Wyniki wyszukiwania - Biblioteka Nauki

1

STRUCTURAL AND SWELLING PROPERTIES OF HYDROGEL MEMBRANES BASED ON CHITOSAN CROSSLINKED WITH GLUTARALDEHYDE AND SODIUM TRIPOLYPHOSPHATE

100%

Gierszewska-Drużyńska M. , Ostrowska-Czubenko J.

Progress on Chemistry and Application of Chitin and its Derivatives

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2015

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tom 20

43-53

EN

Chemically and physically crosslinked chitosan hydrogel membranes were obtained by treatment of chitosan (Ch) with glutaraldehyde (GA) and with GA and subsequently with sodium tripolyphosphate (TPP). The formation of covalent and ionic crosslinks between Ch, GA and ionic TPP was confirmed by FTIR spectroscopy. The studies of dynamic swelling behaviour of synthesized membranes in buffer solutions of different pH (1.0, 7.4, 9.0) indicated that the swelling process obeyed a second-order kinetics. Values of an apparent swelling rate constant for Ch/GA and Ch/GA/TPP membranes were of the same order for acidic and neutral swelling media but they increased for alkaline solutions.

2

Swelling properties of pulp treated with deep eutectic solvents

88%

Jablonsky M. , Skulcova A. , Majova V. , Sima J.

Drewno : prace naukowe, doniesienia, komunikaty

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2018

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tom vol. 61, nr 202

153--164

EN

The reaction of cellulose with water produces swelling and structural changes of the fibres, both effects being of crucial importance for the understanding of paper formation. It was investigated how the treatment of pulp with deep eutectic solvents affects the swelling kinetics of the fibres. Unbleached kraft pulp was treated with three deep eutectic solvents containing choline chloride (ChCl) – ChCl:lactic acid (1:9), ChCl:oxalic acid (1:1) and ChCl:malic acid (1:1) – and with the system alanine:lactic acid (1:9). The rate and maximum swelling of the pulp in water were determined using a modified monitoring unit for measuring swelling ability. Since paper swells extremely rapidly in water even at 23°C, this apparatus made it possible for the first time to obtain accurate rate data on the swelling of DES-delignified pulp in water.

3

KINETICS OF ACTIVE SUBSTANCE RELEASE FROM FLAT BIOPOLYMER MULTILAYER FILMS

88%

Michalak I. , Traczyk D. , Mucha M.

Progress on Chemistry and Application of Chitin and its Derivatives

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2010

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tom 15

107 - 116

EN

Abstract. Polymer films were made of different biodegradable materials. Solid support of model active substance (salicylic acid) was unmodified and modified (crosslinked with glutaraldehyde) chitosan and outside layers were polylactid acid (PLA). The aim of the study was to obtain the controlled release kinetics of active substance, in medium of pH 5.6 which is similar to conditions occurring on the human skin surface. The chitosan films were investigated with swelling kinetics while multilayer films were studied with release kinetics of active substance (salicylic acid). The amount of salicylic acid released from film was measured using a UV-VIS spectrophotometer. The appropriate mathematical model was also adjusted to the experimental points. The results prove that the swelling process follows the first order kinetics but the results of release process are fitted with Peppas model.

4

Accelerated Ageing of Newsprint Paper: Changes in Swelling Ability, WRV and Electrokinetic Properties of Fibres

75%

Jablonský M. , Botková M. , Šutý Š. , Šmatko L. , Šima J.

Fibres & Textiles in Eastern Europe

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2014

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tom Vol. 22, no. 2 (104)

108--113

EN

The present paper deals with the effect of accelerated ageing on the ability of fibres to undergo saturation with water and the corresponding swelling kinetics. Changes in the surface charge of aged paper fibres were also investigated. Accelerated ageing was performed with newsprint paper at 98 °C and 50% RH during 0, 3, 5,7, 10, 15, 20 and 30 days. The rate and maximum swelling of accelerated aged paper in water were obtained with a modified monitoring unit measuring wood swelling ability. Since paper swells extremely fast in water, even at 30 °C, this apparatus made it possible for the first time to obtain accurate kinetic data on aged paper swelling in water. The polyelectrolyte titration technique was used to investigate changes in the surface charge on fibres from accelerated aged paper.

PL

Praca dotyczy efektów przyspieszonego starzenia papieru gazetowego na zdolność włókien do nasycenia wodą związanego z kinetyką spęczniania. Badano również zmiany w ładunkach powierzchniowych włókien po przyspieszonym starzeniu. Szybkość oraz maksymalną wielkość spęcznienia badano za pomocą zmodyfikowanego przyrządu służącego do badania pęcznienia drewna. Biorąc pod uwagę, że papier pęcznieje w wodzie ekstremalnie szybko, badania prowadzone wspomnianym przyrządem pozwoliły po raz pierwszy określić pęcznienie papieru z dużą dokładnością. Technika miareczkowania polielektrolitycznego pozwoliła zbadać zmiany w ładunkach powierzchniowych.

5

Badanie kinetyki uwalniania biocydów ze spęcznionych żeli metakrylan hydroksyetylu/N-winylopirolidon

63%

Połowińska A. , Szosland A. , Połowiński S.

Polimery

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1999

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tom T. 44, nr 5

151-155

PL

Zbadano kinetykę uwalniania modelowych biocydów z częściowo spęcznionych żeli stanowiących różniące się składem kopolimery metakrylan hydroksyetylu/N-winylopirolidon (HEMA/NYP) usieciowane różnymi ilościami dimetakrylanu butanodiolu (DMBD). Jako biocydy zastosowano estradiol rozpuszczalny w etanolu i kwas salicylowy rozpuszczalny w wodzie. Środkiem spęczniającym żel i medium, do którego następowało wydzielanie, były odpowiednio etanol i woda. Stwierdzono, że szybkość wydzielania obydwu biocydów zależy od budowy chemicznej żelu i od związanej z nią wartości współczynnika retencji (WR) (tabeli 2). Im większa jest wartość WR, tym wydzielanie zachodzi szybciej. W początkowym okresie wydzielania (5-6 h) zaobserwowano liniową zależność ilości wydzielonego biocydu od czasu. Stwierdzono, że w odniesieniu do wszystkich badanych układów zależność szybkości wydzielania od wartości WR jest opisana tą samą uniwersalną funkcją (rys. 3).

EN

Radical polymerization was used to prepare 2-hydroxyethyl methacrylate (HEMA) and N-vinyl-2-pyrrolidone (NVP) copolymers differing in component proportions, which were crosslinked with butylene glycol dimethacrylate (DMBD) used in various amounts, containing ethanol-soluble estradiol or water-soluble salicylic acid as a model biocide. Ethanol and water were used as respectively a gel-swelling agent and a medium into which the model biocide was released. The kinetics of release of estradiol into ethanol was examined and described by an exponential equation. At the start, a zero-order kinetic equation was found to describe the release (Table 1). The kinetics of release of salicylic acid into water is summarized in Table 2. The release rate, k, was found to be related to the chemical structure of the gel and to the equilibrium content of ethanol or water (swellability) in the co-polymer as expressed by the solvent retention value, WR(E) or WR(W). During the first 6 hours, the rate of release was constant and related to the contents of HEMA and DMBD in the copolymer (Figs. 1 and 2). The higher the WR-value, the faster was the rate of release. The rate could be described by a universal function (Fig. 3) for each system under examination. The mechanism of the slow release of estradiol and salicylic acid appears to be related to the rate of solvent diffusion into the gel.