Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 8

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  supercritical fluids
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
Biocomposite foam scaffolds of poly(ε-caprolactone) (PCL) with different porogenes were producedwith batch foaming technique using supercritical carbon dioxide (scCO2)as a blowing agent. Inperformed experiments composites were prepared from graphene-oxide (nGO), nano-hydroxyapatite(nHA) and nano-cellulose (nC), with various concentrations. The objective of the study was to explorethe effects of porogen concentration and foaming process parameters on the morphology and me-chanical properties of three-dimensional porous structures that can be used as temporary scaffolds intissue engineering. The structures were manufactured using scCO2as a blowing agent, at two variousfoaming pressures (9 MPa and 18 MPa), at three different temperatures (323 K, 343 K and 373 K) fordifferent saturation times (0.5 h, 1 h and 4 h). In order to examine the utility of porogenes, a number oftests, such as static compression tests, thermal analysis and scanning electron microscopy, have beenperformed. Analysis of experimental results showed that the investigated materials demonstrated highmechanical strength and a wide range of pore sizes. The obtained results suggest that PCL porousstructures are useful as biodegradable and biocompatible scaffolds for tissue engineering.
PL
Przedmiotem pracy jest proces wytwarzania kompozytowych struktur porowatych metodą spieniania przy użyciu ditlenku węgla w stanie nadkrytycznym. Materiałem poddawanym procesowi spieniania był poli(ɛ-kaprolakton) wzbogacony cząstkami porotwórczego hydroksyapatytu w różnych stężeniach. W pracy dokonano charakterystyki procesu spieniania poprzez wykonanie specjalistycznej analizy właściwości otrzymanych struktur. Otrzymane struktury charakteryzowały się rozmiarami porów w zakresie 5÷280 µm oraz wartościami porowatości 78÷89 %, co jest cechą pożądaną dla zastosowań tych struktur w biomedycynie.
EN
The aim of this work is the investigation into production of porous structures from composite materials based on poly(ɛ-caprolactone) supplemented with hydroxyapatite by supercritical foaming process using scCO2. The analysis of obtained porous structures’ properties using specialized analytical methods was performed. The obtained porous structures were characterized by the pore size in a range from 5 to 280 µm and porosity between 78 and 89%. These results ensured that obtained foams are suitable for potential applications in bone tissue engineering.
EN
The results of experimental investigations into foaming process of poly(ε-caprolactone) using supercritical CO2 are presented. The objective of the study was to explore the aspects of fabrication of biodegradable and biocompatible scaffolds that can be applied as a temporary three-dimensional extracellular matrix analog for cells to grow into a new tissue. The influence of foaming process parameters, which have been proven previously to affect significantly scaffold bioactivity, such as pressure (8-18 MPa), temperature (323-373 K) and time of saturation (1-6 h) on microstructure and mechanical properties of produced polymer porous structures is presented. The morphology and mechanical properties of considered materials were analyzed using a scanning electron microscope (SEM), x-ray microtomography (μ-CT) and a static compression test. A precise control over porosity and morphology of obtained polymer porous structures by adjusting the foaming process parameters has been proved. The obtained poly(ε-caprolactone) solid foams prepared using scCO2 have demonstrated sufficient mechanical strength to be applied as scaffolds in tissue engineering.
PL
Określono wpływ parametrów realizacji procesu spieniania poli(ε-kaprolaktonu) przy użyciu CO2 w stanie nadkrytycznym na właściwości otrzymywanych struktur porowatych. Zbadano wpływ na przebieg procesu następujących parametrów: temperatura (50-M00°C), ciśnienie (8÷18 MPa), czas nasycania polimeru ditlenkiem węgla (1÷6 h), szybkość dekompresji mieszaniny (1600-3600 bar/min) oraz czas spieniania (5÷30 min). Wytworzone struktury poddano analizie przy użyciu specjalistycznych metod badań. Wykazano silny wpływ warunków realizacji procesu spieniania na strukturę i właściwości pian stałych.
