Accession Number : ADA019038

Title :   Experimental Relationship Between Macroscopic Moduli and Molecular Bond Moduli: A Laser Raman Study of Monocrystalline Fibers of Poly-HDU.

Descriptive Note : Technical rept.,

Corporate Author : BROWN UNIV PROVIDENCE R I DEPT OF CHEMISTRY

Personal Author(s) : Mitra,Vijay K. ; Baughman,Ray H. ; Risen,William M. , Jr

Report Date : 19 DEC 1975

Pagination or Media Count : 25

Abstract : The application of a tensile stress to a macroscopic monocrystalline fiber of a polydiacetylene, an extended-chain polymer, causes the Raman-observed C triple bond C and C=C in-chain vibrational frequencies to decrease linearly with elongation. The polymer studied, poly-HDN, results from the solid-state polymerization of R-C triple bond C triple bond C-R where R = CH2OCONHC6H5. This experimental relationship between the molecular bond (spectroscopic) effects and the macroscopic properties is analyzed by relating the bond moduli (force constants) and Young's modulus for the fibers. It is shown that possible effects due to stress-induced changes in electron-delocalization in this fully conjugated polymer are negligible and the principal contributions to the bond frequency shifts is due to bond anharmonicity. Models which assume that the entire effect is due to bond anharmonicity produce calculated dependencies of V(C=C) and V(C triple bond C) upon fractional elongation which are in good agreement with that observed. (Author)

Descriptors :   *Polymers, *Acetylenes, *Tensile stress, *Raman spectroscopy, Chemical bonds, Single crystals, Synthetic fibers, Modulus of elasticity, Fibers

Subject Categories : Polymer Chemistry
      Textiles
      Plastics
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE