Sandra Paszkiewicz - Academia.edu (original) (raw)

Papers by Sandra Paszkiewicz

Polymers, 2016

A series of poly(trimethylene terephthalate)-block-poly(ethylene oxide) (PTT-b-PEOT) copolymers w... more A series of poly(trimethylene terephthalate)-block-poly(ethylene oxide) (PTT-b-PEOT) copolymers with different compositions of rigid PTT and flexible PEOT segments were synthesized via condensation in the melt. The influence of the block length and the block ratio on the micro-separated phase structure and elastic properties of the synthesized multiblock copolymers was studied. The PEOT segments in these copolymers were kept constant at 1130, 2130 or 3130 g/mol, whereas the PTT content varied from 30 up to 50 wt %. The phase separation was assessed using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The crystal structure of the synthesised block copolymers and their microstructure on the manometer scale was evaluated by using WAXS and SAXS analysis. Depending on the PTT/PEOT ratio, but also on the rigid and flexible segment length in PTT-b-PEO copolymers, four different domains were observed i.e.,: a crystalline PTT phase, a crystalline PEO phase (which exists for the whole series based on three types of PEOT segments), an amorphous PTT phase (only at 50 wt % content of PTT rigid segments) and an amorphous PEO phase. Moreover, the elastic deformability and reversibility of PTT-b-PEOT block copolymers were studied during a cyclic tensile test. Determined values of permanent set resultant from maximum attained stain (100% and 200%) for copolymers were used to evaluate their elastic properties.

Polish Journal of Chemical Technology, 2015

In the work viscosity, curing process of epoxy resins, electrical conductivity and mechanical str... more In the work viscosity, curing process of epoxy resins, electrical conductivity and mechanical strength of epoxy composites with carbon nanotubes were investigated. As a component was used Epidian 6 epoxy resin cured with 1-buthylimidazole by anionic polymerization. Compositions with nanofillers were prepared by sonification of multiwall carbon nanotubes (BAYTUBES 150 P and BAYTUBES 150 HP) in epoxy resin without any solvent. The morphology of prepared nanocomposites was examined by using SEM . Scanning electron microscopy confirms good dispersion of CNTs, but the presence of agglomerates is also identified. Viscosity of compositions with two kind of carbon nanotubes was established by means of ARES rheometer. Curing process with ARES rheometer and DSC was investigated. Bending strengths and electrical conductivity were performed on composites made of an epoxy resin loaded with 0.1, 0.2, 0.5, 1 and 2 wt.% both types of MWNTs. The incorporation of MWCNT to epoxy resin results in a sha...

Graphene has attracted considerable interest over recent years due to its intrinsic mechanical, t... more Graphene has attracted considerable interest over recent years due to its intrinsic mechanical, thermal and electrical properties. Incorporation of small quantity of graphene fillers into polymer can create novel nanocomposites with improved structural and functional properties. This work introduced the recent research in preparation and properties of graphene derivatives polymer based nanocomposites. It has been confirmed that in situ polymerization is the good method for preparation nanocomposites which can avoid the agglomeration of nanoparticles in polymer matrices and improve the interfacial interaction between nanofiller and polymer matrix. Morphologies of the nanocomposites were examined using both SEM and TEM, and it was revealed that the nanocomposites exhibit well dispersed graphene platelets. The influence of graphene derivatives (expanded graphite (EG), graphene oxide (GO)) on the structure and mechanical properties of polymer matrices (PET, PTT and PTT-PTMO) was examine...

eXPRESS Polymer Letters

Graphene Nanoplatelets/Carbon Nanotubes/poly(trimethylene terephthalate-block-poly(tetramethylene... more Graphene Nanoplatelets/Carbon Nanotubes/poly(trimethylene terephthalate-block-poly(tetramethylene oxide) segmented copolymer (PTT-PTMO) hybrid nanocomposites were synthesized via in situ polymerization. A remarkable synergistic effect between GNPs and SWCNTs on improving thermal and mechanical properties of nanocomposites based on segmented block copolymers was observed. Heterogeneous structure of the PTT-PTMO allowed for a better and more uniform distribution of both types of nanoparticles and stabilized the structure in question. This enabled to observe a so-called “synergistic effect”, caused by the use of mixture of carbon nanotubes and graphene nanopletelets, on enhancement of thermal and mechanical properties of the obtained polymer. In order to ascertain the influence of mentioned carbon nanostructures on the nanoseparated phase structure of the synthesized PTT–PTMO block copolymers, DSC and DMTA measurements were performed. SEM and TEM images of the PTT-PTMO nanocomposites d...

