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1

Optimizing Fused Deposition Modelling Process Parameters for Medical Grade Polymethylmethacrylate Flexural Strength

Obaeed Nareen Hafidh, Hamdan Wisam K.

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 1

349--359

EN

The production of functional parts, including those employed by the biomedical industry has been achieved a promising candidate in Fused Deposition Modelling (FDM). The essential properties of these biomedical parts which manufactured by additive manufacturing as compared to some other conventional manufacturing processes depend on structural and process parameters rather than material properties alone. Regarding to the evaluation the flexural strength of medical-grade, Polymethylmethacrylate PMMA has been received relatively very little investigation to date. PMMA is a biocompatible filament that be used in manufacturing of patient-specific implants such as dental prosthesis and orthopaedic implants. The proposed work explores the effect of three process parameters that vary with respect of three levels on the flexural strength. These levels can be specified by layer height (120, 200, 280 µm), infill density (40, 65, 90 %) and skewing angle (0º, 45º, 90º) on the flexural strength of medical-grade PMMA. Maximum and minimum flexural strength that be obtained in this work about (93 and 57 MPa) respectively. The analysis of variance (ANOVA) results shows that the most effective factor is the layer height followed by infill density. The flexural strength rises significantly with decreases layer height and the skewing angle is in zero direction. The process parameters have been optimized through utilizing of genetic algorithms. The optimal results that emerged based on genetic algorithm technique are approximately (276 μm) as layer height, (46 %) infill density and skewing angle (89 º) which maximize the flexural strength to (97 MPa) at crossover for ten generation.

2

Bezskurczowy materiał polimerobetonowy do wyrobów elektroizolacyjnych

Szubzda Bronisław, Paściak Grzegorz, Mączka Tadeusz, Kozieł Konrad

Wiadomości Elektrotechniczne

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2023

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R. 91, nr 6

9--12

PL

Polimerobeton bazujący na polimetakrylanie metylu (PMMA) charakteryzuje się wieloma właściwościami pożądanymi w wyrobach elektroizolacyjnych. Szczególnie istotna jest niskoenergetyczna technologia wytwarzania. Jednakże proces ten obarczony jest dość znacznym skurczem technologicznym utrudniającym właściwe uformowanie rozwiniętej drogi upływu elementu elektroizolacyjnego. W artykule omówiono sposób technologicznego niwelowania skurczu oraz dokonano prezentacji wyników badań wykonanych eksperymentów.

EN

Polymer concrete based on polymethyl methacrylate (PMMA) is characterized by many properties desirable in electrical insulating products. Also low-energy manufacturing technology is particularly important. However, this process results in quite significant technological shrinkage, which makes it difficult to properly form the developed leakage path of the insulating element. The article discusses the method of technological reduction of shrinkage and the presentation of the results of the performed experiments.

3

Effect of carbon fiber surface treatment with HNO3 and KOH on the interfacial bonding of PMMA resin composite

Jian Li

Materials Science Poland

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2023

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Vol. 41, No. 2

301--310

EN

This work studied the surface, interface state and physicochemical properties of HNO3-treated and KOH-treated carbon fiber. Poly(methyl methacrylate) (PMMA) composites were prepared by the autoclave molding process using surface-treated carbon fiber as reinforcements. The physical and chemical states of the carbon fiber surfaces and the micro-interface properties and interlaminar shear properties of the composites were studied. The results show that the surface of the HNO3-treated carbon fiber has more groove structure and higher surface roughness and thus forms a better physical bond with the resin matrix. Although the oxygen-containing functional groups of the two carbon fibers are equivalent, the surface oxygen of the HNO3- treated carbon fiber is relatively high, which is beneficial to form a better chemical bond with the matrix resin, and the interfacial shear strength is about 14% higher than that of the KOH-treated carbon fiber composite.

