A mathematical model of the melting of polymeric materials in extruders. Investigation of the form of the interface and of melt velocity profiles

Conclusions The form of the interface in the melting of a polymer in an extruder has been studied. It has been found that it differs considerably from right-angled, and melting of the polymer takes place over its entire curvolinear surface.The three components of polymer melt velocity have been constructed: The change in these both over the cross-sectional area of the extruder screw and also along its length has been noted.In the liquid phase of the polymer, an intense circulation of the melt takes place in the transverse plane of the screw channel.Translated from Khimicheskie Volokna, No. 5, pp. 40–42, September–October, 1984.     

Determination of the Melting Point and Glass Transition Temperature of Polymers with the Lattice Model

The melting point and glass transition temperature of polymers is estimated with the lattice model of the bulk polymer phase. The good agreement of the predictions of the theory and the experimental findings on melting of polyethylene is demonstrated. The dependence between the melting point and glass transition temperature of polymers is obtained with the statistical thermodynamic theory and is in good agreement with the experimental data.__________Translated from Khimicheskie Volokna, No. 1, pp. 33–35, January–February, 2005.     

Mathematical model of fusion of polymeric materials in extruders

Conclusions The melting of polycaproamide flake has been studied experimentally on a 32 mm laboratory extruder under various processing regimes. The lengths of the extruder charging and melting zones have been measured, plus the cross-sectional area of the polymer plug along the length of the melting zone.The results of the experimental studies agree well with the calculated data, which indicates adequacy of the theoretical model for a real process.Translated from Khimicheskie Volokna, No. 6, pp. 38–40, November–December, 1985.     

A mathematical model of the melting of polymeric materials in extruders. Circulation currents and temperature fields in the polymer. Pressure distribution along the length of the extruder screw

Conclusions Circulation currents of the polymer melt in the transverse section of the extruder screw channel, temperature fields in the polymer melt and in the solid plug, and the pressure distribution (pressure gradient) along the length of the melting zone have been investigated.It has been show that under definite conditions of extruder operation, hot regions are form at the bottom of the left channel wall, in which the polymer can be considerably overheated or thermally decomposed.Depending on the extruder output, the pressure along the length of the polymer melting zone can either increase or decrease.Translated from Khimicheskie Volokna, No. 5, pp. 42–44, September–October, 1984.     

Ultrastrong fibres fabricated by orientational crystallization from gel. A review

The methods of fabrication of ultrastrong chemical fibres from flexible-chain polymers examined in the review require use of a starting polymer with an ultrahigh-molecular-weight. Attaining ultrahigh draw ratios is a common technological condition. This is almost exclusively determined by the ratio between the deformation rate, temperature, and initial state of the polymer. Gel technology is a priority method of fabrication of ultrastrong fibres. The polyester fibres fabricated by this method attain strengths of 6–7 GPa and Young's modulus of 220–250 GPa. All ultrastrong fibres have the structure of a fibrillar crystallite with a significant fraction of KVTs. All ultrastrong fibres have a melting point 5–10°C higher than for oriented fibres and elevated technical stability with high temperatures and moderate loads.Ukrainian Scientific-Research Institute of Fibres, Kiev. Translated from Khimicheskie Volokna, No. 6, pp. 8–17, November–December, 1992.     

Strengthening of polypropylene fibre

Conclusions It has been shown that elongation of polypropylene fibre at a temperature above the melting point of the unoriented polymer is accompanied not only by an increase in structure orientation, but also by formation of a denser structure, which ensures a high fibre strength.All-Union Scientific Research Institute for Synthetic Fibres (VNIIV). Translated from Khimicheskie Volokna, No. 5, pp. 12–13, September–October, 1969.     

Nature of the thermal stability of polyheteroarylenes

Conclusions The dependence between structure and thermal stability of polyheteroarylenes has been examined.It has been shown that the thermal stability of polymers depends on two basic factors — an energy factor, determined by the breaking energy of skeletal bonds in the polymer chain, and an entropy factor, which characterizes the probability of effecting the elementary acts of chemical reactions and is expressed via the mobility of the macromolecules.Symmetry of the monomeric units in a chain, regularity in the macromolecules, the absence of bulky substituents, and a high degree of crystallinity aid in reducing the molecular mobility of heterocycloaromatic polymers and in increasing their thermal stability.Analysis of the factors which aid in thermal stability has made it possible to arrive at the conclusion that the polymer glass transition point or melting point can serve as a criterion of the thermal stability of polyheteroarylenes.Published in discussion order.Translated from Khimicheskie Volokna, No. 4, pp. 22–26, July–August, 1987.     

