Accession Number : ADA130022

Title :   The Structure of Polyurethane Elastomers.

Descriptive Note : Final rept. 1 Mar 76-30 Sep 82,

Corporate Author : CASE-WESTERN RESERVE UNIV CLEVELAND OH

Personal Author(s) : Blackwell,John

PDF Url : ADA130022

Report Date : 14 Jun 1983

Pagination or Media Count : 23

Abstract : Polyurethane elastomers derive their properties from phase separation into hard (urethane) and soft (polyether or polyester) domains. We have used x-ray diffraction and conformational analysis to determine the structure of the hard domains in MDI/diol/polyester polyurethanes. A new structure has been developed for MDI/butandiol (C4) hard segments, based on the following approaches. Solution of structures of two MDI derivatives showed the basic features of the polymer conformation, packing, and hydrogen bonding. Better quality x-ray patterns allowed determination of the unit cell. Potential energy conformational analysis was applied to polyurethanes for the first time. The results point to a fully extended poly(MDI/butandiol) chain linked to its neighbors in a stabillizing two-dimensional hydrogen bonding network. This work was expanded to the polyurethanes prepared using the C2-C8 homologous series of diols. The even diol series (except C2) adopt fully extended structures like that for the C4 polymer. In contrast the odd diol series adopt higher energy contracted conformations, probably in order to form intermolecular hydrogen bonds.

Descriptors :   *Polyurethane resins, *Elastomers, *Molecular structure, Urethanes, Polyester plastics, Polyethers, Chains, X ray diffraction, Hydrogen bonds, Block copolymers

Subject Categories : Polymer Chemistry
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE