Search results for "Plastics"

Dielectric measurements have been performed at several frequencies on samples of a cycloaliphatic epoxy resin filled with aluminum hydroxide. The samples were thermally treated at three different temperatures for times up to 2,000 hours. At low aging temperatures and times an improvement of the characteristics is observed due perhaps to an assessment of the bulk of the polymer and more precisely to a change in the free volume. At high temperatures and times a thermo-oxidation involving layers deeper and deeper becomes the predominant mechanism responsible of the decrease in the properties with respect to the virgin material.

chemistry.chemical_classificationMaterials sciencePolymers and Plasticschemistry.chemical_elementPolymerDielectricEpoxychemistry.chemical_compoundColloid and Surface ChemistrychemistryVolume (thermodynamics)Aluminiumvisual_artThermalMaterials Chemistryvisual_art.visual_art_mediumHydroxidePhysical and Theoretical ChemistryComposite materialGlass transitionColloid and Polymer Science

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Functional Polymer-Opals from Core-Shell Colloids

2007

Colloidal photonic crystals were prepared from monodisperse core-shell particles. The shell is hereby formed from a functional monomer, such as glycidylmethacrylate or different reactive ester monomers, which can perform chemical reactions and the core from a standard monomer, which yields highly monodisperse colloids. It was possible to crystallize the core-shell particles into artificial opals with excellent optical properties. Reactions on the functional surface of the colloids were carried out, which lead to a dramatic rise in the mechanical stability or to a functionalization of His-tagged silicatein, which acts as nanoreactor to synthesize and immobilize gold nanoparticles from auric …

chemistry.chemical_classificationMaterials sciencePolymers and Plasticsdigestive oral and skin physiologyOrganic ChemistryDispersityEmulsion polymerizationNanoreactorPolymerColloidal crystalchemistry.chemical_compoundMonomerchemistryChemical engineeringColloidal goldPolymer chemistryMaterials ChemistrySurface modificationMacromolecular Rapid Communications

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Synthesis of polyvinyl acetate-graft-poly-2-oxazolines

1994

Poly(vinyl acetate-co-vinyl chloroformate) (1) was synthesized via phosgenation of poly(vinyl acetate-co-vinyl alcohol). It was shown that (1) is capable of initiating the polymerization of 2-phenyl-2-oxazoline and 2-methyl-2-oxazoline, when the counter ion is exchanged using potassium iodide. Polyvinyl acetate-graft-poly-2-phenyl-2-oxazoline and polyvinyl acetate-graft-poly-2-methyl-2-oxazoline are obtained in the grafting reaction.

chemistry.chemical_classificationMaterials sciencePolyvinyl acetatePolymers and Plasticsorganic chemicalsOrganic Chemistrytechnology industry and agriculturechemistry.chemical_elementAlcoholmacromolecular substancesChloroformateGraftingIodineRing-opening polymerizationchemistry.chemical_compoundchemistryPolymerizationPolymer chemistryMaterials ChemistryCounterionPolymer International

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Synthesis, Characterization and Preliminary Biological Evaluation of P(HPMA)-b-P(LLA) Copolymers: A New Type of Functional Biocompatible Block Copoly…

2010

We describe a synthetic pathway to functional P(HPMA)-b-P(LLA) block copolymers. The synthesis relies on a combination of ring-opening polymerization of L-lactide, conversion into a chain transfer agent (CTA) for the RAFT polymerization of pentafluorophenyl methacrylate. A series of block copolymers was prepared that exhibited molecular weights $\overline M _{\rm n}$ ranging from 7 600 to 34 300 g · mol(-1) , with moderate PDI between 1.3 and 1.45. These reactive precursor polymers have been transformed into biocompatible P(HPMA)-b-P(LLA) copolymers and their fluorescently labeled derivatives by facile replacement of the pentafluorophenyl groups. The fluorescence label attached to this new …

chemistry.chemical_classificationMaterials scienceRAFT polymerizationPolymers and PlasticssynthesisStereochemistryOrganic ChemistryFluorescence correlation spectroscopyfluorescence correlation spectroscopyPolymerchainMethacrylatebiocompatible block copolymerspolylactide block copolymersTransfer agentchemistryPolymerizationPolymer chemistryAmphiphileHPMA block copolymersMaterials ChemistryCopolymerReversible addition−fragmentation chain-transfer polymerization

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Hydrothermal ageing of radiation cured epoxy resin-polyether sulfone blends as matrices for structural composites

2010

Abstract The hydrothermal ageing of epoxy–thermoplastic blends, used as matrices for carbon fibre composites, cured by electron beam, has been studied. Two different thermoplastic percentages have been adopted. A suitable choice of both curing process and formulation parameters allows to carry out irradiation at mild temperature with several advantages, coming from a “non thermal” process, for both the final properties of the materials and the environment. Nevertheless the occurring of vitrification phenomena needs the use of a short thermal treatment after irradiation on the already solid materials, in order to complete the cure reactions. Radiation cured epoxy based matrices have been sub…

chemistry.chemical_classificationMaterials scienceThermoplasticPolymers and PlasticsPlasticizerEpoxyThermal treatmentCondensed Matter PhysicsRadiation curing structural composites hydrothermal ageing fracture thoughnessFracture toughnesschemistryMechanics of Materialsvisual_artMaterials Chemistryvisual_art.visual_art_mediumIrradiationComposite materialThermal analysisCuring (chemistry)Polymer Degradation and Stability

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