TIT# Thermoplastic Polyurethane crosslinked by functionalized silica.
     Nanostructure evolution under mechanical load
AUT# Stribeck, Norbert; Zeinolebadi, Ahmad; Harpen, Frauke; Luinstra, Gerrit A.;
     Eling, Berend; Botta, Stephan
SOU# Macromolecules (2013) 46(10), 4041-4052
LOC# xv139
CLA#
COM# http://dx.doi.org/10.1021/ma400512b
APP#
MAT#
ABS# TPU composites containing 0 to 0.5 wt-% 3-aminopropyltriethoxysilane
     functionalized silica spheres are strained and subjected to load-cycling.
     Tests are monitored by SAXS and analyzed by the CDF method. Extensibility
     of the soft phase is limited. Macroscopic strain is accomplished by
     failure of single soft-domains. Broken entities comprise the
     overstretched soft domain, sandwiched between two hard domains.
     Macroscopic strain at failure determines the most probable thickness of
     the sandwich. Failure propagates from disordered regions into
     well-arranged ensembles (WAE) of domains. The higher the nanosphere
     content, the earlier the WAE are affected. Outbursts of local failure
     happen at strains of 100% and 200%. They relieve WAEs. Load-cycling does
     not induce failure of pure TPU, but of the nanocomposites. Here failure
     spreads in the material. The fraction of material that is not affected is
     a function of the nanosphere content. Extrapolation yields
     1.25 wt.-% when all the material would be affected. Relaxed samples contain
     sandwiches.