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Structural Characterization of Segmented Polyurethanes by Small Angle Neutron Scattering

Published online by Cambridge University Press:  17 March 2011

Loren I. Espada ,
Joseph T. Mang ,
E. Bruce Orler ,
Debra A. Wrobleski ,
David A. Langlois  and
Rex P. Hjelm
Loren I. Espada
Affiliation:
Los Alamos Neutron Science Center (LANSCE-12) Los Alamos National Laboratory Los Alamos, NM 87545
Joseph T. Mang
Affiliation:
Dynamic Experimental Division (DX-2) Los Alamos National Laboratory Los Alamos, NM 87545
E. Bruce Orler
Affiliation:
Materials Science and Technology Division (MST-7) Los Alamos National Laboratory Los Alamos, NM 87545
Debra A. Wrobleski
Affiliation:
Materials Science and Technology Division (MST-7) Los Alamos National Laboratory Los Alamos, NM 87545
David A. Langlois
Affiliation:
Materials Science and Technology Division (MST-7) Los Alamos National Laboratory Los Alamos, NM 87545
Rex P. Hjelm
Affiliation:
Los Alamos Neutron Science Center (LANSCE-12) Los Alamos National Laboratory Los Alamos, NM 87545
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Abstract

The beneficial mechanical properties of segmented polyurethanes derive from microphase separation of immiscible hard and soft segment-rich domains at room temperature. We are interested in the structure of the domains, how these are affected by hydrolytic aging, and how the structure is modified by low molecular weight plasticizers. To assessed the distribution of the plasticizer in polyurethane, we did small-angle neutron scattering measurements on mixtures of 23% hard segment poly(esterurethane) with different amounts of either non-deuterated or deuterated plasticizer. We analyzed the results using a simple model in which the contrast, Δρ = ρH Š ρ, between the hard and soft segment-rich domains is varied by the amount of deuterated or hydrogenated plasticizer, using the fact that I(Q) ∼ Δρ2. The result demonstrated that the plasticizer is largely associated with the soft segment rich domains. The structure of PESU with the chain extender of the hard segment was assessed after aging under hydrolytic conditions. The results show that the microphase structure coarsens and segregates and that the hard and soft segments segregated as a result of the loss of constraints from hydrolytic soft segment chain scission. The results on plasticizer distribution and the effects of hydrolytic aging give insight on the loss of mechanical properties that occur in each case.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 710: Symposia DD – Polymer Interfaces and Thin Films , 2001 , DD11.11.1/AA10.11.1
Copyright
Copyright © Materials Research Society 2002

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References

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