The viscoelastic properties of a halogen-free polymer composition, for cable products

The viscoelastic properties of a halogen-free polymer composition for cable products have been investigated. The influence of temperature parameters, shear rate on the die-swell ratio of the polymer composition has been determined; the dependence of the melt density on a temperature was investigated. The polymer matrix is a mixture of polyolefins (linear low density polyethylene; polyolefin elastomer and maleic anhydride modified linear low density polyethylene) as a flame retardant filler for the polymer composition is trihydrate alumina. The content of flame retardant filler in the polymer composition is 60 %. The polymer composition was manufactured on the compounding line of X-Compound, Switzerland. The investigation of both melt density and die-swell ratio of the polymer composition has been conducted with help of capillary viscometer type IIRT-AM. To determine the density of the melt the ratio of capillary length to diameter L/D=8/2 was used. The results of the study of the dependence of the melt density of the polymer matrix from a temperature of 150–190 °C at different loads showed that this parameter decreases from 789 to 744 kg/m3 and for polymer composition from 1309 to 1268 kg/m3. The die-swell ratio in the case of an increase of the shear rate at temperatures of 150–190°C for the polymer matrix increases from 1,102 to 1,520, and for the polymer composition decreases from 1,056 to 1,018. The investigation results of the dependence of both die-swell ratio of the polymer matrix and the polymer composition on the ratio of the length of the forming tool to the diameter indicates that the die-swell ratio for the polymer matrix was reduced from 1,296 to 1,152, and for the polymer composition from 1,045 to 1,01. It was established that the viscoelastic properties of the halogen-free polymer composition are significantly influenced by: processing temperature, shear rate, melt density, the ratio of the length of the forming tool to the diameter. The research results give a possibility for a reasonable approach for the determination of technological parameters of an insulation, sheathing of power cables and optical cables of microtube construction. It will also allow to quickly adjust the geometrical parameters of the forming tool of cable heads.

Experimental settling, floatation and compaction of plagioclase in basaltic melt and a revision of melt density

Centrifuge-assisted piston cylinder experiments were conducted on plagioclase in basaltic melt at 1140–1250 °C, 0.42–0.84 GPa and mostly 1000 g. One set of experiments assesses the settling velocity of a dilute plagioclase suspension; a second sinks or floats plagioclase in a MORB-type melt exploring conditions of neutral buoyancy; and a third set examines floatation of plagioclase from an evolved lunar magma ocean composition. A compaction rate for plagioclase cumulates is established. The experiments demonstrate that neutral density of plagioclase An74 in a MOR-type tholeiitic basalt occurs at 0.59 ± 0.04 GPa (1200 °C), contrasting predictions by present models on melt density which yield a density inversion pressure at 0.10–0.15 GPa. In nature, the level of neutral buoyancy depends on melt composition; nevertheless, for the onset of plagioclase crystallization in dry tholeiitic basalts, our result is robust. As the molar volume of plagioclase is well known, the experimentally determined pressure of neutral buoyancy indicates a correction of -1.6% to previous density models for silicate melts. It follows that for (tholeiitic) layered mafic intrusions, plagioclase is negatively buoyant for early, relatively primitive, parent melts. In contrast, the extreme Fe enrichment of a fractionating lunar magma ocean leads to melt densities that let anorthite always float. Compaction φ/φ0 of experimental plagioclase cumulates is quantified to φ/φ0 = − 0.0582 log (Δρ·h·a·t) + 1.284, where φ0 is the porosity after settling (67 ± 2%), h the cumulate pile height, a acceleration and φ porosity as a function of time t. Gravitational-driven compaction in tens of m-thick plagioclase cumulate in basaltic magmas reaches down to ~ 40% porosity within hundreds of years, a timescales competing with characteristic cooling times of cumulate layers of mafic intrusions. To achieve plagioclase modes > 80% due to compaction, an additional overload of ~ 100 m (layers) of mafic minerals would be required. Compaction of a lunar anorthosite crust of 35 km to 20% porosity (i.e. ~ 90% plagioclase after crystallization of the interstitial melt) would require 30 kyrs.

Amorphous Porous Phase of Nitinol Generated by Ultrafast Isobaric Cooling

Titanium nickelide (nitinol) is of great applied interest in various industries due to unique combination of its physical and mechanical characteristics. In the present work, we consider the possibility of obtaining nitinol with mesoporous structure by rapidly cooling the molten sample to room temperature. Based on molecular dynamics simulation data, it was shown that the rapid cooling of the nitinol melt leads to formation of a porous structure. It was shown that the inner pore wall is formed mainly by titanium atoms, which provide biocompatibility of nitinol. It was found that the porosity of nitinol weakly depends on the cooling rate, while the porosity increases linearly with decreasing melt density.

