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Laser-modified PLGA for implants: in vitro degradation and mechanical properties

Kobielarz Magdalena, Tomanik Magdalena, Mroczkowska Katarzyna, Szustakiewicz Konrad, Oryszczak Magdalena, Mazur Anna, Antończak Arkadiusz, Filipiak Jarosław

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 1

179--192

EN

Irradiations of poly(lactic-co-glycolic acid) surface by CO2 laser lead to alterations of physicochemical properties of the copolymer. Effects of PLGA irradiations depend on the process parameters determining different cases of surface modification. Hence the main goal of presented studies was to define the influence of CO2 laser irradiation with different process parameters, inducing three cases of surface modification, on mechanical properties and topography of PLGA during degradation in the aqueous environment. Methods: Hydrolytic degradation of untreated and treated by CO2 laser thin specimens of PLGA was performed in distilled (demineralized) water. Mechanical properties of PLGA specimens before and during incubation were conducted in accordance with the PN-EN ISO 527-3:1998 standard. The pH of incubation solutions, topographies, masses and geometrical dimensions of specimens were controlled during the process. Results: During the hydrolytic degradation, gradual changes in failure mode were observed from ductile failure characteristic for untreated PLGA to brittle failure of incubated PLGA regardless of the case of induced modification. Tensile strength decreased with degradation time regardless of the case of surface modification with insignificant fluctuation Young’s moduli at the level of means. The pH of solutions for each case decreased and topography od specimens become smoother with incubation time. Conclusions: PLGA surface modification by CO2 laser below the ablation threshold (P1) and at the ablation threshold (P2) led to surface functionalization, however, irradiation above the ablation threshold (P3) caused marked degradation of PLGA and accelerated specimens disintegration during incubation in the aquatic environment.

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The influence of sterilization on properties of polyurethane/polylactide blend

Bednarz P., Bernasik A., Laska J.

Science, Technology and Innovation

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2018

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Vol. 2, no. 1

13--18

EN

The biodegradable polyurethane/polylactide blend was treated with low temperature hydrogen peroxide plasma, ethylene oxide and immersing in ethanol combined with ultraviolet radiation. The samples sterilized by hydrogen peroxide and ethylene oxide stood practically unaffected, while UV/EtOH caused distinct changes in their mechanical properties. For example the significant reduction of tensile strength occurred, elongation at break became twice lower, while the Young’s modulus increased by 23%. The XPS measurements showed that after all types of treatment atomic carbon and nitrogen concentrations in the surface layer was slightly lower than in the bulk. Instead the surface layer was more enriched with oxygen. Ethylene oxide sterilization caused that both surfaces became more hydrophobic i.e. the contact angle increased about 15% for the top surface and 8% for the bottom surface, respectively. Sterilization with ethanol and UV radiation changed the nature of surface into more hydrophilic, the contact angle of the top surface was reduced about 6% and the bottom about 24%. The FT-IR spectra of all sterilized samples were recorded and discussed. From all used sterilization methods only hydrogen peroxide plasma is fully suitable for biodegradable PU/PLA blend.

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The Effect Of Sodium Alginate Concentration On The Rheological Parameters Of Spinning Solutions

Brzezińska M., Szparaga G.

Autex Research Journal

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2015

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Vol. 15, no. 2

123--126

EN

The aim of the study was to determine the rheological properties of solutions of two types of sodium alginate in water. Rheological studies were carried out to determine the rheological properties of the spinning solutions. Polymer solutions of different concentrations were obtained. Based on the preliminary research of the concentrations of solutions, the proper n and k parameters were selected in order to obtain fibre by wet spinning from solution method. For selected concentrations of polymer solutions, the calcium alginate fibres were obtained.

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Kompozyty ceramika-polimer o osnowie z ceramicznego tworzywa porowatego z gradientem porowatości

Szafran M., Rokicki G., Bobryk E., Lamenta A.

