Phase structure and tensile creep of recycled poly(ethylene terephthalate)/short glass fibers/impact modifier ternary composites

Binary and ternary composites of recycled poly(ethylene terephtalate) (rPET), short glass fibres (SGF) and/or impact modifier (IM) were prepared by melt compounding and injection moulding. SEM images of rPET/IM fracture sur- faces indicated that IM particles of about 1-2 μm in diameter were uniformly distributed in the rPET matrix, but with a poor adhesion level. Microphotographs of PET/SGF composites evidenced brittle fracture proceeding through the matrix and strong adhesion between components. In ternary composites SGF were evenly distributed, while IM particles were no longer detectable. Tensile creep of rPET and prepared composites was investigated under short and long term testing conditions at various stress levels. Main part of the tensile creep corresponded to the elastic time-independent component, while the time- dependent component was rather limited even at relatively high stresses. While SGF accounted for a significant decrease in the overall creep compliance, the incorporation of IM induced a small decrease in the compliance and a non-linear vis- coelastic behavior. In ternary composites, the reinforcing effects of SGF was dominating. Under a constant stress, the log- arithm of compliance grew linearly with the logarithm of time. The creep rate, which resulted to be generally very small for all tested materials, was slightly reduced by SGF and increased by IM

Barrier Properties of Filled High-impact Polystyrene

Tato práce je zaměřena na hodnocení vlivu různých druhů plniv o různých koncentracích v hPS na bariérové a mechanické vlastnosti. Cílem je srovnat vliv různých druhů (nano)plniv na propustnost pro plyny a vodní páru. Úroveň rozmíchání nanoplniva v polymerní matrici bylo stanoveno pomocí RTG analýzya TEM. Získané výsledky naznačují, že zde existuje korelace mezi velikostí částic nanoplniva a konečnými vlastnostmi. Některé vzorky vykázaly zlepšení bariérových vlastností.This work is focused on the evaluation of the effect of different kinds of fillers with various concentrations in high impact polystyrene on barrier properties, hardness and resilience. The aim is doing comparison of the effect of different kinds of fillers and nanofillers on gas and water permeability. Dispersion of nanofiller in polymer matrix was determined by X-ray diffraction and transmission electron microscopy. Gathered results indicate that there is a correlation between the size of the filler particles and final compound properties. Some samples showed an improvement of barrier propertie

The Genealogy of the Plzeň Revolt on June 1, 1953: An Analysis of Public Collective Protests of the Plzeň City Population in the Years 1948-1953

P edkládaná diserta ní práce analyzuje jeden z nejrozsáhlejších protest éry eskoslovenského stalinismu, plze skou ervnovou revoltu proti pen žní reform v roce 1953. Metodologicky p itom vychází z teorií tzv. nových sociálních hnutí. Známý plze ských incident proto zasazuje do kontextu p edchozích protestních akcí, které se odehrály v plze ské lokalit v rozmezí let 1948-1953. Takový postup autorovi umož uje mapovat vývoj n kolika r zných protestních kultur, které dlouhodob p sobily v jednotlivých ástech spole nosti v západních echách a které v roce 1953 každá svým osobitým zp sobem inspirovaly vznik i pr b h plze ské revolty. Práce tak p ináší nejen výrazn zp esn ný kritický popis ervnových protest , ale též jejich kulturní rodokmen. Prost ednictvím tohoto rodokmenu autor odkrývá strukturu hlavních sociálních hnutí, která se revolty ú astnila, a s nimi spojený soubor spole enských konflikt , ze kterých protesty vycházely. Byly to zejména tyto t i: sociáln motivované stávkové hnutí pr myslových d lník , hnutí pro-západn orientované studentské i d lnické mládeže a latentní pnutí uvnit komunistické strany, které se projevovalo pasivní rezistencí její lenské základny v i lokálním stranickým "diktátor m".The presented dissertation thesis analyzes one of the largest protests of the Czechoslovak Stalinism-era - the Plze revolt against the currency reform in June 1953. From a conceptual perspective, the work draws on the theory of the so-called new social movements. Therefore it sets the well-known Plze incident into the context of previous protest actions that occurred in the Plze region in the course of the years 1948-1953. This method enables the author to chart the development of several varied protest cultures which had been employed in particular parts of society in Western Bohemia on a long term basis and which inspired the inception and the course of the Plze revolt in the year 1953. This way the work offers not only a considerably more precise critical description of the June protests but also their cultural genealogy. By the means of this genealogy the author reveals the structure of the main social movements that took part in the revolt and an associated complex of social conflicts that caused the protests. There were in particular the following three: a socially-motivated strike movement of industrial blue-collars, a pro-western movement of both student and blue-collar youth and a latent tension within the communist party which was becoming evident through a passive resistance of its rank...Institute of Czech HistoryÚstav českých dějinFilozofická fakultaFaculty of Art

