Spectroscopic and Transport Behavior of HAB-6FDA Thermally Rearranged (TR) Nanocomposite Membranes

Nanocomposite membranes are a class of innovative filtering materials made up of nanofillers embedded in a polymeric or inorganic oxide matrix that functionalized for the membrane. Thermally rearranged (TR) polymers are found to have a good blending of selectivity and permeability. Chemical iridization is a process for used to make HAB-6FDA polyimide from 3,3 dihydroxy-4,4 diamino-biphenyl (HAB) & 2,2-bis-(3,4-dicarboxyphenyl) hexafluoro propane dianhydride (6FDA). The sample is first changed from a pure polymer membrane to a silica nanofiller doped polymer layer and explain thermally rearrangement for gas permeability in polymer nanocomposite layers and its relationship with kinetic diameter of different gases. The selectivity is decreases as the permeability increases that shows on a trade-off relationship between permeability & selectivity. The CO2 permeability of the HAB-6FDA TR polymers is greater than that of other classes of polymers by equal free volume and indicating that these TR polymers have free volume distribution that supports high permeability. Thermally rearranged polymer nanocomposite exhibits higher gas permeability than that of silica doped and pure polymer. The selectivity for H2/N2 and H2/CO2 gas pairs exceeds towards Robeson's upper bound limit and in case of H2/CH4 gas pair this limit were crossed the Robeson’s upper bond limit. UV spectroscopy shows the change in transmission at higher wavelengths, while XRD show the reduction in FWHM with thermal treatment temperature. Polymer nanocomposite can be utilized to obtain high purity hydrogen gas for refinery and petrochemical applications.

Research on Performance Evaluation of PPG/Polymer Flooding System

Aiming at the PPG/polymer flooding system developed by Daqing Exploration and Development Research Institute, this paper conducts research on its viscosity increasing, viscosity stability, rheological properties, viscoelasticity and seepage ability. The experimental results show that:PPG has a thickening effect on the system, and the thickening range is between 37% and 66%;the viscosity retention rate of the PPG/polymer system is higher (88%) than the ordinary 25 million polymer solution (75%) ); Under the same shear rate conditions, the apparent viscosity of the PPG/polymer system is higher than 25 million pure polymer; the PPG/polymer system has a resilience effect, and its G’ and G” values are greater than that of a pure polymer solution;PPG/The polymer system can migrate to the deep part of the oil layer and still maintain high seepage resistance, which can realize deep profile control.

An Analysis of the Effect of ZIF-8 Addition on the Separation Properties of Polysulfone at Various Temperatures

The transport of H2, He, CO2, O2, CH4, and N2 at three temperatures up to 65 °C was measured in dense, thick composite films formed by amorphous Polysulfone (PSf) and particles of the size-selective zeolitic imidazolate framework 8 (ZIF-8) at loadings up to 16 wt%. The morphological and structural properties of the membranes were analyzed via SEM and density measurement. The addition of ZIF-8 to PSf enhances the H2 and He permeabilities up to 480% with respect to the pure polymer, while the ideal H2/CO2 and He/CO2 selectivities of MMMs reach values up to 30–40% higher than those of pure PSf. The relative permeability and diffusivity enhancements are higher than those obtained in other polymers, such as PPO, with the same amount of filler. The Maxwell–Wagner–Sillars model is able to represent the MMM H2/CO2 separation performance for filler volume fractions below 10%.

Water-Polymer Perturbation Characterization and Rules of Polymer Flooding in Offshore Heavy Oilfield

Water injectors and polymer injectors coexist after well pattern infilling in some offshore oilfields, which exerts a deep impact on oil exploitation. In order to quantitatively characterize the injected water-polymer perturbation degree and analyze perturbation laws, water-polymer perturbation coefficient is proposed and established by comparing the displacement process of water-polymer coflooding and pure polymer flooding, which quantifies the dynamic change of displacement volume of injected water and polymer, and controlling strategy is discussed correspondingly to improve the development effect of water-polymer coflooding. Finally, a field case is used to demonstrate this new evaluation method. The results show that water-polymer perturbation coefficient has a good correlation with oil increasing, and water-polymer coflooding process can be divided into five stages according polymer perturbation coefficient. In addition, water-polymer coflooding has a better oil increasing effect than pure polymer flooding at the initial stage, but for a long period, development effect of pure polymer flooding is much better. The result has a great significance to quantitatively characterize water-polymer perturbation degree and make adjustment measurements.

Pyrolysis of Mixed Plastic Waste: I. Kinetic Study

Plastic wastes have become one of the biggest global environmental issues and thus recycling such massive quantities is targeted. Low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS) are considered among the main types of plastic wastes. Since pyrolysis is one of the most promising recycling techniques, this work aims to build knowledge on the co-pyrolysis of mixed polymers using two model-fitting (Criado and Coats–Redfern) methods. Seventeen co-pyrolysis tests using a thermogravimetric analyzer (TGA) at 60 K/min for different mixed compositions of LDPE, HDPE, PP, and PS were conducted. It was observed that the pyrolysis of the pure polymer samples occurs at different temperature ranges in the following order: PS < PP < LDPE < HDPE. However, compared to pure polymer samples, the co-pyrolysis of all-polymer mixtures was delayed. In addition, the synergistic effect on the co-pyrolysis of polymer blends was reported. The Master plot of the Criado model was used to determine the most suitable reaction mechanism. Then, the Coats–Redfern model was used to efficiently obtain the kinetic parameters (R2 ≥ 97.83%) and the obtained values of the activation energy of different polymer blends were ranging from 104 to 260 kJ/mol. Furthermore, the most controlling reaction mechanisms were in the following orders: First order reaction (F1), Contracting sphere (R3), and then Contracting cylinder (R2).

PVC-Based Copper Electric Wires under Various Fire Conditions: Toxicity of Fire Effluents

Ventilation-controlled fires tend to be the worst for toxicity, because they produce large amounts of fire effluent containing high yields of toxic products. In order to examine the dependence of the amount of chosen few main combustion gases under ventilation-controlled conditions, a PVC-insulated copper electric wire with unknown composition (PVC filled with chalk) was studied by mean of a steady state tube furnace. For the tested wire, lower values of CO2 yields at different ventilation conditions were obtained than for the reference pure polymer unplasticized PVC and additionally tested pure LDPE, the yields were higher three times in the case of PVC and two times in the case of LDPE than those received for wire at the same ventilation conditions, which pointed out decreasing contribution of hyperventilation effect to human during cable fire. In contrast, higher values of toxic CO yields, four times higher, were obtained for the PVC-insulated electric wire rather than for the pure polymers. The maximum value of CO yield (0.57 g/g) was determined in the case of 5 L/min of primary airflow and decreased with increasing ventilation. The measured yields of hydrocarbons were similar to the reference values except for the equivalence ratio ϕ = 0.27, where hydrocarbon yield was equal to 0.45 g/g. The HCl yield of fire effluents from the PVC-insulated wire was shown to be independent of ventilation conditions. The corrosive reaction between copper and the HCl species and the flame-retardant mechanisms of the additives, caused the lower values of HCl in the fire effluent of the PVC-insulated copper wire than for pure polymer.