Effect of hydroxyl-terminated polyethersulfone on the phase separation of polyetherimide-modified epoxy resin

摘要

Hydroxyl-terminated polyethersulfone (HPES) is added as a second toughener to a polyetherimide (PEI)-modified epoxy resin, and phase separation initiated by curing is studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and time-resolved light scattering (TRLS). SEM shows that, by adding HPES with a higher molecular weight, phase inversion can be observed at different temperatures, and the dispersed particles show a bimodal size distribution. The TRLS experiment reveals that the peak scattering vector q(m) shifts towards a smaller angle or towards a larger angle, depending on the molecular weight of HPES added. The TEM experiment shows that, at an early stage of phase separation, dissimilar morphologies are observed when HPES of different molecular weights is added. The rheometry and TRLS results indicate that the morphology is pinned up by the low mobility of the two components before gelation or vitrification. [References: 20]