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 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

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 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

Charge densities and topological analysis

Lecture compares conventional X-ray diffraction analysis on single crystals with more precise techniques based on kappa-refinement and multipole refinement. The results that can be obtained from precise charge denstity studies and topological analysis are listed. Examples taken from practice show how to calculate atomic charges, double-bond characters etc. from both experimental X-ray data and theoretical quantum chemistry calculations

Rastrovací elektronová mikroskopie mokrých vzorků syntetických polymerů

Synthetic polymers with high content of water (wet synthetic polymers,hydrogels) are frequently used in tissue engineering. Investigation of their 3D-structure by means of scanning electron microscopy is very difficult: in a standard electron microscope water almost immediately evaporates and the structure breaks down. Nevertheless, hydrogels morphology can be visualised by means of low-vacuum scanning electron microscopy in cryo conditions (cryoLVSEM) and by environmental scanning electron microscopy (ESEM). The two techniques are described and compared

Novel embedding resins for 3D-SEM

The report contains the detailed analysis of novel embedding resins for 3D-SEM

Příprava a charakterizace isometrických zlatých nanočástic s předem spočítanou velikosti

We prepared and characterized Au particles with different sizes in solution by UV/vis spectroscopy and in solid state by TEM and powder diffraction

Novel embedding resins for 3D-SEM II

Research report for Thermo Fisher Scientific s. r. o., based on common project awarded by TA CR (program: National center of competence, TN01000008)