PTFE as a toughness modifier of high‐performance PEI/PBT blends: Morphology control during melt processing

Abstract

High‐performance PEI/PBT blends are brittle because of phase distribution and blends densification. New morphologies developed by adding PTFE to PEI matrix during melt processing favor the toughness improvement of PEI/PBT blends. Ternary PEI/PBT/PTFE processability is not compromised by PTFE addition, and miscibility study by modulated differential scanning calorimetry and harmonic mean method shows that PTFE does not interfere with PEI and PBT interaction. Dual‐phase and spore‐like morphologies are formed for both PEI/PBT and PEI/PBT/PTFE blends, and they strongly influenced their mechanical performance. Although tensile strength of ternary blends does not decrease by PTFE addition, elongation at break deteriorates for blends with PEI concentrations <70 wt%. Nevertheless, blends with 80 wt% increase their ductility, and a synergic effect is observed in impact resistance results. PTFE acts as an impact modifier of PEI/PBT blends due to its distribution in the PEI matrix as debonded spheres and nanoparticles well‐embedded in PEI matrix.Highlights Step‐by‐step melt processing enhances PTFE powders spheroidization Complete wetting of PTFE in PEI matrix PTFE do not interfere in partial miscibility of PEI/PBT blends Nanosized PTFE droplets inhibits PEI densification PTFE improves elongation at break and toughness of PEI/PBT blends