Carbon Membranes from Polyamideimide and Polyetherimide

century tissue layers from Polyamideimide and PolyetherimideCARBON MEMBRANES FROM POLYAMIDEIMIDE AND POLYETHERIMIDE FOR northward AND METHANE SEPARATION AND ITS PARAMETER STUDYABSTRACT vitamin C tissue layers prep ard from polyamideimide and polyetherimide were under show upvass to find turn up the effects of assorted parameters on tissue layer characteristics. Their properties were analyse to watch its scope in methane purification. Different compositions were tried to find out the optimum polymer composition as well as the optimum pass composition. They were pyrolyzed at various temperatures to study the effect of pyrolysis temperature on the morphology of the membrane. Efforts incur been made for obtaining a designate centralize distribution as northward and methane lead comparable sizes. Analysis of the micro grammatical construction of membranes using XRD confirms the variations in chain wadding density and d-spacing of polymer chains as a result of a transmut e in pyrolysis temperature. CHN analysis revealed the percentage composition of different elements in the membrane as it was important to function measuring rod of oxygen in the membrane. glaze transition temperature is plant using DSC to confirm perfect blending of polymers. TGA has been do to find out how the polymer composition affects adulteration temperature and to study the chemical changes occurring during pyrolysis. SEM images, both cross section, and pop out pay been taken to analyze condense construction of the membrane.Keywords Polyetherimide, Polyamideimide, Pyrolysis, XRD, SEM, CHN.INTRODUCTION membranes have been astray received as a burnished technology in squander separation processes. This is due to its high reliability, rugged capital investment and low energy usage which overshadow formal torpedo separation techniques such as cryogenic distillation, liquid absorption, wardrobe swing adsorption etc. These established conventional techniques ar c ognise for their complexity in processes and high energy intensity. For this reason, researchers atomic number 18 making efforts for an pick way that promises to give high-cost effectiveness and easy handling (1).Polymer membranes have been widely studied for their application in gas separating units, but they always set about drawbacks like low caloric and chemical stability. Henceforth studies have been foc utilize on atomic number 6 membranes, which are the novel and advanced type of membranes. They have been giving promising results ever since and marked a new benchmark for the selectivity of gasses. Excellent ability to withstand high temperature and chemicals made cytosine membranes a new branch of study for the researchers to follow. (2) blow membranes are fain by pyrolysing polymer membranes. Pyrolysis is the most signifi abidet step in the preparation of coke membrane. in that location are different pyrolysis factors that affect membrane properties. During pyroly sis the parameters like pyrolysis temperature, heating rate, atmospheric condition, soaking time etc. can forge the transport properties of the membrane. These factors are chosen wisely base on the application of the membrane. (3) actual option is the prime factor concerning in preparation of carbon membrane. There are wide varieties of precursor polymers available for preparation of carbon membrane (4). filling of polymer is the important factor as pyrolysis of different polymer gives carbon membrane with but different properties. The precursor polymer should satisfy momentimum criteria such as it should non soften nor liquefies during pyrolysis. It should be able to withstand high temperature (5).Polyamidimides and polyetherimides are world recently studied and are assemble to be giving suitable results due to its high melting point and thermic stability (6). Fuertes and Centeno apply polyetherimide to prepare supported carbon membrane for gas separation (7). They cond ucted gas permeability studies for exclusive gasses as well as for many mixtures of gasses. They to a fault use phenolic resins for their studies (8).Different polymers are always blended to in effect combine the desirable properties of the blending polymers. Gas separation properties of carbon membranes are enhanced while combining different materials. New studies are deprivation on investigating the blending techniques for an optimized result (9).Pore size control is one of the most challenging factors in carbon membrane preparation. due north and methane is having a kinetic diameter of 3.6A and 3.8A respectively (10). So in order to separate them by molecular(a) sieving very narrow concentre distribution has to be obtained. To get very specific pore size, pyrolysis temperature was changed accordingly.Two types of polymers were chosen so as to understand the effect of individual polymer on membrane properties. Membrane parameters such as polymer niggardliness, pyrolysis temp erature were wide-ranging to understand the morphological as well as chemical changes taking orchestrate in the membrane. Comparison of carbon membrane with polymer membrane was carried out, which showed interesting results that can be moreover used to study gas permeation properties of the membranes. Results revealed that these membranes can be used for the separation process of nitrogen from methane.EXPERIMENTALMaterialPolyamideimide (PAI) polymer and Polyetherimide (PEI) polymer which are required for the preparation of polymer membrane were purchased from UTM, Malaysia. N-methyl 2-pyrrolidone (NMP) was the solvent used and it was purchased from Merck deportment Science Private Limited, Mumbai, India. Methanol used for washing was bought from Titan Biotech Limited, Rajasthan, India. acetone was purchased from Merck Specialities Private Limited, Mumbai, India. either reagents were used without any further purification.Polymer Membrane formulationPolymers that were chosen for preparation were polyamideimide and polyetherimide. The solvent used was N-Methyl-2- pyrolidone. The polymer concentration in NMP was varied from 2- 20 wt.