Relevance of the acid–base approach in prediction of adhesion properties in two‐component injection moulding

We demonstrate the use of innovative wetting method in prediction of the adhesion properties of biobased polymers for two‐component injection moulding, taking into account the acid–base surface properties of joined materials. The measurements were carried out in accordance with modified Berger method by calculation of the difference in shortened acidity parameter ΔD_short between hard and soft component. Correlation factors up to 0.99 were observed between ΔD_short and peel force. In comparison to results obtained by conventional wetting methods, high potential for the selection of components with high interface adhesion and for prediction of the functionality by the acid–base approach was demonstrated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43048.     

Area-specific subsidies and population dynamics: Evidence from the Australian zone tax offset

This paper studies the effect of the zone tax offset (ZTO), a place based income subsidy implemented in rural Australia since 1945. The policy was intended to improve the welfare of inhabitants and provide an incentive for settlement. Our empirical approach exploits the geographical discontinuity in the eligibility for the subsidy to identify its causal effect on population growth. Using data on population by locality from the historical censuses we find that the ZTO had a positive but only temporary effect on population growth in the targeted areas.     

Operating limits and features of direct air capture on K2CO3/ZrO2 composite sorbent

Potassium carbonate-based sorbents are prospective materials for direct air capture (DAC). In the present study, we examined and revealed the influence of the temperature swing adsorption (TSA) cycle conditions on the CO₂ sorption properties of a novel aerogel-based K₂CO₃/ZrO₂ sorbent in a DAC process. It was shown that the humidity and temperature drastically affect the sorption dynamic and sorption capacity of the sorbent. When a temperature at the sorption stage was 29 ℃ and a water vapor pressure in the feed air was 5.2 mbar (1 bar = 10⁵ Pa), the composite material demonstrated a stable CO₂ sorption capacity of 3.4% (mass). An increase in sorption temperature leads to a continuous decrease in the CO₂ absorption capacity reaching a value of 0.7% (mass) at T = 80 ℃. The material showed the retention of a stable CO₂ sorption capacity for many cycles at each temperature in the range. Increasing P_H2O in the inlet air from 5.2 to 6.8 mbar leads to instability of CO₂ sorption capacity which decreases in the course of 3 consecutive TSA cycles from 1.7% to 0.8% (mass) at T = 29 ℃. A further increase in air humidity only facilitates the deterioration of the CO₂ sorption capacity of the material. A possible explanation for this phenomenon could be the filling of the porous system of the sorbent with solid reaction products and an aqueous solution of potassium salts, which leads to a significant slowdown in the CO₂ diffusion in the composite sorbent grain. To investigate the regeneration step of the TSA cycle in situ, the macro ATR-FTIR (attenuated total reflection Fourier-transform infrared) spectroscopic imaging was applied for the first time. It was shown that the migration of carbonate-containing species over the surface of sorbent occurs during the thermal regeneration stage of the TSA cycle. The movement of the active component in the porous matrix of the sorbent can affect the sorption characteristics of the composite material. The revealed features make it possible to formulate the requirements and limitations that need to be taken into account for the practical implementation of the DAC process using the K₂CO₃/ZrO₂ composite sorbent.     

Peculiarities in thermal evolution of precipitated amorphous calcium phosphates with an initial Ca/P ratio of 1:1

Thermal evolution of amorphous calcium phosphate (ACP) powder from a fast nitrate synthesis with a Ca/P ratio of 1:1 were studied in the range of 20–980?°C. The powder consisted of amorphous dicalcium phosphate anhydrate (CaHPO₄) after heating to 200?°C. CaHPO₄ gradually condensed to amorphous calcium pyrophosphate Ca₂P₂O₇ (CPP) between 200 to 620?°C. Amorphous CPP crystallized at 620–740?°C to a metastable polymorph α′-CPP of the high-temperature phase α-CPP and β-CPP. The α′-CPP/ β-CPP phase ratio reached a maximum at 800?°C (60?wt% α′-CPP/40?wt% β-CPP), and α′-CPP gradually transformed to β-CPP at a higher temperature. Some β-TCP occurred at 900?°C, so that a three-phasic mixture was obtained in the powder heated to 980?°C. The occurrence of metastable α′-CPP is attributed to Ostwald’s step rule, and a mechanism for β-TCP formation is proposed. The advantages of prospective biomaterials from these powders are discussed.     

