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Search Results: 1 - 10 of 400735 matches for " M. Rojek "
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Butadiene-acrylonitrile elastomers as PVC modifiers
M. Rojek,J. Stabik
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: The purpose of the paper is to present the results of research programme on influence of acrylonitrile-butadiene copolymers on plasticized polyvinylchloride compounds used as window gasket material.Design/methodology/approach: Short review concerning application of modified plasticized PVC compounds as gasket material was presented. In experimental part two types of acrylonitrile-butadiene copolymers were used as elastomeric plasticizers for PVC. Formulations with fifteen different levels of elastomeric modifiers content (up to 25% by weight) were prepared and tested. As reference formulations three commercial compounds were additionally tested. Shore hardness, short-term and long-term elastic recovery, tensile strength, elongation at break and migration of plasticizers from gasket material to unplasticized PVC were searched.Findings: Incorporation of acrylonitrile-butadiene copolymers into PVC enhanced many properties essential for its application as window gasket material. The most important changes occurred for long-term and short term elastic recovery, tensile strength and elongation at break. At the same time addition of these butadiene-acrylonitrile elastomers did not change migration of other plasticizers contained in gasket material into rigid PVC in being in contact with gasket. Obtained results showed that among tested compounds best properties as gasket material exhibited plasticized PVC with 23% of acrylonitrile-butadiene copolymer Chemigum P83. Reference commercial formulations exhibited worse performance properties than new compounds with this acrylonitrile-butadiene copolymer.Practical implications: Research programme allowed to elaborate plasticized PVC compounds modified with acrylonitrile-butadiene copolymer that can be industrially applied for PVC window gaskets.Originality/value: Obtained results are of scientific and practical value. Research programme allowed to investigate the influence of elastomeric modifiers on plasticized PVC properties. Research results are also of practical importance.
Mechanical and electrical properties of mined coal filled polyethylene and polyamide
M. Rojek,J. Stabik
Archives of Materials Science and Engineering , 2009,
Abstract: Purpose: The purpose of the present paper is to present results of basic mechanical properties research of high-density polyethylene and polyamide 6 filled with two kinds of mined coal particles. Because composites with carbon are expected to poses low electric resistance also surface resistivity was measured.Design/methodology/approach: Dependences of tensile strength, elongation at break, impact strength, ball hardness and surface resistivity on volume content of mined coal in polymeric matrix are measured and discussed.Findings: Introduction of mined coal fine particles to polyethylene did not cause significant changes in tensile strength, while the same property of polyamide composites decreased significantly. Brinell ball hardness of all polyethylene and polyamide composites increased almost proportionally to coal content. Pronounced lowering of deformability (elongation at break) with increasing coal content was observed for all formulations. Also impact strength significantly decreased after mined coal filling. Significant lowering of surface resistivity was noticed especially for coal-polyamide composites.Research limitations/implications: Obtained results showed that mined coal fine particles can be applied as a filler of thermoplastic polymers but poor adhesion between polymer matrix and filler particles was achieved. Additional research on mined coal fine particles modification by coupling agents is needed to develop better adhesion.Practical implications: Obtained results showed that mined coal fine particles can be applied as a filler of thermoplastic polymers but poor adhesion between polymer matrix and filler particles was achieved. Additional research on mined coal fine particles modification by coupling agents is needed to develop better adhesion.Originality/value: Polymer composites with carbon as a modifier has been used for many years but there have been only a few experiments on introducing fine particles of mined coal into thermoplastics.
The influence of X-rays on strength properties of polyester vascular system prosthesis
M. Rojek,J. Stabik
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: of this paper was to evaluate the influence of X-ray irradiation on mechanical properties of polyester yarn used in production of vascular system prosthesis. Patients with such prosthesis are subjected to multiple X-ray radioscopic exposures. This can negatively influence prosthesis strength and durability.Design/methodology/approach: Polyester yarn tensile strength properties were measured before sterilisation and X-ray irradiation. Next a part of yarn was subjected to irradiation sterilisation. Sterilised and non-sterilised yarn was next exposed to multiple X-ray irradiation and to continuous irradiation. After each irradiation dose tensile strength and elongation at break were measured.Findings: The influence of X-ray irradiation dose on mechanical properties was evaluated. It was established that dose equivalent to multiple X-ray radioscopic exposures did not substantially influenced strength properties of polyester yarn.Research limitations/implications: To fully evaluate the influence of X-ray irradiation on prosthesis strength and durability working in human body environment it is planned to continue described research. Simultaneous influence of X-ray irradiation and body fluids on mechanical properties of polyester yarn will be tested.Practical implications: Research results proved that patients with polyester vascular prosthesis may be subjected to X-ray radioscopy without any anxiety concerning prosthesis strength properties or durability.Originality/value: The main research value is its basic conclusion that multiple X-ray irradiation does not significantly influence strength and flexibility of polyester yarn applied to vascular system prosthesis manufacture.
