Teresa Mikołajczyk

Correlation Between Copolymer Characteristics, Conditions of Fiber Formation, and Mechanical Properties of PAN Carbon Fiber Precursor: Part I: Effect of Copolymer Intrinsic Viscosity Distribution on Mechanical Properties

We present an..analysis of the copolymer molecular weight distribution effect on the mechanical properties of polyacrylonitrile (PAN) fibers. The conditions of the fiber forming process are constant for each of six copolymers. The analysis shows that the highest values of Youngs modulus are obtained for copolymers that contain 70% by weight of fractions having intrinsic viscosities that range from 1 and 3. The tensile strength of the fibers depends on deformations occurring during the fiber forming process rather than on the molecular weight distribution of the copolymer.

Correlation Between Copolymer Characteristics, Conditions of Fiber Formation, and Mechanical Properties of PAN Carbon Fiber Precursor Part II: Effect of Intrinsic Viscosity of Acrylonitrile-Methyl Methacrylate Copolymer on Mechanical Properties

We have studied the effect of intrinsic viscosity of acrylonitrile-methyl methacrylate copolymer on the structure and mechanical characteristics of polyacrylonitrile (PAN) fibers. The fiber properties are determined for different values of thermal stretch. The tensile strength and Youngs modulus of PAN fibers increase as the intrinsic viscosity of the copolymer increases. The increase in intrinsic viscosity is accompanied by an increase in the content of the paracrystalline phase, the degree of ordering. and the molecular orientation.

Fibrous Polymeric Composites Based on Alginate Fibres and Fibres Made of Poly-ε-caprolactone and Dibutyryl Chitin for Use in Regenerative Medicine

This work concerns the production of fibrous composite materials based on biodegradable polymers such as alginate, dibutyryl chitin (DBC) and poly-ε-caprolactone (PCL). For the production of fibres from these polymers, various spinning methods were used in order to obtain composite materials of different composition and structure. In the case of alginate fibres containing the nanoadditive tricalcium phosphate (TCP), the traditional method of forming fibres wet from solution was used. However in the case of the other two polymers the electrospinning method was used. Two model systems were tested for biocompatibility. The physicochemical and basic biological tests carried out show that the submicron fibres produced using PCL and DBC have good biocompatibility. The proposed hybrid systems composed of micrometric fibres (zinc and calcium alginates containing TCP) and submicron fibres (DBC and PCL) meet the requirements of regenerative medicine. The biomimetic fibre system, the presence of TCP nanoadditive, and the use of polymers with different resorption times provide a framework with specific properties on which bone cells are able to settle and proliferate.

Correlation Between Copolymer Characteristics, Conditions of Fiber Formation, and Mechanical Properties of PAN Carbon Fiber Precursor Part III: Effect of Fiber Formation Conditions on Mechanical Properties

Our aim in this study was to find the optimum temperature of thermal drawing and stabilization at values of deformation lower than the maximum values in order to keep fiber structural defects to a minimum. Fibers with the best mechanical properties were obtained when the drawing process was done at 185°C and the stabilization temperature was 210°C.

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.

Glycolide/L-Lactide Copolymer (PGLA) Fibers Formed by Wet Spinning from Solution and Modified with Ceramic Nanoadditives

Abstract The paper presents the results of research into glycolide/L-lactide copolymer (PGLA) fiber formation by wet spinning from solution. The selected process conditions led to fibers with a specific tensile strength of more than 35 cN/tex. Furthermore, ceramic nanoadditives such as hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) were used to obtain fibers with osteoconductive properties. It was found that the ceramic nanoadditives reduced the specific strength of fibers (to 24 cN/tex for β-TCP and to 27 cN/tex for HAp). The paper also presents wide-angle X-ray scattering (WAXS) evaluation of the supramolecular structure of the fibers as well as their porosity parameters and microscopic structure. The obtained fibers were woven into a textile fabric with potential applications in biomedical engineering.

Einfluß der Herstellungsbedingungen auf die Eigenschaften von Precursor-Polyacrylnitrilfasern und daraus erzeugten Kohlenstoffasern

C-Fasern sind wegen ihrer herausragenden Festigkeit und ihres hohen Moduls fur die verschiedensten technischen Einsatzgebiete von groser Bedeutung. Deshalb werden viele Anstrengungen unternommen, Fehlstellen in den Fasern, die die Eigenschaften praktisch begrenzen, zu minimieren. Eine deutliche Hilfe hierbei ist die Optimierung der Struktur der PAN-Fasern, die zu C-Fasern weiterverarbeitet werden. In der vorliegenden Arbeit wird fur nasgesponnene PAN-Fasern beschrieben, wie es durch Aufteilung der Verstreckung und angemessene Temperaturfuhrung gelingt, Faser-Strukturen einzustellen, die zu besseren C-Faser-Eigenschaften fuhren. Die praktischen Ergebnisse werden durch Strukturanalysen belegt. Carbon fibres are of great importance for a large number of industrial applications, owing to their high modulus and outstanding strength. Therefore, great efforts have been made to minimize the imperfections of the fibres limiting their potential properties. This can be achieved, for instance, by optimizing the structure of the PAN fibres from which the carbon fibres are made. The present paper describes the possibilities to improve the properties of carbon fibres by adjusting the structures of wet-spun PAN fibres by using appropriate drawing stages and temperatures. The practical results are confirmed by structural analyses.