Effect of moisture in polycaproamide flake and of types of melting devices on polymer properties after repeated melting

Conclusions A calculation of the equilibrium moisture content of polycaproamide flake has been given, with allowance for specific conditions of synthesis and processing on spinning machines.In processing flake with an equilibrium moisture content on machines of the extruder type, a lack of change in polymer molecular weight after repeated melting and a high chemical uniformity are assured.Translated from Khimicheskie Volokna, No. 3, pp. 44–46, May–June, 1986.     

Heterogeneity of poly-p-phenylene-1,3,4-oxadiazole solutions

Conclusions The heterogeneity of spinning dopes is mainly caused by impurities contained in the starting raw materials.Heterogeneity of concentrated POD solutions (above 13%) is connected with the formation of crystal solvates.The melting points of the crystal solvates in POD solutions dependls on the polymer content of the solution, the molecular weight of the POD, the sulfuric acid concentration, and the nature of the modifying components.Translated from Khimicheskie Volokna, No. 3, pp. 26–28, May–June, 1986.     

Cure studies and thermal stability of an acetylene-functionalized polyphenylene resin

Summary Samples of an acetylene-functionalized polyphenylene resin have been thermally cured to determine the effects on char yield and thermooxidative stability. The material's lack of a processing window led to difficulties in handling; it was found that quickly heating small samples above the melting point resulted in complete polymer melting prior to resolidification due to cure. Curing in air and in an inert atmosphere led to decreases and increases in char yields, respectively, at 900°C. Char yields in excess of 90 weight % were obtained at 900°C. The thermooxidative stability of the cured polymer was slightly better than that of the uncured resin, with the biggest improvement being in the 200–400°C range.     

Effect of fluctuations in polymer melt temperature of linear density of yarn

Conclusions The effect of polymer melt temperature fluctuation at the inlet to the metering pump on nonuniformity in yarn linear density has been studied.It has been shown that considerable fluctuation in yarn linear density, caused by change in melt temperature, takes place also in individual working sites.A considerable difference in the temperature of the melt going to individual working sites of machines for spinning technical yarns has been discovered.Fluctuation in the linear density of yarn caused by variation in melt temperature at the inlet to the metering pump may reach 0.3–0.8% in spinning technical yarns, depending on the construction (group or individual) of the spinning machine melting devices.Translated from Khimicheskie Volokna, No. 5, pp. 45–47, September–October, 1984.     

Preparation of polyolefin fibres

Conclusions 1. A procedure has been developed for obtaining low-stretch, high-denier (bulk-braided) thread from polypropylene and fibrillated film from polyolefins (propylene and polyethylene) for manufacturing carpets. Fibrillated film is also used for making bagging and twisted-thread artefacts.2. A method has been developed for strengthening polypropylene fibre at temperatures above the melting point of the unoriented polymer; this makes it possible to obtain high-strength fibre.All-Union Scientific Research Institute for Synthetic Fibres (VNIIV). Translated from Khimicheskie Volokna, No. 5, pp. 11–12, September–October, 1969.     

A mathematical model of the melting of polymeric materials in extruders

Conclusions The contemporary state of the theory of melting of polymeric materials in plasticizing extruders has been discussed.A new, more refined theory of melting in the screw channel has been presented, based on solution of the fundamental equations of motion, energy transfer, heat conductance, and state.Translated from Khimicheskie Volokna, No. 3, pp. 51–53, May–June, 1984.     

Poly[4-Amino-2,6-pyrimidinodithiocarbamate] and Its Cobalt, Nickel, and Copper Complexes

The pyrimidinodithiocarbamate polymer was prepared from the reaction of 2-mercapto-4,6-diaminopyrimidine with carbon disulfide, followed by condensation through the removal of H₂S gas. Three polymer–metal complexes of cobalt, nickel, and copper were then prepared. The polymer and its complexes were investigated by elemental analyses, UV, IR, and magnetic susceptibility. The DC electrical conductivity variation, with the temperature in the region 298–498 K, of the polymer in its undoped and doped (5% iodine and 5% NiCl₂) states and, also, of the three polymer complexes was determined. All the complexes showed an increase in conductivity with an increase in temperature in a semiconductor behavior. The thermal stability of the complexes was studied using the TGA technique. The structures of the polymer and its complexes were assigned. The proposed structure of the complexes is (MLX ₂.mH₂O)_n. All the polymer complexes are thermally stable, are insoluble in common organic solvents, and have high melting points.     

