Modification and processing of polymers using supercritical fluids

This thesis describes the application of supercritical CO sub 2 to the modification and processing of polymeric materials. Chapter 1 begins by outlining the physical properties of supercritical fluids (SCF's) and the characteristic signatures of critical point phase transitions. This chapter then goes on to describe some of the current applications of SCF's and the advantages that can be gained by working in such media with particular reference to applications involving polymers. Whilst SCF's may offer several advantages compared to conventional liquid solvents, the switch to a SCF process is by no means a straightforward task and requires consideration of several factors in its development. Such considerations are discussed in the first part of chapter 2, again with particular reference to the modification and processing of polymers. Chapter 3 details the preliminary results obtained from experiments performed with the new high-pressure IR cell; initial experiments were carried out to study the effectiveness of the technique for the measurement of the kinetics and thermodynamics of supercritical fluid extraction and impregnation processes. Chapter 4 describes one particular application of scCO sub 2 in polymer processing. We have focused on the modification of ultra-high molecular weight polyethylene (UHMWPE), the material currently used as a load-bearing surface in prosthetic replacement