Micro-hardness of surface layer of irradiated Polybutene Terephthalate (PBT)

Using high doses of beta radiation for polybutylene terephthalate (PBT) and its influence on the changes of micromechanical properties of surface layer has not been studied in detail so far. The specimens of PBT were made by injection moulding technology and irradiated by high doses of beta radiation (0, 132, 165 and 198 kGy). The changes in the microstructure and micromechanical properties of surface layer were evaluated using WAXS and instrumented microhardness test. The results of the measurements showed considerable increase in micromechanical properties (indentation hardness, indentation elastic modulus) when high doses of beta radiation are used.Ministry of Education, Youth and Sports of the Czech Republic within the National Sustainability Programme [LO1303 (MSMT-7778/2014)]; European Regional Development Fund under the project CEBIA-Tech [CZ.1.05/2.1.00/03.0089]; internal grant of TBU in Zlin [IGA/FT/2016/010]; Ministry of Education, Youth and Sports of the Czech Republi

Ultra nano-hardness of surface layer of irradiated high-density polyethylene (HDPE)

Using high doses of beta radiation for high-density polyethylene (HDPE) and its influence on the changes of micromechanical properties of surface layer has not been studied in detail so far. The specimens of high-density polyethylene (HDPE) were made by injection moulding technology and irradiated by high doses of beta radiation (0, 33, 66 and 99 kGy). The changes in the microstructure and micromechanical properties of surface layer were evaluated using WAXS and instrumented ultra nano-hardness test. The results of the measurements showed considerable decrease in micromechanical properties (indentation hardness, indentation elastic modulus) when low doses of beta radiation are used. © The Authors, published by EDP Sciences, 2017

Mechanical properties of surface layer of unfilled polypropylene

Using high doses of beta radiation for unfilled polypropylene (PP) and its influence on the changes of micromechanical properties of surface layer has not been studied in detail so far. The testing sapmles polypropylene (PP) were made by injection moulding technology and irradiated by high doses of beta radiation (0, 15 and 33 kGy). The changes in the microstructure and micromechanical properties of surface layer were evaluated using WAXS and instrumented ultra nano-hardness test. The results of the measurements showed considerable increase in micromechanical properties (indentation hardness, indentation elastic modulus) when low doses of beta radiation are used. © The Authors, published by EDP Sciences, 2017

The role of pediatric nurse and midwife in the laboratory screening of newborns

Newborn laboratory screening represents a pro-active blanket search for diseases in their early, pre-clinical stages. It uses an analysis of a dried blood drop on filtration paper. The blood is taken under specific conditions from all newborns born on the territory of the Czech Republic. The blood samples are collected by midwives and pediatric nurses, who are responsible for correct execution of the test. In 2009 the number of screened diseases increased from nine to thirteen. The samples are accompanied with double NCR cards to record all data about the newborn and the conditions of blood collection, including an NCR copy of demographical data. The midwife or pediatric nurse shall instruct the mother who should be present during the blood collection. In the theoretical part the author deals with the history of newborn screening, characteristics of the newborn screening and its principles, tested diseases, preparation, procedure and care after the test. The practical part used a combination of quantitative and qualitative research survey. The quantitative survey used inquiring with a questionnaire technique. The objective number 1 of the survey was to map the knowledge of pediatric nurses/midwifes about laboratory screening of newborns. The objective 1 was fulfilled. The hypothesis formulated in connection with the objective was: Pediatric nurses and midwives are familiar with the principles of laboratory screening. The hypothesis was confirmed. The research technique used for the qualitative survey was an in-depth interview. The objective number 2 was to map obstacles to the laboratory screening of newborns from the viewpoint of pediatric nurses and midwives. The objective 2 was fulfilled. The research question formulated in connection with the objective was: What are the obstacles to the collection of samples for laboratory screening of newborns? The research question was answered. The most frequent obstacles are poor blood flow, necessity to make more than one puncture and the fact that one prescribed drop of blood may not be sufficient for the testing. This bachelor degree thesis may serve as a source of information and study material for students of midwifery. The results of the research may be used as a teaching material at the University of South Bohemia

Surface Properties of Plasma-Modified Poly(1-butene)

Surface properties of poly(1-butene) films has been modified by a radio frequency plasma treatment. To minimize degradation and ageing effects it is necessary adjusted the gas composition and the plasma conditions on the polymer type. For this purpose plasma containing five various gasses or their mixtures: air, argon, argon then allylamine, argon wearing ammonia and argon with octafluorocyclobutane, were used. Changes in the surface hydrophilicity, roughness and the chemical composition of modified poly(1-butene) films were investigated by contact angle measurements, atomic force microscopy and X-ray photoelectron spectroscopy. All types of plasma treatment expect fluorocarbon plasma cause increase of polar functional groups on the surfaces and their hydrophilicity. On the other hand, fluorocarbon plasmas cause increase of contact angle and hydrophobicity

Thermal-induced transformation of mechanical properties of polybutene-1

The work directs attention towards the influence of annealing temperature on transformation of polymorphic composition and mechanical properties of isotactic polybutene-1 (PB-1). For these purposes, three different commercial-available grades of PB-1 were chosen. Specimens prepared by injection molding were annealed at given temperature (-22, +6, +22, +40 and +60°C) in the interval from 0 to 48 days. The changes in structure and properties were followed by tensile testing. A nonmonotonic evolution of tensile properties was observed

