The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The biocompatibility of contact lenses is closely related to their oxygen permeability. In hydrogel lenses, this characteristic can be attributed to the water permeability resulting from a combination of viscous and diffusive fluxes. Hydrogel lenses were studied by means of nuclear magnetic resonance (NMR) relaxation times, resulting in a mathematical model which evaluated the water self-diffusion...
Superabsorbent copolymers, based on acrylamide, 2-acrylamido-2-methyl-propanosulfonic acid and a divinyl crosslinker, N,N'-methylenebisacrylamide, have been synthesized by free radical solution and inverse emulsion polymerization. The copolymerization has been carried at different pH values of the monomer mix reaction medium.The copolymers were characterized by their dynamic swelling behavior in deionized...
n-Hexane zero-concentration diffusivity in high density polyethylene obtained 'indirectly' from integral desorption measurements using the free volume concept was compared with the zero-concentration diffusivity obtained directly at low-n-hexane activities using a quartz-spring system. The difference between the results obtained by the indirect and direct methods was within the experimental error...
Lactic acid polymers were synthesised from oligomers by the addition of highly reactive 1,6-hexamethylene diisocyanate (HMDI) and 2,2'-bis(2-oxazoline) (BOX) as chain extenders. The effects were studied of adding the extenders simultaneously and sequentially and in different amounts. The reactions were followed and the polymers obtained were structurally characterised by size exclusion chromatography...
Poly(styrene-co-styrene sulfonate) (PS-PSS) latexes have been coated with thin overlayer of polyaniline (PANI) to produce electrically conductive 'core-shell' particles (PANI/PS-PSS) in the size of range 30-50nm in diameter. PS-PSS core particles were prepared by radical emulsion copolymerization and PANI was oxidatively polymerized using ammonium peroxydisulfate (APS) on the surface of PS-PSS latex...
Polythiophene (PTh) is of interest for transistors, light emitting diodes and sensors. Plasma polymerization is a solvent-free, room temperature process that can be used to rapidly deposit thin polymer films onto a wide variety of substrates. This paper describes the synthesis of plasma polymerized thiophene (PPTh) and the dependence of molecular structure and properties on the polymerization conditions...
The miscibility and interactions of binary blends of poly(4-hydroxystyrene) brominated (P4HSBR) with poly(ε-caprolactone) (PCL), poly(vinyl acetate) (PVA) and poly(vinyl methylether) (PVME) are investigated by means of differential scanning calorimetry (DSC). Glass transition temperatures, T g s, are used to assess the miscibility of these systems. All of them were found to be miscible over...
The structures of ( OCH 2 CHR ) with R=CH 2 S(CH 2 ) 6 SO 2 (CH 2 ) M H (ATP-M; M=5,7,9) or R=CH 2 SO 2 (CH 2 ) 6 SO 2 (CH 2 ) M H (ASP-M; M=5,7,9) were studied using X-ray diffraction and differential scanning calorimetry. The X-ray patterns of all ATPs and ASPs studied show a series...
We report first on the interpolyelectrolyte complex formation (PEC) between one polycation of integral type having about 95mol% of N,N-dimethyl-2-hydroxypropyleneammonium chloride units in the backbone (PCA 5 ) and poly(sodium styrenesulfonate) (NaPSS), in dependence on the polyion concentrations and the mixing order. The PEC formation was qualitatively followed by viscometry, conductometry...
The energies and structures of neutral benzenoid and neutral quinonoid polyphenylenes in the gas phase were calculated at the ab initio and semi-empirical levels for oligomers containing up to 11 rings as a function of the torsion angles between consecutive aromatic rings. In the gas-phase poly(p-phenylene) (PPP) simulations, a transition to the aromatic benzenoid structure occurs in the centre of...
The poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) was toughened by melt extrusion through its blending with a styrene-b-ethylene/butadiene-b-styrene triblock copolymer (SEBS), or with maleic anhydride (MA) grafted SEBS (SEBS-g-MA). Their morphology, mechanical properties, and rheology have been investigated. Transmission electron microscopy revealed that both kinds of blends had an island-sea structure...
Surfaces of spin-coated and solution-cast poly(3-hexylthiophene) (P3HT) films are analysed by X-ray Photoelectron Spectroscopy and Low Energy Ion Scattering. Here, we use the P3HT-siloxane system with only 2% siloxane monomers in the bulk as a model system to study segregation and surface orientation of molecules in polymers. The surfaces are enriched in siloxane due to the intermolecular segregation...
Rheometers, especially the moving die rheometer (MDR), is used under isothermal conditions for the cure of rubbers. Thus, at least three experiments are necessary at different temperatures selected within a rather narrow temperature window, for determining the kinetic parameters of the cure. Moreover, it takes some time for the sample to attain the selected temperature, and for a high temperature...
New kinds of solid-solid phase change materials (PCMs) with netted structure have been prepared. In these new materials, the rigid polymer cellulose diacetate (CDA) serves as skeleton, and the flexible polymer polyethylene glycol (PEG) serves as functional branch chain. The transition mechanism of these functional polymers is the transfer between the amorphous and crystal states of the PEG. During...
Swelling degrees of poly(N-vinyl-2-pyrrolidone) (PVP) gel were measured in aqueous salt solutions and in water/organic solvent mixtures to find marked ion- and solvent-specificities. In order to investigate any correlation of those specificities with hydration or solvation of PVP, IR spectra band of the C O group was monitored by means of ATR method both for PVP gel and the relevant solution systems...
Hydrogels constitute an important class of responsive materials that are employed in numerous biomedical and personal-care applications, most notably of which are controlled drug delivery, separations and superabsorbency. Since aqueous hydroxypropylcellulose (HPC) solutions exhibit lower critical solution behavior, hydrogels produced from this cellulose ether are temperature-responsive, swelling at...
Dihydridocarbonyltris(triphenylphosphine)ruthenium (Ru) catalyzes the copolymerization of α,ω-divinylsiloxanes with aromatic ketones such as acetophenone to give polymers which have regularly alternating 2,6-diethylene-acetophenone and disiloxane units in the backbone. These copolymers absorb light in the UV λ max ~280nm, and are photochemically active. Monomeric model systems 2-(2'-trimethylsilylethyl)acetophenone...
Several types of polybenzoxazine/clay hybrid nanocomposites have been prepared from organically modified montmorillonite (OMMT) and mono- or bifunctional benzoxazine, 3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (Pa) or bis(3-phenyl-3,4-dihydro-2H-1,3-benzoxazinyl) isopropane (Ba), respectively. OMMT was prepared by a cation exchange of montmorillonite (MMT) with ammonium salts of amines such as tyramine,...
Osmotic pressure measurements were satisfactorily used to compute the effective charge of poly(acrylic) acid (PAA) at different pHs and with different monovalent and divalent counterions. This experimental method is sensitive to the osmotically active species (polymer and counterions). After correction for the polymer contribution to the total osmotic pressure (solvency and excluded volume), the remaining...
Relaxation behavior of ionomer molecule in melt state was investigated by Brownian simulation where motion of a bead-rod chain representing a linear ionomer molecule was calculated in two-dimension. Entanglement between the other molecules was assumed by a repulsive interaction between the chain and randomly located entanglement points. Effect of ion aggregates was also introduced by an attractive...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.