Results 41 to 50 of about 6,795 (264)

Crystal structures and polymorphism of polymers: Influence of defects and disorder [PDF]

open access: yes, 2018
The crystal structures and the polymorphism of polymers are described on the basis of the main principles that define the conformation of polymer chains in the crystalline state and the modes of packing of macromolecules.
Auriemma, Finizia   +3 more
core   +1 more source

Employing Moment Equations Model to Study the Effect of Different Active Centers on Homopolymerization Kinetics of Ethylene [PDF]

open access: yesعلوم و تکنولوژی پلیمر, 2008
Ethylene was homopolymerized over Ziegler-Natta catalyst and the homopolymerization was modeled using moment equations. Mechanism was modeled according to five different reaction centers of catalyst.
M. Salami-Kalajahi   +3 more
doaj   +1 more source

Ultrasound- and microwave-assisted preparation of lead-free palladium catalysts: effects on the kinetics of diphenylacetylene semi-hydrogenation [PDF]

open access: yes, 2015
The effect of environmentally benign enabling technologies such as ultrasound and microwaves on the preparation of the lead-free Pd catalyst has been studied.
Bonrath, Werner   +6 more
core   +1 more source

Advantages of an Emulsion‐Produced Ziegler‐Natta Catalyst Over a Conventional Ziegler‐Natta Catalyst

open access: yesMacromolecular Materials and Engineering, 2005
AbstractSummary: Self‐supported and MgCl2‐supported Ziegler‐Natta catalysts, produced by two catalyst synthesis methods are compared. Borealis Polymers OY (Finland), who supplied the catalysts, developed the catalyst synthesis methods. The first method (Method One) is based on an emulsion system and consists of an in situ single step preparation.
Mohammed Abboud   +2 more
openaire   +1 more source

Copolymerization of Ethylene and Propylene Using 4th Generation Ziegler- Natta Catalyst: Influence of Cocatalyst, External Electron Donor and Hydrogen [PDF]

open access: yesعلوم و تکنولوژی پلیمر, 2007
Copolymerization of ethylene and propylene was investigated using a 4th generation phthalate Ziegler-Natta catalyst in normal hexane in a Buchi reactor.
R. Mehtarani   +4 more
doaj   +1 more source

Gas phase polymerization of ethylene with a silica-supported metallocene catalyst: influence of temperature on deactivation [PDF]

open access: yes, 1997
Ethylene was polymerized at 5 bar in a stirred powder bed reactor with silica supported rac-Me2Si[Ind]2ZrCl2/methylaluminoxane (MAO) at temperatures between 40°C and 80°C using NaCl as support bed and triethylaluminium (TEA) as a scavenger for impurities.
Meier, G.B.   +5 more
core   +2 more sources

Electron Microscopy Transfer System to Protect Atmosphere‐Sensitive Materials for Scanning Electron Microscopy Characterization

open access: yesMicroscopy Research and Technique, EarlyView.
SEM–EDX and XRD characterization confirm that pouches made from readily available aluminum foil, used in combination with a commercial cryo‐EM transfer system, effectively protect highly atmosphere‐sensitive and/or hygroscopic materials from contamination during transfer from inert environments to the SEM vacuum chamber.
Louis G. Corcoran   +8 more
wiley   +1 more source

Olefin Polymerizations Oriented by Rational Designs of Group‐13 Compounds

open access: yesThe Chemical Record, EarlyView.
In coordination olefin polymerization chemistry, boron and aluminum compounds play important roles in both catalyst components and monomers. This personal account introduces our recent progress on the development of catalyst systems featured by the design of group‐13 counteranions, as well as the application of boronic acid‐crosslinked polyolefins to ...
Ryo Tanaka, Yu Zou
wiley   +1 more source

A Silicon-Bridged Bis(substituted Cp) Yttrium Complex [PDF]

open access: yes, 1992
rac-Bis(tetrahydrofuran)lithium [bis(2-trimethylsilyl-4-tert-butyl-η^5-cyclopentadienyl)dimethylsilane] dichloroyttrate, [Li(C_4H_80)_2][Y(C_(26)H_(48)-Si_3)Cl_2], M_r= 755.87, triclinic, Pl, ɑ = 13.110 (8), b = 17.163 (15), c = 20.623 (14) Å, ɑ= 104.02 (
Bercaw, John E.   +3 more
core   +1 more source

Developing Calibration Reference Materials and Standardized Protocols for Reliable DSC of Polyolefins

open access: yesJournal of Applied Polymer Science, Volume 143, Issue 3, January 15, 2026.
Standardized protocol for reducing T m standard deviation. ABSTRACT Differential scanning calorimetry (DSC) serves as a critical analytical tool in the polyolefin industry for quality control and product differentiation. Between 2000 and 2025, 7574 global patent applications referenced DSC data, highlighting its ubiquitous role in the industry.
Xingxing Zhang   +7 more
wiley   +1 more source

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