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Characteristics and serviceability of denim fabrics have undergone major changes. Nowadays denim is commonly used for casual wear. Durability and comfort are important parameters for consumers when choosing a denim garment. Therefore, in this study, abrasion resistance, tear and tensile properties of core–spun yarns and air permeability of denim fabrics with different weft yarns per centimetre and fibre content were analysed. The test results showed that weft yarns per centimetre influences fabric air permeability negatively but abrasion resistance increases. Higher weft yarns per centimetre influences fabric air permeability negatively but abrasion resistance increases. Polyester, elastane, modal, viscose and Lycra T400 were used in the core of weft yarn to analyse the impact of those fibres on the durability and comfort properties. Elastane is used to add stretchability to the fabric, which provides comfort to the wearer. The higher the elastomeric fibre content in the fabric, the greater is its elasticity; however, the tensile properties of the woven fabric decrease. The tear strength of the fabric was increased by the presence of the polyester fibre in the core.

The use of Pt-based cathode catalyst materials hinders the widespread application of anion exchange membrane fuel cells (AEMFCs). Herein, we present a non-precious metal catalyst (NPMC) material based on pyrolysed Fe and Co co-doped electrospun carbon nanofibres (CNFs). The prepared materials are studied as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts in alkaline and acidic environments. High activity towards the ORR in alkaline solution indicated the suitability of the prepared NPMCs for the application at the AEMFC cathode. In the AEMFC test, the membrane-electrode assembly bearing a cathode with the nanofibre-based catalyst prepared with the ionic liquid (IL) (Fe/Co/IL–CNF–800b) showed the maximum power density (Pmax) of 195 mW cm−2, which is 78% of the Pmax obtained with a commercial Pt/C cathode catalyst. Such high ORR electrocatalytic activity was attributed to the unique CNF structure, high micro-mesoporosity, different nature of nitrogen species and metal-Nx active centres.

Thermoplastic cellulose esters are promising materials for bioplastic packaging. For that usage, it is important to understand their mechanical and surface wettability properties. In this study, series of cellulose esters are prepared such as laurate, myristate, palmitate and stearate. The aim of the study is to investigate the tensile and surface wettability properties of the novel synthesized cellulose derivatives to understand their suitability as bioplastic packaging material. Cellulose derivatives are first synthesized from microcrystalline cellulose (MCC), then dissolved in pyridine solution and after solvent casted to thin films. Cellulose derivatives acetylation process is characterized with the FTIR method. Cellulose esters hydrophobicity is evaluated with contact angle measurement. The mechanical properties of the films are tested with the tensile test. For all of the synthesized films, FTIR provide clear evidence of acylation by showing presence of characteristic peaks. Films mechanical properties are comparable to generally used plastics such as LDPE and HDPE. Furthermore, with the increase in side-chain length, the water barrier properties improved. These results show that they are potentially suitable materials for films and packaging materials.

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In this work, 3D porous electrospun scaffolds based on DegraPol® (DP), a polyester urethane, with different concentrations of graphene oxide (GO) (0.0–2.0 wt%) were obtained. In order to produce sc...

In this work, polyacrylonitrile (PAN), styrene–acrylonitrile copolymer (SAN) and multi-walled carbon nanotubes (MWCNTs) composite fibres (PAN/SAN/CNT) were prepared by electrospinning. The electrospun fibres were further pyrolysed (800–1200 °C) in N2 atmosphere with or without prior stabilisation (at 250 °C) in air to produce electrocatalyst materials for oxygen reduction reaction (ORR). The ORR was studied in alkaline solution by linear sweep voltammetry and rotating disc electrode (RDE) method. Scanning electron microscopy images revealed the tubular structure of the pyrolysed PAN/SAN/CNT fibres with visible MWCNTs. According to the X-ray photoelectron spectroscopy results, the prepared catalysts consisted of carbon, oxygen and nitrogen. According to the RDE results, the most active catalyst towards the ORR (the onset and half-wave potential of − 0.13 V and −0.29 V vs SCE in 0.1 M KOH, respectively) was obtained by pyrolysing non-stabilised PAN/SAN/CNT fibres at 1100 °C. The ORR activity of the best performing catalyst is attributed to the nitrogen species, quinone groups and porous tubular structure of the catalyst material.

