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Gas Chromatography—Mass Spectrometry for Characterization of Liquid Products from Pyrolysis of Municipal Waste and Spent Tyres

Pavlova A., Stratiev D., Mitkova M., Stanulov K., Dishovsky N., Georgiev K.

Acta Chromatographica

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2015

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Vol. 27, no. 4

637--655

EN

Liquid products produced from two different types of waste pyrolysismunicipal wastes and spent tyre wastes are investigated using gas chromatography—mass spectrometry. This method has been applied for detailed identification of composition of the samples. The components were characterized in terms of their Kováts retention indices on a PONA capillary column. The obtained analytical data were successfully used for the characterization of the samples. More than three hundred compounds were detected. The liquid products were complex mixtures, composed mainly of C4—C12 compounds. The examination of the selected m/z values very clearly indicates the existence of the different groups of compounds. With a lot of olefins content (31.9%), followed by aromatics (20.0%), paraffins (17.3%), and naphthenes (7.5%), it is described as the liquid product from pyrolysis of municipal solid wastes. The aromatic compounds in liquid product from pyrolysis of spent tyre wastes have the highest concentration (33.5%), and they are followed by naphthenes (28.6%), olefins (19.2%), and paraffins compounds (7.0%). The present study has shown that the pyrolysis of municipal waste and spent tyres can be used as a means for reduction of environmental pollution and production of liquid product which could be used as a fuel source.

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Elastomeric matrix composites: effect of processing conditions on the physical, mechanical and viscoelastic properties

Zaimova D, Bayraktar E., Katundi D., Dishovsky N

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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Vol. 50, nr 2

81--91

EN

Purpose: The aim of this study is to investigate the influence of accelerator-vulcanizing agent system and the vulcanization temperature on the properties of vulcanizates based on Natural rubber/Polybutadiene rubber (NR/ BR) compounds. This preliminary study will allow optimizing the composition for improving the mechanical properties and understanding the damage behaviour. Design/methodology/approach: NR/BR based composites with different vulcanization temperatures and curing systems were characterized in respect of their curing characteristics (for 140°C and 160°C) and mechanical properties. The cure characteristics of the rubber compounds were studied by using the Monsanto MDR 2000 rheometer. The mechanical properties were investigated- tensile strength, elongation at break, tensile modulus at 100% (M100) and at 300% (M300) deformation. The hardness (Shore A) and molecular mass of the samples were also determined. Scanning electron microscopy was used to study the microstructure of the fracture surfaces. Findings: The processing, physical, mechanical and viscoelastic properties and chemical structure of the mixture of Natural rubber/Polybutadiene rubber (NR/BR) compounds have been evaluated in detail for the compounds of D1 and D2 (140/160). Research limitations/implications limitations/implications: Some critical point, control of the temperature during vulcanization in press, can introduce some restrictions; these measurements can play on the final vulcanizates and in the course of processing. Practical implications: In practical way, mechanical test results (tensile and shore A) give very useful information about the damage behaviour of the elastomeric matrix composites. Originality/valut: Natural rubber/Polybutadiene rubber (NR/BR) compounds were mixed by additions of some certain elements to improve physical, mechanical and viscoelastic properties and damage behaviours of these compounds produced under certain conditions.

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State of cure evaluation by different experimental methods in thick rubber parts

Zaimova D, Bayraktar E., Dishovsky N

Journal of Achievements in Materials and Manufacturing Engineering

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2011

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Vol. 44, nr 2

161--167

EN

Purpose: The aims of this paper is to quantify the state of cure by different techniques (physico-chemical; mechanical; thermal; spectroscopic) on the thick elastomeric composites (rubber parts). An optimization is aimed from the experimental results. For this purpose, a detailed comparison is carried out with simulation for industrial applications. Design/methodology/approach: Comparison among the used experimental methods for measuring curing phenomenon is made by choosing the following criteria: destructivity, need of specific sample geometry, reversion detection, error and timing; validation the numerical simulation with experimental results; As a first step, test sheets were obtained from the rubber-based compound. Different methods (DSC, NMR, mass swelling, tensile test, compression set test, relaxation, hardness, shear stress etc.) were used to quantify the state of cure experimentally. The same techniques were applied for evaluating the state of cure in a thick part obtained from the tested compound. Then the results for the thick part were correlated with the results for the test sheets obtained by rheometer. Finally, a comparison was carried out among the used methods by several criteria. Also numerical data obtained for evolution of state of cure in the thick parts is compared by means of special software with the experimental data. Finding Applications of different methods have given very successful results for measuring the state of cure in the test sheets. However, the present results showed that some of the mechanical methods (shear stress, stress-strain, compression set and relaxation) are not suitable for measuring the state of cure in thick parts but NMR, DSC, mass swelling and hardness are very suitable. Research limitations/implications Certain test such as shear stress and Dynamic Scanning Calorimetry (DSC) give high values of error and don’t detect reversion. Additionally, a specific geometry of the specimen is needed for relaxation and tensile tests. Practical implications: Certain tests such as mass swelling, tensile and hardness test give very practical and reliable results for measuring the state of cure in rubber parts in industrial applications. Originality/value A good correlation has been found between numerical and experimental results which give the possibility to make a reliable prediction on the distribution of state of cure in thick parts. Mass swelling method has been adapted to this research conditions and this modified test gave better results than other used methods.