The viscosity properties of dilute solutions of two modifications of Armalon (MD and X) with properties of other rigid-chain aromatic copolyamides are compared. The best affinity of 96% sulfuric acid for PPTA and Armalon-MD and the worst affinity for Armalon-X are demonstrated.As shown in [1], the properties of solutions of macromolecular compounds both dilute and concentrated are determined by the primary structure (chemical structure) of macromolecular chains to a significant degree. In turn, the study of the properties of solutions of polymers can provide varied information on the structure of the macromolecules. It was interesting to compare the viscosity properties of dilute solutions of two modifications of Armalon (MD and X) with the properties of other rigid-chain aromatic copolyamides.The specific viscosity of the polymers in [2] (η sp ) was determined on a suspended-level Ubbelohde capillary viscometer according to GOST 1103482 for solutions of aromatic copolyamides in 96% sulfuric acid at a temperature of 25±0.1°C. The intrinsic viscosity [η] was found by repeated dilution of a solution of the polymer with an initial concentration of 0.5 g/dl and subsequent extrapolation of the direct dependence of the reduced viscosity η re on the concentration of the solution to a zero concentration.The data obtained are reported in Table 1 and Figs. 1 and 2. The linear character of the dependence of the reduced viscosity on the concentration C indicates that the reaction of the macromolecules can be neglected in the investigated region of concentrations of the polymers in the solution.The close values of the intrinsic viscosity (5.5-7.1) obtained with the calculation with the experimental data suggest that despite the differences in the chemical structure of these aromatic copolyamides, the shape and size of the macromolecules are similar.The lack of handbook data on constants K and α in the generalized Staudinger equation for Armalon did not allow determining the precise values of the molecular weight of this polymer, but published sources [3] give constants K and α in the MarkKuhnHouwink equation [η] = K⋅M α for calculating the molecular weight M with the data on the intrinsic viscosity [η] for poly(phenylene terephthalamide) (PPTA) and Terlon (SB and SM). The data on the molecular weight of the polymers obtained as a result of the calculation with this equation are reported in Table 2.An equation that describes the correlation between the intrinsic viscosity and the molecular weight for particles that the solvent cannot penetrate was used for comparing the values of M of polymers with similar structure of the macromolecule [4]:. The data obtained are reported in Table 3. For comparison, accurate values of the molecular weight of the polymers (PPTA, Terlon-SM, Terlon-SB) for which we have the values of K and α in the equation [η] = KM α are reported in the same table.The important (by one order of magnitude) difference in the calculated values of M indicate that the molecules of the rigid-chain polyamides in dilut...
The statistics of accidents at the enterprise “Uralkali” is analyzed. The object of the study was the fourth mine of the third Solikamsk potash mine. SKRU-3 is one of three mines in Solikamsk, where the underground method at a depth of 100 to 500 meters is the extraction of potassium and magnesium salts. A fatal accident was identified, as a result of smoke and fire at the fourth mine at a depth of 363 m, 9 people died – the builders of the contracting organization. The contract for the construction of the trunk was executed by the employees of FSUE Construction Management No. 30 from Bashkortostan. When developing a fire extinguishing system, a functional scheme for controlling a drainage pump and a high-pressure fire pump was constructed. Logical equations and relay-contact circuit equipment are developed. The design part proposes the use of software and hardware based on the Omron microcontroller.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.