Crystalline and thermal properties in miscible blends of PEEK, PPS and PEI obtained by melt compounding

Abstract

The effects of crystal and amorphous polymers on the structure, morphology, crystalline and thermal properties of PEEK have been investigated by using FT-IR, SEM, DSC and TGA. The interaction existing in PEEK/PPS and PEEK/PEI alloys was stronger than that in PEEK/PPS/PEI alloys. The SEM results revealed that homogeneous structure exists in the alloys of PEEK/PPS, PEEK/PEI and PEEK/PPS/PEI. All of the binary and ternary alloys based PEEK exhibits single glass transition temperature (Tg) in full composition range. When PEI was added to the PEEK/PPS alloys, the Tg of PEEK/PPS/PEI alloys increased from 146 °C to 179 °C. The crystallinity degree of PEEK increased when PPS was added, and decreased as PEI added. The crystallization peak of PEEK/PPS/PEI alloy disappears in the ratio of 50/25/25. The thermal decomposition temperature (Td5%) of PEEK/PPS and PEEK/PEI alloys decreased when PPS and PEI were added, the Td of PEEK/PPS/PEI alloy in the ratio of 70/15/15 presented at 510 °C, which was lower than pure PEEK and pure PEI, higher than PPS.