Stanisław Rabiej

A comparison of two X-ray diffraction procedures for crystallinity determination

Abstract The method of Hindeleh and Johnson and the method of Ruland and Vonk were employed for determination of the crystallinity in polyethylene, polypropylene and polyethyleneterephtalate. It was found that the values given by the methods are relatively close. However, using the method of Hindeleh and Johnson, the amorphous background approximation must be changed.

Determination of the crystallinity of polymer blends by an x-ray diffraction method

Abstract A procedure for determination of crystallinity in polymer blends is described. The procedure may be applied to two-component blends composed of a semicrystalline polymer and a completely amorphous one. The results for blends polypropylene/polystyrene and polyethylene/polystyrene are presented.

Ladder-type copolymers—I. Investigation of the molecular structure

Abstract The molecular structure of ladder-type styrene-multimethacrylate copolymers has been investigated by GPC and i.r. GPC has been used for determination of molecular weight distributions and weight-average and number-average molecular weights. Compositions of copolymers have been determined by i.r. spectroscopy.

High crystallinity polyethylene obtained in biphasic polymerization using pyridinium chloroaluminate ionic liquid

A series of N-n-alkylpyridinium chloroaluminate ionic liquids [Cn-py][AlCl4] (where n-alkyl = n-butyl, n-hexyl, and n-octyl) was applied as a medium of the Cp2TiCl2 catalyst, activated by AlEtCl2 or AlEt2Cl, to evaluate the influence of the studied ionic liquids on the performance of the biphasic ionic liquid/hexane ethylene polymerization and the properties of the produced polyethylene (PE). The best results were obtained using N-n-butylpyridinium chloroaluminate. The polyethylene obtained in the biphasic polymerization have the high crystallinity, which was confirmed by DSC, WAXS and PALS methods, as well as the bulk density comparable to commercial HDPE. These unique properties results from the biphasic mode of the ethylene polymerization where the ionic liquid is used to immobilize the catalyst, and polyethylene is produced in the ionic liquids phase.

Ladder-type copolymers—II. Thermal investigations

Thermal properties of ladder-type styrene-multimethacrylate copolymers have been investigated using TG, IGC, DSC and DTA techniques. Thermogravimetric analysis revealed that the copolymers are thermally stable up to 200°C. Diphase structure of the copolymers has been ascertained. Two glass temperatures have been found the first (Tg1) is independent of the copolymer composition and is close to Tg of pure polystyrene while the second (Tg2) is clearly dependent on the copolymer composition. Ideas on the phases have been presented.

New generation butyric-acetate copolymer of chitin (BOC) fibres with ceramic HAp and TCP nanoadditives for the manufacture of fibrous composite materials

An investigation was made of the effect of basic spinning process parameters on the structure and properties of butyric-acetate copolymer of chitin (BOC) fibres. It was found that, considering the resulting tenacity of 20.3 cN/tex simultaneously with high water sorption and retention properties, it is favourable for the BOC fibre spinning process to be carried out with 1 % HAp or TCP nanoadditive. Furthermore, when 3 % of the HAp or TCP nanoadditive is incorporated into the BOC fibre material, no significant changes in the crystal structure occur compared with fibres without the nanoadditives, formed in similar conditions. Analysis of the porous structure and the properties of the surface of BOC fibres with HAp or TCP nanoadditive shows that the parameters are favourable for their medical application.

SAXS and WAXD, Time Resolved Investigations of the Morphology of Polyethylenes

This work shortly describes the morphology of polymers and presents the possibilities of SAXS method in the investigations of the structure of polymers referring to our studies on the structure of homogeneous copolymers ethylene-1-octene. Besides, we describe our computer program SAXSDAT designed for the analysis of SAXS curves of polymers.

A quantitative analysis of small- and wide-angle X-ray diffraction curves of homogeneous ethylene-1-octene copolymers

This paper presents a comparison of the results obtained with two methods employed in the analysis of small-angle X-ray scattering (SAXS) curves of isothermally crystallized homogeneous ethylene-1-octene copolymers: a method based on the calculation of the one-dimensional correlation function and a method based on model calculations and curve fitting. Data obtained from time-resolved SAXS investigations are supported by the results of simultaneous wide-angle X-ray diffraction (WAXD) measurements of crystallinity development during isothermal crystallization.

Modeling of Polymer Structure with the Use of SAXSDAT Computer Program

The most important structural parameters of semicrystalline polymers can be determined by modeling of their structure and best fitting of a theoretical intensity distribution calculated for the assumed model to the experimental SAXS curve. This paper presents a module of a computer program SAXSDAT dedicated to such calculations.

Determination of micropore concentration and size distribution in carbon fibres by the saxs method

The parameters of pores in carbon fibers made from poly(acrylonitrile), such as the volume fraction of pores, the correlation length, the specific surface area etc. were determined by SAXS. The pore size distribution functions were evaluated using the methods of Glatter and Jellinek. Porenparameter von aus Polyacrylnitril hergestellten Carbonfasern, wie z. B. Volumenanteil, Korrelationslange und spezifische Oberflache, wurden mittels SAXS bestimmt. Die Porengrosenverteilungen wurden nach Glatter und Jellinek berechnet.