4

Studying the influence of waste glass and montmorillonite powders on the thermal conductivity and hardness of poly(methyl methacrylate) polymer matrix

Almansoori A., Ghadban R. A., Ali M. H., Sabri M. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2023

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Vol. 118, nr 2

49--56

EN

Purpose The present study aims to evaluate the effect of montmorillonite nanoclay (MMT) and waste glass powder (WGP) on the hardness and thermal conductivity of PMMA polymer composites. Thus, this study concentrates on the potential use of MMT and WGP as reinforcements, in different concentrations, in PMMA polymer matrix, with the expectation of improving the performance of PMMA polymer composites in various applications. Design/methodology/approach There is a growing demand for PMMA with increased mechanical properties and thermal stability for applications where inorganic glass would fail. Montmorillonite (MMT) clay and Waste Glass Powder (WGP) have physical and chemical properties compatible with PMMA. Therefore, they could potentially enhance PMMA’s hardness and thermal conductivity. Silicon dioxide in glass silica and MMT and octahedral aluminium hydroxide sheet in MMT can strengthen both covalent and hydrogen bonding architecture in PMMA composite for better mechanical strength and thermal conductivity. Thus, PMMA composites were designed by combining MMT powder and WGP powder in different ratios before being incorporated into the PMMA polymer matrix and tested for hardness and thermal conductivity. Findings The present study measured Brinell Hardness (HB) and electrical conductivity values of four PMMA composites containing different proportions of MMT and WGP. MMT/WGP filler mix had optimal hardiness (HB number = 74) when glass content was 1% (3MMT1G) or better still (HB number = 63) when an equal mix ratio was used (1MMT1G). PMMA composite with 3MMT1G also had the highest thermal conductivity (0.01899W/m.K-1). However, the higher the glass content, the lower the thermal conductivity of the PMMA composite. Thus, the present study has demonstrated that 3MMT1G filler was the best for enhancing the thermal and mechanical properties of PMMA composite. Research limitations/implications The results of this study demonstrate the potential of this new composite material for a variety of applications. Further research is needed to explore the full potential of this material and to develop new and improved versions. Practical implications Reusing waste glass as filler materials in composites requires minimal processing and therefore has lower environmental impacts than synthetic options. Originality/value Experimental data from the present study has provided new insights into Glass/MMT mix design in PMMA composites. The PMMA composite containing 3MMT1G exhibited the best hardness and thermal conductivity characteristics. Thus, the present study has successfully optimised Glass/MMT mix design for PMMA composite for applications requiring these features.

5

Synthesis of PMMA-HoVO4 nanocomposites by emulsifier-free emulsion polymerization: radical effects

Bulbul B., Pekcaliskan E. Y., Beyaz S.

Materials Science Poland

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2020

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Vol. 38, No. 1

143--150

EN

Poly(methyl methacrylate)-holmium orthovanadate (PMMA-HoVO4) nanocomposites were synthesized using emulsifierfree emulsion polymerization system in two ways. In the first one, the HoVO4 nanoparticle dispersion was added to the emulsion system before or after polymerization start (in situ polymerization). In the other one, nanoparticle dispersion and polymeric latex were mixed together at room temperature (blending). Crystalline HoVO4 nanoparticles (about 60 nm) were synthesized by coprecipitation method. Three different composite latexes were synthesized by varying the potassium persulfate concentration and the time of HoVO4 nanoparticles addition. According to the dynamic light scattering analysis, the size of the polymer beads in the latexes is between 244.8 nm and 502.5 nm and the PDI values are in the range of 0.005 to 0.206. Infrared spectral analysis showed that HoVO4 caused some changes in the structure of the polymer. Luminescence measurements attempted to determine optical properties of the nanocomposites. The results have shown that HoVO4 nanoparticles do not protect their structure due to the reaction with persulfate radicals but that they enter the polymer beads and change the luminescence properties of the polymer forming a new material with different properties.

6

The effect of glassy carbon and cancellous bone admixture on performance and thermal properties of acrylic bone cements

Choryłek P., Postawa P.

Archives of Materials Science and Engineering

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2020

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Vol. 104, nr 1

30--40

EN

Purpose: of the research is to physically modify the composition of bone cements with glassy carbon and cancellous bone to improve its performance, reduce polymerization temperature and reduce the ability of cements the effect of admixture on the phenomenon of relaxation. Design/methodology/approach: SpinePlex bone cement was modified with glassy carbon powder with 20-50 pm granulation with Maxgraft®. Maxgraft cancellous bone has been ground to 20-50 pm grains. Samples of unmodified cements (reference) and modified with glassy carbon and cancellous bone were prepared for the tests. The glassy carbon powder and ground cancellous bone were premixed with the cement copolymer powder, and then the premix prepared this way was spread in a liquid monomer. To delay the polymerization process, all components were cooled before mixing to 15°C. The addition of glassy carbon was 0.4 g and the addition of cancellous bone was 0.2 g per 20 g of cement powder, i.e. about 1.96% by mass. Polymerization temperature, relaxation and differential scanning calorimetry tests were performed on the samples made. Findings: Additives used allow: to reduce the polymerization temperature, as well as rheological properties. During the studies it was found that the additive which can meet the requirements is glassy carbon in form of powder and cancellous bone. Research limitations/implications: The results presented in the publication require further advanced research, which will be the subject of further modification attempts by the research team. Practical implications: The conducted tests showed a significant effect of glassy carbon as a modifier on the mechanical properties of cement after its solidification, but also on the course of the polymerization process. Temperature registration tests during crosslinking, tests of mechanical properties (behaviour of cement samples under load) and DSC differential scanning calorimetry analysis confirmed that the addition of glassy carbon had an effect on each of these aspects. Originality/value: The original in these studies is the possibility to improve fundamental properties of the selected bone cements by using different than commonly used additives.

