APPLIED RESEARCH IN CHEMICAL POLYMER ENGINEERING
Year:2018 | Volume:1 | Issue:2 (2) |Papers Count:6

Nowadays، investigating and researching on energetic polymers in order to increase mechanical، thermodynamic، and detonational properties of them have been highly regarded. One of these energetic polymers is GAP. In this paper، molecular dynamics simulation has been used to compare the properties of GAP and GTP energetic polymers. GTP، in principle is the modified form of GAP، in which functional group of triazolium methyl nitrate has been added instead of azide. The mechanical properties of GAP is a challenging topic in the field of energetic materials. Due to the attributes of the 3 azoliom methyl nitrate ring، the mechanical and thermodynamic properties of GTP are expected to be higher than GAP. The results obtained by molecular dynamics simulation showed that GTP is a stable material and its mechanical properties such as Young، and shear modulus compared to GTP have been decreased 27% and 32% respectively، and bulk modulus، Poisson coefficient، and K/G ratio compared to GTPhave been increased 17%، 42%، and 71% respectively. It was also found that the detonation speed، detonation pressure، and oxygen balance of energetic polymer compared to GAP، have been increased 5%، 14%، and 21% respectively. As a result، usage of GTP will increase as a modified GAP material in applications such as clean and chlorine-free propellants for the solid propellant rockets and also safety systems of automobiles.

The main aim of this paper is to analysis of chemical performance of hydrogen peroxide based on numerical and parametric methods. The proper chemical function of the catalytic bed، as one of the components of monopropellant thruster، plays a significant role in achieving the two design main goals in (minimizing mass and maximizing the specific impulse). To this end، the effect of catalyst diameter (granules) on the bed chemical performance، optimal length and pressure drop، simulations for beds with different catalytic pellet diameters have been made to 0. 4-0. 9 cm diameters. Hydrogen peroxide with a concentration of 90% is defined as an inlet fluid at 0. 014 m/s in simulations. The calculation of flow pressure drop across the catalyst bed is one of the activities undertaken in this study. The results of this study indicate that with increasing the pellet diameter، the reaction effective surface is reduced and the catalyst bed length is increased for complete decomposition of the propellant. In addition to the required length for complete decomposition of hydrogen peroxide، the pressure drop in various catalyst beds have also been calculated and evaluated. The results of the catalytic bed drop evaluation indicate that at a specific flow rate، a minimum pressure drop will be made in a specific diameter. The reason for this is the interaction of reaction surface and catalyst bed lengths on the pressure drop generated during the propellant decomposition process. Verification and validation of achieved results was conducted by comparing with experimental results.

Dispersion type of layered clay plated in aqueous media creates different structures and affects the final properties of its suspension. On the other hand، the presence of different electrolytes in some industrial applications affects the stability of clay suspensions. Considering the application of clay nanoparticles in various industries and the importance of this subject، in this research، the effect of preparation method، nanoparticle concentration، type and ionic strength of electrolytic medium and time elapsed on the stability behavior of laponite nanoparticles suspensions were studied. The results showed that preparing of the suspensions indirectly، results in more stable samples. It was observed that with increasing of sodium chloride concentration، the repulsion between the clay plates decreased and the phase separation and instability of the suspensions increased at higher NaCl concentrations. Furthermore، it was seen that in all electrolyte media، gel-like structure develop with increasing of nanoparticle concentration. In presence of bi-valance CaCl2 salt، most of suspensions were unstable and have two phases and increasing of this salt concentration had not significant effect on their stability. In electrolyte media containing mono-and bi-valance salts (studied in this research)، concentration of calcium cation determines the type of stability behavior of laponite nanoparticles suspensions.

In general، temporary well plugging is essential for repairing of oil and gas wells due to their long life time. One of the newest methods used for this purpose is gel polymer plugging. The strength of the gel in the well conditions is one of the most important challenges in the application of gel polymer in the temporary well plugging in work over operation. In this study، silica nanoparticles were used to improve the strength of polymer hydrogels. The bottle and rheological tests were used to determine the gel strength in desired well conditions (high temperature and high salinity). Also، the gel strength properties and swelling behavior were studied in various conditions such as distilled water، formation water، tap water and oil. It was observed that the strength of the gel increased from 520Pa to about 36kPa (5000% increase) by adding nanoparticles. Also، the gel swelling in the aqueous solution has been significantly reduced. Based on the results obtained in this study، a polymer gel containing 9 wt. % of silica nanoparticles with structural strength and thermal stability at 90 ° C was introduced for field studies.

Presence of filler in the polymeric materials changes the mechanical، dynamic-mechanical، rheological properties and even the swelling behavior of rubber composite due to mechanisms such as hydrodynamics، polymer-filler and filler-filler interactions. Swelling in rubber composites directly affects the polymer chains، also can affect indirectly other structures in composites such as the filler network and reduce mechanical properties suddenly. In this study، the nitrile rubber-nanosilica composite containing different concentrations of modified nanosilica was prepared and the composite structure was studied through rheological، mechanical، dynamic-mechanical tests. Also it was found that the filler network containing over percolation threshold 13phr of filler concentration has a significant contribution to the mechanical properties of composites. To determine the swelling effect on the prepared composite structure، with different degrees of solubility were used. The mechanical properties of the samples were measured in equilibrium swelling state for each of the solvents The decrement of the mechanical properties between the dry samples and swelled ones containing 14. 4، 20 and phr 6. 25 silica in solvent with 15% toluene is significant. These intensive changes in mechanical properties that happen at the low degree of swelling are attributed to the removal of the filler network. Therefore، controlling the swelling of rubber parts in adjacent to the solvent، plays the fundamental role in their performance.

The main purpose of this research is experimental and theoretical study on demulsifying components effect on demulsification rate of water-in-oil emulsions. In other words، some surfactants is considered and their function as a demulsifier in breaking crude oil emulsions has been investigated by bottle test. To develop a theoretical model to take into account the effect of demulsifier agent on demulsification rate of water-in-oil emulsion. Considering similarity between gas adsorption، and agent adsorption on the water-oil interface، a Langmuir isotherm based model is developed to correlate interfacial tension of water and oil phases to demulsifier concentration. Based on the proposed correlation، the collision frequency function in population balance equation is modified to account the effect of demulsifier agent on water droplets coalescence. The proposed model consists of some adjustable parameters that need to be fitted with experimental data. Therefore، a group of surface-active compounds are supplied and their demulsification capability is investigated through bottle test method. The experimental demulsification results are compared with population balance simulation results and it is apperared that the developed model could appropriately reproduce experimental data at different agent concentrations.