Kompozyty

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2004

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R. 4, nr 11

231-236

PL

Przedstawiono wstępne wyniki badań nad otrzymywaniem kompozytów ceramika-polimer o osnowie z ceramicznego tworzywa porowatego z gradientem porowatości. Ceramiczne tworzywo porowate z gradientem porowatości wytworzono metodą laminowania i spiekania folii ceramicznych. Folie otrzymano metodą "tape casting". Proszkiem ceramicznym stosowanym w badaniach był Al2O3 o średniej wielkości ziaren 0,5 [mikro]m i powierzchni właściwej 8,28 m2/g (BET). Folie ceramiczne otrzymywano w układzie wodnym i niewodnym. W układzie wodnym spoiwem był poli(alkohol winylowy) plastyfikowany gliceryną, natomiast w układzie bezwodnym poliwinylowy butyral) plastyfikowany ftalanem n-butylu. Substancją porotwórczą stosowaną w badaniach była mikroceluloza o wielkości cząstek w zakresie 25-75 [mikro]m. W celu uzyskania ceramicznego tworzywa porowatego surowe folie ceramiczne układano w sposób przedstawiony na rysunku 1 i laminowano w temperaturze 110°C. Po procesie laminowania przeprowadzono proces spiekania kształtek w temperaturze 1550°C/1 h, uzyskując próbki o właściwościach przedstawionych w tabeli 1. Do tak przygotowanych ceramicznych kształtek porowatych wprowadzono makromonomery dimetaakrylowe, które syntezowano z dilaktydu i węglanu trimetylenu w sposób przedstawiony na rysunku 2. Założono, że stosunek części węglanowej do laktydowej będzie wynosił jak 1:1, 1:3 i 3:1. Makromonomery wprowadzono w pory, stosując podciśnienie, i przeprowadzono polimeryzację w porach ceramicznego tworzywa porowatego. Stopień zapełnienia porów wynosił od 60 do 81%. Obrazy przełamów osnowy ceramicznej i kompozytu ceramika-polimer przedstawiono na rysunku 5. Badania wytrzymałościowe otrzymanych kompozytów wykazały, że zależność naprężenia od odkształcenia dla kształtek kompozytowych ma inny charakter w porównaniu do kształtek bez polimeru w porach, przy jednoczesnym wzroście wytrzymałości od 10 do 20% (rys. 6 i tab. 3). Przedstawione badania wykazały, że metodą laminowania i spiekania folii ceramicznych można otrzymać ceramiczne tworzywo porowate z gradientem porowatości, którego pory można wypełnić biodegradowalnym polimerem o kontrolowanym stopniu biodegradacji.

EN

In the paper preliminary studies on the preparation of ceramics-polymer composites based on porous ceramic material with porosity gradient are presented. The porous ceramic material was obtained applying lamination and sintering of ceramic tapes. The tapes were prepared using tape-casting method. Al2O3 of average grain size 0.5 [micro]m and specific surface measured by the BET method equal to 8.28 m2/g was used as a ceramic powder. Ceramic tapes were prepared using water or organic solvent as a dispersing medium. In the water system poly(vinyl alcohol) plasticized with glycerin was used as a polymeric binder, whereas in nonaqueous system poly(vinyl butyral) plasticized with dibutyl phtalate was used. Microcellulose of particles size 25+7S um was applied as a porophore. To obtain porous ceramic material green ceramic tapes of different composition were laminated at 110°C (Fig. 1), and sintered at 1550°C for 1 h. The properties of the ceramic samples are presented in Table 1. To obtain ceramics-polymer composite dimethacrylic macromonomers were introduced into pores of the obtained ceramic samples. Macromonomers were synthesized by copolymerization of dilactide and trimethylene carbonate (1:1; 1:3; 3:1) and then reacted with methacryloyl chloride according to the scheme in Figure 2. Macromonomers were introduced into porous samples under reduced pressure and polymerized at room temperature using radical initiator. The degree of pores filling was in the range 60-80%. The pictures of the ceramics-polymer fractures are presented in Figure 5. The mechanical properties investigations of the composites indicated that the strain-stress behaviour is different from this for samples without polymer in pores. Mechanical strength of composite samples was 10 to 20% higher in comparison with that of unmodified ones (Fig. 6 and Tab. 3). The new method of obtaining ceramic material with gradient porosity that can be easily transform into ceramics-polymer composites was developed.