Serwis Infona wykorzystuje pliki cookies (ciasteczka). Są to wartości tekstowe, zapamiętywane przez przeglądarkę na urządzeniu użytkownika. Nasz serwis ma dostęp do tych wartości oraz wykorzystuje je do zapamiętania danych dotyczących użytkownika, takich jak np. ustawienia (typu widok ekranu, wybór języka interfejsu), zapamiętanie zalogowania. Korzystanie z serwisu Infona oznacza zgodę na zapis informacji i ich wykorzystanie dla celów korzytania z serwisu. Więcej informacji można znaleźć w Polityce prywatności oraz Regulaminie serwisu. Zamknięcie tego okienka potwierdza zapoznanie się z informacją o plikach cookies, akceptację polityki prywatności i regulaminu oraz sposobu wykorzystywania plików cookies w serwisie. Możesz zmienić ustawienia obsługi cookies w swojej przeglądarce.
Wyniki wyszukiwania dla: emerytowany profesor Uniwersytetu
Łódzkiego. Zajmuje się kulturą i recepcją literatury romantycznej; poeta-
mi dwudziestolecia międzywojennego Krystyna Ratajska – prof. dr hab.
The rheological properties of aqueous solutions of a hydrophobically modified poly(acrylic acid) were studied by diffusing-wave spectroscopy microrheology at various concentrations and temperatures and the formation of the transient network by hydrophobic association of the polymer chains was characterized. The Winter-Chambon power-law regime was found in a high frequency range accessible by microrheology,...
The relationship between polymer network parameters and speed of viscoelastic (VE) recovery was studied for viscoelastic polyurethane foams. Reactive network simulation method was developed which use relative reactivity parameters derived from literature and from experiment. Relative reactivity of butylene oxide (BO) based secondary hydroxyl groups were estimated by comparing simulation results with...
Coarse-grained molecular dynamics simulations of the formation of 3- and 6-functional polymer networks explicitly shows gelation via large dendritic clusters. The heterogeneous network structures are studied in detail; clusters have pendant structures and occupy significant volume fraction. Cluster fractal dimension and the Fisher exponent for cluster size are consistent with percolation theory and...
Tissue engineering requires scaffolding techniques based on non-toxic processes that permits the fabrication of constructs with tailored properties. Here, a two-step methodology based on the gelation and precipitation of the poly(lactic) acid/ethyl lactate organogel system is presented. With this technique nanofibrous matrices that resemble natural extracellular matrix can be easily obtained, while...
We present a dynamic dual responsive biocompatible composite hydrogel based on Carbopol (CBP) and P123 in presence of salt. The P123 could induce gelation of Carbopol in otherwise nongelled 1% CBP (in presence of salt) even below its pKa which it is believed to make its delivery system viable in strongly acidic environment like gut. The gelation properties of the gel can be tuned in a desired manner...
Heat-induced gelation mechanism of ovalbumin (OVA) in neutral, salt-free aqueous solution was investigated by dynamic light scattering and small-angle neutron scattering. The scattering profiles obtained from OVA solutions/gels showed a correlation peak. It is clarified that the position of the peaks was independent of the concentration after heating. From this fact, we described the gelation mechanism...
Thermal-induced gelation and phase separation was investigated in PAN/DMSO/H2O semidilute solutions utilizing rheological and optical methods. The incipient precipitation temperature, where a distinct decrease in relative light transmittance occurred, was considered as the cloud point (CP). Phase separation mechanism of nucleation and growth was confirmed by various ramp rates experiments and viscoelastic...
1,4-polybutadiene (PB) of varying molecular weight, M, and varying polydispersity (obtained by mixing monodisperse PB) was characterized. As is well-known, some rheological properties are affected by both molecular-weight and polydispersity; however, others show a dependence on M, but not on molecular weight distribution (MWD). We find that the viscosity at constant weight-average M can be accurately...
The effect of intramolecular crosslinking (IC) (cyclization) on gelation was studied using Monte Carlo simulations. The consumption of crosslinker in the IC process is proposed as one of the main reasons of significant overestimation of the gel point by Flory-Stockmayer theory. The system under study is atom transfer radical polymerization (ATRP) of a monomer and bifunctional (e.g. divinyl) crosslinker...
