AVS 49th International Symposium
    Applied Surface Science Tuesday Sessions
       Session AS-TuM

Paper AS-TuM7
SPM Structural Study of Phase Segregation, Thermal Behavior, and Aging of Poly(Ester Urethane) Compression Molded Samples

Tuesday, November 5, 2002, 10:20 am, Room C-106

Session: Polymer Characterization
Presenter: M.E. Hawley, Los Alamos National Laboratory
Authors: M.E. Hawley, Los Alamos National Laboratory
E.B. Orler, Los Alamos National Laboratory
D.A. Wrobleski, Los Alamos National Laboratory
R.P. Hjelm, Los Alamos National Laboratory
Correspondent: Click to Email
Only a limited number of structural studies have been performed on segmented poly urethanes using tapping mode scanning probe techniques to determine both the nanostructure and the corresponding nanophase segregation of hard and soft segments within the s amples. This type of information is needed to better understand the mechanical and thermal properties of these materials and to facilitate modeling efforts. In order to address these issues, we have fabricated a compression molded segmented poly(ester ure thane) samples with varying hard (HS) to soft segment (SS) ratios. Samples were examined using scanning probe phase imaging techniques to obtain the topography and map the corresponding HS and SS segregation before and after heating to over 100 °C both ex-situ and in-situ to and correlate those results with thermal absorption data. Changes in structure were followed as a function of time to address aging issues. A number of significant differences were observed before and after these thermal plastic sampl es were heat treated. Variations in structure and heat-induced morphological changes were directly related to HS content. Fine 10 to 10 nm thick lamellar- or fibril-like structures were most prominent in samples with lower HS content while harder, thicker elongated structures seen to a limited extent on all samples dominated the surface of high HS samples. The disappearance of the fine structures appears to be related to a peak in the endothermal data. The reappeared emanating from the large rod-like structures first as short branching then completely covering the surface after less than 2 days. Surface roughness increased in the process by approximately 10x.