Epitaxial Crystallization and AFM Investigation of a Frustrated Polymer Structure:  Isotactic Poly(propylene), β Phase

1998 ◽  
Vol 31 (3) ◽  
pp. 807-814 ◽  
Author(s):  
Wolfgang Stocker ◽  
Martina Schumacher ◽  
Sabine Graff ◽  
Annette Thierry ◽  
Jean-Claude Wittmann ◽  
...  
Keyword(s):  
Polymer Structure ◽  
Epitaxial Crystallization ◽  
Β Phase ◽  
Poly Propylene

scholarly journals Nucleation of the β-polymorph in Composites of Poly(propylene) and Graphene Nanoplatelets

2019 ◽  
Vol 3 (2) ◽  
pp. 38 ◽  
Author(s):  
Valentina Guerra ◽  
Chaoying Wan ◽  
Tony McNally
Keyword(s):  
Graphene Nanoplatelets ◽  
Laboratory Scale ◽  
Degree Of Crystallinity ◽  
Mixing Efficiency ◽  
Scanning Calorimetry ◽  
Dsc Measurements ◽  
Β Phase ◽  
A Value ◽  
Twin Screw ◽  
Poly Propylene

The effects of graphene nanoplatelets (GNPs) on the nucleation of the β-polymorph of polypropylene (PP) were studied when melt-mixed at loadings of 0.1–5 wt % using a laboratory scale twin-screw (conical) extruder and a twin-screw (parallel) extruder with L/D = 40. At low GNP loadings (i.e., ≤0.3 wt %), the mixing efficiency of the extruder used correlated with the β-nucleating activity of GNPs for PP. GNP agglomeration at low loadings (<0.5 wt %) resulted in an increase in the β-phase fraction (Kβ) of PP, as determined from X-ray diffraction measurements, up to 37% at 0.1 wt % GNPs for composites prepared using a laboratory scale twin-screw (conical) extruder. The level of GNP dispersion and distribution was better when the composites were prepared using a 16-mm twin-screw (parallel) extruder, giving a Kβ increase of 24% upon addition of 0.1 wt % GNPs to PP. For GNP loadings >0.5 wt %, the level of GNP dispersion in PP did not influence the growth of β-crystals, where Kβ reached a value of 24%, regardless of the type of extruder used. From differential scanning calorimetry (DSC) measurements, the addition of GNPs to PP increased the crystallization temperature (Tc) of PP by 14 °C and 10 °C for the laboratory scale extruder and 16-mm extruder, respectively, confirming the nucleation of PP by GNPs. The degree of crystallinity (Xc%) of PP increased slightly at low GNP additions (≤0.3 wt %), but then decreased with increasing GNP content.

Elastomeric Poly(propylene): Influence of Catalyst Structure and Polymerization Conditions on Polymer Structure and Properties

1995 ◽  
Vol 28 (11) ◽  
pp. 3771-3778 ◽  
Author(s):  
William J. Gauthier ◽  
John F. Corrigan ◽  
Nicholas J. Taylor ◽  
Scott Collins
Keyword(s):  
Polymer Structure ◽  
Structure And Properties ◽  
Catalyst Structure ◽  
Poly Propylene ◽  
Polymerization Conditions

Epitaxial crystallization of polyphenylene sulfide on sodium chloride

1989 ◽  
Vol 4 (4) ◽  
pp. 996-1004 ◽  
Author(s):  
X. J. Qian ◽  
S. E. Rickert ◽  
J. B. Lando
Keyword(s):  
Crystal Structure ◽  
Solution Concentration ◽  
Molecular Packing ◽  
Polyphenylene Sulfide ◽  
Two Dimensional ◽  
Lattice Match ◽  
Dimensional Lattice ◽  
Lattice Matching ◽  
Epitaxial Crystallization ◽  
Β Phase

Epitaxial crystallization of polyphenylene sulfide (PPS) from 1-chloronaphthalene solution on NaCl (001) surface has been studied using electron microscopy and electron diffraction techniques. Three different epitaxial morphologies were observed: (1) conventional rodlike structures (fold plane epitaxy); (2) platelet structures (fold surface epitaxy); and (3) roselike structures whose growth mechanism and molecular packing are not completely understood at present. Of primary importance is the fact that a possible new crystal structure β-phase) of PPS was formed in the fold surface epitaxy through a true two-dimensional lattice matching by lateral lattice dimensional adjustment of PPS. Lattice match criterion again shows its merit in explaining the formation of fold surface epitaxy and the new crystal structure of PPS. Solution concentration, crystallization temperature, and time have significant influence on crystal growths, orientations, molecular packing, and morphological arrangements.