% as shown in the control board 1. Different batches of polymer closure were prepared by dissolving the corresponding amount of polymer in 25ml NMP. Polyamideimide-polyetherimide ratio in the solution was varied as 25/75%, 50/50%, 75/25%, 0/100% and prepared different batches accordingly. For eke out dissolution, the solution was unplowed for magnetic stirring for 3 hrs. The temperature was step-upd up to 80oC occasionally for 10 minutes, to avoid undissolved particles in the solution. Later the solution was sonicated in a sonication bath. The solution was then casted on a icing plate using a casting rod. The casting rode that was used has a dimension of 450m. The glass plate was kept in the atmosphere for twain days for evaporation of the solvent. Later it was kept inside a clean oven at 60oC for complete removal of NMP. remand 1 Polymer BatchesSample codificationTotal Polymer (%)PAI/PEI wt percentage (%)PM-01225/75PM-02925/75PM-031225/75PM-041525/75PM-051825/75PM-062025/75Carbon Membrane PreparationPolymer membrane was cut into a rectangular install and transferred into an alumina crucible. It was then kept inside a tubular furnace by VBCC for pyrolysis. It was a horizontal furnace with alumina tube. Nitrogen environment was chosen for pyrolysis. The stream rate of nitrogen was kept at 25ml/min. Polymer membranes with PAI/PEI composition of 25/75% was only further used for making carbon membrane as they showed good geomorphologic stability compared to separate batches.For pyrolysis different communications protocols were followed. The protocols are as shown below,1) 50 to 250 oC at a incline rate of 13.3 Co/min.(2) 250 oC to (Tmax-15) oC at a ramp rate of 3.85 Co/min.(3) (Tmax-15) oC to Tmax oC at a ramp rate of 0.25 Co/min.(4) Soak at Tmax for 2 h. (11)After pyrolysis, it was kept for natural cooling before taking out. The different batches of carbon membranes found on different pyrolysis protocol were prepared as given in the Table 2. Polymer membrane with 9% polymer concentration was the membrane used for perusal different pyrolysis protocols.Table 2 Carbon Membrane BatchesSample canonTotal Polymer (%)Pyrolysis Temperature(oC)CM-012600CM-6009600CM-4509450CM-8009800CM-0312600CM-0415600CM-0518600CM-0620600Characterization of Synthesized MembranesVarious techniques were employed for the characterization of polymer as well as their derivative carbon membranes. Differential Scanning Calorimetry (DSC) was used to find out glass transition temperature of polymer membranes and to study the blending of polymers. on a lower floor nitrogen atmosphere, scans from 50 to 450oC at the heating rate of 10oC/min were performed on a DSC Perkin Elmer model 6000.Thermogravimetric analysis (TGA) was used to study the thermal degradation of the polymer membranes. Degradation temperatur e of the membrane, as well as the clog deprivation during the process, is analyzed. It was carried out on a TGA Perkin Elmer 4000 model, in nitrogen atmosphere at a flow rate of 30 mL min-1. The temperature range was from 50 up to 750 oC.X-ray Diffractometer (XRD) was used to study the structural changes in membrane due to variation in pyrolysis temperature. Perkin Elmer 1621 wide-angle X-ray diffractometer was the instrument used to study the microstructural changes in membrane. Using Braggs law the average d-spacing of the membrane was evaluated. It is as shown below,n = 2d sin , where n is an integral number, is the X-ray wavelength, d is for the inter-layer spacing between the polymer chains and is the diffraction angle.CHN analysis was conducted to study the variation in the chief(a) composition with pyrolysis temperature. Elementar Vario EL was the equipment used here for analysis. Compostion of oxygen was found using separate apparatus.Scanning Electron Microscopy (SEM) was used to get pore size of the membrane as well as get a closer image of the membrane. JEOL Model JSM 6390LV is the model used for the analysis.RESULTS AND DISCUSSION physiologic propertiesBoth PAI and PEI met the requirements for preparing carbon membrane with promising results. While matters of PAI in membrane made the membrane to a greater extent brittle, which is due to its aromatic rings, (10) PEI gave structural support to the membrane. So PAI/PEI content was fixed at 25/75% for all the batches later on.As two polymers are used, the miscibility of the precursors has to be well-tried and glass transition temperature of the membrane was taken as the criteria for the evaluation. For the polymer blends, Tg was found to be in between of that of individual polymers. Tg of PEI and PAI are 217C and 280C respectively. And from the Table 3 it is clear that both the polymers are completely miscible and was short blended together.Table 3 Glass Transition TemperatureSample encryptPA I/PEI wt Percentage (%)Glass Transition Temperature (oC)PM-2525/75233PM-5050/50249PM-7575/25265PM-1000/100219Effect of polymer concentration on thermal characteristics Unlike polymer membrane, carbon membrane was thermally and chemically stable. caloric stability is analyzed by TGA. TGA analysis of all polymer membranes is shown in manikin 1. It shows that concentration does not have much effect on degradation temperature of membranes. But it gives an insight into chose the pyrolysis protocol that has to be followed. There are different pyrolysis protocols for preparation of carbon membranes, based on type of precursors used, one protocol is fixed. haoma 1 Thermal analysis of Polymer MembranesFigure 1 illustrates the exercising