The influence of birch false heartwood was investigated relative to the physical and mechanical properties of wood-plastic composites. Birch wood (sapwood and false heartwood) particles were modified with 5 wt% NaOH (by wood content) and 5 wt% 3-aminopropyl-triethoxysilane (by wood content) before being compounded with polypropylene in a co-rotating twin-screw extruder. The compounded composites were then injection moulded into standard test samples. The resulting composites were grouped into four categories: birch sapwood, modified birch sapwood, false heartwood, and modified false heartwood. Neat polypropylene samples were produced as a reference. The samples were tested for their tensile and flexural properties, water absorption, thickness swelling, and ultraviolet aging. The compositions of the composites were analysed using Fourier transform infrared spectroscopy. The results showed that the tensile strength of all of the samples decreased after water absorption. Water absorption decreased the impact strength of all of the composites. Ultraviolet radiation degraded the neat polypropylene and lowered the mechanical properties of all of the composites. Surface chalking was observed in all of the wood-plastic composites exposed to ultraviolet aging, with colours ranging from brown and brownish black to white.

Electrospinning has recognized as the most versatile and adaptable method for the fabrication of nanofibers. Fiber scientists have extensively introduced original solutions for harvesting and stori...

Fibrous mats were prepared by electrospinning of polyacrylamide-graft-polyaniline copolymers (PAAm-g-PANI) in a mixed solvent of water–dimethylformamide. The grafted copolymers were synthesized by oxidative polymerization of aniline in the presence of polyacrylamide; the effect of aniline/polyacrylamide ratio on the morphology of the fibrous mats and on their electrochemical properties was investigated. The composition and chemical structure of the copolymers were verified with FTIR. Polyaniline content higher than 40 wt% leads to the lack of electrospinability of the corresponding solutions. With polyaniline concentration increasing from 20 to 40 wt%, the fiber diameter decreases from 569 to 248 nm. WAXD study shows that the reflections from polyaniline crystallites are preserved during swelling, and the increasing polyaniline content results in the decreased sample compatibility with water. Galvanostatic charge–discharge, cyclic voltammetry by Trasatti method, and BET measurements reveal that most part of the charge in PAAm-g-PANI fibrous mats is stored via the pseudocapacitance mechanism. Maximum attained capacitances measured at 0.3 A g−1 were 102 F g−1 for the whole mass of electrode and 255 F g−1 for the mass of the active material.

The study is focused on the production of conductive mats from polyaniline - ionic liquid (IL) blends by electrospinning. PAN was used as a binding matrix in blends. The effect of adding 3 to 40 wt.% of polyaniline salt to PAN blend was investigated on the electrical and mechanical properties of the mats. 10 wt.% of IL was used in PAN blends for improving the dispersion of PANi particles. IL increased the conductivity of the material three times, comparing with the materials without IL. The optimum concentration of polyaniline in blend was 10–12.5 wt.% to produce mechanically strong mats.

Owing to its high conductivity, graphene has been incorporated into polymeric nanofibers to create advanced materials for flexible electronics, sensors and tissue engineering. Typically, these graphene-based nanofibers are prepared by electrospinning synthetic polymers, whereas electrospun graphene-biopolymer nanofibers have been rarely reported due to poor compatibility of graphene with biopolymers. Herein, we report a new method for the preparation of graphene-biopolymer nanofibers using the judicious combination of an ionic liquid and electrospinning. Cellulose acetate (CA) has been used as the biopolymer, graphene oxide (GO) nanoparticles as the source of graphene and 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) as the ionic liquid (IL) to create CA-[BMIM]Cl-GO nanofibers by electrospinning for the first time. Moreover, we developed a new route to convert CA-[BMIM]Cl-GO nanofibers to reduced GO nanofibers using hydrazine vapor under ambient conditions to enhance the conductivity of the hybrid nanofibers. The graphene sheets were shown to be uniformly incorporated in the hybrid nanofibers and only 0.43 wt% of GO increase the conductivity of CA-[BMIM]Cl nanofibers by more than four orders of magnitude (from 2.71× 10−7 S/cm to 5.30 × 10−3 S/cm). This ultra-high enhancement opens up a new route for conductive enhancement of biopolymer nanofibers to be used in smart (bio) electronic devices.