7

Comparison of selected properties of cements modified with glassy carbon and cancellous bone

Choryłek P.

Archives of Materials Science and Engineering

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2020

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Vol. 105, nr 1

31--41

EN

Purpose: The aim of this manuscript was to study and analyse the properties of bone cement (VertaPlex) before and after modification with glassy carbon (Alfa Aesar) and human bone (MaxGraft). Design/methodology/approach: To achieve the assumed goal, a series of samples was made - five samples for each mixture, where: 5 bone cement samples, 5 bone cement samples mixed with 20-50 μm glassy carbon in the ratio of 1 g carbon per 40 g of cement, and 5 samples of bone cement mixed with 20-50 μm glassy carbon and human bone in the ratio of 1 g of carbon per 40 g of cement and 0.4 g of bone per 40 g of cement. The produced samples (4 for each mixture, 1 was the reference sample) were subjected to tests - compression test, microscopic observations with a 3D microscope, surface profile tests and hardness tests. Findings: The study has shown that modifications with glassy carbon and bone change the mechanical properties, as well as the strength of the samples. Compression tests have shown that the material without admixtures is characterized by the highest compressive strength and the doping of the glassy carbon itself makes the material more brittle. A significant increase in hardness was also observed for samples with glassy carbon and bones after the pressing process. Practical implications: The study was made synthetically, without taking into account the effect of the environment of body fluids and the human body temperature. This study is an introduction to further considerations where samples for which these conditions will be applied are currently being prepared. Originality/value: For commercial use, in treatment of patients, cements modified with glassy carbon and bone glassy carbon have not been used so far. Due to the prerequisites of a positive effect of glassy carbon addition on osseointegration and biocompatibility, the study in this area has been undertaken.

8

Statistical Comparison of the Hardness and Scratch-Resistance of the PMMA Polymers Used in Orthodontic Appliances

Domagała Ivo, Gil Leszek, Firlej Marcel, Pieniak Daniel, Selech Jarosław, Romek Dawid, Biedziak Barbara

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 4

250--261

EN

The paper presents the studies and results of the Shore hardness and scratch test of polymer materials used in medical devices. Polymers of organic PMMA (poly(methyl methacrylate)) origin for the manufacture of orthodontic appliances were tested. Samples of test materials differed in manufacturing technology. The surface functional properties of four materials were compared. Hardness tests were performed with the Shore D hardness test method. The scratch test was done with a Rockwell diamond cone indenter. The hardness was also calculated from the scratch test. Shore’s highest hardness was demonstrated in 1A material. But the differences in Shore’s hardness were small. Larger differences between the tested materials were shown in the scratch test than in the Shore hardness test. The lowest residual scratch depth (Rd) was obtained for 1A material. 3A material had the highest scratch hardness.

9

The effect of technological parameters of PMMA thermoplastic welding in the hot air stream on the quality of joints

Przewodowski Damian, Golański Dariusz

Welding Technology Review

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2019

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R. 91, nr 8

13--24

EN

The work covers the welding of thermoplastic polymethyl methacrylate (PMMA) and concerns the assessment of the impact of the main welding parameters on joint strength. The strength test of welded joints made of thermoplastic material was carried out. The aim of the study was to determine the influence of the main technological parameters of welding, such as: temperature and welding speed, gas stream output, filler rod pressure, diameter and type of hot air gun nozzle on the strength of the obtained joint. The method of sample preparation and testing was performed in accordance with the guidelines of PN-EN 12814-2:2002 "Tests of welded joints in semi-finished products made of thermoplastics ‒ Part 2: Tensile test". Visual evaluation of welded samples and analysis of results obtained from the tensile test made it possible to draw conclusions about the influence of selected welding parameters on joint strength. The decisive influence on the strength of joints was caused by welding defects, in the form of lack of side wall fusion and porosity.

