Reactive processing of poly(ethylene terephthalate) modified with multifunctional epoxy-based additives

The use of multifunctional epoxy-based modifiers to increase the melt stren gth of poly(ethylene terephthalate) (PET) has been investigated, with the a im of producing PET foams by an extrusion process. The reaction conversion has been studied as a function of time by the measurement of torque in an i nternal mixer. A tetraglycidyl diamino diphenyl methane (TGDDM) resin was s elected for the investigation of the modifier concentration effect on the r eaction conversion. Using a stoichiometric concentration of TGDDM, the mole cular weight distribution of modified PET, as determined by gel permeation chromatography (GPC), showed an eight-fold increase of the z-average molecu lar weight (M-z) and the presence of branched molecules of very large mass. The resulting intrinsic viscosity of the modified PET was 1.13 dl/g. (C) 2 000 Published by Elsevier Science Ltd. All rights reserved.