New Insight into the Chemical and Morphological Differences between Slab and High Resilient Foam Elastomers

By use of Small Angle X-Ray, Infrared and Rheology methods a wealth of knowledge has been generated in the past about the formation and final morphology of the elastomers which constitute Flexible Polyurethane Foams. The current view is that Slab foam polymers have a three phase structure with polyurea microdomains, macrophase separated polyurea and the soft polyether phase. High Resilient foam polymers do not show the polyurea macrophase and have less of the strongly hydrogen bonded urea visible in IR.

The chain length of the polyurea segments is unknown due to experimental difficulties with isolating these structures from a crosslinked polymer. A new method is being described using monols of the same equivalent weight in place of the triols and separating the species containing the hard segments according to their length by solvent extraction. The chemical composition of the urea segment can then be analyzed by 13C NMR or IR. It was found that a considerable number of short urea chains are present in both Slab and HR foam polymers.

X-Ray Microscopy Of Multiphase Polymeric Materials

We have utilized the scanning transmission x-ray microscope at Brookhaven National Laboratory to acquire high energy resolution spectra of various polymers and to investigate the bulk characteristics of multiphasic polymeric materials with chemical sensitivity at a spatial resolution of about 50 nm. We present studies ranging from phase separated liquid crystalline polyesters and polyurethanes to various polymer blends. Improvements in the NEXAFS imaging and spectral acquisition protocol in the recent past provide much improved spectral fidelity and include in situ energy calibration with CO2.

Development of scanning X-ray microscopes for materials science spectromicroscopy at the Advanced Light Source

The development of two zone-plate microscopes for X-ray spectroscopic analysis of materials is described. This pair of instruments will provide imaging NEXAFS analysis of samples in transmission at atmospheric pressure and imaging XPS and NEXAFS analysis of sample surfaces in a UHV environment.