Hybrid composites have lately attracted the attention of researchers with different mixtures bein... more Hybrid composites have lately attracted the attention of researchers with different mixtures being tried out [1-3]. Unlike traditional polymer composites containing micron-scale fillers, the incorporation of nanoscale fillers into a polymer system results in very short distance between the fillers, thus the properties of composites can be largely modified even at an extremely low content of filler. This work introduced the recent research of in situ prepared carbon hybrid nanoparticles/polymer nanocomposites. Morphologies of the nanocomposites were examined using both SEM and TEM, and it was revealed that the nanocomposites exhibit well dispersed hybrid nanofillers. The influence of hybrid nanoparticles (graphene derivatives/CNT) on the structure and electrical conductivity of polymer matrices (PET, PTT and PTT-PTMO) was examined by using dielectric spectroscopy and DSC. The electrical percolation threshold was found of 0.05wt.% for PET/EG [4] nanocomposites and between 0.3 and 0.5w...

Conductive carbon nanotube/poly(ethylene terephthalate-glycol modified) (SWCNT/PETG) composites w... more Conductive carbon nanotube/poly(ethylene terephthalate-glycol modified) (SWCNT/PETG) composites were prepared via in situ polymerization with the assistance of sonication methods. Electron microscopy (SEM) and dielectric spectroscopy were used to characterized the thin films. Electronic microscopy images reveal that the nanocomposites exhibit well dispersed nanotubes. Wide angle X-ray scattering (WAXS) showed that nanocomposite films are amorphous (small peaks’ intensity) and therefore polymer crystallinity didn’t affect electrical properties. A sharp insulator-to- conductor transition for PETG/SWCNTs films was observed with a percolation threshold (Φc) as low as 0.048 wt.%. Synthesis process was conducted in the presence of non-typical, non-classical catalyst- germanium dioxide. This approach may be suitable to obtain nanocomposites with appropriate CNTs dispersion in the PETG matrix with relatively high electrical conductivity.

The addition of expanded graphite and single-walled carbon nanotubes to poly(ethylene terephthala... more The addition of expanded graphite and single-walled carbon nanotubes to poly(ethylene terephthalate) leads to a range of enhanced mechanical and barrier properties in the resultant nanocomposite.

Streszczenie -Zbadano wp³yw dodatku nanonape³niacza wêglowego (ekspandowanego grafitu) na przebie... more Streszczenie -Zbadano wp³yw dodatku nanonape³niacza wêglowego (ekspandowanego grafitu) na przebieg syntezy PETG (kopolimeru PET-ran-PCT), morfologiê nanokompozytu oraz jego przemiany fazowe. Badany nanokompozyt zawiera³ 0,1 % mas. ekspandowanego grafitu (EG) w postaci pojedynczych p³aszczyzn grafenowych oraz (w wiêkszooeci) luŸno z³¹czonych paczek grafenów. Nie stwierdzono wp³ywu nanocz¹stek EG na przemiany fizyczne w kopolimerze PET-ran-PCT. Na termogramach uk³adu zawieraj¹cego 20 lub 30 % mol. PCT nie zaobserwowano piku topnienia ani krystalizacji. Na podstawie analizy ilooeciowej produktów ubocznych metod¹ chromatografii gazowej ustalono, ¿e sk³ad otrzymanego polimeru by³ zgodny z obliczonym na podstawie stechiometrycznych ilooeci g³ównych sk³adników. Budowê chemiczn¹ zsyntezowanego kopolimeru potwierdzono przy u¿yciu spektroskopii 1 H NMR. S³owa kluczowe: polimeryzacja in situ, poli(tereftalan etylenu), 1,4-cykloheksanodimetanol, ekspandowany grafit, struktura, chromatografia gazowa, 1 H NMR, SEM.

Nanocomposites based on poly(trimethylene terephthalate-block-tetramethylene oxide) (PTT-PTMO) co... more Nanocomposites based on poly(trimethylene terephthalate-block-tetramethylene oxide) (PTT-PTMO) copolymer and semicrystalline polyester PTT with single-walled carbon nanotubes were prepared by in situ polymerization. The thermal and mechanical properties of nanocomposites were examined to compare the influence of SWCNT on semicrystalline and multiphase polymer matrix by using DSC and tensile tests. Morphologies of the nanocomposites were examined using both SEM and TEM. The DSC results imply that in both polymer matrices SWCNT act as nucleation agents and accelerate the crystallization of PTT hard phase during the cooling down process from the melt. On the other hand the introduction of linear nanofiller does not have great effect on the glass transition temperature of PTMO-rich soft phase, melting temperature of PTT hard phase and degree of crystallinity of the nanocomposites. With the increasing amount of SWCNT in the nanocomposites, the increase of tensile modulus and yield stress...

