The effect of interchain transesterification reactions on the development of aromatic copolyesters
Frich, Danny Joseph
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https://hdl.handle.net/2142/22922
Description
Title
The effect of interchain transesterification reactions on the development of aromatic copolyesters
Author(s)
Frich, Danny Joseph
Issue Date
1996
Doctoral Committee Chair(s)
Economy, James
Department of Study
Materials Science and Engineering
Discipline
Materials Science and Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Polymer
Engineering, Materials Science
Language
eng
Abstract
Aromatic copolyesters (LCPs) have been a subject of extensive research effort over the past 30 years. This is due primarily to their unique combination of properties and processability. They are limited, however, due to high temperatures required for processing and limitations on achievable mechanical properties due to the anisotropic nature of the polymer. In an attempt to address these issues, a new thermosetting polymer based on all aromatic ester units has been developed. The material displays thermal stabilities to 450$\sp\circ$C in nitrogen, glass transition temperatures to 250$\sp\circ$C, and lap shear adhesive strengths to titanium of up to 20 MPa.
Another interesting feature of this new polymer is the potential to undergo further processing in the solid (cured) state through the occurrence of high temperature interchain transesterification reactions. These unique high temperature reactions are discussed and the mechanisms presented in detail. Their effect on the development and processing of aromatic copolyesters (thermoplastic and thermoset) is discussed. Also, a detailed study is presented to monitor the length scale over which these reactions occur between cured thermosets and between LCP films. It was found that an extent of chemical interpenetration via interchain transesterification of less than 300A is sufficient to permit the formation of a seamless adhesive bond between two cured thermoset films. LCP films showed much larger degrees of interpenetration. This is attributed to the higher mobility of the thermoplastic chains and the higher degree of free carboxylic acid end groups available to catalyze the transesterification reactions.
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