Microstructure, thermooxidation and mechanical behavior of a novel highly linear, vitamin E stabilized, UHMWPE

Abstract

A novel, vitamin E-stabilized, medical grade ultra-high molecular polyethylene, MG003 (DSM Biomedical; The Netherlands), has been very recently introduced for use in total joint replacements. This homopolymer resin features average molecular weight similar to that of conventional GUR 1050 resin (5.5-6*10(6)g/mol), but a higher degree of linearity. The aim of this study was to characterize the microstructure, thermal and thermooxidation properties as well as the mechanical behavior of this novel MG003 resin before and after gamma irradiation in air to 90 kGy. For this purpose, a combination of experimental techniques were performed including differential scanning calorimetry (DSC), thermogravimetry (TG), transmission electron microscopy (TEM), X-Ray Diffraction, electron paramagnetic resonance (EPR), and uniaxial tensile tests. As-consolidated MG003 materials exhibited higher crystalline contents (~62%), transition temperatures (~140 °C), crystal thickness (~36 nm), yield stress (~25 MPa) and elastic modulus (~400 MPa) than GUR 1050 controls (55%, 136 °C, 27 nm, 19 MPa, and 353 MPa, respectively). Irradiation produced similar changes in both MG003 and GUR 1050 materials, specifically increased crystallinity (63% and 60%, respectively), crystal thickness (39 nm and 30 nm), yield stress (27 MPa and 21 MPa), but, above of all, loss of elongation to breakage (down to 442 and 469%, respectively). Thermogravimetric and EPR results suggest comparable susceptibilities to oxidation for both MG003 and GUR 1050 polyethylenes. Based on the present findings, MG003 appears as a promising alternative medical grade polyethylene and it may satisfactorily contribute to the performance of total joint replacements.

Largely enhanced thermal conductivity and thermal stability of ultra high molecular weight polyethylene composites via BN/CNT synergy

“…where DH m is the melting enthalpy of the samples, DH 0 is the melting enthalpy when the crystallinity of UPE is 100% (290 J g À1 ), 48 and 4 is the mass fraction of BN microakes. The thermal conductivity was measured with a hot-wire thermal conductivity instrument (Xiatech TC3000E, China) in accordance with ASTM D5930.…”

Thermal Performances of UHMWPE/BN Composites Obtained from Different Blending Methods

“…is the melting enthalpy of samples, Δ 0 is the standard enthalpy of PE (290 J/g) [25], and is the mass fraction of h-BN platelets.…”

Non-isothermal melting and crystallization behavior of UHMWPE/SCF/nano-SiO2 hybrid composites

“…where W P is the polymer mass percentage, DH c is the enthalpy of non-isothermal crystallization, and DH 0 F is the heat of fusion of an infinitely thick UHMWPE crystal with a value of 290 J g -1 [37].…”