Analytical and Membrane Characterization Capabilities

for Gas Separation Membranes and Applications

Prof. Benny D. Freeman Department of Chemical Engineering The University of Texas at Austin 10100 Burnet Road Bldg. 133 – CEER Austin, Texas 78758 USA Phone: +1-512-232-2803 Fax: +1-512-232-2807 E-Mail: freeman@che.utexas.edu Web: http://membrane.ces.utexas.edu

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Contents Density Gradient Column ....................................................................................................................... 3 Differential Scanning Calorimetry (DSC) .............................................................................................. 4 Dilation Measurement Analysis ............................................................................................................. 5 Dynamic Mechanical Analysis (DMA) .................................................................................................. 6 Fourier-Transform Infrared (FT IR) Spectroscopy ................................................................................ 7 Low Force Micrometer ........................................................................................................................... 8 Magnetic Suspension Balance (MSB) .................................................................................................... 9 Mass Spectrometer ............................................................................................................................... 10 Mixed Gas Permeability System .......................................................................................................... 11 Permeability Measuring Cells .............................................................................................................. 12 Pervaporation System ........................................................................................................................... 13 Solubility (Sorption) Systems ............................................................................................................... 14 Split-Tube Furnace ............................................................................................................................... 15 Thermogravimetric Analysis (TGA) .................................................................................................... 16 Ultraviolet Cross Linker ....................................................................................................................... 17 Vacuum Ovens ..................................................................................................................................... 18 

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Density Gradient Column

Make & Model: Ametek Davenport 772/115 Density Gradient Column Description: The density gradient column allows us to measure the density of

polymeric samples to an accuracy of +/- 0.0001 g/cm3. A salt solution with variable concentration is established in the gradient column and polymer samples are allowed to equilibrate with the solution. Using reference glass beads of known density as floats, the polymer sample density is calculated.

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Differential Scanning Calorimetry (DSC)

Make & Model: TA Instruments Q100 Differential Scanning Calorimeter Description: The DSC is used to measure heat flow in polymers. Practical

uses for the DSC in polymer systems include measuring the glass transition temperature, measuring sub-transitions in polymer chain mobility, and measuring melting point. Our DSC is equipped with a liquid nitrogen cooling system and has a temperature range of -180°C to 725°C at a rate of 0.01°C/min to 100°C/min.

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Dilation Measurement Analysis

Description: The dilation system is used to measure the volume expansion of

polymers in the presence of highly condensable gases. A polymer sample is suspended by a hook in the dilation system, exposed to the condensable gas of interest, and the dilation (isotropic swelling) of the polymer is monitored using a camera. For polymers that swell significantly, dilation is needed as a corrective term for volume measurements in solubility experiments.

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Dynamic Mechanical Analysis (DMA)

Make & Model: TA Instruments Q800 Description: Dynamic Mechanical Analysis measures the mechanical

properties of materials as a function of time, temperature, and frequency. Our Q800 DMA instrument operates over a wide temperature range (-150 to 600°C) and provides multiple modes of deformation including dual/single cantilever and 3-point bending, tension, compression, and shear.

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Fourier-Transform Infrared (FT IR) Spectroscopy

Make & Model: Thermo Nicolet Nexus™ 470 E.S.P. Description: Our FT IR system is equipped with two modes: (1) attenuated

total reflectance (ATR) mode for surface chemistry characterization and (2) transmission mode for polymer film or powder characterization. FT IR is often used to analyze the chemical composition of polymers that are insoluble in common solvents.

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Low Force Micrometer

Make & Model: Mitutoyo Litematic VL-50A Description: When measuring permeability, knowledge of the effective

sample thickness is critical. Our low-force micrometer allows us to measure the thickness of highly swollen polymers (such as hydrogels) and fragile materials without deformation.

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Magnetic Suspension Balance (MSB)

Make & Model: Rubotherm Magnetic Suspension Balance (MSB) Description: Our MSB allows for kinetic and equilibrium sorption and

desorption experiments. Density measurements are also possible with the MSB. The MSB measures the mass uptake of gases in a sample using a very sensitive balance and can operate with temperatures of -20°C to 200°C and pressures of ultra-high vacuum to 150 bar.

