Search

The optimum composition of flame retardant systems (FRS) consisting of 75% aminotrismethylenephosphonic acid ammonium salt (AMP AS) and 25% pentaerythritol (PER) and 1% zeolite (of the weight of the PP composite) which allows obtaining polypropylene with OI = 29.4% is selected. Thermooxidative degradation of PP composites was investigated by TGA. The total amount of volatiles in thermolysis of PP containing 20% three-component FRS (AMP AS/PER/zeolite) is 1.5 time lower than for the initial polymer, which decreases the potential fire hazard of polypropylene.

Electron-probe microanalysis showed that vibration treatment of polymer binders causes changes in the structure of polymer films not only based on latexes but also aqueous solutions of polymers, PAA and PA in particular. The wave effect on the composite based on aqueous solutions of PAA and PA not only affects the physicomechanical properties but also the porosity, air permeability, andsorption capacity of filter nonwovens. A hypothesis is advanced concerning the effect of the wave action on the polymer composites, pore structure, and sorption mechanism of nonwoven filter materials based on these composites.

The following conclusions can be drawn from an analysis of the data reported in the present article: SVM and Armos fibres are now the most promising for use in bulletproof materials; increasing the elongation to 5–6% while preserving the strength at the level of 400–450 kgf/mm 2 allows increasing the efficiency of use of fibres for bulletproofing; the method proposed here allows rapidly and efficiently conducting comparative tests and initial selection of materials and the pack structure of the energy-absorbing polymer support; new types of bulletproof fabrics must be developed to increase the efficiency of manifestation of the energy-absorbing properties of fibres.

For processes of fibre-spinning by the wet method, a general relationship has been found with respect to the proportion of regeneratable solvent from the precipitation and plasticizing baths and from final wash water, which permits one to expertly evaluate a technological process.

For fibres based on aromatic polyamides at a constantv1/v0 ratio, the coefficient of jet expansion β* remains practically unchanged with increase in flow rate, since thereupon the force of yarn tension rises considerably.

It was noted that stiff-chain (para-aramid) and flexible chain (polyethylene) high-strength, high-modulus polymer fibres have been successfully used for ballistic protection of humans. It was hypothesized that new high-strength, high-modulus fibres based on aromatic polyesters could be successfully used for this purpose in the very near future.

In the present article we give procedures for designing communicating and noncommunicating collectors, by use of which it is possible to analyze and calculate any collector, which is shown in the case of a collection having a variable section. Moreover, we examine a new method of treating rheological curves with the objective of obtaining simple analytical formulas for calculating the hydrodynamic characteristics of a solution line, particularly the modulus of a collector-section between take-off points, using rheological constants, as was done for viscose in [4], but with allowance for the molecular weight of the polymer or its degree of polymerization (DP).

A mathematical model has been proposed for the process of heat-exchange between yarn and heating chamber which permits one, with reasonable accuracy, to describe the yarn temperature distribution over the length of the heater and beyond its limits. This model affords the possibility of calculating the amount of heat carried off by the yarn from the heating chamber and to estimate heat losses into the environment, and, consequently, to select the most economical heater.

An experimental and theoretical study has been made of mass-exchange processes in a vibrational apparatus for washing complex yarns. A mathematical description of the process has been set up, with use of the solution obtained for the differential equation for nonstationary diffusion at nonzero initial conditions. A numerical method of calculating mass-exchange processes for a separated complex yarn moving in a countercurrent stream of liquid has been developed; this has been used to determine the length of a vibrational apparatus.

A mathematical description of the kinetics of phase transitions in a gas emulsion has been given. An approach has been formulated to the mathematical description of sedimentation processes in a gas emulsion. Recommendations have been given for optimizing the degassing process regime.

It has been shown that it is advisable to use the coefficient of variation as a criterion to evaluate accuracy in dispensing powder-form polymers. A determination of the minimum necessary number of portions withdrawn from the stream in evaluation of accuracy in dispensing has been proposed. A connection has been established between the type of mixer and the method of sample withdrawal.

The question of optimizing the spinning solution filtration process with respect to a production criterion — the maximum gain in commercial production (profit) — has been examined.

In this article we consider the effect of the frequency of rotation of the pump gears, the pressure drop, the length of pump operation, and the viscosity of spinning solutions of an aromatic polyamide (APA) in dimethylacetamide (DMAc) containing up to 1% by wt. hydrochloric acid on delivery. In the first stage of the investigation, which was carried out on a laboratory unit and under plant conditions, we used new standard IINSh-0.6-I3 pumps of the second group with respect to delivery and pumps which had operated for 500 and i000 h at the following parameters: pressure at inlet (PI), 1 ±0.01 MPa; at the outlet (P2), 0, i, and 2 ± 0.01 MPa; frequency of gear rotation, 0.17, 0.33, and 0.5 sec -~ at a polymer solution viscosity of 40, 58, or 75 Pa. sec. Below we give the nominal designations and intervals of variation of the factors which affect the pump delivery: Factor

As a result of investigation, it has been found that a considerable decrease in the thermal stability of Oksalon fibre is the result of contaminants in the solvent-technical sulfuric acid.

The basic reasons for failure in the operation of spinning gear pumps in metering solutions of polyoxadiazole in concentrated sulfuric acid have been studied. The possibility of eliminating blockage of gear pumps, reducing nonuniformity in delivery of spinning solution, and considerably increasing the stability of spinning Oksalon fibre has been demonstrated.

The frictional force of yarns on yarn-guide bends in spinning and washing essentially does not depend on the linear density of the yarn or its rate of movement within the range 60–300 m/min.

It has been found experimentally that to increase the uniformity of linear density of yarn spun from an aggressive spinning solution of 40–50 Pa·sec viscosity, it is necessary to use metering pumps of high output and to maintain a positive pressure difference of up to 1 MPa between the spinning solution pressure at intake and that at discharge from the pump.

In man-made fibre spinning the solutions are conveyed from the spinning tanks by compressed air or nitrogen. The maximum permitted air concentration C m in the solution is determined by experiment and is usually lower than the concentration C e equiponderant to the atmospheric pressure. According to Henry's law Ce = ChP a where C h is Henry's constant and Pa is the atmospheric pressure. It follows that C m is less than or equal to ChP a •