermic composition is one of the most comon desgin used in clinic.Materials and Methods: In most of the polymer on metal (soft on hard) hip implant devices, Ultra High Molecular Weight Polyethylene (UHMWPE) is used as acetabluar liner. In the presented study, Surface functionalized Multi walled carbon nanotubes (MWCNTs), graphene oxide (GO) and nanodiamond (ND) were used to develop UHMWPE based nanocomposites. Effects of the reinforcement weight% were investigated (lowest of 0.1 wt% and highest of 2 wt% of different reinforcement were tested). Mechanical, thermal and tribological properties of different wt% of UHMWPE composites were characterised for all composites as manufactured, aged and gamma irradiated. The mentioned nanocomposites were compared to virgin UHMWPE as reference material. combination of ball milling and ultrasonication with controlled parameters were used to manufacture the nanocomposites.Results: In thermal properties, the degree of the crystalinity was not significantly affected, whereas the oxidation degradation was delayed significantly for as developed 3 different nanocomposites. The youngs’ modulus were increased by 10-15% for all nanocomposites and fracture stress reduced (from 0wt% to 0.5wt%) by 35%. Wear resistance was increased for UHMWPE/MWCNT nanocomposites at 0.5wt% for up to 30% and thereafter reduced when higher wt% of MWCNTs were added to the polymeric matrix. However, the UHMWPE/GO nanocompostes showed the maximum wear reduction at 2wt% of the reinforcement. For UHMWPE/ND nanocomposites, the wear mechanism showed the most improvement at 0.5 and 0.7 wt% of the reinforcement. The wear particles from wear tests for all different nano composites were collected and analysed via scanning electron microscopy (SEM). No significant differences in particle size distribution and shape among nanocomposites in comparison to the virgin UHMWPE were observed.   Gamma irradiation at 90 KGy affected the thermal, mechanical and tribological properties positively (in comparson to the virging UHMWPE). Whereas the aging reduced the wear resitance by 20% and tensile properties decreased by 30%. In general aging affected the performance of the nanocomposites negatively.Conclusion: Ball milling was successful method for preparation of nanocomposites. The addition of carbone based nano particles showed positive effect of thermal, mechanical and tribological properties of the developed nanocomposites in comparison to virgin UHMWPE.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Tribologi (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Tribology (hsv//eng)

Nyckelord

nanocomposite

joint replacement

biomaterial

Implant wear

Machine Elements

Maskinelement

Publikations- och innehållstyp

ref (ämneskategori)

kon (ämneskategori)