Phase separation in urethane elastomers as Judged by low-angle X-Ray scattering. II. Experimental Results

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Abstract
Supposing complete segregation, volume and density of the hard segment domains in thermoplastic urethane elastomers are easily calculated from the chemical composition of the elastomers. These hypothetical values may be compared with experimental small-angle X-ray findings, resulting in a realistic picture of the actual state of segregation. A similar situation holds true for the specific surface area of the domains. With respect to elastomers of MDI, hydrazine, and a linear polyester or a polyether with a hard segment volume fraction of about 15%, specific surface areas of the domains of about 220 m2/cm3 were found. They are characterized by diffuse transition zones, the width of which was about 20 Å. The segregation was further more incomplete due to isolated MDI blocks dissolved in the soft segment matrix as well as to soft segments included in the domains.