Ultra-high molecular weight polyethylene (UHMWPE) is widely used in artificial joints in the replacement of knee, hip and shoulder that has been impaired as a result of arthritis or other degenerative joint diseases. The UHMWPE made plastic cup is placed in the joint socket in contact with a metal or ceramic ball affixed to a metal stem. Effective reinforcement of multi-walled carbon nanotubes (MWCNTs) in UHMWPE results in improved mechanical and tribological properties. The hydrophobic nature of the nanocomposites surface results in lesser contact with biological fluids during the physiological interaction. In this project, we investigate the UHMWPE/MWCNTs nanocomposites reinforced with MWCNTs at different concentrations. The samples were treated with cold argon plasma at different exposure times. The water contact angles for 60 min plasma-treated nanocomposites with 0.0, 0.5, 1.0, 1.5, and 2.0 wt % MWCNTs were found to be 55.65°, 52.51°, 48.01°, 43.72°, and 37.18° respectively. Increasing the treatment time of nanocomposites has shown transformation from a hydrophobic to a hydrophilic nature due to carboxyl groups being bonded on the surface for treated nanocomposites. Wear analysis was performed under dry, and also under biological lubrication, conditions of all treated samples. The wear factor of untreated pure UHMWPE sample was reduced by 68% and 80%, under dry and lubricated conditions, respectively, as compared to 2 wt % 60 min-treated sample. The kinetic friction co-efficient was also noted under both conditions. The hardness of nanocomposites increased with both MWCNTs loading and plasma treatment time. Similarly, the surface roughness of the nanocomposites was reduced.

A low-energy plasma focus device was used as an electron beam source. A technique was developed to simultaneously measure the electron beam intensity and energy. The system was operated in Argon filling at an optimum pressure of 1.7 mbar. A Faraday cup was used together with an array of filtered PIN diodes. The beam-target X-rays were registered through X-ray spectrometry. Copper and lead line radiations were registered upon usage as targets. The maximum electron beam charge and density were estimated to be 0.31 μC and13.5×1016/m³, respectively. The average energy of the electron beam was 500 keV. The high flux of the electron beam can be potentially applicable in material sciences.

Ultra-high molecular weight polyethylene (UHMWPE) has been used as a surface for acetabular in total joint replacements for the past 60 years. However, the performance of the implant is influenced by the increase in temperature because of the articulating motion and the contact asperities, which affects its longevity. The viscoelastic properties of multi-walled carbon nanotubes (MWCNTs) reinforced UHMWPE nanocomposites with respect to temperature and irradiation dose are not reported so far. Hence, an attempt was made to study the viscoelastic properties of UHMWPE by varying concentration of MWCNTs and intensity of irradiation dose. The test samples were subjected to sinusoidal loading in the temperature range of 30–80°C. Ultra-high molecular weight polyethylene nanocomposites were prepared at different concentrations of MWCNTs such as 0.5, 1.0, 1.5 and 2 wt-% using compression moulding process and the nanocomposites were subjected to ⁶⁰Co gamma irradiation up to 100 kGy dose. The viscoelastic characteristics of UHMWPE, such as storage modulus, loss moduls and damping factor of the irradiated nanocomposites, were studied in detail. It was observed that the storage modulus of the pure UHMWPE was increased by 139% with the addition of 2 wt-% MWCNTs; however, it was found to be reduced by 83% with 100 kGy irradiation doses. The damping factor and loss modulus of the nanocomposites were reduced by 27.3 and 71.6% with 2 wt-% of MWCNTs concentration, but both were increased with 100 kGy irradiation dose by 74.7 and 69% compared to virgin UHMWPE. It is concluded that the storage modulus reduced with the increase in temperature and also irradiation dose, which may lead to higher static deformation of material. However, the presence of MWCNTs would minimise the deformation and pave way for the better functionality of the material.

Crosslinking of UHMWPE by gamma irradiation has been the prime choice to improve the wear resistance of the polymer. However, it is always associated with few setbacks like degradation of material properties during the shelf ageing period. In the present work, nanocomposites were prepared using ball milling process and then compression moulding process where UHMWPE was reinforced by MWCNTs with 0.20 and 0.40 wt. %. The samples were gamma irradiated using⁶⁰Co at 25 and 50 kGy sterilizing doses in air without any post irradiative treatments and then shelf aged for 240 days. The mechanical properties of the composites were studied using small punch technique according to ASTM F2183 standards. Both toughness and hardness of the composites were found to be improved with an increase of irradiation dosage and MWCNT concentration. It is observed that the percentage reduction in Young’s modulus, yield stress and % strain at fracture of 0.4% composite at 50 kGy dose are 6.4%, 8.8% and 12.7%, respectively compared to that of virgin UHMWPE irradiated at same dosage. It is concluded that presence of MWCNTs in UHMWPE prevents the degradation of material properties during the shelf ageing period after irradiation.