Title page for ETD etd-07122007-103925


Type of Document Dissertation
Author Hedrick, Jeffrey C.
URN etd-07122007-103925
Title High performance polymeric networks and thermoplastic blends : microwave versus thermal processing
Degree PhD
Department Materials Engineering Science
Advisory Committee
Advisor Name Title
McGrath, James E. Committee Chair
Eiss, Norman S. Jr. Committee Member
Gibson, Harry W. Committee Member
Marand, Herv L. Committee Member
Ward, Thomas C. Committee Member
Keywords
  • Polymer networks Research.
Date of Defense 1990-10-05
Availability restricted
Abstract
Microwave processing of polymeric adhesives and composites offers great potential for future materials development. However, basic considerations need to be established which will allow the processing of polymeric systems, both as reactive thermosetting systems and as nonreactive thermoplastics. Fundamental studies relating epoxy network generation to processing conditions have been investigated in a tunable, single-mode microwave cavity at a frequency of 2.45 GHz. These studies demonstrate that in as little as ten minutes fully cured networks with good mechanical properties can be generated. Furthermore, toughened epoxy systems which utilize carefully designed amine-terminated poly (arylene ether sulfone) thermoplastics as reactive oligomers have novel phase-separated morphologies. In fact, it has been demonstrated that the morphology in these multiphase systems may actually be controlled by utilizing microwave processing. In addition to epoxy resins, the microwave processing of functionalized poly(arylene ether ketone)s (PEK) has also been demonstrated. PEK's are typically classified as high performance thermoplastics; however, with the appropriate terminal functionalities these ductile thermoplastics may also be transformed into tough, solvent resistant networks. In the current investigation amine-, maleimide- and nadimide-terminated PEK's of controlled molecular weights were synthesized and crosslinked by both electromagnetic radiation (EMR) processing and classical thermal treatments. EMR processing resulted in network formation at rates as high as 20 times faster than conventional thermal treatments at the same isothermal cure temperature. Relationships among processing conditions, curing rates and endgroup functionality were investigated.

Novel poly (arylene ether ketone)/poly(aryl imide) homo- and poly (dimethylsiloxane) segmented copolymer blend systems have been investigated to determine the influence of chemical structure on miscibility and physical property behavior. Melt processing results demonstrate that the glass transition temperature of PEEK™ blends increase monotonically with polyimide content. Indeed, Tg'S as high as 240°C have been achieved for certain blend compositions, while still retaining adequate crystallization to provide solvent resistance. The experimental Tg results are in good agreement with the theoretical values predicted by the Fox equation. Lastly, electromagnetic processing was applied to PEEK™/Ultem™ blends to demonstrate the principles of "microwave calorimetry".

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