In this study the effect of different shape carbon nanofillers by means of carbon nanotubes (1D) ... more In this study the effect of different shape carbon nanofillers by means of carbon nanotubes (1D) and graphene sheets (2D) on morphology, mechanical and electrical properties of poly(etylene terephthalate) based composite fibers was investigated. The amount of carbon nanotubes that were utilized to prepare the conductive fibers was 5wt.%, whereas the amount of graphene sheets was only 2.5wt.%. The masterbatches were prepared by Institute of Materials Science and Engineering. The polyester electro conductive fibers with carbon nanofillers and preliminary characteristic of synthesised nanocomposites were prepared by Torlen Sp. z o.o. in the course of a joint research project MNT ERA NET. The results show that both nanofillers can be incorporated into PET matrix with good dispersion. It was seen that PET nanocomposites demonstrated better mechanical performance especially seen in the tensile modulus. References: [1] Paszkiewicz S., et al., Influence of EG on electrical conductivity of P...

Composite Interfaces, 2015

ABSTRACT This work provides a detailed information on the preparation process and characterizatio... more ABSTRACT This work provides a detailed information on the preparation process and characterization of functionalized multiwalled carbon nanotubes/Epidian 6 nanocomposites using ARES rheometer, TGA, and DSC measurements, with the imidazole derivative as a curing agent. Scanning electron microscopy of the fracture surfaces of the composites with a total nanofiller concentration below 0.5 wt.% reveals a uniform dispersion of MWCNT with only some minor agglomerates. At the same time, the TEM analysis of the composite with a total concentration of MWCNT–COOH higher than 0.5 wt.% confirmed the presence of carbon nanotube aggregates along with a large number of places without any presence of nanoparticles in the whole volume of the epoxy matrix. Mechanical tests (bending as well as dynamic mechanical analysis) show that compared with the neat epoxy resin, the bending strength of the composite was improved by about 30 and 21% after incorporating as little as only 0.1 and 0.2 wt.% MWCNT–COOH, respectively. The work presented hereby is a continuation of a previous study on epoxy-based nanocomposites with different types of multiwalled carbon nanotubes and it is a part of a wider project on precise charting of the influence of carbon nanotubes (particularly multiwalled carbon nanotubes) in the system of epoxy resin with 1-buthylimidazole, as a curing agent.

Incorporation of nanofillers to a polymer matrix gives rise to a new class of materials known as ... more Incorporation of nanofillers to a polymer matrix gives rise to a new class of materials known as polymer nanocomposites, which have more potential for many applications. Significant improvement in properties of the composites depends mainly on: the size and shape of particles nanofiller [1], surface area, degree of surface development, surface energy and on the spatial distribution of the polymer matrix of nanoparticles One of the most currently developing directions of cognitive and applied works is the research on nanocomposites, particularly on polymer nanocomposites. Polymer nanocomposites are obtained by modifying the traditional materials by dispersing the fillers with dimensions of a few nanometers in a polymer matrix. They are therefore complex systems with two or more phases (continued and dispersed) with an explicit separation surface from which the dispersed component is characterized by at least one dimension in the nanometer scale. Interesting from the point of view of their impact on the electrical conductivity seems to be the introduction of two types of carbon nanofillers such as graphene (flake filler-2D type) and carbon nanotubes (a fibrous filler / linear 1D type), which was confirmed by some of the literature data .

Polish Journal of Chemical Technology, 2014

This work is the continuation and refi nement of already published communications based on PET/EG... more This work is the continuation and refi nement of already published communications based on PET/EG nanocomposites prepared by in situ polymerization 1, 2 . In this study, nanocomposites based on poly(ethylene terephthalate) with expanded graphite were compared to those with functionalized graphite sheets (GO). The results suggest that the degree of dispersion of nanoparticles in the PET matrix has important effect on the structure and physical properties of the nanocomposites. The existence of graphene sheets nanoparticles enhances the crystallization rate of PET. It has been confi rmed that in situ polymerization is the effective method for preparation nanocomposites which can avoid the agglomeration of nanoparticles in polymer matrices and improve the interfacial interaction between nanofi ller and polymer matrix. The obtained results have shown also that due to the presence of functional groups on GO surface the interactions with PET matrix can be stronger than in the case of exfoliated graphene (EG) and matrix.

