Quantitative Assessment of the Development of Micromycete Colony on the Surfaces of Polymers and Polymer Composites

The need to ensure the possibility of widespread use of electronic and mobile health-saving technologies requires not only the formation of an appropriate information technology infrastructure and the development of effective algorithms for processing a large amount of personal information. Development of medical devices for recording physiological processes also involves the creation of innovative biologically compatible materials that allow sensors and medical sensors to work continuously in 24/7 mode. Taking into account the long-term positive experience of using large-capacity thermoplastics and elastomers in medical equipment, it seems promising to use the corresponding polymers as the main materials of wearable electronics for medical purposes. At the same time, to ensure the biological compatibility of the materials under discussion, it is necessary to minimize the possibility of the development of pathogenic microorganisms on surfaces in contact with living tissues. This type of pathogenic organisms (pathogens of a number of dangerous diseases – mycoses) includes some types of microscopic fungi - micromycetes (in particular, Aspergillus niger van Tiegem; Aspergillus terreus Thom; Penicillium cycopium Westling). The article examines the effect of surface modification by gas-phase fluorination on the nature and degree of development of a mixed colony of micromycetes on the surfaces of experimental samples made of several types of thermoplastics (polyvinyl chloride, polypropylene, low-density polyethylene, polyethylene terephthalate) and elastomers (butyl- and butadiene-nitrile rubbers, as well as ethylene, propylene and dicyclopentadiene copolymers). The nature and degree of development of colonies are quantitatively described using the original methodology developed earlier. The effect of fluorination on the nanotexture and chemical composition of the surface and near-surface layers of experimental samples was demonstrated using scanning electron microscopy (SEM) and IR Fourier spectroscopy (IRFS). The dynamics and efficiency of fluorination are described using a linearized hyperbolic model, the parameters of which are set by the least squares method.

Estimation of resistance of engine rubber sealants to influence of mixed diesel fuel

The sorption-diffusion properties of rubbers in contact with fuels containing methyl esters of fatty acids derived from non-food raw materials have been studied. The hypothesis was advanced according to which there is a dependence of oil resistance of rubbers on their solubility parameter of butadiene-nitrile rubber. The properties of standard oil-resistant rubbers based on butadiene nitrile rubbers of SKN-18 and SKN-40 brands were compared with those of SKN-18-based rubber and Byprene 110 chloroprene-based rubber, to each of them 30% of the plasticized polyvinyl chloride was added. It was found that the contact with the fuel composition, which consists of 70% diesel fuel and 30% methyl esters of fatty acids made from technical sunflower oil, has the strongest destructive effect on all experimental samples of rubber except for rubber-based rubber of SKN-40 brand. It was determined that SKN-40-based rubber, which is characterized by the maximum solubility parameter, is the most stable in relation to fuel compositions containing methyl esters of fatty acids of various origins. Based on the analysis of experimental data, the recommendations were given for the use of SKN-40-based rubber for the manufacture of car engine seals within the global trend to increase the share of alternative components in diesel fuels.

Functional Properties of Elastomers Based on Butadiene-Nitrile Rubbers

In this article Therban AT 5065 VP, Therban AT 5005 VP - HBNR elastomers of different unsaturation degrees and their combined compositions research results (using optical and atomic force microscopy, DSC, DMA) are described. With these results structure and functional properties operational data of nitrile elastomers was obtained with no need of durable tests under different temperatures. It was found out that filler dispersion rises from 61.8 to 90.5 % and decomposition temperature grows from 261.9 to 275.3 °C while Therban AT 5005 VP share is increased from 20 to 50 weight parts. It is shown that elastomers with rubber ratio of 50:50 within temperature range from minus 30 to plus 150 °C have the lowest elasticity coefficient (from 311 to 1.6 MPa) and mechanical loss tangent (0.20) at the end of the test.

BUTADIENE-NITRILE RUBBERS OBTAINED USING POLYVINYL CHLORIDE GELATED WITH A VULCANIZING SYSTEM

Vulcanizing systems obtained by special methods of processing polyvinyl chloride (PVC) plastisols in a composition with sulfur pastes, in which lactam-containing melts act as a dispersion medium, are effective vulcanizing systems for BNC-based rubbers.

Change of electrical characteristics of rubber in the process of “swelling–deswelling”

Objectives. The main indicator that determines electrical conductivity of rubbers is specific volumetric electrical resistance (ρv ). The purpose of this work is to investigate changes in this indicator during swelling and deswelling of electrically conductive rubbers. When considering the swelling process of rubbers in liquid media at a molecular level, an analogy of this process with mechanical deformation of the material is drawn and common features and differences of these processes are revealed.Methods. For rubber compositions based on paraffinate and alkyl sulfonate nitrile butadiene rubbers, the degree of their swelling and the change in linear dimensions in heptane and in gasoline grades 80, 92, and 95 were determined. The ρ v value was determined by a potentiometric method: the initial value was measured after temperature control of rubbers for 1 h at 120°C, and the second measurement was carried out after these rubbers were swollen in the solvents for 48 h, followed by drying at 20°C to a constant weight and repeated temperature control under the same conditions. Using an IR Fourier spectrometer, spectra of the solvents used were obtained before and after identification of the investigated rubber samples in them.Results. It was shown that the type of rubber and solvent used influence the degree of rubber swelling. Rubber compositions based on natural rubbers with a large amount of attached acrylonitrile, obtained in the presence of an alkyl sulfonate emulsifier, have the highest resistance to swelling. The effect of the used solvent on the change in the degree of swelling is determined by its affinity for rubber and the presence of polar additives that increase the octane number of gasoline. It was established that the linear change of the samples upon swelling in the indicated solvents varies according to the length and thickness of the samples. Results show that depending on the type of rubber used and the degree of its filling, the described rubber processing technology leads to a decrease in the ρ v value by 2 to 20 times. The greatest effect of ρ v reduction is observed in low-filled rubber compositions based on paraffinate nitrile rubbers. The spectra of the frustrated total internal reflection of the solvents after their interaction with the studied rubbers show that particulate extraction of dibutyl phthalate, which was used as a plasticizer in rubber compounding, takes place as a result of rubber swelling.Conclusions. The proposed method of rubber processing reduces the ρ v value by removing dibutyl phthalate from the studied rubbers and forming a more developed carbon–elastomer structure. Furthermore, it solves the problem of the negative effect of the plasticizer on the ρ v value of rubber without excluding it from the rubber composition.

MECHANOCHEMICAL MODIFICATION OF NITRILE-BUTADIENE RUBBER IN THE PRESENCE OF A CHLORINE-CONTAINING REAGENT

This work is devoted to study of halide mechanochemical modification of nitrile-butadiene rubber (BNCS-18AN) with a chlorine-containing reagent. In previous studies, the optimal parameters for modification were established. The modification was carried out in a laboratory rubber mixer. The obtained halogen-containing rubbers were investigated using ESR spectroscopy. Rubber compounds based on obtained chlorinated butadiene-nitrile rubbers (CNBR), were prepared and their tensile stress-strain properties and curing characteristics were investigated. Vulcanization of rubber compounds was carried out under the established optimal conditions. Physical and mechanical properties of the rubbers were determined. Subsequent studies showed the most probable regularities of the mechanochemical halide modification of nitrile butadiene rubber (BNCS-18AN) with a chlorine-containing modifier (CHCl) in a rubber mixer.