TY - JOUR
T1 - Structural development during deformation of polyurethane containing polyhedral oligomeric silsesquioxanes (POSS) molecules
AU - Fu, B. X.
AU - Hsiao, B. S.
AU - Pagola, S.
AU - Stephens, P.
AU - White, H.
AU - Rafailovich, M.
AU - Sokolov, J.
AU - Mather, P. T.
AU - Jeon, H. G.
AU - Phillips, S.
AU - Lichtenhan, J.
AU - Schwab, J.
N1 - Funding Information:
BH would like to acknowledge the financial supports of this work in part by a Young Faculty Grant from DuPont and in part by NSF-MRSEC (DMR9632525). We thank Dr Zhigang Wang for assistance of data analysis in this study. PTM and HGJ acknowledge support from AFRL Materials and Manufacturing Directorate and AFOSR/NL. Research carried out in part at SUNY X3 beamline at the National Synchrotron Light Source at Brookhaven National Laboratory, which is supported by the US Department of Energy.
PY - 2001
Y1 - 2001
N2 - A unique polyurethane (PU) elastomer containing inorganic polyhedral oligomeric silsesquioxane (POSS) molecules as molecular reinforcements in the hard segment was investigated by means of wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) techniques. The mechanical properties of POSS modified polyurethane (POSS-PU) were also compared to those of polyurethane without POSS. The crystal structures of two different POSS molecules were first determined by X-ray powder diffraction analysis, yielding a rhombohedral cell with a = 11.57 Å, α = 95.5̊ for octacyclohexyl-POSS (1,3,5,7,9,11,13,15-octacyclohexylpentacyclo[9.5.1.13,9.15,15.17,13] octasiloxane) and a = 11.53 Å, α = 95.3° for hydrido-POSS (1-[hydridodimethylsiloxy]-3,5,7,9,11,13,15-heptacyclohexylpentacyclo [9.5.1.13,9.15,15.17,13] octasiloxane). WAXD results showed that reflection peaks distinct to POSS crystal diffraction were seen in POSS-modified polyurethane, which suggests that POSS molecules formed nanoscale crystals in the hard domain. During deformation, the average size of POSS crystals in POSS-PU was found to decrease while elongation-induced crystallization of the soft segments was observed at strains greater than 100%. The SAXS results showed microphase structure typical of segmented polyurethanes, with an initial long spacing of 110 A between the domains. At high strains, the average length of strain-induced microfibrillar soft-segment crystals was estimated to be about 60 A by SAXS. The TEM analysis of highly stretched samples showed a preferred orientation of deformed hard domains perpendicular to the stretching direction, indicating the destruction of hard segment domains by strain.
AB - A unique polyurethane (PU) elastomer containing inorganic polyhedral oligomeric silsesquioxane (POSS) molecules as molecular reinforcements in the hard segment was investigated by means of wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) techniques. The mechanical properties of POSS modified polyurethane (POSS-PU) were also compared to those of polyurethane without POSS. The crystal structures of two different POSS molecules were first determined by X-ray powder diffraction analysis, yielding a rhombohedral cell with a = 11.57 Å, α = 95.5̊ for octacyclohexyl-POSS (1,3,5,7,9,11,13,15-octacyclohexylpentacyclo[9.5.1.13,9.15,15.17,13] octasiloxane) and a = 11.53 Å, α = 95.3° for hydrido-POSS (1-[hydridodimethylsiloxy]-3,5,7,9,11,13,15-heptacyclohexylpentacyclo [9.5.1.13,9.15,15.17,13] octasiloxane). WAXD results showed that reflection peaks distinct to POSS crystal diffraction were seen in POSS-modified polyurethane, which suggests that POSS molecules formed nanoscale crystals in the hard domain. During deformation, the average size of POSS crystals in POSS-PU was found to decrease while elongation-induced crystallization of the soft segments was observed at strains greater than 100%. The SAXS results showed microphase structure typical of segmented polyurethanes, with an initial long spacing of 110 A between the domains. At high strains, the average length of strain-induced microfibrillar soft-segment crystals was estimated to be about 60 A by SAXS. The TEM analysis of highly stretched samples showed a preferred orientation of deformed hard domains perpendicular to the stretching direction, indicating the destruction of hard segment domains by strain.
KW - Nanocomposites
KW - Polyhedral oligomeric silsesquioxane
KW - Polyurethane
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U2 - 10.1016/S0032-3861(00)00389-X
DO - 10.1016/S0032-3861(00)00389-X
M3 - Article
AN - SCOPUS:0033770930
SN - 0032-3861
VL - 42
SP - 599
EP - 611
JO - Polymer
JF - Polymer
IS - 2
ER -