Modification of PVC compounds with butadiene-acrylonitrile elastomers
M. Rojek,J. Stabik
Journal of Achievements in Materials and Manufacturing Engineering , 2006,
Abstract: Purpose: The purpose of the paper is to present the research programme on influence of acrylonitrile-butadiene copolymers on properties of plasticized polyvinylchloride as window gaskets material.Design/methodology/approach: Short literature review concerning application of modified PVC as gasket material was presented. In experimental part two types of acrylonitrile-butadiene copolymers were used as elastomeric plasticizers. Compounds with fifteen different levels of modifiers content (up to 25% by weight) were prepared and tested. Additionally three commercial compounds were tested as reference formulations. The following test were performed: Shore hardness, short-term and long-term elastic recovery, tensile strength, elongation at break and migration of plasticizers from gasket material to unplasticized PVC.Findings: Application of acrylonitrile-butadiene copolymers as PVC modifier enhanced many properties essential for window gasket materials such as long-term and short term elastic recovery, tensile strength and elongation at break. At the same time addition of these elastomers did not change migration of other plasticizers contained in gasket material. Obtained results indicated that among tested compounds best properties as gasket material exhibited plasticized PVC with 23% of acrylonitrile-butadiene copolymer Chemigum P83. Reference commercial compounds exhibited worse performance properties than compounds with this acrylonitrile-butadiene copolymer. Practical implications: Research programme allowed to elaborate plasticized PVC compounds modified with acrylonitrile-butadiene copolymer that can be industrially applied for PVC window gaskets.Originality/value: Obtained results are of scientific and practical value. Research programme allowed to investigate the influence of elastomeric modifiers on plasticized PVC properties. Research results are also of practical importance.
Thermographic method of fatigue assessment of polymeric materials
M. Rojek,G. Wróbel
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The article presents the adoption of thermal imaging techniques in assessing methodology of the fatigue degradation degree of the polymeric materials.Design/methodology/approach: Epoxy composites reinforced with glass fiber have been subjected to three point method fatigue bending. The degraded materials were then tested using thermovision method.Findings: In experiments the temperature changes velocity of the samples was determined in the conditions of infrared radiation. The dependence between speed up of temperature and the number of fatigue cycles was determined. With an increasing a number of fatigue cycles drop in temperature speeds up was observed.Research limitations/implications: Restriction is a condition of loading state - as homogeneous as possible, and hence the homogeneous degradation state of the material.Practical implications: Designated diagnostic relation gives a basis for non-destructive evaluation of the degree of exhaustion of load-bearing capacity of the material.Originality/value: Original value of the paper are the experimental results proving the effectiveness of non-destructive thermographic methods for polymeric materials diagnosis.
Hard coal modified with silanes as polyamide filler
M. Rojek,J. Stabik,?. Suchoń
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: This paper shows the influence of coupling agents, especially silanes, on mechanical properties of polyamide 6 filled with hard coal dust.Design/methodology/approach: Before preparing compositions, pulverised filler surface was modified with coupling agents. Then, it was compounded using a twin-screw extruder composite consisting of modified hard coal and polyamide 6. A blend was granulated later and test samples were subjected to injection moulding. Afterwards, mechanical properties were evaluated. These properties have essential meaning for applications of new composites as structural materials.Findings: Tests demonstrated that modification of powdered hard coal surface with coupling agents had not significant effect on mechanical properties of polyamide/hard coal composites.Research limitations/implications: Applied compounding procedure did not allow to achieve good compositions homogenisation. A new method to be applied is planned in future research. Simultaneously, it is necessary to investigate composites with other coupling agents which will improve filler’s adhesion to a polymer. Long-term test are also planned.Practical implications: Hard coal, cheap and widely available filler, used to modify thermoplastic polymers, enable to obtain new materials with attractive properties and many applications.Originality/value: Paper represents innovative polymer filler and methods to modify it.
