Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Stereocomplex crystal

Tsuji, H., Wada, T., Sakamoto, Y. and Sugiura, Y. (2010) Stereocomplex crystallization and spherulite growth behavior of poly(L-lactide)- -poly(D-lactide) stereodiblock copolymers. Polymer, 51, 4937-4947. [Pg.222]

Abstract Stereocomplexes have been formed by mixing the two isotactic poly(a-methyl-a-cthyl-p-propriolactones) (PMEPL) of opposite chirality. This leads to an insoluble complex exhibiting a melting transition which is 40 C above that of the initial isotactic components. Structural differences between these samples have been determined by nuclear magnetic resonance spectroscopy and electron diffraction. It was found by NMR that the stereocomplex crystallizes in a 2 helical conformation whereas the corresponding isotactic chains exhibit a helical or extended chain conformation depending upon the method of sample preparation. Electron diffraction confirms these measurements with the determination of a,b and c dimensions of the orthorombic unit cells. [Pg.131]

PLA crystalline structures. Unit cell parameters for non-blended PLLA and stereocomplex crystals. [Pg.440]

Stereocomplex Crystals of Poly(L-lactide)/Poly(o-lactide)... [Pg.123]

Figure 5.14 (a) WAXS profiles of a stretched PLLA/PDLA blend recorded upon heating. a, a, and denote the a -, a-fbrm homo-crystals, and stereocomplex crystals, respectively. The strong peaks around 20 = 16.5° and 19.0° are the characteristic reflections of the a - and a-form homo-crystals of PLA. The three peaks around 20 = 11.1°, 20.0°, and 23.2°... [Pg.124]

Crystalline structure and molecular dynamics in alpha and alpha crystals of poly(L-lactide) (PLLA) and PLLA/poly(D-lactide) (PDLA) stereocomplex crystals have been investigated by solid-state C CPMAS NMR spectroscopy. The crystal forms of polylactide (PLA) have different line shapes, and resonance splittings in solid-state NMR spectra due to the crystallographically inequivalent sites within crystal unit cell. [Pg.336]

A high voltage in electro-spinning suppressed the formation of a-crystals, and helped to form PLLA/PDLA fibers with predominately stereocomplex crystals. ... [Pg.120]

On the basis of the crystal structure and unit cell parameters, the crystal density q c (g/cm ) of the stereocomplex crystal can be calculated from Equation 5.1 ... [Pg.62]

Table 4.3 Unit Cell Parameters for Non-Blended PLLA and Stereocomplex Crystals... [Pg.153]

Figure 2.8 (a) PDLA (top) and PLLA (bottom) chains in parallel orientation, as located in the stereocomplex crystal. The model has been built by bringing the chains until they fit in the experimental dimensions of the unit cell. Hydrogen-bonding angles for the interactions... [Pg.33]

Xu H, Wu D, Yang X, Xie L, Hakkarainen M (2015) Thermostable and impermeable nano-barrier walls constructed by poly (lactic acid) stereocomplex crystal decorated graphene oxide nanosheets. Macromolecules 48(7) 2127-2137... [Pg.250]

See other pages where Stereocomplex crystal is mentioned: [Pg.180]    [Pg.123]    [Pg.124]    [Pg.124]    [Pg.55]    [Pg.61]    [Pg.106]    [Pg.471]    [Pg.158]    [Pg.158]    [Pg.159]    [Pg.161]    [Pg.152]    [Pg.18]    [Pg.30]    [Pg.30]    [Pg.33]    [Pg.226]    [Pg.228]    [Pg.230]    [Pg.64]    [Pg.18]   
See also in sourсe #XX -- [ Pg.52 ]

See also in sourсe #XX -- [ Pg.158 , Pg.159 , Pg.161 ]



SEARCH



PLLA/PDLA stereocomplex crystals

Poly stereocomplex crystal

Stereocomplex

Stereocomplex crystal structure

Stereocomplexes

© 2024 chempedia.info