PROCESSING-STRUCTURE-PROPERTY RELATIONSHIP OF PEEK-BASED SYSTEMS

Abstract

PEEK is a high-performance semicrystalline thermoplastic. It exhibits excellent thermo-mechanical properties, enabling its applications in a wide range of fields. For many structural applications such as sealing component, mechanical reinforcement of PEEK is very crucial. Commercially available model PEEK/PBI polymer blend systems were firstly studied but the mechanical reinforcement is limited. Young’s modulus and tensile strength are only increased from 3.7 GPa to 5.3 GPa and from 105 MPa to 118 MPa, respectively, with addition of 50 wt.% PBI. PBI is also vulnerable to water, limiting its application in some down-hole scenario where steam or hot wet water are usually presented. Thus, a more efficient reinforcing agent with high resistance to water or other chemicals is needed. MWCNT is a highly efficient reinforcing filler with one of the highest specific modulus and specific strength. Also, MWCNT is not sensitive to water and other chemicals. In this work, we developed a novel and simple solution mixing approach to prepare well-dispersed PEEK/MWCNT nanocomposites. The PEEK/MWCNT nanocomposites exhibit uniform distribution and individual dispersion of MWCNT in PEEK. And the interaction between PEEK and MWCNT is sufficiently strong, resulting in its highly efficient mechanical enhancement. Addition of 10 wt.% MWCNT can significantly improve the Young’s modulus and tensile strength to 7.3 GPa and 128 MPa, respectively, outperforming PEEK/PBI system. Another benefit is that PEEK/MWCNT is less vulnerable to water and shows more retarded stress relaxation behaviors than PEEK/PBI, especially under hot and wet condition. This is crucial for some niche applications such as sealing component in down-hole equipment where the retention of modulus is very important.