Evolution of physical and mechanical properties during phase transformation in poly(1-butene)

The work is focused on study of evolution of the physical and mechanical properties of poly(1-butene) (PB-1). This evolution was observed during the phase transformation from the metastable form II to the thermodynamically more stable form I. Three different commercially-available grades of PB-1 were used in this work; two homopolymers and one ethylene copolymer. Specimens were prepared by compression molding with three various thickness and by extrusion This specimens were annealed at five various temperatures of -22, 5, 22, 40, and 60 degrees C during a time. Content of the form I in specimens was calculated by wide angle X-ray scattering during the phase transformation. Physical properties were measured via density changes of specimens and changes of mechanical properties were measured via tensile testing. From density measurements, it is obvious that the different thicknesses of compression-molded specimens do not influence the evolution of rate of the phase transformation. Densities of compression-molded and extrudates posses virtually the same values after the phase transformation. The evolution of the Form 1 content was confirmed by the trends, which were observed, via density measurements and by tensile testing in the evolution of tensile modulus. The evolution of tensile properties was carried out on extrudates and the results were consequently compared with the evolution of injection-molded specimens. From this observation it was found that values of moduli in extrudates are remarkably higher than in the injection-molded specimens. This is a consequence of different morphological structures, which have direct impact on mechanical properties and the phase transformation in PB-1. It is evident that processing is a key parameter influencing mechanical properties and together with annealing temperature significantly influences the rate of the phase transformation of PB-1

Study of poly(1-butene) surface modified by air plasma treatment

A low-temperature pulsed direct current discharge air plasma treatment has been used to improve the surface properties of poly(1-butene) films. The changes in the surface hydrophilicity and roughness of modified poly(l-butene) films were investigated by contact angle measurements, scanning electron microscopy and atomic force microscopy. These experiments revealed that the plasma treatment can greatly change the surface chemistry as well as morphology of poly(l-butene). The polar functional groups generated due to plasma treatment on the surface of poly(l-butene) sheets causes decrease in contact angle. However, the aging process of the plasma treated samples showed that the effect was not permanent. Scanning electron microscope and atomic force microscope observations revealed that the surface topography was changed by air plasma etching, and the surface roughness increases

The role of molecular parameters of PP in the sensitivity to specific nucleation

The efficiency of β-nucleating agent (NU 100) in commercial isotactic polypropylenes (PP) differing in melt flow indexes (MFI) was analyzed. Polymorphic composition of neat PP and PP containing 0.01 and 0.03 wt.% of NU 100 was analyzed using wide-angle X-ray scattering and differential scanning calorimetry. Morphology was observed by polarized-light microscopy. MFI influenced the β-phase formation only with 0.01 wt.% of NU 100: The step change of β-phase content between PP with MFI 1 and 12 was observed. A significant effect of final temperature of heating on β-phase formation in the samples was detected. PP containing 0.03 wt.% of NU 100 crystallized into β-phase

Vývoj fyzikálních a mechanických vlastností během fázové transformace v poly(1-butenu)

Práce je zaměřena na studium vývoje fyzikálních a mechanických vlastností poly(1-butenu) (PB-1). Tento vývoj byl pozorován během fázové transformace z metastabilní fáze II do termodynamicky více stabilní fáze I. V této práci byly použity tři různé komerčně dostupné druhy PB-1; dva homopolymery a jeden etylen kopolymer. Vzorky byly připraveny lisováním ve třech různých tloušťkách a také vytlačováním. Vzorky byly temperovány v průběhu několika dní při pěti různých teplotách, a to -22, 5, 22, 40 a 60 °C. Obsah fáze I ve vzorcích byl zjištěn pomocí širokoúhlé rentgenové spektroskopie (WAXS) během fázové transformace. Fyzikální vlastnosti byly zjištěny měřením změn hustoty ve vzorcích a změny mechanických vlastností byly měřeny pomocí tahové zkoušky. Z měření hustoty vyplývá, že různá tloušťka lisovaných vzorků nemá vliv na vývoj rychlosti fázové transformace. Hustoty lisovaných a vytlačovaných vzorků vykazují po fázové transformaci prakticky stejné hodnoty. Vývoj obsahu fáze I byl potvrzen měřením hustoty a modulu pružnosti v tahu. Tahové vlastnosti se měřily na vytlačovaných vzorcích a výsledky byly následně srovnány se vstřikovanými vzorky. Bylo zjištěno, že hodnoty tahových modulů ve vytlačovaných vzorcích jsou výrazně vyšší než ve vzorcích vstřikovaných, a to z důvodu různých morfologických struktur, které mají přímý vliv na mechanické vlastnosti a fázovou transformaci v PB-1. Je evidentní, že způsob zpracování je klíčový parametr ovlivňující mechanické vlastnosti a zároveň s temperanční teplotou výrazně ovlivňuje rychlost fázové transformace PB-1.In the article the steps of polymer/clay nanocomposites preparation is described. It is going from the description of possible montmorillonite modifications to the problems of compounding of a polymer melt with nanofiller