Chapter 12 - Characterization of Physical, Chemical, and Mechanical Properties of UHMWPE

Abstract

This chapter discusses the characterization of physical, chemical, and mechanical properties of ultra-high molecular weight polyethylene (UHMWPE). The physical properties of UHMWPE include its morphology, which encompasses both microscopic and macroscopic analysis of the material, as well as thermal properties and molecular weight. Differential scanning calorimetry (DSC) is the most common technique used to measure the thermal properties of the UHMWPE, and it provides the melting point and degree of crystallinity, whereas a scanning electron microscopy (SEM) is used to examine the morphology of the powder before consolidation. An alternative technique to measure the molecular weight is gel permeation chromatography (GPC). In GPC, the polymer is dissolved in a suitable solvent, which for UHMWPE is usually trichlorobenzene. Chemical characterization of the UHMWPE powder is typically performed at the powder-manufacturing site as part of their quality control protocol. There are two common approaches used for chemical characterization of the UHMWPE—namely, trace element analysis and the Fourier transform infrared spectroscopy. Mechanical properties are critical for UHMWPE that is to be used in an orthopedic device. There are several methods used for mechanical characterization such as Poisson's ratio, J-integral tests, tensile testing, fatigue testing, and small punch.