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Strontium ferrite was incorporated into different rubber matrices to prepare rubber magnetic composites. Three types of elastomers, butadiene rubber BR as non-polar elastomer, acrylonitrile butadiene rubber NBR and blend acrylonitrile butadiene rubber-polyvinyl chloride NBR/PVC as polar elastomers were chosen as rubber matrices. Surface modified strontium ferrite as magnetic filler was applied in concentration scale ranging from 0 to 100 phr. Besides the rubber and the filler, the rubber compounds contained only the ingredients of sulfur curing system. The results revealed that thermo-physical and magnetic properties of composites increased with doping content of ferrite. Moreover, the improvement of mechanical properties in dependence on strontium ferrite content was also recorded. It can be stated that the improvement of composite properties is in close correlation with the increase of polarity of the rubber matrix. POLYM. COMPOS., 38:2480-2487, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

In the present work, rubber magnetic composites were prepared by incorporation of strontium ferrite into rubber matrices based on natural rubber (NR) and acrylonitrile butadiene rubber (NBR). The sulfur and peroxide curing systems were introduced in cross-linking of rubber matrices. The research was aimed at the evaluation of magnetic filler content and type of curing system on the cross-link density, physical–mechanical and magnetic properties of prepared composites. The relationship between the composition of elastomers and cross-link structure within the rubber matrices, formed by applying different curing systems, was under investigation through strain–stress behavior of tested materials. The achieved results showed that ferrite behaves as a reinforcing filler in peroxide-cured composites based on NR, and in both, sulfur as well as peroxide-cured composites based on NBR. The results also demonstrated that the cross-linking degree and the type of cross-link structure as well as the composition of rubber matrices, to a large extent, influence the property spectrum of tested composite systems. [ABSTRACT FROM AUTHOR]

This work deals with the preparation and properties evaluation of magnetic composites with acrylonitrile butadiene rubber matrix, which are able to shield electromagnetic radiation. In addition to the rubber matrix, these materials contained soft magnetic filler (Li or H40) and ingredients necessary for vulcanization process of prepared rubber compounds (sulfur, accelerator N-cyclohexyl-2-benzothiazole sulfenamide, activators ZnO, and stearin). This study was aimed at the preparation of elastomeric composite materials and evaluation of the influence of ferrite weight fraction on curing characteristics, physical-mechanical, and magnetic properties. The results showed that with increasing content of filler, the moduli, and tensile strength decline. Conversely, elongation at break increased with increasing amount of filler. All composites containing 200 and more phr of ferrite showed sufficient absorption shielding properties, whereas lithium ferrite shows better shielding properties compared with manganese-zinc ferrite H40. POLYM. COMPOS., 37:2933-2939, 2016. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Rubber magnetic composites were prepared by incorporation of unmodified and surface modified strontium ferrite into rubber matrices based on NBR and NBR/PVC. Strontium ferrite was dosed to the rubber matrices in concentration scale ranging from 0 to 100 phr. The main goal was to investigate the influence of the type of ferrite on the curing process, physical-mechanical and magnetic properties of composites. The mutual interactions between the filler and rubber matrices were investigated by determination of cross-link density and SEM analysis. The incorporation of magnetic fillers leads to the increase of cross-link density and remanent magnetic induction of composites. Moreover, the improvement of physical-mechanical properties was achieved in dependence on the content of magnetic fillers. Surface modification of ferrite contributed to the enhancement of adhesion on the interphase filler-rubber. It can be stated that ferrite exhibits reinforcing effect in the composite materials and this reinforcing behavior was emphasized with the increase in polarity of the rubber matrix. [ABSTRACT FROM AUTHOR]

This article is focused on optimization of derivatization of acidic drugs from the group of non-steroidal anti-inflammatory drugs (NSAID): salicylic acid, ibuprofen, naproxen, ketoprofen and diclofenac. Derivatization is a necessary step for analysis of pharmaceuticals by GC. MSTFA (A'-methyl- A-(trimethylsilyl)trifluoroacetamide) and BSTFA (N,0- bis(trimethylsilyl)trifluoroacetamide) were used as a derivatization reagents and tested under different conditions: volume, temperature and time of derivatization. Results of optimization were compared and optimized conditions were successfully applied for analysis of real samples of wastewater. Wastewater samples were collected from influent and effluent of wastewater treatment plant (WWTP). The whole analytical procedure involved solid phase extraction (SPE), optimized derivatization and analysis by GC-TOF MS. Limits of detection (LOD) ranged between 8.9 - 71.6 ng.L-1 and limits of quantification (LOQ) ranged between 29.5 - 238.7 ng.L-1 depending on the specific compound. Concentration of selected drugs in real samples of wastewater varied from 0.1 to 30 pg.L-1 in influent and from 0.05 to 2 pg.L-1 in effluent, depending on the compound. [ABSTRACT FROM AUTHOR]

