SYNTHESIS AND CHARACTERIZATION OF ANHYDRIDE-FUNCTIONAL POLYCAPROLACTONE

Polycaprolactone-graft-maleic anhydride (PCL-g-MA) copolymer was prepa red by grafting maleic anhydride onto PCL in a batch mixer and in an e xtruder using dicumyl peroxide as the initiator. The graft content was determined with the volumetric method by converting the anhydride fun ctions to acid groups and then titrating with ethanolic potassium hydr oxide. The grafted polymer was extracted with xylene to remove any unr eacted monomer before the estimation step. The effect of temperature a nd the various concentrations of the initiator and monomer used for th e grafting reaction were investigated. The presence of residual initia tor in the reaction product was checked using thin-layer chromatograph y. Molecular weight determination was carried out for the pure and gra fted polymer using gel permeation chromatography to determine if chain scission was present. Results indicate that maleic anhydride is graft ed onto PCL using free radical initiators. The grafting reaction was c onfirmed by FTIR and NMR techniques. FTIR spectra showed absorption ba nds around 1785 and 1858 cm(-1). NMR spectra gave signals for methine proton at 3.47 ppm. For a given peroxide level, a higher temperature o r residence (reaction) time gave higher percentage of grafted MA. Ther e was an optimum temperature and initiator concentration after which t he percentage of MA grafted on PCL decreased. The number-average molec ular weight, tensile strength, and the percent elongation of PCL-g-MA were comparable to those of PCL before grafting. (C) 1997 John Wiley & Sons, Inc.