Radiation grafting of various water-soluble monomers on ultra-high molecular weight polyethylene powder. Part II: Thermal, FTIR and morphological characterisation

Radiation induced grafted polyacrylic acid (PAA), polymethacrylic acid (PMA A), polyacrylamide (PAAm), poly N,N-dimethyl acrylamide (PNDAAm) and poly 1 -vinyl-2 pyrrolidone (PVP) on ultra-high molecular weight polyethylene (UHM WPE) were characterised by DSC, FTIR and SEM analysis. While the effect of irradiation on pure UHMWPE was found to increase crystallinity and cause hi gher enthalpy of crystallisation, grafted UHMWPE powders showed lower cryst allinity and enthalpy of crystallisation. In all grafted UHMWPE there exist ed secondary transitions corresponding to grafting polymers in the first ru n of DSC above 60 degreesC and they became clearer at a higher grafting lev el. In the second run of DSC some Tg values appeared to shift to higher tem peratures while some were not detected. FTIR analysis indicated the presenc e of water-soluble polymers in the grafted UHMWPE. The characteristic peaks of water-soluble polymers became sharper in the grafted UHMWPE. SEM analys is revealed that the grafting occurs both on fiber and microparticles of UH MWPE while flowing characteristic of powder is retained. (C) 2001 Elsevier Science Ltd. All rights reserved.