Novel composite self-disinfecting films of polylactic acid (PLA) filled with nanosized particles of double sodium–copper(II) paratungstate B Na2Cu3(CuOH)2[W12O40(OH)2]·32H2O (POM) were developed. The solvent casting (POM/PLA film) and solvent-free melt extrusion methods (Extr. POM/PLA film) were applied for film preparation. The copper (II) ion release to water from both types of the films after 10 days at different temperatures demonstrated that the PLA matrix acts as a diffusion barrier, and the resulting concentration of released copper in water at room temperature remained low, at 0.79% for POM/PLA film and 0.51% for Extr. POM/PLA film. The POM-containing films reveals a significant inhibitory effect against E. coli ATCC 25922 in the agar diffusion test. The numbers of CFUs in washes of the films after incubation for 24 h were found to be 3.6 log CFU mL–1 (POM/PLA film) and 4.1 log CFU mL–1 (Extr. POM/PLA film). The films combine the antibacterial properties of POM and a bio-based polymer matrix, which makes them a prospective coating material for applications in hospital indoor environments. Excellent thermal stability of POM gives a technological advantage for industrial manufacturing to allow the processing of novel composite material in the solvent free (molten) state.

Obtaining electrospun membranes with good mechanical properties is important for their various applications. Several ionic liquid-based additives (IL-based) for electrospinning solutions have been proven to increase the conductivity of electrospun membranes. The aim of this study was to analyse the dependence of the mechanical properties of electrospun membranes on the additives used. Moreover, the relationship between conductivity, specific stress and the morphology of the membranes was studied. Polyactrylonitrile (PAN) solutions were prepared in dimethylformamide (DMF) and dimethylsulfoxide (DMSO) solvents. Two different ILs (1-butyl-3-methylimidazolium chloride [BMIm]Cl and 1-ethyl-3-methylimidazolium bromide [EMIm]Br) were used at a concentration of up to 10 wt%. Overall, it can be said that, with IL [EMIm]Br, higher specific stress values were achieved. Most stable values of specific stress were achieved with membranes obtained from solutions with DMF, especially with added IL [BMIm]Cl. The highest specific stress value achieved was 87.93 ± 5.15 mN/tex.

For the first time, the oxygen reduction reaction (ORR) is studied on pyrolysed electrospun multi-walled carbon nanotube (MWCNT) and styrene–acrylonitrile (SAN) composite fibre catalysts in alkaline medium. Scanning electron microscopy images revealed that the prepared catalysts mainly consist of MWCNTs, while nitrogen doping of the catalysts is confirmed by X-ray photoelectron spectroscopy. This indicates that SAN can be used as a nitrogen precursor. The ORR studies carried out by rotating disc electrode (RDE) and rotating ring-disc electrode (RRDE) methods showed that the prepared catalysts were considerably more active towards the ORR than the pristine MWCNTs.

Aim of this research was to electrospin conductive composite membrane of styrene-co-acrylonitrile (SAN) reinforced with carbon nanotubes (CNTs). To improve electrical conductivity of final membrane...

Additives like ionic liquids (ILs) have proven to be excellent materials useful in improving the electrospinnability and conductivity of both synthetic and biopolymers. The aim of this study is to ...

Cellulose esters with long carbon side chains (e.g. stearate) were produced via a homogenous reaction in ionic liquids. The degree of substitution was calculated to approximately 2. The melt rheology was studied for the pure cellulose esters but also combinations of the esters and polypropylene to study the processability of a blended composite material. It was shown that the compatibility between the two components was weak, which resulted in a phase-separated composite material. The morphology and permeability of water and oleic acid of the composite films were studied and it was shown that the water permeability decreased upon addition of the cellulose ester to the polymer. The permeability of oleic acid was however unchanged, which is most probable a result of high solubility in the cellulose ester rich domains of the composites. Also, the following hypothesis is stated: cellulose stearate influence the polypropylene crystallization process by decreasing the size of spherulites.

