Search results for "Gel point"

showing 4 items of 4 documents

Hydrogen bonded ferroelectric liquid crystal gels in freely suspended film geometry

2003

We study freely suspended films of smectic C* liquid crystalline gels by means of polarizing microscopy. The gel point of the system is determined from the suppression of flow in the films. The network of hydrogen bonds is mechanically fragile but stabilizes orientation patterns of the sample, in particular it stores the texture present during gelation. Electro-optical experiments are performed to study the dynamics of the sample reorientation under the influence of in-plane electric fields. Mesogen orientation and optical properties can be switched in electric fields of a few kV m−1. After removal of electric fields, the network restores the ‘frozen-in’ texture. This texture can be erased …

Gel pointHydrogenChemistryHydrogen bondMesogenGeneral Physics and Astronomychemistry.chemical_elementFerroelectricityCrystallographyLiquid crystalElectric fieldTexture (crystalline)Physical and Theoretical ChemistryComposite materialPhysical Chemistry Chemical Physics
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In vitro evaluation of poloxamer in situ forming gels for bedaquiline fumarate salt and pharmacokinetics following intramuscular injection in rats

2019

Graphical abstract

In situPO Propylene oxideIV IntravenousP338 Poloxamer 338lcsh:RS1-441Pharmaceutical Sciencechemistry.chemical_compoundn Sample sizeSD Standard deviationIM Intramuscularchemistry.chemical_classificationC0 Analyte plasma concentration at time zeroDoE Design of experimentsUV UltravioletPharmacology. TherapyK2.EDTA Potassium ethylenediaminetetraacetic acidLC–MS/MS Liquid chromatography-tandem mass spectrometryH&E Hematoxylin and eosintmax Sampling time to reach the maximum observed analyte plasma concentrationIn situ forming gelsCMC Critical micellar concentrationCmax Maximum observed analyte plasma concentrationIntramuscular injectionDN Dose normalizedGPT Gel point temperaturePLGA Poly-(DL-lactic-co-glycolic acid)TFA Trifluoroacetic acidCAN AcetonitrileATP Adenosine 5′ triphosphateSalt (chemistry)Polyethylene glycolPoloxamerArticlelcsh:Pharmacy and materia medicaPharmacokineticsIn vivoUHPLC Ultra-high performance liquid chromatographyPharmacokineticsAUClast Area under the analyte concentration versus time curve from time zero to the time of the last measurable (non-below quantification level) concentrationEO Ethylene oxideNMP N-methyl-2-pyrrolidoneComputingMethodologies_COMPUTERGRAPHICSAUC∞ Area under the analyte concentration vs time curve from time zero to infinite timeP407 Poloxamer 407In vitro releasePoloxamerCMT Critical micellar temperatureGel erosionIn vitrot1/2 Apparent terminal elimination half-lifechemistryMDR-TB Multi-drug resistant tuberculosisAUC80h Area under the analyte concentration versus time curve from time zero to 80 htlast Sampling time until the last measurable (non-below quantification level) analyte plasma concentrationMRM Multiple reaction monitoringNuclear chemistrySustained releaseInternational Journal of Pharmaceutics: X
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Rheological study of gel phenomena during epoxide network formation in the presence of sepiolite

2012

The dynamic behaviour during the crosslinking of an epoxy polymer near the gel point was monitored using rheological multiple frequency experiments. The influence of a needle-shaped inorganic nanofiller, sepiolite, either non-modified or organically surface modified during the cure process in the presence of an aliphatic and an aromatic hardener was investigated. The validity of various criteria for determining the gel point was examined for the crosslinking of these filled thermosets. The Winter–Chambon criterion at the gel point is obeyed by the unfilled and by the non-modified sepiolite-filled epoxy matrix with either of the two hardeners. However, physical gels are formed in the presenc…

chemistry.chemical_classificationGel pointMaterials sciencePolymers and PlasticsSepioliteOrganic ChemistryRelaxation (NMR)EpoxideThermosetting polymerEpoxyPolymerchemistry.chemical_compoundchemistryRheologyvisual_artMaterials Chemistryvisual_art.visual_art_mediumComposite materialPolymer International
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Behaviour of modified and unmodified polybutadienes in the semidilute regime

1997

Abstract The association behaviour of polybutadiene modified with 4-phenyl-l,2,4-triazoline-3,5-dione was studied in semidilute solution through static (SLS) and dynamic light scattering (DLS). The results were compared with the unmodified polybutadiene, whose behavior in semidilute solution was also studied as function of the molecular weight. At higher concentrations a small-angle excess scattering in SLS and a slow mode motion in DLS were observed both for modified and unmodified polybutadienes suggesting the presence of large clusters. Increasing the polymer concentration, the mass fraction of the slow motion increases up to values near 1, indicating a proximity to the gel point. For po…

chemistry.chemical_classificationGel pointPolymers and PlasticsScatteringOrganic ChemistryIntermolecular forceAnalytical chemistryGeneral Physics and AstronomyConcentration effectPolymerPolybutadienechemistryDynamic light scatteringPolymer chemistryMaterials ChemistryMass fractionEuropean Polymer Journal
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