Jarosław Janicki

DSC, WAXD and SEM studies of biodegradation of poly(L-lactide-glycolide-trimethylene carbonate) shape memory terpolymer

Presented study is a part of structural project devoted to elaborating the basis of manufacturing technology of l-lactide–glycolide–trimethylene carbonate polymer system—a novel full biodegradable and resorbable shape–memory polymers. In this paper we took an attempt to describe the transformation of structure of studied shape–memory terpolymers under the influence of the process of biodegradation that occurred in time of implantation samples using first of all the differential scanning calorimetry and supplementary—the wide angle X-ray diffraction and scanning electron microscopy methods. After a 5-year-period of ageing the distinct increase of crystallinity of fibres was found.

Phenomenological analysis of microphase separation in relation to SAXS investigations of polymer blend fibres

Based on the Takayanagi models, the phenomenological analysis of microphase separation for PE/ABS and PS/PMMA blend fibres is presented. The supermolecular structure parameters, including the value of the long period, the thickness of the transition layer between phases and the average inhomogeneity lengths, were determined by means SAXS. The changes in parameters of the supermolecular structure correspond well with conclusions drawn from phenomenological analysis.

Preparation and Properties of Composite PAN/PANI Membranes

The methods of modifying PAN membranes have been known and used for many years. An interesting solution seems to be to give the sensory properties to this type of membranes. This paper presents the results of research on the method of obtaining PAN/PANI membranes using phase inversion method from a solution in DMF, following two methods: () dissolving both polymers (PAN and PANI) and then coagulating in water or in an aqueous solution of CSA and () forming the membranes from polyacrylonitrile solution and coagulation in water, followed by coating of CSA with a solution of TFE. The membranes obtained as a result of the experiment were tested for physical and chemical properties, transport properties, surface morphology, degree of dispersion of composite components, and sensitivity to the presence of dilute acids and bases. FTIR microspectroscopy and scanning electron microscopy were used to study the surface morphology. The sensory properties of membranes that are inherently colored were determined visually and by UV-Vis spectrophotometry. Furthermore, when choosing the method of membrane forming, we can obtain membranes with good physical and chemical and transport properties or ones characterized by high sensitivity to the pH of the solution.

Study of PET fibres modified with phosphorus–silicon retardants

In this study, flame-retardant poly(ethylene terephthalate) (PET) fibres were produced using a high-temperature bath method similar to dyeing fibres with disperse dyes. A mixture of aqueous solutions of silicon and phosphorus compounds was used as the flame retardant. Samples of the modified fibres were examined by thermogravimetric analysis. The residue left after limited oxygen index test was analysed by scanning electron microscopy. Effect of the flame retardant on changing the supermolecular structure of PET fibres was evaluated using wide-angle X-ray diffraction. Mechanical properties of the modified PET fibres as compared with standard fibres were also examined.

Application of Raman Spectroscopy for Evaluation of Chemical Changes in Dibutyrylchitin Fibres

Microporous dibutyrylchitin (DBC) fibres formed by means of a dry-wet method were treated with aqueous solutions of potassium hydroxide. By applying various parameters of the alkaline treatment, fibres can be transformed into fibres from regenerated chitin or even into chitosan fibres. In the first stage, with the application of 5% KOH solutions and temperatures ranging from 20 to 90 °C, fibres from regenerated chitin were obtained. The subsequent treatment stage with saturated KOH solutions and the temperature range 70 140 °C resulted in obtaining fibres from chitosan with different deacetylation degrees.Structural changes in the fibres occurring in the course of their chemical treatment were analysed using RAMAN spectroscopy. Raman spectra were next mathematically processed by means of GRAMS software within the range 1800 820 cm-1 in order to evaluate the changes quantitatively. A new method is described for the determination of butyrylation and deacetylation degrees of dibutyrylchitin, chitin and chitosan. Analysis of the fibres obtained carried out by means of RAMAN spectroscopy proves that in the process gradual degradation of the polymer chains takes place.

