STUDIES ON THE PHASE-SEPARATION OF POLYETHERIMIDE MODIFIED TETRAFUNCTIONAL EPOXY-RESIN - II - EFFECTS OF THE MOLECULAR-WEIGHT

The effects of molecular weight on the phase separation of phenyl term inated polyetherimide (P-PEI) modified tetraglycidyl-4,4'-diaminodiphe nylmethane (TGDDM) diaminodiphenylsulfone (DDS) systems were investiga ted by using Differential Scanning Calorimetry (DSC), Time-resolved Li ght Scattering (TRLS) and Scanning Electron Microscope (SEM). The P-PE I modified systems showed faster cure rate than the neat epoxy resin. An increase of the molecular weight of P-PEI raised the cure rate of t he modified systems and changed the morphology from polyetherimide-ric h domain in the low molecular weight P-PEI modified system to polyethe rimide-epoxy co-continuous phase structure in the high molecular weigh t ones. The phase separation of high molecular weight P-PEI modified s ystems may proceed as a two stage process and result in the epoxy-rich spherical domains dispersed in the P-PEI-rich matrix.