منابع مشابه
Growth Shape of Isotactic Polystyrene Crystals in Thin Films
The crystal growth of isotactic polystyrene (it-PS) is investigated in very thin, 11 nm thick films. The it-PS crystals grown in the thin films show quite different morphology from that in the bulk. With decreasing crystallization temperature, the branching morphology in a diffusion field appears: dendrite and compact seaweed. The branching morphology is formed through a morphological instabili...
متن کاملCrystal Growth of Isotactic Polystyrene in Ultrathin Films : Film Thickness Dependence
The film thickness dependence of crystal growth is investigated for isotactic polystyrene (it-PS) in thin films, the thickness of which is from 20nm down to 4nm. The single crystals of it-PS grown at 180 in the ultrathin films show the morphology typical in the diffusion-controlled growth: dense branching morphology (DBM), fractal seeweed (FS). The characteristic length of the morphology, i.e. ...
متن کاملPhase-field modeling on morphological landscape of isotactic polystyrene single crystals.
Spatio-temporal growth of isotactic polystyrene single crystals during isothermal crystallization has been investigated theoretically based on the phase field model by solving temporal evolution of a nonconserved phase order parameter coupled with a heat conduction equation. In the description of the total free energy, an asymmetric double-well local free energy density has been adopted to repr...
متن کاملOne-pot synthesis of isotactic-capped syndiotactic polystyrene with a bimetallic homogeneous catalytic system
INTRODUCTION Polystyrene can be obtained in atactic (aPS), isotactic (iPS) or syndiotactic (sPS) form by a variety of catalytic systems1,2 and initiators. For instance, it is known that (pentamethylcyclopentadienyl)titanium derivatives activated by methylaluminoxane (MAO) afford a highly sPS, with %m (defined as meso diads content, calculated by 13C-nuclear magnetic resonance (NMR)) below the i...
متن کاملEngineering of Syndiotactic and Isotactic Polystyrene-Based Copolymers via Stereoselective Catalytic Polymerization.
This contribution presents an updated overview of the different copolymers containing stereoregular polystyrene blocks. Special emphasis is placed on syndiospecific and isospecific copolymerization of styrene with co-monomers (ethylene and α-olefins, conjugated and non-conjugated dienes, styrene derivatives, etc.). The catalytic systems involved are described and the polymerization mechanisms a...
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ژورنال
عنوان ژورنال: Journal of Polymer Science Part A-2: Polymer Physics
سال: 1970
ISSN: 0449-2978,1542-9377
DOI: 10.1002/pol.1970.160080415