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1

Preparation of hexamethylol melamine resin with low crystallization water and low viscosity for hexamethylol melamine/polyvinyl alcohol composite membrane

Liu Xing-Jian, Gu Yan-Wen, Zhen Jian-Fei, Wu Jiang, Hu Bing

Polish Journal of Chemical Technology

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2022

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Vol. 24, nr 1

47--56

EN

Hexamethylol melamine resins (HMM) with low crystallization water content and low viscosity were prepared by inhibiting the condensation polymerization of low hexamethylol melamine. The effects of catalyst, pH, formalde-hyde/melamine ratio, reaction temperature and time on the synthesis parameters of HMM were investigated. The results showed that the sample (HMM8) synthesized with Na2CO3-NaHCO3 as catalyst had the crystallization water content lower than 10%, being with a viscosity of about 0.26 Pa·s. The melting temperature of HMM8/polyvinyl alcohol (PVA) curing system was about 164.3 oC. It was found that the higher the amount of formaldehyde, the greater the hydroxyl methyl bounded to each triazine ring. Compared with the traditional melamine formaldehyde resin which had the crystallization water content of about 20–30%, the production of this resin was expected to reduce the energy consumption of industrial reaction, while the resin with 10% crystallization water content was more conducive to the development of alloying HMM/PVA composite membrane.

2

The relationship between the structural anisotropy of the PFA polymer/compressed expanded graphite-matrix composites and acoustic emission characteristics

Berdowska Sylwia, Berdowski Janusz, Aubry Frederic

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 5

art. no. e138235

EN

The main aim of the study was to search for the relationship between the anisotropy of the structure of polyfurfuryl alcohol (PFA) – polymer/compressed expanded graphite (CEG)-matrix composites at subsequent stages of the technological process and characteristics of the acoustic emission (AE) descriptors. These composites, obtained after successive technological procedures of impregnation, polymerization, and carbonization, possess different structure, densities, porosity, and other physicochemical properties. In the structures of composites prepared on the basis of CEG, two basic directions can be distinguished: parallel to the bedding plane of graphite sheets and perpendicular to it. The measurements were carried out for the stress acting in these two main directions. The investigation has shown that the AE method enables the detection of anisotropy in the structure of materials. The results of the research show that all four of the acoustic emission descriptors studied in this work are sensitive to the technological stages of these materials on the one hand and their structure anisotropy on the other. Fourier analysis of the recorded spectra provides interesting conclusions about the structural properties of composites as well as a lot of information about the bonding forces between the carbon atoms of which the CEG matrix is composed and the PFA polymer or turbostratic carbon.

3

Study of Graphite - Polymer - Turbostratic Carbon Composites by Acoustic Emission Method at Perpendicular Geometry

Berdowska A., Berdowski J., Aubry F.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1287--1293

EN

The purpose of this paper was to search the relations between the structure of the compressed expanded graphite–polymer–turbostratic carbon composites on successive stages of technological treatment and parameters describing the acoustic emission phenomena in these materials. The acoustic emission method can be used for measurements of changes in the structure and many different properties of materials. These investigations are a continuation of our earlier studies concerning physical, mechanical and chemical properties of porous composites created on the basis of a compressed expanded graphite matrix, obtained after successive technological procedures of impregnation, polymerization and carbonization of polyfurfuryl alcohol. The aim of this work was to investigate materials obtained at different levels of technological processing, thus with different densities, porosity, physical and chemical properties, by using the acoustic emission method. In compressed expanded graphite composites structures one can differentiate two basic directions: perpendicular to the bedding plane of graphite flakes and parallel to this one. The all presented results were obtained for the uniaxial strain applied in the direction perpendicular to the bedding plane of the composite structure. Analysis of acoustic emission parameters provides information on physical and chemical processes in these materials.

4

Vibration analysis of composite circular and annular membranes

Siedlecka U., Zamorska I., Kukla S.

Journal of Applied Mathematics and Computational Mechanics

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2016

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Vol. 15, nr 1

149--159

EN

In this paper a solution to the free vibration problem of composite circular and annular membranes is presented. The vibrations of membranes whose material densities and/or thicknesses varied step-wise with the radial co-ordinate are considered. This approach is applied to approximate the solution to the vibration problem of a membrane with continuously varying density and/or thickness with the radial co-ordinate. The obtained analytical solutions are used in numerical investigations into the effect of parameters characterizing the composite membranes on their eigenfrequencies.

