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Polyolefin Backbone (polyolefin + backbone)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Free Radical Graft Copolymerization of Methyl Methacrylate onto Polyolefin Backbone: Kinetics Modeling through Model Compounds Approach

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 13-14 2009
Thierry Badel
Abstract The grafting of poly(methyl methacrylate) (PMMA) from poly[ethylene- co -(1-octene)] in the molten state by in situ radical polymerization of methyl methacrylate (MMA) was investigated through a kinetic modeling using a model compound approach. We resorted to pentadecane (C15H32) and 2,6,10,15,19,23-hexamethyltetracosane (Squalane, C30H62) as models for both the copolymer ethylene and octene moieties. The attention was focused on the simulation of MMA conversion and PMMA average polymerization degree according to temperature, reaction time, and initiator ratio required for the polymerization of MMA in the presence of alkoxyl radicals and alkanes. [source]

Probing the Effects of Hydrophilic Branch Size, Distribution, and Connectivity in Amphiphilic Polyethylene

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2008
Erik B. Berda
Abstract Acyclic diene metathesis (ADMET) polymerization/hydrogenation methodology was used to synthesize a family of amphiphilic polyethylenes (PEs) with precisely placed poly(ethylene glycol) branches. Four structural parameters are varied in this report: size of the hydrophilic pendant group, manner in which the pendant group is connected to the backbone, distance between the pendant moieties along the backbone, and saturation of the polyolefin backbone. Varying the branch size with other parameters held constant results in negligible effects on thermal behavior. However, when either the distribution of branches or manner of connection of the branches is altered, changes in the thermal behavior become clear. These slight structural changes allow tunability of the structural morphology from fully amorphous to semicrystalline materials melting over a range of temperatures above 60,°C. [source]

Novel Polyolefins Containing Crystallizable Isotactic Polystyrene Side Chains

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 18 2008
Barbara T. Gall
Abstract Vinyl-terminated isotactic polystyrene macromonomers were copolymerized with ethylene and 1-octene to new polyolefin graft copolymers with crystallizable polystyrene side chains. The iPS content was varied from 4 to 78 wt.-% using different metallocene and halfsandwich catalysts. No solubility problems of the stereoregular macromonomer occured, because iPS does not crystallize during polymerization. In addition the polymers show nanophase separation of the polyolefin backbone and the iPS side chains. The crystallization of iPS, having a melting point of about 200,°C, can be achieved by annealing. This synthesis strategy allows the fabrication of a new class of thermoplastic elastomers with improved heat distortion temperatures. [source]

Dynamic Monte Carlo Simulation of Graft Copolymers Made with ATRP and Metallocene Catalysts

MACROMOLECULAR SYMPOSIA, Issue 1 2006
Mamdouh Al-Harthi
Abstract The synthesis of polyolefin graft copolymers made with coordination polymerization was studied by dynamic Monte Carlo simulation. Narrow molecular weight distribution macromonomers, containing terminal vinyl groups made with atom-transfer radical polymerization (ATRP), were incorporated randomly into the polyolefin backbone. In addition to average molecular weights and polydispersity index, the model predicts the complete molecular weight distribution (MWD) and branching density of the graft copolymer. The effect of the concentration of macromonomers on the grafting efficiency was also studied. [source]