The modulatory effect of oligoguluronate (GB) on the gelation of macromolecular alginate (ALG) was investigated by means of dynamic oscillatory rheology, fluorescence and AFM measurements. An inhibitory effect in the range of 0.25 < R (Ca/G) < 0.60 and a promotive effect in the range of R > 0.60, were quantified. The two effects are thought to be associated with the different molecular events...
The study focuses on the structure and viscoelasticity of poly(ethylene oxide)/carbon black fluids. The hybrids when subjected to extreme thermal annealing (at temperatures far above the melting point of the matrix) exhibit a 3–4 orders of magnitude increase in viscosity. Surprisingly, the effect is reversible and the viscosity reverts back to its initial value upon subsequent cooling. This rather...
A library of novel well-defined (bis)amide-based (co)polymers was prepared through postpolymerization modification of poly(pentafluorophenyl acrylate) with amines including ammonia and amide derivatives of amino acids. Products were characterized using a combination of NMR and FT-IR spectroscopies and size exclusion chromatography; results conformed to the expected structures obtained through quantitative...
Complex crystal induced gelation of poly(l-lactic acid) (PLLA) solutions was studied for a series of solvents, including N,N-dimethylformamide (DMF). By cooling the solutions prepared at elevated temperatures, PLLA gels were produced in solvents that induced complex crystals (ε-crystals) with PLLA. Fibrous structure of PLLA in the gel with DMF was observed by polarizing optical microscopy, field emission...
This work theoretically deals with the kinetics of the hyperbranched polymerization with A2, AB and B3 monomers. The analytical expressions of the size distribution function and the various molecular parameters of the resulting hyperbranched polymers were derived. The structure and molecular parameters of the products depend on the monomer feed ratios and the conversion of groups. Gelation is easy...
Diphenylacetylene having a trimethylsilyl group and two methoxy groups [p-(CH3)3SiC6H4CCC6H4-m,p-(OCH3)2 (1a)] polymerized with TaCl5/n-Bu4Sn catalyst to provide a high-molecular-weight polymer (2a). In contrast, monomers without trimethylsilyl group (1b) and having two t-butyldimethylsiloxy groups (1c) hardly polymerized because of poor solubility of the produced polymer 2b and steric hindrance of...
The gelation process of N-Phenylaminomethyl-POSS/PU (polyurethane) nanocomposites during curing and at the stable state after curing was investigated by rheology. An increase in dynamic shear moduli, G′ and G″, was observed during the dynamic temperature ramps of the sample. In time-resolved mechanical spectroscopy (TRMS), G′ and G″ increased with curing time at constant curing temperatures over a...
The epoxy-silica hybrids have been prepared by the non-aqueous sol–gel process and the in situ generation of nanosilica from tetraethoxysilane was initiated with borontrifluoride monoethylamine (BF3MEA). The DGEBA based epoxy networks with aliphatic, cycloaliphatic and aromatic amines were used as matrices. The solventless technique made it possible to avoid drawbacks of the classical aqueous procedure...
Rheological characteristics evolved during chemical gelation of semidilute dextran solutions are reported at different temperatures, levels of epichlorohydrin (ECH as a cross-linker), polymer concentration, and amount of catalyst i.e., NaOH. Increasing temperature, cross-linker, polymer and NaOH concentrations, all lead to faster gelation. Gelation at higher temperatures resulted in weaker incipient...
The dynamics of Tetra-PEG prepolymer in ionic liquid (IL) and their gelation kinetics were investigated by means of time-resolved dynamic light scattering (TR-DLS). From the DLS measurements of prepolymer solutions at chain-overlapping concentration, c * , it was found that the prepolymers are dispersed homogeneously in the IL. The intensity correlation functions (ICFs) were well fitted with...
The random living copolymerization of vinyl and divinyl monomers with fast initiation and slow propagation was simulated using two Monte Carlo methods: one, purely statistical, corresponding to the mean-field Flory–Stockmayer (FS) theory and the dynamic lattice liquid model (DLL). The results were compared with experiments in which atom transfer radical polymerization (ATRP) method was used. Molecular...
Podaj zakres dat dla filtrowania wyświetlonych wyników. Możesz podać datę początkową, końcową lub obie daty. Daty możesz wpisać ręcznie lub wybrać za pomocą kalendarza.