Peel tests and neutron reflectivity studies of interface widths in thin films of poly(urethane) block copolymers
- E.I. DuPont de Nemours & Comapny, Wilmington, DE (United States); and others
The rate of self-adhesion development between optical quality thin films of Poly(Urethane) (PU) block copolymers has been investigated. The dramatic increase in self-adhesion relative to adhesion to an impenetrable substrate(Mylar{reg_sign} or glass), is evidence for inter-diffusion in this system. The interfaces were found to remain relatively narrow by neutron reflection, even after long annealing times, because the interpenetration of the mobile blocks is strongly limited by the physical cross-links. The advantage of thin, smooth films for peel tests is that measurements can be made at early times when the interface strengths are very low, and visco-elastic dissipation effects can be reduced. Visco-elastic dissipation is also seen to be reduced by the highly elastic nature of PU, explaining the very weak adhesion to Mylar{reg_sign}. Because the films are smooth, the results are independent of pressure. The time dependence of the peel strength for self-adhesion between very thin films of PU follows a t{sup {1/2}} dependence, as has been predicted and experimentally verified for interdiffusion of linear polymers, suggesting that diffusion of mobile blocks is the limiting process, even though center of mass motion of entire PU chains is prohibited.
- OSTI ID:
- 539090
- Report Number(s):
- CONF-960807-; TRN: 97:004029-0159
- Resource Relation:
- Conference: 212. national meeting of the American Chemical Society (ACS), Orlando, FL (United States), 25-30 Aug 1996; Other Information: PBD: 1996; Related Information: Is Part Of 212th ACS national meeting; PB: 1830 p.
- Country of Publication:
- United States
- Language:
- English
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