Microstructural Control of Polyaryletherketones and their Fiber Reinforced Composites

Restricted (Penn State Only)
Author:
Veazey, Dustin Montgomery
Graduate Program:
Chemical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 27, 2018
Committee Members:
  • Enrique Daniel Gomez, Thesis Advisor
  • Michael Anthony Hickner, Committee Member
  • Michael John Janik, Committee Member
Keywords:
  • polymer
  • composites
  • crosslink
Abstract:
Interest in polyaryletherketones (PAEKs) and their carbon fiber reinforced composites continues to grow, and is driven by their increasing use in critical, high performance applications. Though these materials have seen widespread use in oil and gas, aerospace, medical and transportation industries, applications are currently limited by the thermal and mechanical properties of available PAEK polymer chemistries. The theme of this Master’s thesis is the improvement of PAEK properties through control of the polymer microstructure. It includes a review of state of the art PAEK polymer chemistries, mechanical properties of their carbon fiber reinforced composites, and interfacial engineering techniques used to improve the fiber-matrix interfacial bond strength. The original research presented is aimed at improving the high temperature steam resistance of PAEKs through covalent crosslinking and control of the crystalline microstructure. The effect of high temperature steam on the crystallinity and mechanical properties of existing PEEK and PEKK(T/I) polymers is investigated in order to aid design of more effective PAEK materials for high temperature steam applications. DSC, WAXD and DMA experiments show these materials undergo significant crystallization and reorganization after prolonged exposure to steam and suffer from embrittlement. Xanthydrol-based crosslinks are used to stabilize the PEKK crystal structure in order to prevent steam-assisted crystallization. Mechanical tests demonstrate the ductility is preserved for longer exposures to steam compared to neat PEKK, while DSC and WAXD data indicate xanthydrol crosslinks effectively stabilize the crystal structure against steam-assisted crystallization.