An ever increasing worldwide energy demand drives the need for the development of more efficient and greener energy production and storage technologies.1 In recent years, one-dimensional nanofibrous materials (NFMs) have drawn a lot of attention and been widely studied to address these topical problems. For example, the electrospun NFMs can be employed as an oxygen reduction reaction (ORR) catalyst at the fuel cell cathode. The NFMs are appealing because of their attractive properties e.g. high specific surface area, high length/diameter ratio, specific porosities and multiple functionalities. For the preparation of NFMs, a simple and versatile technique called electrospinning can be applied.2 In our previous study of NFMs, we investigated pyrolyzed electrospun multiwall carbon nanotube (MWCNT) and styrene-acrylonitrile copolymer (SAN) fiber materials as ORR catalysts in alkaline solution. It was found that during the thermal decomposition of SAN, the ORR-active N-functionalities can be embedded into the carbon nanomaterial.3 For further optimization of the catalyst material ORR activity, another nitrogen-containing polymer (polyacrylonitrile, PAN) was incorporated into the NFM composition to study the ORR performance of three-component composite material (SAN/PAN/MWCNT) in our latest work regarding NFMs.4 The ORR performance of SAN/PAN/MWCNT-based catalysts was evaluated in 0.1 M KOH solution by rotating disk electrode and linear sweep voltammetry methods. The catalyst with the highest activity toward the ORR was prepared via pyrolysis at 1100 °C (SAN/PAN/MWCNT-1100) and this material outperformed the best electrospun two-component, SAN and MWCNT, composite fiber-based catalyst from our previous study.3 For physical characterization of the materials, scanning electron microscopy (SEM), X–ray photoelectron spectroscopy (XPS), Raman spectroscopy and N2 adsorption-desorption studies were performed. The structure of the catalysts is nanofibrous with visible MWCNTs according to the SEM images (Figure 1a). The high ORR activity of the catalysts prepared in this work is most likely attributed to the nitrogen species as determined by XPS. The catalyst SAN/PAN/MWCNT-1100 also showed good stability during long-term testing in 0.1 M KOH solution (Figure 1b).4 The material with the highest ORR performance used in the present study (SAN/PAN/MWCNT-1100) is a promising catalyst for the development of efficient cathode catalysts for low-temperature fuel cells.4 References 1. A. Sarapuu, E. Kibena-Põldsepp, M. Borghei, and K. Tammeveski, J. Mater. Chem. A, 6, 776 (2018). 2. Q. Liu, J. H. Zhu, L. W. Zhang, and Y. J. Qiu, Renew. Sustain. Energy Rev., 81, 1825 (2018). 3. M. Mooste, E. Kibena-Põldsepp, L. Matisen, M. Merisalu, M. Kook, V. Kisand, V. Vassiljeva, A. Krumme, V. Sammelselg, and K. Tammeveski, Catal. Lett., 148, 1815 (2018). 4. M. Mooste, E. Kibena-Põldsepp, V. Vassiljeva, M. Merisalu, M. Kook, A. Treshchalov, V. Kisand, M. Uibu, A. Krumme, V. Sammelselg, and K. Tammeveski, J. Mater. Sci., 54, 11618 (2019). Figure 1

Adding conductive additives to electrospinning solutions has been proven to increase the conductivity of electrospun membranes. The aim of this study was to learn the effect of ionic liquids (ILs) on the polyacrylonitrile membranes conductivity. Three different ionic liquids were used with concentration to 10 wt%. The conductivity of the membranes increases from picoS range without using IL to microS range with adding IL. At concentration 8 wt% ILs the percolation threshold was observed with maximum conductivity of the electrospun membranes. The maximum conductivity was measured to be 2.39 μS/cm.

This study explores possible ways to make Additive Manufacturing (AM) a cradle-to-cradle process, that is, use the leftover from one process as the raw material for another process. The main goal of this study is to develop a set of new polymeric blends with innovative properties, suitable for using in 3-D printing of prosthetic limbs using Fused Deposition Modeling (FDM) technology. Sustainable acting is achieved by reusing polymeric material left over from Selective Laser Sintering (SLS) processes for making raw material for FDM processes. Test specimens of polyamide 12 (PA-12) in its virgin form and used- , un-sintered form alongside specimens of used PA blended with TPU, aramid, or graphite, were produced in a micro-injection moulding machine and then tested for their mechanical properties. This paper provides information about the differences in mechanical characteristics of these different material blends. An unexpected but positive finding was that the differences between virgin and recycled PA-12 are insignificant. The aforementioned additives influenced PA-12 by producing specimens that responded with predictable characteristics which is a significant accomplishment as it lays the groundwork for the next stages of the project.

The aim of this research was to investigate how the addition of IL [Bmim]Cl* and MWCNTs** into SAN*** solution will influence the viscosity and the electrical conductivity of the electrospinning solution and to find out the impact of IL and CNTs on the electrical and mechanical properties of the obtained membranes and on the morphology of the produced nanofibres. MWCNTs were added into two types of SAN solutions, with and without [Bmim]Cl, and then electrospinning was performed. All membranes were investigated by SEM analysis. The electrical conductivity and viscosity of the solutions were measured and their effect on the morphology of the fibres, as well as electrical and mechanical properties was estimated.

Water-soluble, partially cross-linked poly-2-isopropyl-2-oxazoline combining the properties of chemical and physical gels was synthesized by a two-step procedure. Thermally induced sol-gel transition in its aqueous solution was studied by rheology, light scattering, and turbidimetry. It was demonstrated that the synthesized product is bimodal, it consists of linear and cross-linked components. The cross-linked components are responsible for the gelation, while the linear ones abate the viscosity growth. Heating the solution above the phase transition temperature leads to the self-assembly of the particles into a physical gel. The combination of chemical and physical cross-linking was found to be a prospective route for thermosensitive gel development.