PL

Praca obejmuje zagadnienia spawania tworzyw termoplastycznych polimetakrylanu metylu (PMMA) i dotyczy oceny wpływu głównych parametrów spawania na wytrzymałość złącza. Przeprowadzono badanie wytrzymałościowe spawanych złączy z materiału termoplastycznego. Celem badania było określenie wpływu głównych parametrów technologicznych spawania takich jak: temperatura i prędkość spawania, wydatek strumienia gazu, docisk spoiwa, średnica i rodzaj dyszy palnika na wytrzymałość otrzymanego złącza. Sposób przygotowania próbek i przeprowadzenia badania wykonano zgodnie z wytycznymi PN-EN 12814-2:2002 "Badania połączeń spawanych w półproduktach z tworzyw termoplastycznych - Część 2: Próba rozciągania". Ocena wizualna próbek po spawaniu oraz analiza wyników otrzymanych z przeprowadzonej próby rozciągania, umożliwiła wyciągnięcie wniosków na temat wpływu wybranych parametrów spawania na wytrzymałość złącza. Decydujący wpływ na wytrzymałość złączy mają niezgodności spawalnicze, w postaci przyklejeń brzegowych i pęcherzy gazowych.

10

Vertebroplasty and kyphoplasty - advantages and disadvantages used bone cement of PMMA

Choryłek P.

Journal of Achievements in Materials and Manufacturing Engineering

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2019

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Vol. 92, nr 1-2

36--49

EN

Purpose: This paper is a review of literature where the analyses of the commonly used bone cements were carried out especially: methods of manufacturing, surgical techniques, mechanical properties, biocompatibility studies as well as possibility of improvement some properties by using additives. Design/methodology/approach: The aim of this publication is the analysis of the state of knowledge and treatment methods on compression fractures, approximation of the specifics of compression fractures, presentation of minimally invasive percutaneous surgical techniques, description of features of the most common used bone cement on matrix Poly(methyl methacrylate) – (PMMA) and presentation cement parameters which affect potential postoperative complications. Findings: In considering to review of actual state of knowledge there is a need to find the additives which allow: to reduce the polymerization temperature, improve the biocompatibility as well as mechanical properties. During the studies it was found that the additive which can meet the requirements is glassy carbon in form of powder. Practical implications: Discussion allows to prepare samples during practical work with new kind additives in composite with bone cement as matrix. Originality/value: The original in this discussion is the possibility to improve fundamental properties of the selected bone cements by using different than commonly used additives.

11

Changes of structure and properties of PMMA-based bone cements with hydroxyapatite after degradation process

Laska-Leśniewicz Anna, Raczyńska Małgorzata, Wrotniak Maciej, Sobczyk-Guzenda Anna

Engineering of Biomaterials

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2019

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Vol. 22, no. 151

9--16

EN

PMMA-based bone cements are commonly used for implant fixation or as bone void fillers. Hydroxyapatite added as a filler to bone cement may positively affect the final properties of the material, in particular its biological properties. In this study, the preparation of poly(methyl methacrylate)-based bone cements with incorporated hydroxyapatite (HAp) is reported. The purpose of this article is to examine the proper-ties of bone cements enriched with HAp filler (the concentration of 3wt% and 6wt%) and reveal the changes in the composites properties (chemical structure, surface morphology and distribution of HAp in the composite matrix, moisture absorption, hardness in Shore D scale) during the long-term incubation in the PBS (phosphate-buffered saline) solution at 37°C. The incubation lasted up to 21 days, but only the period when the changes actually occurred was analysed. The studies have shown that the samples containing HAp absorb more moisture and have a lower hardness. These characteristics vary depending on the concentration of HAp. There is no elution of HAp and ZrO2 from the composite during the incubation. The surface morphology and chemical structure do not change during long-term studies. The obtained bone cements are characterized by high stability in the PBS solution.

