Control of Polyimide Condensation Composite Processing.

Abstract

AFR700B is a high temperature polyimide resin having the advantages of a high glass transition temperature (750 deg F) and superior thermo-oxidative stability, but the disadvantage of a volatile management problem. This study explored a new process simulation model, new sensing technology, and new concepts in process control in order to advance the state of processing science and to make the processing of AFR700B composite parts cost effective. The new devolatilization model was experimentally verified by comparing its predictions for pressure and temperature distribution through the laminate thickness with experimentally measured pressure and temperature profiles. The verified model was used to successfully predict the concentration and rate of removal of volatiles during composite cure for several heating rates and vacuum bag pressures. Comparison of measured dielectric ionic viscosity and devolatilization model prediction for volatile mass fluxes during processing shows that microdielectrometry can indicate (a) the start of polycondensation reaction, (b) the temperature-time window in which maximum devolatilization occurs and voids develop between laminate plies, (c) the end of the polycondensation reaction, and (d) the effects of water absorbed during freezer storage on the polyimidization reaction and devolatilization process. Artificial neural network models proved superior to classical graduatic regression approaches in capturing the non-linear relationships that exist between product quality and processing variables. Intermediate secondary measurements, taken while the cure cycle is in progress, can be used to detect unmeasured disturbances; hence, providing some feedback correction to the on-line model used.

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Document Details

Document Type
Technical Report
Publication Date
Mar 01, 1994
Accession Number
ADA306779

Entities

People

  • Babu Joseph
  • Donghee Kim
  • Jiri L. Vasat
  • John L. Kardos
  • Milorad P. Dudukovic

Organizations

  • Washington University in St. Louis

Tags

Communities of Interest

  • Energy and Power Technologies
  • Sensors
  • Space

DTIC Thesaurus Topics

  • Chemical Reactions
  • Chemistry
  • Composite Materials
  • Computers
  • Glass Transition Temperature
  • Laminates
  • Materials
  • Materials Laboratories
  • Materials Processing
  • Materials Science
  • Materials Testing
  • Neural Networks
  • Polymer Matrix Composites
  • Pressure Distribution
  • Pressure Measurement
  • Reinforced Plastics
  • Transition Temperature

Readers

  • Computational Modeling and Simulation
  • Polymer Science and Engineering.
  • Thermal Physics or Thermal Science.

Technology Areas

  • AI & ML
  • AI & ML - Bayesian Inference
  • AI & ML - Machine Learning Algorithms