5

Study of properties of expanded graphite - polymer porous composite by acoustic emission method

Berdowski J., Berdowska S., Aubry F.

Archives of Metallurgy and Materials

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2013

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Vol. 58, iss. 4

1331--1336

EN

The purpose of this paper was to investigate the physical and mechanical properties of compressed expanded graphite (CEG) and their porous derivatives after impregnation, polymerization; and carbonization by the use of acoustic emission method (AE). The mechanical and structural characteristics of compressed expanded graphite and their three groups of porous composites after each technological process are presented and discussed. The measurements of acoustic emission parameters in these materials were carried out at wide range of frequency of the waves (0.1÷2.5 MHz). The changes of two of parameters: - AE pulses counts rate and spectrum distribution of AE waves - are presented in this paper. The analysis of the respective parameters AE also gives possibility to determine the micro- and macro structural changes of materials at different levels of technological processes. Applications of these materials as catalysts with high specific surface make them very interesting subject of study. Also compressed expanded graphite composite membranes prepared from furfuryl alcohol polymers are promising for gas separation.

PL

Cel pracy stanowiło zbadanie przy użyciu metody emisji akustycznej (EA) fizycznych i mechanicznych właściwości sprasowanego grafitu ekspandowanego (SGE) i jego porowatych pochodnych kompozytowych, otrzymanych po procesach impregnacji, polimeryzacji i karbonizacji. Przedstawiono i przedyskutowano mechaniczne i strukturalne charakterystyki sprasowanego grafitu ekspandowanego i trzech porowatych kompozytów otrzymanych na jego bazie, po kolejnych procesach technologicznych. Pomiary parametrów zarejestrowanych sygnałów EA w tych materiałach wykonano w szerokim przedziale częstotliwości emitowanych w materiale fal (0,1-2,5 MHz). W pracy przedstawiono zmiany dwu z tych parametrów: szybkości zliczeń impulsów i rozkładu widmowego emitowanych fal. Analiza poszczególnych parametrów emisji akustycznej stwarza możliwości określenia mikro- i makrostrukturalnych zmian w materiałach, wytworzonych na różnych etapach procesu technologicznego. Przewidywane szerokie zastosowanie tych materiałów jako katalizatorów, posiadających bardzo duże powierzchnie właściwe, czyni je niezwykle interesującym przedmiotem badań. Również bardzo perspektywiczne jest wykorzystanie kompozytowych membran z matrycą ze sprasowanego grafitu ekspandowanego, wypełnionego polimerem alkoholu furfurylowego. do separacji gazów.

6

Green's functions for interior and exterior Helmholtz problems

Kukla S., Siedlecka U., Zamorska I.

Prace Naukowe Instytutu Matematyki i Informatyki Politechniki Częstochowskiej

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2012

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Vol. 11, nr 1

53-62

EN

In the paper, the derivation of Green's functions for Helmholtz equation in circular, annular and exterior circular domains is presented. The Green's functions are assumed of the form a cosine series. An example of application of the Green's functions in frequency analysis of a composite membrane is presented.

7

Wpływ stężenia roztworu modyfikującego na kompozytową membranę PP/PDMS do separacji gazów

Bojarska M., Macierzyńska I., Szwast M., Piątkiewicz W.

Inżynieria i Aparatura Chemiczna

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2011

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Nr 5

22-23

PL

Najczęściej wykorzystywane do separacji gazów są membrany kompozytowe, składające się z warstwy nośnej i selektywnej. Zasadnicza separacja odbywa się w warstwie selektywnej, dlatego właśnie skupiono się na doborze odpowiednich warunków jej wytwarzania. Analiza wyników pozwala stwierdzić, iż niskie stężenia należy wykorzystywać do wykonywania warstwy uszczelniającej. Natomiast do warstwy selektywnej należy wybierać wyższe stężenia, co w efekcie daje jednolitą i o średniej grubości warstwę. Słowa kluczowe: separacja gazów, membrana kompozytowa, PDMS

EN

Composite membranes are frequently used for gas separation. They ar made of a support and selective layer. Separation takes place in the sclectiv layer. Our attention was focuscd on the selection of appropriate modificatio conditions. It was found that low concentrations should be used to perfon the sealing layer. However, the selective layer should be made from highc concentrations. Which results in an average thickness and uniform layer.

8

Membrany kompozytowe przeznaczone na implanty okulistyczne

Stodolak E., Krok M., Gumuła T., Błażewicz S.

