Vol 65, No 5 (2023)

The structural diversity of organosilicon compounds used in decorative and care cosmetic products is studied. The unique physicochemical properties of silicones allowing their application as emollients, moisturizers, emulsifiers, film formers, viscosity regulators, and antistatic and binding agents are described. Mechanisms of action of various structure silicones, due to which organosilicon compounds are advantageously used to impart certain properties to cosmetic products, are demonstrated. A comparative analysis of the efficiency of silicones versus natural compounds serving similar functions in cosmetic products is performed. The issue of silicone safety for human health is considered.

Composite fibers containing boron(III) have been obtained based on solid solutions of cellulose in N-methylmorpholine-N-oxide and orthoboric acid with their subsequent transformation into a viscous-flow state. The rheological behavior of cellulose solutions with different content of orthoboric acid and water studied under conditions of continuous and dynamic shear loading has confirmed the intermolecular interaction between the components. It has been shown that the mechanical characteristics of the composite fibers obtained from a 16% solution in N-methylmorpholine-N-oxide are comparable to these for hydrated cellulose fibers. The process of transformation of the composite fibers of various compositions into carbon fiber has been investigated by means of thermogravimetric analysis and differential scanning calorimetry. Chemical, structural and morphological properties of composite hydrated cellulose fibers and carbon fibers obtained from them have been studied using FTIR-spectroscopy, X-ray diffraction, and scanning electron microscopy. The influence of boron(III) compounds on the carbonization process and the formation of graphite-like structures in carbon fiber has been investigated by Raman-spectroscopy.

The effect of introduction of polyamide nonwoven materials on the thermal and mechanical properties of polymer composite materials based on phthalonitriles and a carbon fabric is studied. It is shown that the addition of 3 wt % of polyamide nonwoven material causes a 44% increase in the specific work of delamination. At room temperature elastic mechanical characteristics, such as compressive strength and compressive modulus, for the composite modified with the nonwoven material increase by 12 and 100%, respectively. According to dynamic mechanical analysis, upon reaching 169°C the melting of polyamide occurs; however, there remains the possibility to use the composites above this temperature, as confirmed by mechanical tests performed at 200°C.

The paper presents the results of mechanical and electrical tests of composite materials based on biodegradable polymers (polyvinyl alcohol, polyacrylamide, starch) and synthetic layered double hydroxides (Ni–Al, Zn–Al) obtained by two-stage (chemical) and one-stage (plasma chemical) methods. The one-stage method for producing composites involves the formation of filler structures during the burning of low-temperature plasma in the bulk of an aqueous polymer solution. Electrode materials were used as precursors. Regardless of the production method, 2D hexagonal structures are formed and embedded in the polymer matrix. This is evidenced by IR spectroscopy data showing shifts in the main characteristic bands and the appearance of new ones. It has been established that layered fillers can be both plasticizers and reinforcing agents. The influence of the viscosity of the polymer matrix on the mechanical characteristics of the composites has been revealed. The introduction of fillers changes the surface roughness, leading to an increase in hydrophobicity of the composites. It has been established that the current–voltage curves of the composites are nonlinear, so that such composites can be considered as flexible analogues of nonlinear electronic components.

Условия эксплуатации изделий из полимерных материалов оказывают существенное влияние на срок их службы. В данной статье представлены результаты исследования продолжительности воздействия естественных климатических факторов Республики Саха (Якутия) (зона очень холодного климата) на структуру и свойства полиэтилена марки 273-83. С помощью метода ИК-спектроскопии установлено, что при продолжительном натурном экспонировании в материале протекают радикальные окислительные реакции, вызывающие снижение молекулярной массы полимера. Исследование показателя текучести расплава показало, что в полимере кроме реакций, сопровождающихся разрывом макромолекулярных цепей, протекают также процессы сшивания. Оба процесса приводят к снижению молекулярной массы полимера и расширению молекулярно-массового распределения. Изменение степени кристалличности и размеров ламелярных образований имеет немонотонный характер и определяется метеоусловиями в период экспонирования. Изменения интенсивности солнечного излучения, а также среднесуточных и сезонных температур окружающего воздуха в совокупности с химическими изменениями, протекающими в полимере при натурном экспонировании, приводят к появлению областей упорядоченных структур в аморфной фазе, в результате чего толщина аморфного пространства, обусловливающего пластичность материала, снижается. При этом напряжения в макромолекулярных цепях полимера, находящихся в аморфной фазе повышаются настолько, что полимер демонстрирует поведение хрупкого материала.