Polymer Bulletin, 2012

Poly(trimethylene terephthalate-block-tetramethylene oxide) (PTT-PTMO) copolymer/organoclay nanoc... more Poly(trimethylene terephthalate-block-tetramethylene oxide) (PTT-PTMO) copolymer/organoclay nanocomposites were prepared by in situ polymerization. They showed an intercalated silicate structure, as determined by X-ray diffraction and transmission electron microscopy. The influence of intercalated organoclay on the two-phase structure and mechanical properties of PTT-PTMO block copolymer was examined by using DSC and tensile tests. The DSC results imply that the silicate layers (Nanofil 32) in PTT-PTMO act as nucleation agents and accelerate the crystallization of PTT hard phase during the cooling down process from the melt. The introduction of silicate layers does not have great effect on the glass transition temperature of PTMO-rich soft phase, melting temperature of PTT hard phase, and degree of crystallinity of the nanocomposites. As the organoclay loading in the nanocomposites increase, the enhanced tensile modulus and yield stress was observed. The cyclic tensile tests showed that obtained nanocomposites have values of permanent set comparable to the neat PTT-PMO copolymer.

Polimery, 2013

Journal of Thermal Analysis and Calorimetry, 2014

The decomposition and thermal behavior of poly(ethylene terephthalate) (PET)/carbon nanotubes (CN... more The decomposition and thermal behavior of poly(ethylene terephthalate) (PET)/carbon nanotubes (CNTs) nanocomposites were studied using thermogravimetric (TG) analysis in air atmosphere. A series of PET/ single-walled CNTs (SWCNTs) materials of varying nanoparticles concentration were prepared using the in situ polymerization technique. Transmission electron microscopy and scanning electron microscopy micrographs verified that the dispersion of the SWCNTs in the PET matrix was homogeneous, while some relatively small aggregates co-existed at higher filler concentration. Two-stage decomposition was observed in the experiments. During first stage, strong chemical bonds are broken, i.e., aliphatic bonds and benzyl ring containing molecules decompose into small molecules in the gaseous phase. During second stage, when temperature is higher, the remaining nanotubes along with the residues of the first stage are burned. Kissinger and Coats-Redfern (5, 10, 20, 50 K min -1 ) methods were applied to TG data to obtain kinetic parameters (activation energy, Arrhenius constant at 600 K and A factor) and Criado method to kinetics model analysis. In this kinetic model, energy activation is increasing with the increase of nanotubes concentration.

European Polymer Journal, 2014

Poly(trimethylene terephthalate-block-tetramethylene oxide) (PTT-PTMO) copolymer/ graphene oxide ... more Poly(trimethylene terephthalate-block-tetramethylene oxide) (PTT-PTMO) copolymer/ graphene oxide nanocomposites were prepared by in situ polymerization. From the SEM and TEM images of PTT-PTMO/GO nanocomposite, it can be seen that GO sheets are clearly well-dispersed in the PTT-PTMO matrix. TEM images also showed that graphene was well exfoliated into individual sheets, suggesting that in situ polymerization is a highly efficient method for preparing nanocomposites. The influence of GO on the two-phase structure, melt viscosity and mechanical properties of PTT-PTMO block copolymer was examined by using DSC, ARES rheometer and tensile tests. The DSC results imply that the introduction of GO did not affect the glass transition temperature of PTMO-rich soft phase, melting temperature of PTT hard phase and degree of crystallinity of the nanocomposites. As the graphene oxide loading in the nanocomposites increase, the enhanced Young's modulus and yield stress was observed. The tensile strength slightly increased with the increase of GO from 0 to 0.5 wt% when elongation at break was higher or comparable to the value of neat PTT-PTMO copolymer.

European Polymer Journal, 2015

ABSTRACT This work is aimed at determining the effect of polyhedral oligomeric silsesquioxanes (P... more ABSTRACT This work is aimed at determining the effect of polyhedral oligomeric silsesquioxanes (POSS) on the microstructure and phase separation of PTT-block-PTMO based nanocomposites, which were prepared by the means of in situ polymerization. Scanning electron microscopy images (along with EDS analysis) confirmed the occurrence of the reaction between the (n-octyl)dimethylsiloxy groups of POSS and functional groups of PTT-block-PTMO copolymer during in situ polymerization, which leads to the formation of excellent dispersed POSS nanoparticles with good interfacial adhesion. The results showed that the addition of POSS affected the crystallization of the PTT rich phase. The DSC results imply that POSS cages in PTT-block-PTMO act as anti-nucleation agents and inhibit the crystallization of PTT hard phase during the cooling down process from the melt shifting crystallization temperature toward lower values. The introduction of POSS does not have great effect on the glass transition temperature of PTMO-rich soft phase, melting temperature of PTT hard phase and degree of crystallinity of the nanocomposites. Moreover, the influence of the presence of nanoparticles on the phase separation of polymer matrix has been observed.