Search results for "Polyvinyl acetate"

showing 8 items of 8 documents

Co-deposition and characterization of hydroxyapatite-chitosan and hydroxyapatite-polyvinylacetate coatings on 304 SS for biomedical devices

2019

During the last decades, biomaterials have been deeply studied to fabricate and improve coatings for biomedical devices. Metallic materials, especially in the orthopedic field, represent the most common materials used for different type of devices thanks to their good mechanical properties. Nevertheless, low/medium resistance to corrosion and low osteointegration ability characterizes these materials. To overcome these problems, the use of biocoatings on metals substrate is largely diffused. In fact, biocoatings have a key role to confer biocompatibility features, to inhibit corrosion and thus improve the lifetime of implanted devices. In this work, the attention was focused on Hydroxyapati…

CorrosionChitosanGalvanic depositionOrthopedic implantSettore ING-IND/24 - Principi Di Ingegneria ChimicaSettore ING-IND/23 - Chimica Fisica Applicata304 stainless steelSettore BIO/10 - BiochimicaPolyvinyl acetateSettore ING-IND/34 - Bioingegneria IndustrialeCytocompatibilityHydroxyapatite
researchProduct

Calcium phosphate/polyvinyl acetate coatings on SS304 via galvanic co-deposition for orthopedic implant applications

2021

Abstract In this work, the galvanic deposition method is used to deposit coatings of brushite/hydroxyapatite/polyvinyl acetate on 304 stainless steel. Coatings are obtained at different temperatures and with different sacrificial anodes, consisting of a mixture of brushite and hydroxyapatite. Samples are aged in a simulated body fluid (SBF), where a complete conversion of brushite into hydroxyapatite with a simultaneous change in morphology and wettability occurred. The corrosion tests show that, compared with bare 304, the coating shifts Ecorr to anodic values and reduces icorr Ecorr, and icorr has different values at different aging times due to chemical interactions at the solid/liquid i…

Materials scienceGalvanic anodeCytotoxicitySimulated body fluidPolyvinyl acetate02 engineering and technologyengineering.material010402 general chemistry01 natural sciencesHydroxyapatiteCorrosionchemistry.chemical_compoundCoatingMaterials ChemistryGalvanic cellBrushiteOrthopedic implantsSettore ING-IND/24 - Principi Di Ingegneria ChimicaPolyvinyl acetateSettore ING-IND/34 - Bioingegneria IndustrialeSurfaces and InterfacesGeneral Chemistry021001 nanoscience & nanotechnologyCondensed Matter Physics0104 chemical sciencesSurfaces Coatings and FilmsAnodeCorrosionGalvanic depositionSettore ING-IND/23 - Chimica Fisica ApplicataChemical engineeringchemistryengineering0210 nano-technologySurface and Coatings Technology
researchProduct

SAXS investigation on aggregation phenomena in supercritical CO2.

2004

Synchrotron Small-Angle X-Ray scattering (SAXS) measurements on aggregate formation of a Polyvinyl acetate- b-Perfluoro octyl acrylate (PVAc- b-PFOA) block copolymer in supercritical CO(2) are here reported. Experiments were carried out for a series of different thermodynamic conditions, changing the solvent density by profiling both the pressure at constant temperature and the temperature at constant pressure. This block copolymer and in general fluorocarbon-hydrocarbon di-blocks form aggregates depending on the value of CO(2) density. A sharp transition between monomers dissolved as random coils and micelles characterized by a solvophilic shell and a solvophobic core occurs when the CO(2)…

Polyvinyl acetateMaterials scienceSmall-angle X-ray scatteringBiophysicsThermodynamicsSurfaces and InterfacesGeneral ChemistryCritical valueMicelleSupercritical fluidCondensed Matter::Soft Condensed Matterchemistry.chemical_compoundchemistryCopolymerGeneral Materials ScienceSoft matterSolvophobicBiotechnologyThe European physical journal. E, Soft matter
researchProduct

Influence of PVP/VA copolymer composition on drug–polymer solubility

2015

In this study, the influence of copolymer composition on drug-polymer solubility was investigated. The solubility of the model drug celecoxib (CCX) in various polyvinylpyrrolidone/vinyl acetate (PVP/VA) copolymer compositions (70/30, 60/40, 50/50 and 30/70 w/w) and the pure homopolymers polyvinylpyrrolidone (PVP) and polyvinyl acetate (PVA) was predicted at 25 °C using a thermal analysis method based on the recrystallization of a supersaturated amorphous dispersion (recrystallization method). These solubilities were compared with a prediction based on the solubility of CCX in the liquid monomeric precursors of PVP/VA, N-vinylpyrrolidone (NVP) and vinyl acetate (VA), using the Flory-Huggins …