Kompozyty

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2009

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R. 9, nr 4

352-357

PL

Zaprojektowano i wykonano materiał kompozytowy przeznaczany na śródgałkowy implant okulistyczny (implant keratocytowy). Materiałem bazowym był syntetyczny niedegradowalny terpolimer (PTFE-PVDF-PP) o stwierdzonej biozgodności (norma PN-EN ISO 10993). Jako fazę porotwórczą zastosowano biodegradowalny polimer-alginian sodu (NaAlg), którego użyto w formie proszku i włókien. Biopolimer mieszano z roztworem terpolimeru. Kompozyty otrzymywano metodą odlewania, a następnie poddawano je obróbce fizykochemicznej w celu nadania im niezbędnej porowatości. W ten sposób otrzymano biomateriał o wysokiej porowatości otwartej z systemem porów połączonych. Średnia wielkość porów w biomateriale zależy od rozmiaru cząstek fazy porogennej oraz od jej rodzaju (włókna lub proszek NaAlg). Membrana kompozytowa jest tworzywem trwałym, odpornym na długotrwałe obciążenia zarówno statyczne, jak i dynamiczne. Niewielki wzrost porowatości i wzrost wielkości porów obserwowany po testach zmęczeniowych nie powoduje deformacji tworzywa membrany i nie prowadzi do jej zniszczenia. Powierzchnie membran mają charakter silnie hydrofobowy (wyniki pomiarów kąta zwilżania i energii powierzchniowej), co utrudnia adhezję makromolekuł, będącą powodem blokowania się porów membrany. Wysoki kąt zwilżania utrzymuje się również w przypadku zastosowania jako cieczy pomiarowej medium hodowlanego wzbogacanego albuminą. Otrzymane wyniki eksperymentalne stanowiły podstawę do podjęcia dalszych badań nad zachowaniem się materiałów membranowych w warunkach in vivo.

EN

Glaucoma is an disease in which increased intraocular pressure causes damages of the eye structure. This leads to destruction of ophthalmic nerve, and as a result, changes of the field of vision. As a secondary effect secondary changes in the eye structure are observed. The disease is caused by blocking of a natural porous eyeball structure so called drainage angle. Inflow of the aqueous medium from inside the eye to the anterior chamber is more difficult than in physiological state. This state leads to excessive accumulation of the aqueous medium in the eye ball. As a result, the increased intraocular pressure causes tissue ischemia and afterwards their necrobiosis leaing to atrophy of the ophthalmic nerve. The role of materials used in therapy of glaucoma is to decrease the pressure inside eye. Materials for such application should fulfill main criteria, such as biocompatibility, biostability and appropriate high porosity. Moreover, it is necessary to provide nonpenetrating filtration inside the eye. For long-term-use, the material applied for cornea implants also have to withstand static pressure and dynamic pressure changes and have to be stable in biological environment. Therefore, its durability in in vitro conditions plays an important role. A new composite material for intraocular ophthalmic implant (keratitis implant) was designed and manufactured. The composite matrix based on a synthetic non-degradable terpolymer (PTFE-PVDF-PP) with certified biocompatibility (PN-EN ISO 10993 standard). As a porogenic phase bio-degradable polymer - sodium alginate (NaAlg) in the form of powder and fibres was used. The biopolymer was mixed with terpolymer solution. Composites were manufactured by casting technique followed by such a physicochemical treatment which led to obtaining appropriate porosity. This procedure enable to manufacture biomaterial possessing high open porosity with interconnected pore system. The average pore size in biomaterial remains in relation with size of porogenic phases and the type of porogenic phases (fibres or particles of NaAlg). The composite membrane is a material durable and resistant to long-term static and dynamic loads. The slight increase of total porosity and pore size which was observed after fatigue tests did not lead to deformation of the membrane material and did not lead to its destruction. Surfaces of the membrane materials were highly hydrophobic (results of wetting angle measurements and surface energy determination). That prevent adhesion of macromolecules responsible for blocking of membrane pores. High value of wetting angle were registered not only in case of distilled water but also in case of using plasma enriched with albumins. On the basis of results of these experiments new tests in in vivo conditions were continued.

9

Anisotropic gas transfer through the composite membranes

Kurchatov I. M., Laguntsov N. I., Okunev A. Y., Pisarev G. I., Tronin V. N., Uvarov V. I.