Thermodynamics of Melting of Polymers at High Pressures

Equations that allow determining the melting point, change in volume, and other thermodynamic parameters of melting of polymers at high pressure are proposed based on the statistical-thermodynamic theory of melting of polymers. The good agreement of the predictions of the theory and the experimental data for polyethylene is demonstrated.__________Translated from Khimicheskie Volokna, No. 1, pp. 29–32, January–February, 2005.     

Preparation of alkaline PVA-based polymer electrolytes for Ni–MH and Zn–air batteries

Alkaline PVA polymer electrolyte with high ionic conductivity of about 0.047 S cm^–1 at room temperature was obtained by a solution casting method. The PVA polymer electrolytes, blended with KOH and H₂O, were studied by DSC, TGA, cyclic voltammetric and a.c. impedance methods. The PVA polymer electrolytes show good mechanical strength and high ionic conductivity. The electrochemical stability window at the metal–electrolyte interface is ±1.2 V for stainless steel. Ni–MH and Zn–air batteries with PVA polymer electrolytes were assembled and tested. Experimental results show good electrochemical performances of the PVA-based Ni–MH and Zn–air batteries.     

Synthesis of Nanocomposites of Metal Nanoparticles Utilizing Miscible Polymers

Summary Gold nanoparticles modified with poly(2–methyl–2–oxazoline) have been prepared via chemical reduction of HAuCl₄ by NaBH₄. The gold nanoparticles were homogeneously dispersed in poly(vinyl chloride) as a polymer matrix by the miscibility between the protecting polymer of the nanoparticle and the polymer matrix. Differential scanning calorimetry and UV–vis absorption measurement clearly showed that the miscibility played an important role for incorporation of the metal nanoparticles in the polymer matrix.     

Service of mullite-corundum refractories in the center portion of the roof of high-power electric arc furnaces

Conclusions Type MKS domestic mullite-corundum parts to Technical Standard 14-8-140-75 have been introduced for the center portion of the water cooled roof of high-power arc steel melting furnaces at Belorussian Metallurgical Plant. The length of the roof campaign reached 180–220 heats without intermediate repairs, which is 25% longer than the life of imported refractories.The design of the center portion of the roof without a hole for charging of loose materials provides with the forms and dimensions of the parts used a symmetric lining and uniform distribution in it of the thermomechanical loads, which provides uniform wear of the lining and eliminates deformation of it during service of furnaces.On the basis of investigation of samples of the imported and domestic mullite-corundum roof parts after service it was established that wear of the lining occurs by fusion as the result of interaction of the refractories with the melting dust at 1660–1710°C.Different relative rates of chemical transformation and fusion of the mineral phases of the refractories were revealed. Mullite interacts with the melting reactants and fuses most intensely. In connection with this its content in mullite-corundum roof parts must not exceed 15–20%.Translated from Ogneupory, No. 1, pp. 56–60, January, 1987.     

A rechargeable battery of the type polyaniline/propylene carbonate-LiClO4/Li-Al

A secondary battery of the type polyaniline/propylene carbonate-LiClO₄/Li–Al is described. The polymer is made by aniline oxidation with ammonium persulphate in NH₄F, 2.3 HF as solvent. The discharge capacity of the polymer is 100 Ah kg^–1 at 25°C and 140 Ah kg^–1 at 40°C for current densities of 0.5 mA cm^–2 and for an amount of material giving a capacity of 10 mAh. The voltage in open circuit for the fully charged battery is 3.6 V. The average usable potential is 2.8–3 V. The energy density for the polymer lies between 280 and 420 Wh kg^–1. The ratio of the amounts of electricity in discharge and charge is one for several hundred deep cycles. The behaviour with regard to self discharge and to constant applied voltage (floating life) is excellent.     

Hybrid Metallocene–Phosphazene Polymers

The incorporation of ⁶-arene, ferrocene, and ruthenocene side groups into phosphazene high polymers generates properties such as high melting behavior and electronic conductivity, and provides insights into reaction mechanisms and ring–polymer equilibria. The design and synthesis of these polymers is facilitated by model compound studies using small molecule cyclic phosphazenes.