This work aims towards the optimization of porous carbon saturated nanofibres composition for electrical-double layer (EDL) electrode's preparation. The properties of microporous carbide-derived carbon (CDC) based electrospun electrodes are discussed. The variable electrode composition and their mechanical properties were observed to obtain the highest EDL capacitance. Effect of densification pressure and -temperature of electrospun electrodes are discussed. Thin electrode layer enables faster charge-discharge capability and perform higher power with same consumption of electrode materials. The EDL capacitance of 114 Fg-1, determined by cyclic voltammetry method within the voltage range of 0–2.7 V, was achieved.

Polyvinylidene fluoride (PVDF) was electrospun into fibrous membranes from its solutions in mixture of dimethylformamide (DMF) and acetone with and without an anionic fluorosurfactant. The results indicate that PVDF fibers contain a number of beads at any solvents compositions and solution concentrations. Addition of the surfactant does not affect considerably the morphology of fibers, however it helps to decrease the surface tension of the solution and reduce the beading of fibers. The most important factor affecting the fiber morphology is sonication. Sonication of the spinning solution promotes the formation of perfect, uniform, thin and cylindrical PVDF nanofibers without any beading.

In this work thermoplastic materials from cellulose fatty acid esters were manufactured, their properties described and application and processing perspectives evaluated. Rheological properties of some cellulose esters in melt were studied under conditions similar to those usually used in industrial polymer processing. Thermoplastic properties of cellulose esters were compared with properties of low density polyethylene under the same conditions. It was discovered that long chain fatty acid cellulose esters could be processed in the same way as commodity polymers, but these materials need further improvement for being industrially applied as thermoplastic polymers.

Current work focuses on establishing optimal growth conditions for covering commercial grade polymer blown films with a gas barrier oxide layer. As opposed to regular solid state substrates, low density polymers host an abundance of free space in the form of pores and voids between large polymer chains (MW > 1000) and a heterogeneous crystallized phase. In the following we will show how the structural peculiarities of the polymer matrix influence the ALD process for growing TiO2 and Al2O3 gas blocking layers on top of the LDPE substrate. Possible causes of low gas barrier performance, thermal expansion coefficient differences, are proposed and commercial process additives, such as slip or antioxidants, are suggested.

The aim of this research was to investigate how addition of IL [Bmim]Cl 1 into SAN 2 solution in 1,2-DCE 3 will influence electrospinning variables, stability of process and morphology of obtained nanofibers and find out the appropriate way of utilizing [Bmim]Cl in the electrospinning process. The solutions of pure SAN in 1,2-DCE of different concentrations (10–20%) and solutions with different concentrations (0.5–20%) of IL were spun at different variables (10–20 cm and 10–20 kV). All results were investigated by optical and SEM microscopy. Also solution parameters like electrical conductivity, surface tension and viscosity were measured and their effect on the obtained fibers morphology estimated.

In this work, three different methods of preparation of polyacrylonitrille (PAN) with carbon black (CB) solutions further used in electrospinning for producing conductive fiber mats are discussed. CB is used as conductive filler. Content of CB in polymer matrix is varied, CB/PAN = 1/2, 1/1, and 3/2. The solution properties and obtained fiber morphology are analyzed. The effect of preparation on fiber morphology and conductivity is analyzed, as well as the effect of sonication on solution properties, morphology, and conductivity of PAN+CB samples.

The preparation of ionogels by sol–gel processing has attracted much attention, because the final ceramic materials combine properties of both inorganic matrix (thermal and mechanical stability) and the ionic liquid (ionic conductivity). The aim of this study was to combine different imidazolium based ionic liquids (1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF 4 ], 1-butyl-3-methyl imidazolium tetrafluoroborate [BMIM][BF 4 ], 1-decyl-3-methylimidazolium tetrafluoroborate [DMIM][BF 4 ] and 1-methyl-3-[3′-(triethoxysilyl)propyl]imidazolium chloride MTICl) with titanium(IV) butoxide to prepare homogenous hybrid fibers through aqueous sol–gel reaction. The study showed that ionic liquid miscibility with metal alkoxide plays an important role in the preparation of homogenous fibers. Unlike simple imidazolium salts functionalized ionic liquid was dispersed homogenously in fibers, but the main advantage is derived from its chemical structure. New stable ionic liquid can be involved in sol–gel processes through ethoxy groups and as a result it associates with titanium alkoxide network by covalent bonding providing non-leaking ceramic hybrid material. Indirect and direct characterization studies of the product were carried out by energy-dispersive X-ray spectroscopy (EDX), silicon-29 nuclear magnetic resonance spectroscopy ( 29 Si NMR), scanning electron microscopy (SEM) and optical microscopies; also infrared spectra (IR) were recorded. Thermal analyses were performed by differential scanning calorimetry (DSC).