Densities and electrochemical potential window of the BaCl2-NaCl-NaF-AlF3 electrolyte

The effect of melt composition (BaCl2-NaCl-NaF-AlF3) on its density, resistivity and redox potentials of the main electrode processes is reported. A three-factor two-level experimental design was used to study the effects of cryolite ratio (1.1-1.6) and BaCl2 (0-60wt%) or NaCl (0-10wt%) content on the melt density. The obtained equation satisfactorily describes the measured melt densities. The observed non-linear behavior of melt density with BaCl2 additions is assigned to the formation of BaClF complex. Unlike BaCl2, additions of 0-10 wt% NaCl have little effect on the melt density, however, affect the melt conductivity significantly.

Mathematic simulation of atomic structure of multicomponent oxide-fluoride melt for continuous casting machines

Determination of relation between oxides melts properties, based on silicates and calcium alum-silicates and magnesium and their chemical composition and structure is an important condition to provide a rational slag mode in a continuous casting machines mold. A mathematical simulation of slag melts and casting powders accomplished. The oxide-fluoride system was chosen for the simulation, for which the structure after solidification was determined by experiment. Results of molecular-dynamic simulation of CaO–SiO2–Al2O3–MgO–Na2O–K2O–CaF2–FeO system, correspondent to industrial casting powders composition, used during steel casting for slag formation in a CCM mold (35.35 % SiO2; 30.79 % CaO; 8.58 % Al2O3; 1.26 % MgO; 13.73 % CaF2; 7.57 % Na2O; 0.88 % K2O; 1.82 % FeO). Taking into account the concentration, a re-calculation was accomplished to mole shares and correspondent number of ions in the model for each component calculated. Simulation of the 8-component oxide-fluoride melt with 2003 ions size in the main cube (a side length of 31.01 Å) was accomplished at the experimentally determined temperature of solidification onset (1257 K) under periodic boundary conditions and fixed volume. The Coulomb interaction was taken into account by the Ewald–Hansen method. The time step was 0.05t0, where t0 = 7,608×10–14 sec is the internal unit of time. The melt density was taken as 3.04 g/cm3 based on the experimental data. The inter-particle interaction potentials were chosen in the Born–Mayer form. According to the simulation results, the structure of sub-crystalline groups of atoms present in the melt at the temperature of the onset of solidification was determined. A discussion of the simulation results and their comparison with the literature data presented.

Study the Relation between Flow, Thermal and Mechanical Properties of Waste Polypropylene Filled Silica Nanoparticles

This paper investigates the flow, thermal and mechanical properties of waste polypropylene (WPP) reinforced with silica (SiO2) nanoparticles (NPs). Recently the researches prove that the addition of NPs to the thermoplastic polymer produces significant change in its properties. SiO2 NPs of 0.001, 0.003, 0.006, 0.009, 0.012 and 0.015wt% were mixed with the WPP using twin screw extruder. The mixing process performed at 10 rpm and 190°C. The topography and particle size distribution of 0.001, 0.006 and 0.015 of SiO2 NPs concentrations samples are analyzed using atomic force microscopy (AFM). The crystallinity of nanocomposite was examined by X-ray diffraction. The melt flow rate (MFR) and melt volume rate (MVR) are tested due to SiO2 NPs concentration at standard condition using melt flow index (MFI) device. The shear viscosity and melt density are calculated using MFR and MVR values. Differential Scanning Calomitry (DSC) is used to show the effect of SiO2 NPs concentration on the thermal history of nanocomposite. Charpy impact strength and hardness are tested. The results show that the MFR and MVR increase with the NPs concentration increasing. The shear viscosity decreases with MFR and MVR increasing. The crystallinity level and the crystallinity temperature decreases with SiO2 NPs concentration increasing while impact and hardness increasing. Clear difference between solid and melt density is observed. There is a compatible between the thermal, flow and mechanical properties of different SiO2 nanocomposite samples.

Research of Precision Injection Control System Based on the on-Line Measurement of Polymer Melt Density

Based on the quality factors of the precision injection product, the control system structure of precision injection molding product and proposes the on-line measurement of melt density which controls the injection weight is analyzed in this thesis. The important of the on-line measurement of melt density is shown in this paper. Then, the approach of off-line and on-line measurement of melt density is introduced. At last, the control approach and the precision injection control principle of using the on-line measurement of melt density is discussed also.