Recrystallization (geology)PolymersChemistry PharmaceuticalPharmaceutical Science02 engineering and technologyFlory–Huggins solution theory030226 pharmacology & pharmacy03 medical and health scienceschemistry.chemical_compound0302 clinical medicineDrug StabilityPolymer chemistrymedicineVinyl acetateCopolymerSolubilityPolyvinyl acetatePolyvinylpyrrolidonePovidone021001 nanoscience & nanotechnologyMonomerSolubilitychemistryCelecoxibThermodynamicsPolyvinylsCrystallization0210 nano-technologyHydrophobic and Hydrophilic Interactionsmedicine.drugEuropean Journal of Pharmaceutical Sciences
researchProduct

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
researchProduct

Gelchromatographie. 1. Mitt. Trennung von oligomeren

1966

Vernetzte Polymere werden hergestellt und ihre Eignung zur gelchromatographischen Trennung von Gemischen von Oligomeren gepruft; im einzelnen wurden untersucht: mit Isocyanaten modifiziertes Sephadex; Polymethyl-und Polybutylmethacrylat, vernetzt mit Glykoldimethacrylat bzw. mit Polyathylenoxid-dimethacrylat; Polyvinylacetat, vernetzt mit n-Butandioldivinylather; Polystrol, vernetzt mit Divinylbenzol; ferner Silicagel. Der Einflus der Molekulgestalt auf das Elutionsvolumen wurde gepruft. Die Elutionsvolumina von p-Oligophenylenen, die eine stabchenformige Molekulgestalt besitzen, sind groser als die von Oligourethanen gleichen Molekulargewichts; o- und m-gewinkelte Oligophenylene zeigen geg…

chemistry.chemical_classificationchemistry.chemical_compoundPolyvinyl acetatechemistryButanediolSephadexSilica gelElutionPolymer chemistryDivinyl benzenePolystyrenePolymerDie Makromolekulare Chemie
researchProduct

Über die temperaturabhängigkeit einiger übertragungskonstanten der radikalischen polymerisation von vinylacetat über die verzweigung des polyvinylace…

1964

Die Aktivierungsenergie der Ubertragungsreaktion zwischen wachsendem Polyvinylacetat und Vinylacetat bzw. Athylacetat wird aus kinetischen Messungen im Temperaturbereich von 20–60°C ermittelt. Es ergeben sich 3,15 bzw. 3,45 kcal/Mol. Hieraus kann abgeleitet werden, das die relative Ubertragungsreaktion zwischen radikalisch wachsendem und „totem” Polyvinylacetat der Gleichung log Cp = −;1,54–723/T gehorcht. Die relative Geschwindigkeitskonstante der Endgruppenverzweigung ist kurzlich von D. J. STEIN(4) bestimmt worden und kann als unabhangig von der Temperatur angesehen werden. Damit ist es moglich, die Gesamtverzweigung des Polyvinylacetats als Funktion der Temperatur und des Umsatzes zu be…

chemistry.chemical_compoundPolyvinyl acetatechemistryPolymer chemistryVinyl acetateDie Makromolekulare Chemie
researchProduct

Darstellung von block- und pfropf-copolymeren des trioxane. 25. Mitt. Über polyoxymethylene

1965

Die kationische Polymerisation von Trioxan wird durch makromolekulare Verbindungen mit reaktionsfahigen COC-Gruppen wie Polyvinylacetat (PVA), Polyathylenterephthalat (PET), Poly-1,3-dioxolan oder Polyvinylbultyral (PVB) ubertragen. Dabei entstehen je nach der Art des makromolekularen Ubertragers Pfropf-Copolymere, Block-Copolymere oder vernetzte Copolymere. Die Produkte sind uberwiegend thermisch stabil. Bei der kationischen Polymerisation von Trioxan mus auch eine Ubertragung an den Acetalgruppen des Polyoxymethylens erwartet werden. Polymeric compounds with reactive COC groups such as polyvinyl acetate (PVA), polyethylene terephthalate (PET), poly-1,3-dioxolane or polyvinyl butyral (PVB)…

chemistry.chemical_compoundPolyvinyl butyralPolyvinyl acetateTrioxanechemistryPolyoxymethylenePolymerizationPolymer chemistryCationic polymerizationCopolymerChain transferDie Makromolekulare Chemie
researchProduct