Current paper concentrates on the wear resistance of a particle reinforced polymer matrix composite material. The composite material consists of unsaturated polyester resin that is filled with aluminum hydroxide. Aluminum hydroxide acts as hard phase and polyester as binding agent. The aim of the work was to understand the influence of particle size and filler material mass fraction to the wear resistance of the composite. The wear properties were determined according to standard test method using rubber wheel and silica.

Cellulose stearates were prepared in a 1-butyl-3-metylimidazolium chloride ionic liquid. The addition of base pyridine as well as catalyst Tin octoate sufficiently increases the degree of hydroxyl group substitution. The new path for preparation of cellulose mixed esters, namely cellulose acetate stearate (CAS), is performed. The 1H NMR data confirmed the structure of obtained mono- and mix- cellulose esters.

Recently, a deliberate interest to look for composites that are eco-friendly and biodegradable appears. Therefore materials based on raw materials derived from natural resources of plant are being studied. One of the most promising bio-based polymers that have attracted the interest of many researchers is poly(lactic acid), which is made from plants and is readily biodegradable. Cellulose is one of the strongest and stiffest fibres available and it has a high potential to act as reinforcing agent in biopolymers. In our work we esterified cellulose using stearoyl chloride in ionic liquid and studied the effect of cellulose stearate addition to matrix polymers on thermal and rheological properties.

The cluster crystals of Na2[SiF6] were obtained in the aqueous solutions of different methylalkylimidazolium (ethyl-, butyl- and decyl-) tetrafluoroborate ionic liquids (IL) in borosilicate glassware. It is demonstrated that sodium hexafluorosilicate crystalline compounds with good regularity and narrow size distribution containing dialkyl imidazolium ions between the hexagonal crystalline clusters interconnected to each other to a whole hexagonal aggregate can be obtained in large quantities. This characteristic phenomenon of crystallization of sodium hexafluorosilicate containing IL ions is reported for the first time. The mechanism of formation of various [RMIm]BF4–Na2[SiF6] microcrystalline morphologies and the influence of temperature on the growth kinetics are discussed. Crystallographic studies of the product were carried out by X-ray diffractometer (XRD), characterization by scanning electron microscopy (SEM) and optical microscopies; also infrared spectra (IR) were recorded. Thermal analysis were performed by differential scanning calorimetry–thermogravimetric analyzer (TGA–DSC). Presence of ionic liquid cations was confirmed by high resolution mass spectrometry (HRMS).

Non-isothermal crystallization processes in fractions of Ziegler-Natta (ZN) and single site (SS) based ethylene/1-butene and ethylene/1-hexene copolymers have been studied by differential scanning calorimetry (DSC). Fractionation of used copolymers was done according to molar mass (MM) and composition (comonomer content). It was observed in DSC scans that for fractions with high MM (larger than 10 kg/mol) in addition to the main high-temperature crystallization peak (HTCP), a very-low temperature crystallization peak (VLTCP) is present at temperatures in between 60–75 °C. Such peak is absent for the first fractions having very-low MM. The partial crystallinity and peak temperatures, obtained from VLTCP, increase with MM and level off at MM around 60–100 kg/mol. It was found that the crystallinity as related to the area of the VLTCP is catalyst type dependent, and is higher for the SS catalyst compared to the ZN. Peak temperature of VLTCP linearly decreases with increasing comonomer content at fixed MM while the partial crystallinity practically does not change with comonomer content.

A new design of hot-stage (temperature controlling cell) and methodology were developed for investigating the kinetics of fast phase transitions of polymers at higher supercooling. The contact cooling rate of the hot-stage can be increased up to 1000 °C/s (between 200 °C and 80 °C) by means of flowing liquid cooling, the response rate of the whole device due to immediate temperature measurement and an original automation unit. This design enables one to study isothermal crystallization of polyethylene down to 80 °C, and its relative simplicity makes it suitable for routine measurements. Description of the parameters of the automation unit and the heating/cooling cell are reported.