Structure characterization and biodegradation rate of poly(ε-caprolactone)/starch blends

The present paper focuses on the effects of blending poly (ε-caprolactone) (PCL) with thermoplastic starch (TPS) on the final biodegradation rate of PCL/TPS blends, emphasizing the type of environment in which biodegradation takes place. The blends were prepared by melt-mixing the components before a two-step processing procedure, which strongly affects the degree of plasticization and therefore the final material morphology, as was detailed in the previous work, was used for the thermoplastic starch. The concentration row of pure PCL over PCL/TPS blends to pure TPS was analyzed for biodegradation in two different environments (compost and soil), as well as from a morphological, thermomechanical, rheological, and mechanical point of view. The morphology of all the samples was studied before and after biodegradation. The biodegradation rate of the materials was expressed as the percentage of carbon mineralization, and significant changes, especially after exposure in soil, were recorded. The crystallinity of the measured samples indicated that the addition of thermoplastic starch has a negligible effect on PCL-crystallization. The blend with 70% of TPS and a co-continuous morphology demonstrated very fast biodegradation, with the initial rate almost identical to pure TPS in both environments while the 30% TPS blend exhibited particle morphology of the starch phase in the PCL matrix, which probably resulted in a dominant effect of the matrix on the biodegradation course. Moreover, some molecular interaction between PCL and TPS, as well as differences in flow and mechanical behavior of the blends, was determined. © Copyright © 2020 Nevoralová, Koutný, Ujčić, Starý, Šerá, Vlková, Šlouf, Fortelný and Kruliš.MH CR [NV15-31269A]; Technology Agency of the CR [TE01020118, TN01000008]; Ministry of Education, Youth and Sports of the CR, program NPU I [POLYMAT LO1507

The Effect of processing on the PVC/Clay Nanocomposites Structure

Reported nanocomposites of poly(vinyl chloride) have been prepared using bentonite-based clay, Na-montmorillonite (nature clay) and organophilic clay 30B. Polymer nanocomposites of differing compositions were produced using Buss KO-kneader via melt intercalation method. The effect of different type of plasticizer (both low molecular and high molecular) and compounding conditions on the structure of PVC/clay nanocomposites was investigated. Different compounding conditions were tested to study their influence on nanoparticles dispersion, orientation and exfoliation in PVC/clay nanocomposites. The structure of PVC/MMT nanocomposites was observed using X-ray diffraction, transmission electron microscopy (TEM) and AFM (Atomic Force Microscopy). It was found that the Na-montmorillonite offer low exfoliation level, while 30B modified by plasticizer exhibits fine dispersion of partial to nearly full exfoliated MMT. Moreover the processing conditions play also important role in nanocomposite production

The effect of short polystyrene brushes grafted from graphene oxide on the behavior of miscible PMMA/SAN blends

A new concept of utilization of particle-polymer hybrids as multifunctional additives for polymer blends was introduced in this study. Graphene oxide particles with short densely grafted polystyrene brushes (GO-g-PS) were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). Melt rheology studies revealed that GO-g-PS suppressed the phase separation of miscible poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) (PMMA/SAN) blends. The studies suggested specific interactions of GO-g-PS with the PMMA phase and this was confirmed based on calculations of activation energies of segmental relaxations by broadband dielectric spectroscopy (BDS). These unusual interactions of GO-g-PS with PMMA phase were assigned to the specific and precise architecture of the GO-g-PS particles as well as chemical nature of PS polymer brushes. The short chains of PMMA and PS provide miscibility originating from UCST behavior of PMMA/PS blend of short polymer chains. Additionally, BDS also revealed improved charge transport in PMMA/SAN blend in presence of GO-g-PS hybrid. © 2020 Elsevier LtdAction Austria - Slovakia, Co-operation in Science and Education program [56337]; National Science Centre, PolandNational Science Center, PolandNational Science Centre, Poland [UMO-2016/23/P/ST5/02131]; European Unions' Horizon 2020 research and innovation program under Marie Sklodowska-Curie grant [665778]; Research & Innovation Operational Programme - ERDF [313021T081]; project VEGAVedecka grantova agentura MSVVaS SR a SAV (VEGA) [2/0129/19]; Technology Agency of the CR [TN01000008]; Ministry of Education, Youth and Sports of the Czech Republic - DKRVO [RP/CPS/2020/003