EN
The influence of process conditions of supercritical foaming of poly(ε-caprolactone) (PCL) on properties of obtained porous foams was investigated. The foaming experiments were performed at temperature varied in a range from 25 to 100°C, pressure from 8 to 18 MPa, saturation time from 1 to 6 hours with different depressurization rates. Finally, the properties of obtained porous three-dimensional structure using various analytical methods were identified. A strong influence of process parameters on morphology and mechanical properties of solid foams were noticed.
5
Content available remote Experimental investigations into foaming of biodegradable polymers using scCO2
EN
Results of experimental investigations of batch foaming of poly(ε-caprolactone) using scCO2 are presented in the paper. The high pressure system consisting of CO2 cylinder, scCO2 pump, high pressure cell, pressure and temperature gauge and back pressure regulator was applied in the experiments. The porous three-dimensional solid-gas structures were prepared for the following range of process parameters: temperature 298+373 K, pressure 8+18 MPa, time 1+4 h and depressurization rate 0.007+4 MPa/s. The significant influence of process parameters on the obtained foams morphology was identified.
PL
W pracy przedstawiono wyniki badań doświadczalnych procesu spieniania polikaprolaktonu (PCL) przy użyciu CO2 w stanie nadkrytycznym. Badania przeprowadzono w instalacji złożonej z butli CO2, pompy do płynów nadkrytycznych, komory wysokociśnieniowej, miernika ciśnienia i temperatury oraz regulatora ciśnienia wstecznego. Badania wykonano dla zakresu zmienności parametrów operacyjnych: temperatura: 398÷373 K, ciśnienie: 8÷18 MPa, czas nasycania: 1÷4 h, szybkość dekompresji: 0,007÷4 MPa/s. Wykazano silny wpływ warunków realizacji procesu spieniania na strukturę wytwarzanych pian.
EN
The improved one-pot synthesis of dimethyl carbonate and propylene glycol from propylene oxide, supercritical carbon dioxide, and methanol with potassium bicarbonate as the catalyst has been reported in this paper. As far as we know, it is the first time to use potassium bicarbonate only as the catalyst in the production process which is simple and cheap. Satisfactory conversion rate of propylene oxide and yield of the products could be achieved at the optimized conditions with quite a small amount of by-products. Our new method offers an attractive choice for the production of dimethyl carbonate in large-scale industry efficiently and environmental friendly.
PL
Ciecze jonowe i płyny nadkrytyczne to nowa klasa rozpuszczalników o unikatowych właściwościach, dzięki którym mogą być doskonałym zamiennikiem tradycyjnych rozpuszczalników w wielu procesach technologicznych. Nie stanowią one zagrożenia dla zdrowia człowieka i środowiska naturalnego, spełniają więc wymagania zielonej chemii. Ich zastosowanie napotyka pewne bariery wynikające z wysokiej ceny w przypadku cieczy jonowych oraz instalowania kosztownej aparatury w przypadku ekstrakcji płynami nadkrytycznymi.
EN
Ionic liquids and supercritical fluids are a new class of solvents. Their unique properties make them an excellent alternative to traditional solvents in many technological processes. They pose a threat neither to human health nor to natural environment - in that way they meet the 'green chemistry' requirements. Their application meets, however, some barriers which stem from high costs, when it comes to ionic liquids, and employing high pressure equipment as well as bearing expenses on compressing solvents in the case of supercritical fluid extraction.
8
EN
Investigation of the diffusion process taking place during removal of ethanol as a primary solvent from silica alcogel structure with near-critical carbon dioxide as a secondary solvent is presented. The investigation was conducted with two methods following this unsteady-state drying process. In the first method advantage was taken of the phenomenon of partial internal sample destruction during the process of secondary solvent removal. The second method was based on the analysis of the history of outlet concentration of the primary solvent. The experimental techniques are briefly described. The obtained values of effective diffusion coefficients of near-critical carbon dioxide and ethanol in the gel structure are listed. The correlation of the effective diffusion coefficient in the porous structure of silica gel is presented.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.