Rubber magnetic composites were prepared by incorporation of strontium ferrite into natural rubber-based continuous matrix. The prepared rubber compounds have model character and besides the rubber and the filler, they contained only ingredients of peroxide curing system, dicumyl peroxide as curing agent, and ethylene glycol dimethacrylate as co-agent. The work was focused on the evaluation of curing system composition and magnetic filler content on curing process, cross-link density, physical–mechanical and magnetic properties of tested materials. The achieved results revealed that the evaluated properties are dependent on the composition of curing system and on the content of ferrite too. Ferrite incorporated in the rubber matrix imparts magnetic properties to the composites considerably. In addition, the improvement of physical–mechanical properties with doping content of ferrite was observed. [ABSTRACT FROM AUTHOR]

The goal of the present work was to study the preparation and properties of rubber magnetic composites and investigation of strontium ferrite activity in examined materials. Three types of rubber matrices, namely butadiene rubber as non-polar elastomeric matrix, nitrile butadiene rubber (NBR) and NBR/poly(vinyl chloride) blend as polar elastomeric matrices, were compounded with strontium ferrite and other additives in order to prepare rubber magnetic composites. Ferrite dosage was given in modified and unmodified forms in concentration scale ranging from 0 to 100 phr. The influence of magnetic filler content on the mechanical properties of composites was investigated. Correlation between Wolf activity coefficient and Payne effect in relation to the mechanical properties of tested systems was discussed. The results revealed that the observed characteristics are dependent on the type of rubber matrix and also on the type of ferrite. [ABSTRACT FROM PUBLISHER]

Four types of peroxides in combination with two types of co-agents were used as cross-linking agents for the preparation of rubber compounds based on natural rubber. The effects of Type I and Type II co-agents on cross-linking and physical-mechanical properties of vulcanizates were investigated. The correlation between mechanisms of the interaction of co-agents with the rubber matrix in relation to the characteristics of tested systems was discussed. The results showed that the Type I co-agent influenced the rate and the state of cure. Physical-mechanical properties were improved by addition of the Type I co-agent. By contrast, the Type II co-agent had no contribution to the rate and state of cure. Moreover, physical-mechanical properties of vulcanizates deteriorated in the presence of this type of co-agent. [ABSTRACT FROM AUTHOR]

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Four different peroxides as curing agents were used to prepare vulcanizates based on natural rubber (NR). The effects of temperature and peroxide concentration on the vulcanization characteristics of rubber compounds, cross-link density ( ν) and physical-mechanical properties of equivalent vulcanizates were investigated. The results revealed that the vulcanization temperature and also the relative amount of peroxide decomposition products are of significant importance in the properties of vulcanizates. Lower vulcanization temperature and lower concentration of peroxides were found to be better factors, showing a proper balance between the degree of cross-linking of the rubber and degradation of the macromolecular chains by side reactions in relation to the crystallization of NR, which imparts vulcanizates based on NR outstanding properties. [ABSTRACT FROM AUTHOR]

In this work, rubber magnetic composites were prepared by incorporation of strontium ferrite into elastomeric matrix based on natural rubber. Cross-linking of the rubbermatrix was performed by using sulfur and peroxide curing system. The study was aimed at the investigation of the type of curing systemand magnetic filler content on curing process and cross-link density of preparedmaterials. Then, the influence of both factors on physical-mechanical andmagnetic properties was observed. The obtained results demonstrate that sulfur-cured composites show better physical-mechanical properties, especially at lower content of strontium ferrite. With increasing amount of ferrite, the differences between the characteristics of both types of composites became less visible, while peroxide-cured sample with maximum ferrite content showed superior tensile strength in comparison with tensile strength of maximally filled sample cured with sulfur system. The obtained results demonstrate better compatibility between the rubber and the filler when peroxide system was introduced for cross-linking of the rubber matrix. [ABSTRACT FROM AUTHOR]

Rubber magnetic composites were prepared by incorporation of strontium ferrites in natural rubber-based elastomer matrix. The work was aimed at the evaluation of magnetic filler influence on physical-mechanical, magnetic and thermal properties of prepared composites. The study was also dedicated to the investigation of microstructure and evaluation of interactions between strontium ferrites and natural rubber. The observed parameters are dependent on the type of ferrite and on the content of applied ferrite, too. Surface modification of ferrite leads to the improvement of interfacial conditions and adhesion between the rubber matrix and the magnetic filler. [ABSTRACT FROM AUTHOR]