The study results of the influence of butadiene-nitrile rubber different grades concentration, cross-linking agent type and content on the physico-mechanical and thermo-deformation properties of polymer compositions based on polypropylene are presented. Mixing of the components was carried out on hot rollers in the melt mode at 170 °C. A preliminary study of rubber concentration affect on the properties of compositions based on polypropylene showed that the introduction of an elastomeric component leads to a regular decrease in the strength and elongation at break of the compositions. The results of investigation of the thermo-deformation properties of polymer compositions showed that at a rubber concentration of 30wt%, and higher on thermomechanical curves, the region of the high-elastic state characteristic of rubbers is noticeably distinguished. Taking into account that the rubber materials are obtained during the process of their vulcanization, it seemed interesting to crosslink materials with two types of vulcanizing agents – dicumyl peroxide and sulphur for obtaining comparable results. The concentration of dicumyl peroxide was varied between 0.5 - 2.0 wt%. It was found that the use of dicumyl peroxide in an amount of 1.0-2.0 wt% is accompanied by intense occurrence of crosslinking with the formation of an irreversible highly crosslinked structure in the polymer composition. Based on the evaluation of the melt flow index of the vulcanized compositions, it was found that at the concentration of dicumyl peroxide in an amount of 0.5 wt% they still retain the ability to flow. At concentrations above 0.5 wt% of dicumyl peroxide the polymer compositions completely lose the fluidity of the melt. It was found that with an increase in the sulphur concentration from 3.0 to 10 wt% the decrease in the melt flow index from 2.76 to 0.616 g/10 min is observed. It was found that the crosslinking process predominantly proceeds through double bonds of butadiene-nitrile rubber, thereby facilitating the production of dynamically vulcanized polymer materials with a unique combination of structure and properties. This was confirmed by the results of a study of the thermo-deformation characteristics of compositions, according to which a transition from the region of a high-elastic state to viscous-flow state is observed in all samples subjected to sulfur vulcanization. The results of the study make it possible to state that dynamic thermoplastic elastomers can be obtained only if the ratio of the components used in the polymer composition is correctly selected.
The effect of additives of metal-containing nanofillers including nanoparticles of zinc oxide stabilized on a polymer matrix of maleinized polyethylene on the properties of nanocomposites based on isotactic polypropylene by methods X-ray phase and thermogravimetric analyses was studied. The improvement of the strength and rheological indexes, as well as the thermooxidative stability of the nanocomposites obtained was revealed.
Рассмотрено влияние концентрации бутадиен-нитрильного каучука и технологического режима литья под давлением на комплекс основных свойств эластопластов на основе термопластичных полиолефиновполиэтилена низкой плотности и полипропилена. Использование пероксида дикумила в качестве сшивающего агента позволило в процессе «монотрем» технологии получить динамически вулканизованные эластопласты с улучшенными физико-механическими и технологическими свойствами.
The article presents the results of a study of the influence of the type and concentration of nitrile butadiene rubber on the main physical and mechanical properties of polymer compositions based on compatibilized ethylene/1-hexene copolymer (EHC*). SKN-18, SKN-26, and SKN-40 were used as nitrile butadiene rubber. The compatibilizer – polyethylene-graft-methacrylic acid was used to improve the compatibility of the mixed components of the mixture. At the first stage, the task of the study was to investigate the effect of the concentration of the considered nitrile rubbers on such properties of the compositions as yield strength, tensile strength, elongation at break, flexural strength, melt flow rate and heat resistance. It was found that, regardless of the type of used nitrile butadiene rubber, with an increase in its content in the composition of the ethylene/1-hexene copolymer, a regular decrease in strength parameters, heat resistance, and melt fluidity is observed. It is shown that with the loading of 30 wt% SKN-18 or 40 wt% SKN-26 and SKN-40 into the composition of the ethylene/1-hexene copolymer phase inversion occurs in the composite materials, according to which the dispersed phase becomes a dispersed medium. The thermomechanical properties of the considered samples were studied. It was found that in those samples in which phase inversion occurred, a region of a highly elastic plateau is formed, which increases with an increase in the content of the rubber component. This area indicates the formation of elastomer with rubber properties. The regularities of crystallization of the compositions depending on the content of the amorphous component were studied by the method of stepwise dilatometry. The mechanism of crystal formation was studied depending on the content of the amorphous component. The influence of the crosslinking agent concentration – dicumyl peroxide on the main properties of dynamically vulcanized elastomers has been studied.
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