Materials Science Forum Vol. 955

Abstract: Presented work deals with the development of bio-source and biodegradable composite material for 3D printing. Polymer blend based on poly (3-hydroxybutyrate) (60 wt%) and poly (lactic acid) (25 wt%) plasticized by tributyl citrate (15 wt%) was used as a matrix. This base blend was filled with 10 vol% of kaolin or limestone. Zinc stearate was used for the surface treatment of the limestone samples. The mechanical and thermal properties of the composites, as well as their behavior during 3D printing process, were compared with unfilled blend and commercial poly (lactic acid) based 3D printing filament. Warping behavior, one of the main problems of 3D printing materials, was studied by means of warp coefficient. Cross-sections of specimens 3D printed under the same processing conditions were observed by the optical microscope. In the case of composite samples, individual filaments were separated. Despite the separation, composites filled with kaolin and with surface treated limestone exhibited satisfying mechanical properties. Scanning electron microscopy analysis confirmed good particle distribution of the samples with kaolin and surface treated limestone. No significant particle agglomerates were formed in the composites with limestone proving good dispergation ability of zinc stearate. Thermogravimetric analysis and Differential scanning calorimetry analysis showed no degradable effect of the used fillers on base polymer matrix. Observed results indicate that kaolin and surface treated limestone are suitable fillers for the bio-source composites used for 3D printing.

Abstract: Alkali substances are present in cements used as a binder in concrete only in a minimum content. The most known process that alkali causes is the alkali-silica reaction. In this reaction, the alkali contained in the cement or supplied from the outside with an inappropriately selected aggregate containing amorphous SiO₂. This reaction results in the development of hydration products, resulting in an increase in the volume of the original components, which can cause a breakage of the concrete structure and subsequent disintegration. The range of alkali-silica reaction can be reduced by the use of a suitable aggregate or the use of Type II admixtures which are characterized by pozzolanic or latently hydraulic activity. These admixtures react with alkali and then no longer react with the amorphous SiO₂ contained in the aggregate. Alkalis also affect other properties of concrete such as basic physical-mechanical properties, frost resistance and pH.In the experimental part the pH values were compared between mixtures of Portland cement and alkaline activated blast furnace slag using slag aggregate from the heap Koněv.

Abstract: In this paper, a novel technique for modification of PEDOT:PSS surface by the arginine-glycine-aspartic (RGD) acid, using a bifunctional photolinker sulfosuccinimidyl 6-(4’-azido-2’-nitrophenylamino) hexanoate (sulfo-SANPAH), is presented. The technique is based on the UV light initialized immobilization of the photolinker to the surface of the polymer and subsequent link of the RGD peptide to the photolinker via coupling reaction. The aim of this modification is the improvement of the biocompatibility and hydrophilicity of the polymer PEDOT:PSS. To confirm if the process of conjugation of RGD peptide to the surface of the polymer PEDOT:PSS was successful, the contact angle measurement, Fourier transform infrared spectroscopy, Raman spectroscopy and elemental analysis was performed. All of the obtained results indicate the conjugation of RGD peptide to the PEDOT:PSS surface was successful.

Abstract: Polyhydroxyalkanoates (PHA) are biodegradable polyesters, which are produced by various bacteria including numerous halophiles. Employment of halophilic strain for PHA production brings numerous benefits such as robustness of the process against contamination by ubiquitous mesophiles or possibility to isolate polymer from bacterial biomass via hypotonic lysis. In this work, we screened three moderate halophiles – Halomonas halophila, Halomonas organivorans and Halomonas salina for the presence of phaC gene encoding for PHA synthase and, subsequently, we have investigated their PHA production potential on various sugars. Among tested strains, H. organivorans demonstrated the extraordinary capacity of PHA production in particular on galactose and mannose since on these saccharides PHA content in dried bacterial cells reached 83 and 90 wt. % on mannose and galactose, respectively. Therefore, H. organivoras can be considered being promising PHA producing strain in particular suitable for the valorization of lignocellulose materials rich in galactomannans such as spent coffee grounds.

Abstract: In our research the influence of thermal heating on the release of plasticizers from plastics into the meat product and water was researched. The two most widely used plasticizers, dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), were detected. Both of the plasticizers have a negative effect on the health. And both are regulated by regulation of the European Union. In this study were researched phthalates in products prepared by sous-vide technology and it was studied effect of reheating on migration of phthalates. The average concentrations of both phthalate esters, DBP and DEHP, in heated water decreased. The average concentration of DBP in water before heating was detected 0.82 mg/100 ml and after heating 0.52 mg/100 ml, the average concentration of DEHP in water before heating was established 0.33 mg/100 ml and after heating 0.19 mg/100 ml. In plastic wraps, average DBP concentration with reheating increased and average DEHP concentration with reheating dropped. The average DBP concentration in plastic packaging, heating at 60 °C/12 h was determined of 9.87 mg/dm² after reheating 60 °C/1 h was detected of 15.40 mg/dm². The average concentration of DEHP in plastic packaging, heating at 60 °C/12 h was determined of 58.71 mg/dm² and after reheating 60 °C/1 h was detected of 28.28 mg/dm². The average DBP concentration in meat products due to reheating decreased, the average DEHP concentration in meat products increased. The average DBP concentration in meat products heating at 60 °C/12 h was detected of 8.39 mg/g dry matter and after reheating of 6.43 mg/g dry matter, the average DEHP concentration heating at 60 °C/12 h was determined of 25.37 mg/g dry matter and after reheating of 65.51 mg/g dry matter..

Abstract: The paper is devoted to application of the theoretical knowledge of material engineering into building practice through the transfer of knowledge. Companies do not have access to newly acquired research knowledge without active communication with research organizations, so they cannot implement the latest knowledge in their production processes, use them to innovate their products and thus improve their market position. This state of affairs, ie the use of outdated and overcome procedures, in the long run, causes the production of products which, by their quality, do not meet the expectations of customers and lead to a loss of competitiveness on the relevant market. The transfer of knowledge addresses the issue of improving the surface quality and extending the life of prefabricates using new knowledge from the research sphere and by improving the production processes in the company. As part of the experiment, the production of prefabricated concrete components was monitored in cooperation with the academic sphere and the cooperating company. Based on this observation, errors were identified in the production process and consequently remedial measures were proposed to improve the quality of end products and extend their service life.

Abstract: In this study the curing of an epoxy resin consisted of a diglycidyl ether of bisphenolA (DGEBA) resin and an aromatic Polyamine hardener was monitored combining a Raman-spectrometer and shear rheometry (Rheo-Raman). The set-up allow to carry out curing experiments at various temperatures (100, 120, 140 and 160 °C) where rheological measurements were performed using an oscillation rheometer and a plate-plate geometry while simultaneously Raman spectra were recorded. Raman-spectroscopy allows the determination of the reaction turnover and therefore the degree of cross-linking. Combined with the rheological data obtained, e.g. the gel point and the vitrification point, one can get a better insight in the processes occurring and the influence of different measurement parameters on the obtained rheological properties. Thus, the reaction turnover has been investigated at significant stages of the curing process.