The crystallization behavior of Ziegler-Natta (ZN) and single site (SS) based ethylene/1-butene and ethylene/1-hexene copolymers and SS copolymer fractionated by composition and molar mass (MM) has been studied by differential scanning calorimetry. It was observed that in addition to the high temperature crystallization peak (HTCP), and for ZN copolymers in addition also to low temperature crystallization peak (LTCP), a very-low temperature crystallization peak (VLTCP) is present at temperatures in between 60-75 °C. Peak temperature of VLTCP, T VLTCP , decreases with increasing comonomer content (C comon ) at fixed MM. If C comon is kept approximately constant, T VLTCP increases with increasing MM. It turns out that T VLTCP does not depend on the type of catalyst used. The degree of crystallinity calculated from the VLTCP is independent of the chemical nature of the comonomers present, but slightly changes with C comon . It also steeply increases with MM and levels off at MM around 5okg/mol. It was found that the crystallinity as related to the area of the VLTCP is catalyst type dependent, and is higher for the SS catalyst used compared to the ZN catalyst.

Effect of molar mass distribution (MMD) and composition distribution (CD) on crystallization behavior of linear low-density polyethylene materials at moderate and high supercooling was studied using differential scanning calorimetry, hot-stage polarized light microscopy, small-angle light scattering, and chip nanocalorimetry methods. A set of uni- and bimodal materials having small variation in average molar mass, density, and melt flow rate, but large differences in MMD and CD, was investigated. The results indicate a clear effect of structural heterogeneity on morphology and crystallization behavior of the materials. Broader MMD and CD increased in average radius of superstructures, melting, crystallization temperatures, and isothermal crystallization rate at different supercoolings. Origin of such behavior is discussed.

Crystallisation of high density polyethylene (HDPE) blends with broad bimodal molar mass distribution was investigated by differential scanning calorimetry (DSC) under non-isothermal conditions. The blends were prepared by blending a high molar mass PE (Mw=330 kg/mol, Mw/Mn=4.8) and a low molar mass linear PE (Mw=34 kg/mol, Mw/Mn=10) in different ratios in xylene solution. The samples were analysed by the normal DSC at different crystallisation rates and by a thermal fractionation technique. The blends and their parent polymers behaved according to general expectations i.e., crystallinity and density decreased when the molar mass of the samples increased. Additionally, non-linear relationships between MM and different analysed parameters were found. Small addition of the high molar mass parent polymer to the low molar mass parent polymer increased crystallisation temperature, although the general trend was decreasing. Furthermore, a complicated relationship between the reciprocal of crystallisation half-time and sample composition was found. The value increased first with increasing molar mass, reached a maximum when the average molar mass of the blend was between 150 and 200 kg/mol and then decreased. The detected maximum correlated with the broadest molar mass distribution of the blends. The crystallinities and densities of the blends with the broadest molar mass distribution also deviated from the linear correlation between them and molar mass. The Avrami index under non-isothermal conditions was analysed with a method developed by Harnisch and Muschik. The results indicated that thermal nucleation and spherical growth regimes are present in all studied materials.

This article describes a device developed for measuring crystallization kinetics of fast crystallizing polymers, for example, high density polyethylene. It consists of a commercial polarized light microscope with image acquisition system, a unique hot stage with temperature control system and software for temperature control and image analysis. The device enables controlled cooling rate of 1000°C/min and on-line image analysis capacity of five pictures per second. Suitability of the device’s cooling rate for the analysis of polyethylene crystallization is explained. The image analysis process is described. Two different algorithms for object counting are compared and their object recognition capacities are explained. Some results obtained with this device concerning a high density polyethylene sample are presented.

Isothermal crystallisation of high density polyethylene (HDPE) blends and their parent polymers was investigated. The blends having broad bimodal molar mass distributions and various compositions were prepared by blending a high molar mass (Mw=330 kg/mol, Mw/Mn=4.8) and a low molar mass HDPE (Mw=34 kg/mol, Mw/Mn=10) in different ratios in xylene solution. The blends and their parent components were characterised by size-exclusion chromatography, dynamic rheological and density measurements. Crystallisation kinetics were studied using a polarised light microscope equipped with an in-house built hot stage and by differential scanning calorimetry. The Avrami theory was applied for crystallisation kinetics analysis. Such crystallisation kinetics parameters as nucleation rate, nucleation density, the Avrami index and cystallisation rate contant were determined for the blends and their parent polymers. According to the results obtained an increasing polydispersity of the sample had a slight increasing effect on the Avrami index, indicating gain in prevalence of the thermal nucleation over the athermal one. In all samples nucleation density increased continuously during crystallisation verifying that the presence of a certain thermal nucleation was typical for all the materials studied. Both the crystallisation rate constant and the nucleation rate decreased with increasing molar mass of the sample. The nucleation density increased proportionally to the increase in average molar mass and the values were larger at lower crystallisation temperatures. The formed supermolecular structure was found to be sensitive to the blend composition and crystallisation temperature. Irregular banded or non-banded spherulites were observed in the materials. Banding of spherulites was typical for the samples having higher average molar mass. The superstructures observed in this work were smaller and vaguer than the superstructures reported in the earlier studies of polyethylene materials having similar average molar mass but narrow molar mass distribution.