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Mass Spectrometer

Make & Model: Thermostar GSD 320 Mass Spectrometer Description: Our mass spectrometer is an attachment to our thermogravimetric

analyzer which allows us to analyze the byproducts of chemical reactions or decomposition products. This instrument is useful in determining thermal stability and in determining reaction mechanisms of thermal reactions in polymer films.

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Mixed Gas Permeability System

Description: The mixed gas permeation systems are designed to measure the

permeability of two or more components using a Hewlett Packard G1540A gas chromatograph. Mixtures of gases sweep over the top of a polymer film, sorb and diffuse across the film, and permeate at the downstream. The downstream permeate gases are carried in a sweep gas to the gas chromatograph and the composition of gases in the permeate can be calculated. The mixed gas system is often used to measure the effect of plasticization for mixtures of CO2/CH4, C2H4/C2H6, and C3H6/C3H8.

Current Capacity: 2 systems

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Permeability Measuring Cells

Description: We have both constant-volume, variable pressure, and constant-pressure-variable volume pure gas permeability cells. For the constant-volume systems, gas permeates through a film into a vacuum-tight container of known volume. The increase in pressure of the known volume can be converted to a molar flux using an appropriate equation of state and the permeability can be calculated from this measurement along with knowledge of film thickness and the pressure driving force across the film. The constant-pressure system also measures permeability, but does so by measuring the permeate flow rate at atmospheric downstream pressure using a bubble flow meter. The constant-volume system allows permeability measurements of thick or low-flux polymer films. The constant-pressure systems allow permeability measurements of thin or high-flux polymer films.

Current Capacity: 10 constant-volume, variable pressure systems and 1

constant-pressure, variable volume system

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Pervaporation System

Description: Our pervaporation system measures the flux of membranes with a

liquid feed and a vapor permeate. In conjunction with our gas chromatograph, we can measure mixed composition feeds and permeates.

Current Capacity: 2 systems, one set up for nontoxic/nonflammable feeds,

one for toxic/flammable feed

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Solubility (Sorption) Systems

Description: The sorption cells are used to measure equilibrium mass uptake of gases in polymer films. The cells are designed with two chambers: a charge and a sample chamber. The charge chamber is first pressurized with a gas of interest. Using an equation of state (EOS) such as the Virial EOS or the Soave-Redlich-Kwong EOS, the moles of gas in the charge cell are calculated from the pressure of the charge cell. When the valve connecting the charge and sample cell is opened and closed, a certain number of moles of gas are released from the charge cell into the sample cell. The moles in the sample cell are constant, but the pressure in the sample cell will decrease, thus indicating a mass uptake of gas in the polymer film.

Current Capacity: 5 pure gas systems, 1 mixed gas system

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Split-Tube Furnace

Make & Model: Carbolite HZS 12/600 Slit-Tube Furnace Description: The split-tube furnace is used to chemically convert polymer

samples that undergo thermal rearrangement reactions or to ash samples. The furnace has a heating range of ambient to 1200°C with a maximum power of 3.0 kW.

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Thermogravimetric Analysis (TGA)

Make & Model: TA Instruments Q500 Thermogravimetric Analysis (TGA) Description: The TGA is used to measure the mass loss of a polymer as a

function of temperature. The temperature of our TGA can be varied between room temperature and 1000°C at a rate of 0.1 to 100°C/min. Our TGA is equipped with a high resolution feature, which allows us to automatically slow down the heating rate if the mass loss changes significantly. We also have a mass spectrometer attached to the TGA that allows us to analyze the reaction products or decomposition products as a function of temperature.

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Ultraviolet Cross Linker

Make & Model: Spectrolinker XL-100 UV Crosslinker Description: Our ultraviolet (UV) crosslinker enables us to crosslink polymers

that are sensitive to UV crosslinking reactions. The Spectrolinker XL-100 can be set to perform crosslink reactions for varying energies, times, or intensities.

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Vacuum Ovens

Make & Model: Jeio Tech OV-11, Jeio Tech OV-12, Fisher 281A, Fisher 280A, VWR 1400E, National 5831

Description: Our vacuum ovens allow for us to cast multiple samples that

contain high boiling point solvents. The vacuum ovens have temperature ranges between ambient conditions and ~275°C.

Current Capacity: 10 systems, (1) Jeio Tech OV-11 oven, (2) Jeio Tech OV-

12 ovens, (1) VWR 1400E oven, (3) Fisher 281A ovens, (1) Fisher 280A oven, (2) National 5831 ovens