12

Bond between single artificial teeth and the base plate in removable denture metal framework

Taczała J., Sawicki J.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 90, nr 1

11--21

EN

Purpose: The purpose of this paper is to analyse attempts at improving the bond between acrylic artificial teeth and the denture base plate - considered in the context of single incisors in framework denture. Design/methodology/approach: It is a review article focusing on the analysis of state of the art in the field of the bond between the polymerised acrylic (teeth) and the polymerising acrylic resin during the production of denture (denture plate). Previous works regard the issue of individual incisor teeth (both upper and lower) breaking off from the metal partial denture. Findings: The bond between artificial acrylic teeth and the acrylic denture plate of the prosthesis was discussed. Ways of improving this bond were also presented. Although researchers and companies offer many methods for improving this bond, none of them refer directly to the issue discussed in this article. In conclusion- the hitherto scientific achievements work well in the case of acrylic prostheses without a metal frame, which constitutes an obstacle for achieving the effect required. In this work, it is suggested that further research would not only develop and provide more detail on the issue of the bond between artificial teeth and the denture plate, but also solve the problem appearing in cases of metal partial denture. Originality/value: This article shows a significant problem that hasn’t been discussed in detail in the past.

13

Wpływ modyfikacji plazmowej na właściwości powierzchni elastycznych podłoży polimerowych przeznaczonych do zastosowania w transparentnej elektronice

Rogala J., Wojcieszak D., Obara K.

Elektronika : konstrukcje, technologie, zastosowania

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2018

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Vol. 59, nr 7

7--9

PL

W niniejszej pracy przedstawiono wyniki badań wpływu modyfikacji plazmowej na wybrane właściwości podłoży z poli(metakrylanu metylu) (PMMA), na które naniesiono cienką warstwę dwutlenku tytanu (TiO₂). Obróbkę plazmową dla różnych parametrów przeprowadzono w atmosferze argonu. Pomiary kąta zwilżania powierzchni podłoży z PMMA (dla wody) wykazały, że modyfikacja plazmowa ma wpływ na wzrost stopnia ich zwilżalności. Kąt zwilżania z początkowej wartości ok. 82° zmalał do ok. 52°. Wywołany efekt hydrofilowy nie miał bezpośredniego wpływu na zwilżalność cienkiej warstwy TiO₂, którą naniesiono później na podłoża z PMMA. Dodatkowo dla niepokrytych podłoży zbadano występowanie efektu starzenia. Potwierdzono, że wywołany efekt hydrofilowy zanikał z upływem czasu. Badania profilometrem wykazały, że chropowatość powierzchni PMMA zmieniała się w sposób nieliniowy wraz z czasem obróbki plazmowej.

EN

In this paper, effect of plasma treatment on chosen properties of poly(methyl methacrylate) (PMMA) surface was investigated. Plasma modification of PMMA substrates was performed in Ar atmosphere for different parameters. Measurements of wettability of PMMA surface demonstrated, that plasma modification enhanced its hydrophilic properties. Water contact angle decreased from 82° to 52°. Plasma-induced hydrophilic effect on PMMA surface has no direct effect on the wettability of TiO₂ thin layer, deposited after a plasma process. In addition, age effect of uncoated PMMA substrates was investigated. The research proved, that increased wettability of PMMA surface decreased in time after the treatment. At the same time, roughness of PMMA surface was changing in nonlinear way as a function of duration of plasma treatment.

14

Wpływ dodatku poli(metakrylanu metylu) na właściwości reologiczne paku węglowego

Ciesińska W.

Przemysł Chemiczny

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2017

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T. 96, nr 4

724--727

PL

Zbadano właściwości reologiczne paku węglowego modyfikowanego poli(metakrylanem metylu) (PMMA). Badania przeprowadzono za pomocą reometru w trybie oscylacji. Umożliwiło to analizę zmian właściwości lepkich i sprężystych bitumu, a na jej podstawie, ocenę oddziaływań między składnikami paku i modyfikatorem polimerowym. Otrzymane kompozycje odznaczały się zwiększoną odpornością termiczną i mechaniczną.

EN

Coal-tar pitch was blended with poly(methyl methacrylate) at 270°C for 0.5 h and studied for softening and dropping temps. and for rheol. properties (storage modulus, phase angle, loss factor, viscosity) by using an rheometer in oscillation mode. The pitch/poly(methyl methacrylate) blends showed an increased thermal and mech. resistance.

15

Evaluation of hydrophobic properties of organic layers modified with graphene flakes

Stańczyk B., Góra K., Jach K., Dobrzański L.