Phase Transformation In Ti-6al-4v Alloys

1972 ◽  
Vol 30 ◽  
pp. 584-585
Author(s):  
Shiro Fujishiro
Keyword(s):  
Phase Transformation ◽  
Grain Boundary ◽  
Cryogenic Temperature ◽  
Β Phase ◽  
Heat Treated ◽  
Mixed Microstructure ◽  
Ductile Behavior

The Ti-6 wt.% Al-4 wt.% V commercial alloys have exhibited an improved formability at cryogenic temperature when the alloys were heat-treated prior to the tests. The author was interested in further investigating this unusual ductile behavior which may be associated with the strain-induced transformation or twinning of the a phase, enhanced at lower temperatures. The starting materials, supplied by RMI Co., Niles, Ohio were rolled mill products in the form of 40 mil sheets. The microstructure of the as-received materials contained mainly ellipsoidal α grains measuring between 1 and 5μ. The β phase formed an undefined grain boundary around the a grains. The specimens were homogenized at 1050°C for one hour, followed by aging at 500°C for two hours, and then quenched in water to produce the α/β mixed microstructure.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

Molecular dynamics of poly(propylene) glycol in nanometer confinements

2000 ◽  
Vol 10 (PR7) ◽  
pp. Pr7-271-Pr7-274 ◽  
Author(s):  
A. Schönhals ◽  
H. Goering ◽  
K.-W. Brzezinka ◽  
Ch. Schick
Keyword(s):  
Molecular Dynamics ◽  
Propylene Glycol ◽  
Poly Propylene

ULTRASONIC STUDIES OF THE POLYMER STRUCTURE OF THE CHALCOGENIDE GLASSES

1981 ◽  
Vol 42 (C4) ◽  
pp. C4-955-C4-958
Author(s):  
V. A. Ratobylskaja ◽  
L. A. Simonova
Keyword(s):  
Chalcogenide Glasses ◽  
Polymer Structure

Uptake, Internalization and Degradation of the Novel Plasminogen Activator Reteplase (BM 06.022) in the Rat

1995 ◽  
Vol 74 (06) ◽  
pp. 1501-1510 ◽  
Author(s):  
J Kuiper ◽  
H van de Bilt ◽  
U Martin ◽  
Th J C van Berkel
Keyword(s):  
Plasminogen Activator ◽  
Liver Cells ◽  
The Novel ◽  
Uptake Mechanism ◽  
Liver Uptake ◽  
Lysosomal Compartment ◽  
Β Phase ◽  
Α Phase ◽  
Parenchymal Liver

SummaryThe catabolism of the novel plasminogen activator reteplase (BM 06.022) was described. For this purpose BM 06.022 was radiolabelled with l25I or with the accumulating label l25I-tyramine cellobiose (l25I-TC).BM 06.022 was injected at a pharmacological dose of 380 μg/kg b.w. and it was cleared from the plasma in a biphasic manner with a half-life of about 1 min in the α-phase and t1/2of 20-28 min in the β-phase. 28% and 72% of the injected dose was cleared in the α-phase and β-phase, respectively. Initially liver, kidneys, skin, bones, lungs, spleen, and muscles contributed mainly to the plasma clearance. Only liver and the kidneys, however, were responsible for the uptake and subsequent degradation of BM 06.022 and contributed for 75% to the catabolism of BM 06.022. BM 06.022 was degraded in the lysosomal compartment of both organs. Parenchymal liver cells were responsible for 70% of the liver uptake of BM 06.022. BM 06.022 associated rapidly to isolated rat parenchymal liver cells and was subsequently degraded in the lysosomal compartment of these cells. BM 06.022 bound with low-affinity to the parenchymal liver cells (550 nM) and the binding of BM 06.022 could be displaced by t-PA (IC50 5.6 nM), indicating that the low-density lipoprotein receptor-related protein (LRP) could be involved in the binding of BM 06.022. GST-RAP, which is an inhibitor of LRP, could in vivo significantly inhibit the uptake of BM 06.022 in the liver.It is concluded that BM 06.022 is metabolized primarily in the liver and the kidneys. These organs take up and degrade BM 06.022 in the lysosomes. The uptake mechanism of BM 06.022 in the kidneys is unknown, while LRP is responsible for a low-affinity binding and uptake of BM 06.022 in parenchymal liver cells.

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