An Assessment of the Accuracy of Semi-Empirical Quantum Chemistry Calculations of the Mechanical Properties of Polymers

Abstract

The ultimate mechanical properties of polymers, assuming perfect morphology, will be limited by the mechanical properties of a single, ideal polymer chain. Previous calculations of polymer chain moduli using semi- empirical (SE) quantum chemistry methods have resulted in modulus values much higher than experimentally measured. This study investigated the error in the calculated inherent to the method of calculation by comparing SE results for C-C bond potentials in two well characterized polymers, polyethylene and polydiacetylene. It was found that the SE calculation systematically overpredicted bond stiffness in these polymers by approximately 25% to 30%. This is the upper limit on the modulus overprediction, depending on the importance of bond extension/compression (as compared to other deformation modes) in the overall deformation of the polymer chain.

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Document Details

Document Type
Technical Report
Publication Date
Mar 01, 1991
Accession Number
ADA238682

Entities

People

  • James R. Shoemaker

Organizations

  • Air Force Institute of Technology

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Accuracy
  • Air Force
  • Alkynes
  • Computational Science
  • Crystal Structure
  • Failure Mode And Effect Analysis
  • First Principles Calculations
  • Frequency Shift
  • Materials
  • Materials Laboratories
  • Mechanical Properties
  • Mechanics
  • Molecules
  • Spectra
  • Spectroscopy
  • Wave Equations
  • X Rays

Readers

  • Computational Modeling and Simulation
  • Mechanical Engineering/Mechanics of Materials.
  • Polymer Science and Technology

Technology Areas

  • Quantum Computing