Research on polyamide matrix composites filled with hard coal
M. Rojek,J. Stabik,M. Szymiczek,?. Suchoń
Archives of Materials Science and Engineering , 2012,
Abstract: Purpose: The aim of this paper is to present the summary results of studies on polyamide composites filled with hard coal. Research on the use of coal as a filler of polymers are conducted for many years in Division of Metallic and Polymeric Materials Processing, Silesian University of Technology. This paper summarizes results obtained in different research programmes preformed in recent years. Described materials are polyamide 6 composites filled with modified and unmodified hard coal powder.Design/methodology/approach: All the resulting compositions intended for research have been produced using twin screw extruder. The resulting mixtures of various compositions were then subjected to a process of granulation. The prepared composites have undergone a process of injection moulding which allowed to obtain samples for strength tests. Full statement of research results obtained for composites could help to predict the material with the best mechanical properties and hence the best material for construction.Findings: It has appeared from studies that in both a composite made of unmodified coal and of coal modified with coupling agents show a decrease in mechanical properties in comparison with the neat polymer. Apart from this these composites are interesting materials because of low prize of the filler.Research limitations/implications: It can be concluded from research that all types of obtained composites are characterized by a decrease in mechanical properties.Practical implications: Applications of hard coal as a filler of polymer composites is way to produce new materials. It is worth noting that the main features of the filler used is its prevalence, low cost and electrical conductance.Originality/value: The results describe new fillers of thermoplastic polymers and the possibility of its modification.
Simulation studies of fatigue degradation process with reference to composite pipes
G. Wróbel,M. Rojek,M. Szymiczek
Journal of Achievements in Materials and Manufacturing Engineering , 2012,
Abstract: Purpose: The work deals with the principle of utilization of simulation models of fatigue degradation processes of composite materials as well as acoustic wave propagation for diagnostics of state of exhaustion carrying capacity of composite pipes.Design/methodology/approach: The basic aim of the assignment is working out the model of the propagation of the acoustic waves in inhomogeneous resilient resort representing the composite material, in the condition of acoustic diagnostic signal stimulation.Findings: The modelled analysis of the results of the process of the acoustic wave propagation with the use of material of thin-walled coating of pipe made of epoxy-glass, confirms the possibility the parameters of physical model of fatigue degradation process to be identified.Research limitations/implications: The dynamic load by course and distribution of surface corresponds to the cycle of the diagnostic impulse of the acoustic wave.Practical implications: The application of the procedure of simulation with reference to propagation of acoustic wave with identical period to models of various degradation level, allowed to seize the impact of structural features of the model on the speed of the wave propagation.Originality/value: Paper is representing simulation models of fatigue degradation processes of composite materials.
Influence of select parameters of drawing process on the expansive deposition of inner PE lining in pipelines
G. Wróbel,M. Rojek,M. Szymiczek
Journal of Achievements in Materials and Manufacturing Engineering , 2012,
Abstract: Purpose: This paper shows the influence of select parameters of drawing process on the expansive deposition of inner PE lining in pipelines.Design/methodology/approach: The study included assessment of the impact of diameter reduction degree, drawing die angle, temperature, introductory pipe diameter, and introductory pipe wall thickness on the viscoelastic return. Obtained dependencies were assumed to be the basis for formulation of conclusions as to the choice of essential process conditions for the technological sequence of PE lining deposition in the outer coating of installation pipes or reconstruction of a transmission channel.Findings: The final effect presentation is worked out methodology used in identification of physical parameters of a PE pipe drawing model as the main phase of a viscoelastic deposition of lining in two-layer pipes. Particular attention was focused on the need to take into consideration changing friction conditions in the drawing die area and to determine the value of the friction factor.Research limitations/implications: The research did not show the influence of the length of the sizing and drawing speed on the viscoelastic return.Practical implications: The practical effect is to develop the characteristics of the impact of process parameters on the size of time to viscoelastic return.Originality/value: Paper represents model of PE lining deposition in the outer coating of installation pipes or reconstruction of a transmission network.
Investigation of processing properties of polyamide filled with hard coal
J. Stabik,?. Suchoń,M. Rojek,M. Szczepanik
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: The aim of this article is to present the influence of contents and kind of hard coal used as powder filler on rheological properties (viscosity) of polyamide 6.Design/methodology/approach: Preparation of composite of polyamide 6 with hard coal was carried out on laboratory twin screw extruder. Extruded composite was granulated and in this form was used for MFR analysis. Taking into account MFR results viscosity was calculated. The influence of filler content on viscosity was next searched.Findings: Results of research showed that addition of powdered hard coal to polyamide 6 matrix cause pronounced decrease of MFR index. In this way significant increase of viscous flow was observed. It is often observed phenomenon for polymer composite filled with powder materials.Research limitations/implications: It is necessary to carry out the research with surface modified hard coal with coupling agents which provide better adhesion of polymer matrix to filler.Practical implications: Hard coal used as a filler in composites makes it possible to gain new and cheaper polymeric materials with many possible applications.Originality/value: Investigation described in article shows possibility of hard coal application as innovatory filler of polymers. The influence of this filler on rheological properties indicate that processing of these new materials may be accompanied with some problems.
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