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Amorphous States (amorphous + states)
Selected AbstractsSyntheses and properties of cross-linked polymers from functionalized triglyceridesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Hui-Ping Zhao Abstract A number of functionalized triglycerides were synthesized from glyceryl trioleoate via epoxidation followed by reduction to give glyceryl tris(9-hydroxy)trioleoate (a triol) or hydrolytic ring opening to obtain glyceryl tris(9,10-dihydroxy)trioleoate (a hexaol). A selective monoepoxidation reaction of glyceryl trioleoate was also carried out and the resulting monoepoxide was hydrolyzed to give glyceryl 9,10-dihydroxytrioleoate (a diol). Glyceryl tris(9-hydroxy)trioleoate was brominated followed by displacement with sodium azide and reduction to give glyceryl tris(9-amino)trioleoate (a triamine) and glyceryl tris[9-(N -isopropylamino)]trioleoate. These functionalized triglycerides were crosslinked with 1,4-phenylene diisocyanate. The crosslinked polymers exhibit thermoset characteristics. Thermal analysis results suggest that the polymers are in amorphous states, and their thermal stability was significantly affected by crosslink degree. The crosslinked polymer derived from the diol retained 56% of its weight at 408°C, whereas the polymers derived from the aforementioned hexaol with higher crosslink degree retained only 36% of the original weight. Glass transition temperatures of these polymers range from ,1.0°C to 10.2°C. The thermal stable polymer, 12, derived from the aforementioned diol exhibits a linear viscoelastic character and can be used as thermoplastics. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] In situ Raman and optical microscopy of the relaxation behavior of amorphous ices under pressureJOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2010Yukihiro Yoshimura Abstract The transformation of low-density amorphous (LDA) ice produced from high-density amorphous (HDA) ice was studied up to 400 MPa as a function of temperature by in situ Raman spectroscopy and optical microscopy. Changes in these amorphous states of H2O were directly tracked without using emulsions to just above the crystallization temperature Tx. The spectra show significant changes occurring above ,125 K. The results are compared with data reported for the relaxation behavior of HDA, to form what we call relaxed HDA, or rHDA. We find a close connection with expanded HDA (eHDA), which is reported to exist as another metastable form in this P,T region. The observation of this temperature-induced LDA transition under pressure complements the previously observed pressure-induced reversible transition between LDA and HDA at 120,140 K. Copyright © 2009 John Wiley & Sons, Ltd. [source] Crystallization behavior of Sb70Te30 and Ag3In5Sb60Te32 chalcogenide materials for optical media applicationsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2008M. L. Lee Abstract Addition of In and Ag into eutectic Sb70Te30 fast-growth material was studied. We explored the optical transitions and crystallization kinetics of Sb70Te30 and Ag3In5Sb60Te32 recording films. The results showed that Ag3In5Sb60Te32 has a higher crystallization temperature but a similar melting point compared to Sb70Te30. In both the crystalline and amorphous states, addition of Ag and In increased the refractive index and decreased the extinction coefficient of Sb70Te30. Ag3In5Sb60Te32 has better thermal stability and a lower crystallization speed than Sb70Te30 film. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Precursor-derived Si,(B,)C,N ceramics: thermolysis, amorphous state and crystallization,APPLIED ORGANOMETALLIC CHEMISTRY, Issue 10 2001Joachim Bill Abstract The preparation of silicon nitride- and carbide-based ceramics by solid-state thermolysis of polysilazanes and polysilylcarbodiimides is described. Results on the ceramization of the preceramic compounds and the architecture of the corresponding amorphous states obtained by spectroscopic means and by X-ray and neutron scattering are reviewed. Fundamental correlations between the composition and structure of the preceramic compounds and the architecture of the amorphous state are revealed. Furthermore, the crystallization behavior of the amorphous precursor-derived Si,C,N ceramics is treated. Moreover, the influence of boron on the thermal stability of the amorphous state is described. The high-temperature behavior of these Si,B,C,N solids can be correlated with their phase composition. Ceramic materials with compositions located close to the three-phase equilibrium SiC,+,BN,+,C exhibit a high temperature stability up to 2000,°C. This effect is accompanied by the formation of a metastable solid consisting of Si3N4 and SiC nanocrystals that are embedded in a turbostratic B,C,N matrix phase. Based on thermodynamic considerations, a model for the high-temperature stability effect is proposed. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||