Morphology of Highly Porous Conducting Polyaniline Nanofibres Synthesized in a Multi-phase System

Polyaniline nanofibres are typically synthesized in a two-phase system with aniline placed in one liquid phase and the initiator in the other. The authors modified this method by introducing the monomer as a salt, thus creating a third, solid phase. This salt is in the organic phase as acetonitrile. Salts of aniline+DBSA and aniline+CSA were examined. As both these salts have limited solubility in acetonitrile, they do not dissolve during polymerization. To further reduce their solubility, acid was also added to both liquid phases. DBSA and CSA were used in the organic phase while in the aqueous phase, hydrochloric acid, sulfuric acid, DBSA and CSA were used along with the initiator (APS). Numerous polymerizations were carried out to examine various phase compositions. SEM, FTIR and UV-Vis observations revealed interesting properties of the polyaniline obtained in this way. Its morphology and spectroscopic properties strongly depend on the combination of the components used in each phase. Amorphous polyaniline was obtained as were well-developed spatial forms such as blades, spheres or nanofibres.

Time-resolved small-angle X-ray scattering and wide-angle X-ray diffraction studies on the nanostructure of melt-processable molecular composites

Novel melt-processable molecular composites were obtained from isotactic polypropylene (iPP) and liquid-crystalline oligoester (LCO). The nanostructure and thermal behaviour of molecular composites were examined by real-time synchrotron small-angle X-ray scattering and wide-angle X-ray diffraction methods, and differential scanning calorimetry. The synthesized oligoester, with low melting temperature (391 K), exhibits the ability to form a thermotropic mesophase. It was shown that strong rigid rod-like macromolecules of LCO are dispersed at the molecular scale in iPP matrix and act as reinforcing fibres.

Properties and Structure of Cellulosic Membranes Obtained from Solutions in Ionic Liquids Coagulated in Primary Alcohols

Abstract This paper presents the results of studies on the preparation of cellulosic membranes, from a solution in 1-ethyl-3- methylimidazolium acetate (EMIMAc), using the phase inversion method. Initially, the membranes were obtained by coagulation of the polymer film in water and primary alcohols (methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol), 1-hexanol, 1-octanol) resulting in membranes with significantly differing morphologies. Subsequently, composite membranes were produced, with the support layer being a membrane with the largest pores, and the skin layer a membrane with smaller pores. The resulting membranes were tested for physicochemical and transport properties. The morphology of the membrane surfaces and their cross-sections were investigated by using a scanning electron microscope (SEM). The structure of the membranes, on the other hand, was investigated by FTIR spectroscopy and WAXS structural analysis.

FORMATION AND PROPERTIES OF DBC/PLA MICROFIBRES

In this study, a solution of dibutyrylchitin (DBC)/polylactide (PLA) blend micro and nanofibres were successfully fabricated using blends of 2,2,2-trifluoroethanol (TFE) as solvents. Fibres were produced from the solutions by electrospinning. The DBC/PLA blend solutions in various ratios were studied for electrospinning into micro/nanofibres. The morphology of the micro and nanofibres was observed by scanning electron microscope (SEM). The biggest diameters of DBC/PLA fibres were obtained for the blended microfibres in ratios of 10/90 and 25/75. The smallest diameter was observed for pure polymers. The antibacterial properties were examined for materials obtained by electrospinning. In the experiments, materials with antibacterial properties were made. It is likely that the electrospun micro and nanofibres will be used in the native extracellular matrix for tissue engineering.

Study of Structure of Polypropylene Microfibres Modified with Multi-Walled Carbon Nanotubes

The paper presented is concerned with studies of a supermolecular structure and its transformation during the process of drawing new composite microfibres obtained from isotactic polypropylene (iPP) – as a matrix and multi-walled carbon nanotubes (MWCNT) used as the filler. The nanostructure of iPP/MWCNT microfibres as spun and after drawing at a temperature of 95°C was investigated using scanning electron microscopy (SEM), wide angle X-ray scattering (WAXS), small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) methods.