Materiały Elektroniczne

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2017

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T. 45, nr 1

18--24

EN

The paper presents the results of our research on graphene composites with organic polymers in various media. The following composites have been tested: PVDf/DMf/gr, PVDf/nMP/gr, PVDf/acetone/toluene/gr and PMMa/gr. The main purpose of this study is to evaluate hydrophobic properties of the selected materials by the contact measurements angle using the static method. the highest obtained value of the contact angle approached 180º for a superhydrophobic composite PVDf/acetone/toluene/gr.

PL

W artykule przedstawiono rezultaty prac dotyczących kompozytów grafenowych z polimerami organicznymi w różnych ośrodkach. Badano PVDF/DmF/GR, PVDF/NmP/GR, PVDF/aceton/toluen/GR i PmmA/GR. Główny przedmiot badań stanowiła ocena właściwości hydrofobowych wytypowanych materiałów. weryfikowano je za pomocą pomiarów kąta zwilżania metodą statyczną. Najlepszymi parametrami charakteryzował się kompozyt PVDF/aceton/toluen/GR, który wykazywał właściwości superhydrofobowe z wartościami kąta zwilżania wodą zbliżonymi do 180º.

16

Fabrication and Characterization of PMMA/HMX-based Microcapsules via in situ Polymerization

Jia X., Hou C., Tan Y., Wang J., Ye B.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 3

559--572

EN

Microcapsule technology was applied with nitramine explosives to improve their performance. Polymethyl Methacrylate (PMMA) was selected for the fabrication of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) based microcapsules. The PMMA/HMX-based microcapsules were prepared via a facile in situ polymerization of PMMA on the surface of the HMX crystals. Structural characterization of the PMMA/HMX microcapsules was studied systematically by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, and their thermal durability as well as their mechanical sensitivities were measured. The results indicated that spherical microcapsules were formed, with PMMA as the capsule wall and HMX as the core material. The SEM results showed that the grains of the PMMA/HMX microcapsules were spherical and that the particle distribution was homogeneous. XRD and FT-IR analyses indicated that the HMX polymorph was preserved in the optimal β-form during the whole preparative process. The DSC results showed that the PMMA/HMX microcapsules had better thermal decomposition performance, and that the apparent activation energy of the microcapsules had increased by 47.3 kJ/mol compared to the recrystallized HMX, and its thermal stability had greatly improved. In addition, the drop height (H50) had increased from 30.45 cm to 58.49 cm, an increase of 65.81%. Thus, microcapsule technology will have a very wide range of applications in reducing the sensitivity of high energy materials in the future.

17

DMA analysis of the structure of crosslinked poly(methyl methacrylate)s

Barszczewska-Rybarek I. M., Korytkowska-Wałach A., Kurcok M., Chladek G., Kasperski J.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 1

47--53

EN

Purpose: This paper presents the study aimed at the development of crosslinked poly(methyl methacrylate)s (X-PMMA) of varied crosslink density and the investigation of the relationships between the polymer network structure and dynamic mechanical properties. Methods: A series of model X-PMMA networks were crosslinked by the introduction of: 1, 2, 5, 10 and 20% of triethylene glycol dimethacrylate (TEGDMA). The copolymerizations led to various glass-rubber relaxation properties of the polymer networks, as revealed by dynamic-mechanical analysis (DMA). Glass temperature (Tg) and storage modulus above the Tg ( ) Erubbery  were a sensitive function of network architecture. DMA data were used for calculating the network parameter (Mc), crosslink density (q) and its alternative measure – the degree of crosslinking (DX). Results: The viscoelastic properties as well as structural parameters calculated from those showed correlation with the amount of the crosslinker. The increase in TEGDMA content resulted in the Tg, q and DX increases, whereas Mc decrease. The possible incomplete conversion of double bonds was detected in the DMA analysis, which was confirmed by the degree of conversion (DC), measured by FTIR spectroscopy. Additionally, some amount of sol fraction was found by 1H NMR experiments. Conclusions: The structure-property relationships developed for the system presented in this work could be useful in tissue engineering, where X-PMMA is applied. The direct measure of storage modulus values before and above glass transition may serve as a simple and fast indicator of the X-PMMA crosslink density.

18

The influence of deformation of selected thermoplastics on the friction with steel

Kujawa M, Niemiec A., Wieleba W.

