GRAFTING OF OXAZOLINE FUNCTIONAL-GROUP TO POLYCAPROLACTONE

A twin-screw extruder was used to graft oxazoline reactive group onto polycaprolactone (PCL) by free radical initiation reaction. A low-vola tility oxazoline compound was used to facilitate a high-temperature gr afting reaction. The effect of melt temperature, screw speed, and init iator and monomer concentrations on graft content were evaluated. The graft content ranged from 0.7 to 2.6%. Increased melt temperature and reduced screw speed increased the graft content. Molecular weight and molecular weight distribution evaluated with the help of intrinsic vis cosity and gel permeation chromatography measurements gave values that were close to that of the unmodified PCL. The oxazoline-grafted polye ster gave considerable increase in the tensile force when compared wit h that of pure PCL. The grafting reaction was confirmed using Fourier transform infrared spectroscopy and nuclear magnetic resonance techniq ues. A probable reaction mechanism for the grafting reaction is propos ed. (C) 1998 John Wiley & Sons, Inc.