The polymerizable monomer of 1-(6-hydroxyhexyl)-3-methylimiadazolium bromide ionic liquid (IL) was synthesized. The thin layer chromatography tests were conducted at each step to verify the reactions. It was observed that the ionic liquid compound formed after 48 hours though confirmed the presence of starting materials. A high viscous transparent liquid was extracted and believed to be formed of 99% yielding of ionic liquid. Apart from that, the synthesis of ionic liquid was also performed using microwave treatment and heating to stimulate the reaction. Surprisingly, it was observed that the reaction was taking place within a fraction of second when the synthesis process was conducted with microwave treatment. In the second step, esterification IL with methacryloyl chloride was done to obtain monomer of polymerizable ionic liquid (m-PIL). The final product was a high viscous yellowish liquid.

This study examines the effect of different post cure parameters to a polymer matrix particulate reinforced composite material. The goal is to evaluate the importance of different factors and to suggest a well-balanced post cure mode that supports the application of the material.Polymer matrix composites are post cured at elevated temperature to increase the amount of cross linking to achieve better chemical and heat resistance and mechanical properties. Every material has an individual post cure process that depends from the raw materials. Post curing variables include temperature, duration of cure, the time between initial curing and post curing and temperature profile gradient.There are several ways to determine the cure state of a polymer. It can be evaluated based on the mechanical and physical properties, residual styrene content, glass transition temperature, residual exotherm or solvent swelling test. For the determination of the suitable post cure parameters test slabs were casted and post cured with varying time and temperature. Glass transition temperature, residual exotherm, softening in ethanol, surface hardness, flexural strength and flexural modulus were determined. It is shown that the material should be cured at 60 °C – 80 °C. With higher temperature and extended time of cure the glass transition temperature raises but the material becomes too brittle.DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2435

This paper describes manufacturing of economically affordable renal biopsy phantoms for radiology residents and practicing radiologists. We reconstructed a realistic 3-dimensional patient-specific kidney model from CT data, manufactured an organ mould and casted the kidney phantoms. Using gelatin gel materials with calibrated parameters allowed making phantoms with realistic mechanical, ultrasound and CT properties including various pathologies. The organ phantoms with cysts included were further casted into gelatin gel medium. They were validated by radiology residents in biopsy training and compared against self-made phantoms traditionally used in the curriculum of interventional radiology. The realism, durability, price and suitability for training were evaluated. The results showed that our phantoms are more realistic and easier to use than the traditional ones. Our proposed technology allows creating a low-cost (50$/kg) alternative to the pricy commercial training phantoms available today.

Blends of high-density polyethylene (HDPE), moderate and hyper-branched LLDPEs (LLDPE and HbPE, respectively) have attained widespread commercial applications, though the understanding of the mechanical and melt-flow properties of such blends has been handicapped by the absence of a consensus concerning the degrees of mixing of the components. Moreover, usually the blends are obtained by melt blending, which may not ensure the initial homogeneity of the components. In our work the mixtures were prepared by dissolving the conventional LLDPE having branching content 7.2wt% with HbPE with comonomer content 17.8wt% in xylene at 130°C and stirring for 2 hours. The same procedure was applied for the blending of HDPE with HbPE. After dissolving the mixtures were cooled in liquid nitrogen and after that freeze dried in vacuum line. The ratio of components in the blends was varied. Differential scanning calorimetry has been used to investigate the miscibility and thermal behavior of the blends. For this purpose isothermal and non-isothermal treatment of prepared blends were conducted. By preliminary study the double melting peaks in non-isothermal endotherms have been observed in all the studied blends. The presence of two peaks in DSC scan can be attributed to the formation of separated crystals from both the high density/linear low density and highly branched components. However, certain limited degree of co-crystallization is detected in all the LLDPE/HbPE blends and HDPE/HbPE blend rich in HbPE component.http://dx.doi.org/10.5755/j01.ms.17.3.589