Tribologia

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2016

|

nr 4

137--143

EN

Friction and wear of materials with additional deformation or stress is not a broadly described case. However, scientific publications considering this issue point out that additional deformation and stress ought to be taken into account during wear and friction analysis. In this article, the influence of strain in thermoplastics (POM, PTFE, PE-HD, PMMA) over the friction coefficient is described. Materials were deformed under tensile stress and examined after 24 hours. For specimens in which plastic strain was maintained, the decline of hardness (PE-HD: approximately 70% decrease, PTFE: approximately 40% decrease) and the reduction of the coefficient of kinetic friction (both PTFE and PE-HD: about 20% decrease) were observed. POM returned to its pre-deformed shape and PMMA was deformed without reaching its elastic limit. In these cases, only small changes in hardness (POM; approximately 10% decrease, PMMA: approximately 6% increase) and friction coefficients (maximum 4% change) occurred.

PL

Tarcie i zużycie materiałów odkształconych lub naprężonych w wyniku działania sił niepochodzqcych od współpracy w skojarzeniu nie jest obszernie opisanym zagadnieniem. Jednakże publikacje traktujące o tej tematyce są zgodne w jednym: stan odkształcenia i naprężenia w materiale powinien być brany pod uwagę przy analizie zjawiska tarcia i zużycia. W artykule opisano wpływ odkształcenia polimerów termoplastycznych POM, PTFE, PE-HD i PMMA na współczynnik tarcia polimer-stal. Materiały rozciągnięto i pozostawiono w stanie nienaprężonym na 24 godziny. W próbkach, w których wystąpiło i utrzymało się trwałe odkształcenie plastyczne zaobserwowano zmniejszenie twardości (dla PE-HD o okolo 70%, dla PTFE o okolo 40%) i redukcji współczynnika tarcia kinetycznego (dla obu polimerów o ponad 20%). POM, który całkowicie powrócił do pierwotnej postaci i PMMA rozciągnięty tylko w zakresie sprężystym wykazały niewielkie zmiany odnośnie do twardości (POM spadek o okolo 10% i PMMA wzrost o okolo 6%) i współczynnika tarcia (zmiana o maksymalnie 4%).

19

Characterisation of the bone cements on the basis of PMMA and organosilicon polymers

Sobczyk-Guzenda A., Rejs K., Kamińska M., Kaczorowski W., Szymanowski H., Niedzielski P.

Engineering of Biomaterials

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2016

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Vol. 19, no. 138 spec. iss.

99

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Problemy laminacji modułów PV z układem EVA-PMMA

Drabczyk K., Starowicz Z., Sobik P.

Elektronika : konstrukcje, technologie, zastosowania

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2016

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Vol. 57, nr 7

12--14

PL

Najczęściej spotykanym układem materiałów w modułach fotowoltaicznych jest układ szkło-EVA-ogniwo-EVA-tworzywo sztuczne. Układ taki gwarantuje bardzo dobre zabezpieczenie przed szkodliwym wpływem warunków zewnętrznych oraz stosunkowo dobrą statyczną wytrzymałość mechaniczną. Wadą takiego układu jest stosunkowo wysoka waga oraz niezbyt dobra odporność na obciążenia dynamiczne. Wady te wynikają z faktu zastosowania jako warstwy nośnej i zabezpieczającej szyby ze szkła hartowanego o typowej grubości 3,2 mm. W niniejszym artykule przedstawiono pierwsze badania dotyczące procesów laminacji modułów fotowoltaicznych w których zastąpiono szybę taflą polimetakrylanu metylu (PMMA). Do badań wybrano ogniwa na bazie krzemu polikrystalicznego oraz układy materiałów: (1) PMMA-EVA-ogniwa-EVA-tworzywo sztuczne oraz (2) PMMA-EVA-ogniwa-EVA-PMMA. Przedstawiono pierwsze problemy związane z zastosowaniem takich układów oraz zaproponowano sposoby ich rozwiązania.

EN

The most common PV module design is the layout of glass-EVAcell-EVA-plastic. This layout provides very good protection for external conditions and good mechanical strength. The disadvantage is the relatively high weight and limited mechanical resistance for dynamically changing stresses. These problems arise from the fact that the carrier and protective layer is made of thick (3.2 mm) tempered glass. This article presents the first study on the process of lamination of photovoltaic modules were the glass has been substituted by polymethyl methacrylate (PMMA). Polycrystalline silicon solar cells used for the experiments and applied in the two distinct configurations: (1) PMMA-EVA-cell-EVA-plastic, and (2) PMMA-EVA-cell-EVA-PMMA. The first initial issues of such layout were defined and solutions to address these issues were proposed and impelented.