weight variation of polymer membranes during the heating process up to 800C. According to the TGA thermo-diagram, the degradation temperature (Td) is 550C and was defined as the temperature corresponding to 15% weight loss. This indicates the high thermal resistance of the membrane. The total weight loss at 800C, with 10/min heating rate, was approximately 60%. The enhanced thermal stability of the membrane highlights its quality as a precursor for the preparation of carbon molecular sieve membranes.Effect of polymer concentration on complex body part of membraneFigure 2 XRD of Carbon Membrane of different concentrationsEffect of polymer concentration on construction of carbon membrane is shown in Figure 2. As the concentration of polymer was increased from 2% to 20%, peak intensification took place, resulting in a more compact structure. Pore size was reduced and membrane with higher wadding density is formed.Effect of pyrolysis temperature on microstructure of membraneStructural analysis on carbon membranes was done by obtaining XRD spectra as a function of pyrolysis temperature. As shown in Figure 3, the XRD spectrum for membrane prepared at 450oC is a jointure of two peaks at 22.7o and 18.8o. With increase in pyrolysis temper ature, the peaks joined into a unmarried but intensified peak with a shift toward the smaller pore sizes indicating a decrement in average d-spacing.Figure 3 XRD of Carbon Membrane prepared at different temperaturesd-spacing in carbon membrane refers to interlayer distances, with increase in temperature more compact structures are formed. 800 C was found to be the optimum pyrolysis temperature as membrane having high density and wadding efficiency are formed at this temperature. (1)Effect of pyrolysis temperature on membrane compositionIn order to study how pyrolysis temperature changed the chemical composition of the membrane, elemental analysis has been conducted for both polymers as well as carbon membrane. In Figure 4, the point zero in x-axis corresponds to precursor membrane and it has the final carbon content and they started to increase with increase in pyrolysis temperature. However other elemental contents like oxygen, nitrogen and hydrogen was reduced with increase in temperature.Presence of oxygen compounds in the carbon membrane surface can make the membrane more deliquescent and can ride swelling of membranes (11). For the better performance of carbon membrane oxygen content has to be less than 4% (12).When pyrolysis temperature in increased, oxygen content is reduced. Membrane prepared at 800oC has oxygen content less than 4%.So the effect of pyrolysis temperature on hydrophilictiy of the carbon membrane was tested to study the influence of oxygen in the membrane. From the Table 4 it is clear that as pyrolysis temperature is increased, amount of water absorbed is decreased, thus increasing the hydrophobic nature of carbon membranes. This can be explained by the reduction in oxygen containing root in membrane with pyrolysis temperature.Figure 4 Elemental analysis of membranesTable 4 Hydrophilicity of carbon membranesSample-CodePyrolysis Temperature (C)Wet weight of the membrane (g)Dry weight of the membrane (g)Amount of water absorbed (g)CM -4504500.05880.05530.0035CM-6006000.05230.05030.0020CM-8008000.06870.06070.0008Morphology of MembranesThe surface and cross-sectional morphologies of carbon membranes as well as polymer membranes were investigated by SEM (Scanning Electron Microscopy) techniques. issue image of polymer membrane is shown in Figure 6. It shows a smooth and deformity free surface without any deformation. go bad section of the polymer membrane is also shown below. Compared to carbon membrane it does not have uniform pore distribution. All the pores are elongated pores and the membrane formed is very dense. Thickness of polymer membrane was found to be 250m.The honey-comb structure of carbon membrane shows the pore structure in the membrane (Figure 5). It is clear from the image that the membrane is rich in pores and has quite a uniform pore distribution. The membrane was having a sponge-like ground substance unlike polymer membrane. This uniform pore distribution allows carbon membrane to have high selectivity over polymer membrane. (b)Figure 5 SEM images (a) Top surface and (b) Cross section of Carbon Membrane (b)Figure 6 SEM images (a) Top surface and (b) Cross section of PolymerMembrane CONCLUSIONDifferent polymer blends were tried for the preparation of polymer membrane and membranes derived from Polyamideimde/Polyetherimide (25/75wt.%) exhibited more attractive performance than the other blends. Polymer concentration was varied from 2-20% and at 9% it was found to be exhibiting best results. Polymer membranes prepared from PAI/PEI were transparent hydrophilic membranes. Polymer membranes were thermally unstable compared to carbon membrane and were found to have degradation temperature around 450oC. Complete miscibility of both the polymers was confirmed and the glass transition temperature of the polymer membrane was also found.For the preparation of carbon membrane different protocols were followed for pyrolysis, and 800oC was found to be the optimum temperature for py rolysis. Thermal analysis of membrane had conducted, which proved the higher thermal stability of the carbon membrane. Morphological studies shows that carbon membrane prepared at 800oC have desirable pore size compared to other membranes prepared at lower temperatures. XRD studies of the carbon membrane showed that as temperature increases, more compact membranes are obtained, which decreases the permeability of the membrane. All the membranes have shown promising results that can be further investigated for gas separation studies.References1. 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