Ars Separatoria Acta

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2007

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No. 5

45-54

EN

Using of stochastic dynamics methods, the probability distribution function of molecules by their moving directions in arbitrary porous media, where free molecular flow takes place, was determined. It was shown that, in some cases, the molecules in the channel can generally move athwart the channel, while an average velocity of molecules moving along the channel can significantly decrease. The anisotropic phenomenon and the hysteresis of permeability through composite asymmetric membranes were qualitatively explained.

10

Membranowe materiały kompozytowe na potrzeby medyczne - podstawowe badania materiałowe i biologiczne

Stodolak E., Zaczynska E., Błażewicz M., Wołowska-Czapnik D., Leszczyński R.

Kompozyty

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2006

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R. 6, nr 4

47-51

PL

Badaniu poddano serie próbek kompozytowych: włókno z alginianu sodu w osnowie polimeru syntetycznego, różniących się udziałem procentowym włókien (1, 1,5, 2; 2,5 i 3% włókien). Za osnowę kompozytów posłużył terpolimer PTFE-PYDF-PP o zawartości procentowej poszczególnych merów: 56% PTFE, 27% PVDF i 17% PP. Czysta folia polimerowa niezawierająca włókien stanowiła odniesienie w stosunku do próbek kompozytowych. Wprowadzenie włókien z biopolimeru do hydrofobowego materiału polimerowego miało na celu poprawę biozgodności kompozytu. Dodatkowo spodziewano się, że włókna z alginianu sodu, rozpuszczanie w wodzie, ulegną w trakcie inkubacji rozpuszczeniu i wymyciu z osnowy polimerowej, a tym samym utworzą nowy rodzaj materiału: membranę, której średnica porów równa będzie przekrojowi pojedynczego włókna. Badaniu poddano zestaw kompozytów, dla których określono: wielkość kąta zwilżania przed i po wypłukiwaniu włókien, wyznaczono procentowy ubytek masy, a także zmianę grubości kompozytu przed i po inkubacji. Wykonano również test przepuszczalności otrzymanych membran kompozytowych, określając zmianę stężenia soli NaCl po przejściu przez membranę. Test prowadzono przez 14 dni w temperaturze 37 stop. C. Teksturę powierzchni i wzrost udziału porów obserwowano w skaningowym mikroskopie elektronowym (SEM). Membrany kompozytowe do zastosowań medycznych poddano ocenie cytotoksyczności. Próbki kontaktowano z ludzką linią komórek nabłonkopodobnych raka płuc po 24 i 72 godz. kontakcie komórka--materiał (ATCC CCL 185 - A549) określano zmiany ilościowe i morfologiczne komórek (odwrócony mikroskop kontrastowo--fazowy). W celu określenia przeżywalności komórek zastosowano metodę kolorymetryczną - barwienie błękitem trypanu.

EN

Polymer implant materials have been widely applied in medicine within the past several years. Polymers defined as biostable find use as vascular implants, surgical threads and elements of various types of endoprostheses. They are also useful as laryngological, dental, cardiosurgical and neurological implants. Recently, composites made of polymers combined with such materials as bioactive ceramics, ceramic or carbon fibres, are being increasingly used in clinical practises. Fibrous polymer implants become an alternative to pure ceramic or metal implants in biomaterials engineering. The distribution of fibers in polymer matrix affects not only its mechanical parameters, but also the surface properties, such as wettability, roughness, etc. It seems necessary to examine the effects of fibers on polymer matrix before commencing works on design of composite materials for medical applications. It is also important to define whether composites based on polymer matrix would not be toxic for living cells. The experiments were carried out on polymer membranes made of polymer and soluble alginate fibres. The aim of the work was the analysis of cellular response to polimer matrix, functionalized with use of resorbable (soluble) fibres. Materials in form of membranes and fibre/polymer composites of different microstructures were put in contact with one type of cell under in vitro conditions (viability of cells presented in Tables 2-3). The surface morphology of composite materials was observed using scaning electron microscope Jeol, JSM-5400. Figure 2 AI-EI shows surface images of polymer sample (foil), and surface of composite materials before dissolved the alginate fibres. Figure 2 AII-EII presents the photomicrographs of membrane surfaces. Changes of masses and thickness of composites material during dissolved biopolimer fibres (32 h/80°C) are shown in Table 1. Polymer membranes produced by washing out of alginate fibres have surfaces showing pores of irregular as well as spheroidal shape. This study suggests, that the composite materials which is compounds with biostable matrix and alginate fibres (biopolymer) may be used like membrane in ophthalmology (cornea implants).