New insights into the photochemistry of carotenoid spheroidenone in light-harvesting complex 2 from the purple bacterium Rhodobacter sphaeroides

Light-harvesting complex 2 (LH2) from the semi-aerobically grown purple phototrophic bacterium Rhodobacter sphaeroides was studied using optical (static and time-resolved) and resonance Raman spectroscopies. This antenna complex comprises bacteriochlorophyll (BChl) a and the carotenoid spheroidenone, a ketolated derivative of spheroidene. The results indicate that the spheroidenone-LH2 complex contains two spectral forms of the carotenoid: (1) a minor, ‘‘blue’’ form with an S2 (11 Bu ?) spectral origin band at 522 nm, shifted from the position in organic media simply by the high polarizability of the binding site, and (2) the major, ‘‘red’’ form with the origin band at 562 nm that is associated with a pool of pigments that more strongly interact with protein residues, most likely via hydrogen bonding. Application of targeted modeling of excited-state decay pathways after carotenoid excitation suggests that the high (92%) carotenoid-to-BChl energy transfer efficiency in this LH2 system, relative to LH2 complexes binding carotenoids with comparable double-bond conjugation lengths, derives mainly from resonance energy transfer from spheroidenone S2 (11 Bu ?) state to BChl a via the Qx state of the latter, accounting for 60% of the total transfer. The elevated S2 (11 Bu ?) ? Qx transfer efficiency is apparently associated with substantially decreased energy gap (increased spectral overlap) between the virtual S2 (11 Bu ?) ? S0 (11 Ag -) carotenoid emission and Qx absorption of BChl a. This reduced energetic gap is the ultimate consequence of strong carotenoid–protein interactions, including the inferred hydrogen bondin

Engineering of a calcium-ion binding site into the RC-LH1-PufX complex of Rhodobacter sphaeroides to enable ion-dependent spectral red-shifting

The reaction centre-light harvesting 1 (RC-LH1) complex of Thermochromatium (Tch.) tepidum has a unique calcium-ion binding site that enhances thermal stability and red-shifts the absorption of LH1 from 880 nm to 915 nm in the presence of calcium-ions. The LH1 antenna of mesophilic species of phototrophic bacteria such as Rhodobacter (Rba.) sphaeroides does not possess such properties. We have engineered calcium-ion binding into the LH1 antenna of Rba. sphaeroides by progressively modifying the native LH1 polypeptides with sequences from Tch. tepidum. We show that acquisition of the C-terminal domains from LH1 α and β of Tch. tepidum is sufficient to activate calcium-ion binding and the extent of red-shifting increases with the proportion of Tch. tepidum sequence incorporated. However, full exchange of the LH1 polypeptides with those of Tch. tepidum results in misassembled core complexes. Isolated α and β polypeptides from our most successful mutant were reconstituted in vitro with BChl a to form an LH1-type complex, which was stabilised 3-fold by calcium-ions. Additionally, carotenoid specificity was changed from spheroidene found in Rba. sphaeroides to spirilloxanthin found in Tch. tepidum, with the latter enhancing in vitro formation of LH1. These data show that the C-terminal LH1 α/β domains of Tch. tepidum behave autonomously, and are able to transmit calcium-ion induced conformational changes to BChls bound to the rest of a foreign antenna complex. Thus, elements of foreign antenna complexes, such as calcium-ion binding and blue/red switching of absorption, can be ported into Rhodobacter sphaeroides using careful design processes

Electronic Music in Bohemia

Tato bakalářská práce se v první části zabývá iniciativou vzniku elektronické hudby, samotnou definicí tohoto odvětví, historickými fakty, které vedly k její realizaci a rozšíření do celého světa. Druhá část je pak věnována základnímu rozdělení elektronické taneční hudby, od historie po současnost a samotnou návaznost na Českou hudební scénu.ObhájenoThis bachelor thesis deals in it's first part with the initiative of the creation of electronic music, the very definition of the industrial part, historical facts, which led to it's implementation and expansion throughout the whole world. The second part is devoted to the basic division of electronic dance music, from the past to the present and links to the Czech music scene itself