György Czél

MAgPP an Effective Coupling Agent in Rice Husk Flour Filled Polypropylene Composites

Different properties (tensile strength, elongation, modulus, impact strength) of rice husk (RH) reinforced polypropylene (PP) coupled by Maleic-Anhydride grafted Polypropylene (MAgPP) have been investigated. MAgPP is an effective coupling agent, not only in cellulosic-fibre filled polyolefine composites, but in rice husk flour filled polypropylene composite systems as well. It gives a utilizable construction polymer matrix composite (PMC) material even at a 40 wt.% RH filling degree. The strength and modulus increases by adding the rice husk but the elongation decreases in a non-monotonic way. Micrographs shows weak coupling in between RH and PP without MAgPP.

Single, Binary and Ternary Ion Exchanged Zeolite as an Effective Bioactive Filler for Biomedical Polymer Composites

The preparation and modelling of single, binary and ternary ion exchanged zeolites that express antimicrobial efficiency is discussed. As experimental material A type zeolite was used and different variations of Ag, Cu and Zn ions were incorporated into the crystal structure. Antimicrobial efficiency is based on the ion concentration and ion release of the zeolite, therefore the maximum cation-exchange capacities (CEC) were determined for each of the single ions. After the determination of CEC the preparation of binary and ternary ion-exchanged zeolite samples were prepared by the mixture of silver, copper and zinc nitrate solutions and the composition of the samples was determined by atomic absorption spectroscopy (AAS). To verify the bioactive effect, the minimum inhibitory concentration (MIC) of single, binary and ternary ion-exchanged zeolite A was determined for bacteria strains.

Set Point Based Material Selection Method in Case of Recycled Polypropylene Application

Due to the economic reasons of the injection moulding process, robust technology set point was given in the case of a polypropylene part manufacturing. The part, named lid plate was a relatively humble product not sensitive for small strength parameter changing. K392 coded polypropylene (PP) was given as reference raw material for injection moulding. The technical task was to replace the reference material by using recycled PP. It was necessary to keep the production cycle term. The flow characteristics of the offered recycled polymers were previously unknown. New method and capillary rheometry experimental technique was used to aid the material selection. In the method, the repeatability and the accuracy of rod type capillary rheometry was investigated in order to get more reliable flow behavior data of recycled PP polymer. Relatively low repeatability deviance could be determined in the range of 800-1100 s-1 shear rate range by using rod capillary rheometry. By means of the adequate validated rheometry, the recycled polypropylene could be applied for the given technology set point based forming process.

Degradation Behaviour of Zeolite Filled Polyurethanes under In Vitro Aging Process

In this study the degradation and ion/zeolite release processes of in vitro aged zeolite loaded polyurethane composites were evaluated. Two in vitro artificial aging solutions were used; artificial lysosomal fluid (ALF) and Gamble ́s solution and the total exposure time was 12 weeks. Periodically, SEM micrographs were taken of the surface of polyester type polyurethane-zeolite composites. After exposure to ALF solution the samples showed round holes and a rougher surface in general over time. Micrographs of the samples immersed in Gamble’s solution exhibited different signs of degradation with damage features on the surfaces, understood as black holes and a rougher surface pattern. In addition varying amount of salt was also observed on the surfaces that might influence the ion/zeolite release. Furthermore, the zeolite filler caused remarkable changes in mechanical properties after the aging process, which could not be discerned.

Modelling of Ion Distribution in Single, Binary and Ternary Ion Exchanged Zeolite Used for Biomedical Applications

Based on the previously published sodium and Ag, Cu, Zn ion-exchange and re-excange experiments we took an attempt to modeling its structure. We also took in account the ion release experimental results and the rigorous survey of the literature data when we positioned the ions in zeolite crystal structure. Therefore the current study aimed to modeling the ion distribution of single, binary and ternary ion-exchanged zeolite systems used for antimicrobial purposes, where the variation of silver, copper and zinc is incorporated into the zeolite structure. The tool of modelling was “CrystalMaker6” developed by CrystalMaker Software Ltd.

Flame Retardant Polyethylene Terephthalate Fibers Added with Melamine Based FR Additive

Polyethylene terephtalate (PET) was modified with a melamine derivative additive in order to obtain flame resistance of fiber products. The effect of flame retardant (FR) agent was determined by measuring rheological and combustion properties of PET linear polyester. The solubility of additive was investigated using a torque-rheometer. In course of the rheological investigation, the rate of solution was determined. The effect of FR additive on the melt rheology could well be traced by using a torque-rheometer and its evaluation method. After preparation of polyethylene terephtalat and melamine mixture melt, fibers were made by coextrusion centrifugal apparatus. The flame retardancy of fibers were determined by standard combustion tests. These tests were performed in order to determine the oxygen index of fiber products. It was proven that a favourable degree of combustibility of PET can be obtained under the influece of adding melamine-derivative additive.

Pulsed Laser Deposition of Bioglass Coatings on Dental Implants

Bioactive implants coated with Bioglass 45S5 film, as the subject of the research, were produced, evaluation of the adhesion strength of coatings and technology optimisati on were carried out with success. In order to have effective deposition technology for dent al applications, Pulsed Laser Ablation and Deposition techniques (PLAD) and special equipment w as developed as well. The present paper intends to give a summary of the experimental re sults and the optimisation process itself in case of pilot scale production of dental screws.