Study of Evaporative Convection in an Open Cavity under Shear Stress Flow

When a layer of volatile liquid is exposed to a shear flow of inert gas, thermal patterns, in the form of interfacial ripples and bulk plumes, are created by the combined action of evaporative, shear-driven and surface-tension-driven instabilities. The topology of the interfacial thermal patterns is mainly influenced by the geometry of the evaporating surface, the thickness of the evaporating layer, the intensity of the shear flow and by the physic-chemical properties of the working fluid. In this paper, by means of numerical simulations, we focused our attention on the dynamics of the interfacial thermal patterns for different working fluids and thicknesses of the volatile liquid layer. This study has been performed in the frame of the ESA sponsored Space Program on heat and mass transfer CIMEX-1. The choice of the fluids—ethyl alcohol and FC72 (n-perfluorohexane)—the reference values for the inert gas flow rate, the thickness of the liquid layer as well as the geometrical features of the computational domain correspond exactly to the ones foreseen for the CIMEX-1 experiment. However, the main conclusions can be considered of more general validity.     

Experimental Study of Film Condensation of FC-72 Vapour on Disk-Shaped Fin

The results of activity made in the framework of preparation of the experiment SAFIR (Single fin condensAtion: FIlm local measuRements) of European Space Agency are presented. First prototype of the test cell has been developed and tested. Confocal technique has been adopted for condensate film thickness measurements. Experiments on condensation of the liquid FC-72 have been carried out. Average heat transfer coefficient has been measured in the range of 880–1440 W/m² K and compared to the Nusselt theory.     

Investigation of the Conservative System of Equations for a Vertically Flowing Liquid Film

A new system of equations for modeling the dynamics of long-wave perturbations on the surface of a viscous liquid film flowing down a vertical plane was investigated. It is shown that the system obtained agrees with a known system derived by the variable changing method but unlikely has a conservative form that is perfect for designing of numerical efficient conservative difference schemes. The system is reduced to a single conservative equation for the function analogous to the hydrodynamic stream function with the appropriate boundary conditions. For the case of moderate Reynolds number it is noted that the equation with boundary conditions coincide with the well known Shkadov’s model under the assumption of self-similar profile of longitudinal velocity. At small Reynolds numbers typical to the condition of microgravity it was proved that the system is reduces to one evolution equation for the film thickness.     

Experimental Study of Laminar Convective Condensation of Pure Vapor Inside an Inclined Circular Tube

Convective condensation of pure ethanol vapor inside a smooth tube of inner diameter 4.8 mm and of length 200 mm is studied. The experiments have been carried out at temperature 58°C corresponding to the pressure of 440 mbar, the vapor mass velocity varying from 0.24 to 2.04 kg/(m² s). The dependency of the Heat Transfer Coefficient (HTC) is investigated experimentally both subject to the temperature difference between the saturated vapor and the wall and subject to the condenser inclination. The results show that the HTC reduces with growth of the temperature difference. The dependency of the HTC on inclination has a maximum in the range 15°–35° due to the complex gravity drainage mechanism of the condensed liquid. The results could be useful for development of compact effective cooling systems for space and ground application.     

Formation of a Network Structure in the Gaseous Reduction of Magnetite Doped with Alumina

Reduction of un-doped magnetite is developed topochemically with the formation of a dense iron shell. However, the reduction of alumina-doped magnetite to wüstite proceeds with the formation of a network-like structure which consists of criss-crossed horizontal and vertical plates of wüstite. Reduction of magnetite includes the conversion of Fe³⁺ to Fe²⁺ and the movement of iron cations from the tetrahedral sites on the {400} and {220} planes of magnetite to the octahedral sites on the {200} planes of wüstite. Alumina has a negligibly small solubility in wüstite. In the reduction of magnetite doped with Al₂O₃, rejected Al³⁺ cations from wüstite diffuse to the magnetite–hercynite solid solution. Enrichment of the Fe₃O₄–FeAl₂O₄ solution with alumina in the vicinity of the reduction interface restricts the growth of {220} planes of wüstite and nucleation of {220} planes adjusted to the existing planes, preventing the merging of wüstite plates during the reduction process. Reduction of magnetite from the magnetite–hercynite solid solution practically stops when the Al³⁺ content at the interface approaches the solubility limit. Wüstite in the separated plates is reduced further to iron.