Polydimethylsiloxane Membranes Containing Multi-walled Carbon Nanotubes for Gas Separation

Abstract

Polydimethylsiloxane (PDMS) membranes with different concentrations of multi-walled carbon nanotubes were prepared in order to evaluate their gas separation performances. Mixed matrix membranes were characterized by scanning electron microscopy, thermogravimetric analysis, Fourier transformed infrared, positron annihilation lifetime and Raman spectroscopies and X-ray diffraction. The permeabilities to CO 2 , CH 4 , N 2 and O 2 were determined. No phase separation was noticed. For carbon nanotubes content of 1 wt%, it was shown a decrease in membrane permeability with slight increase in ideal selectivity, compared to pure PDMS. However, the increase in the filler load up to 6.7 wt% increased the free volume average size of the membranes, improving the contribution of the diffusion to the transport and decreasing ideal selectivities of CO 2 /CH 4 , CO 2 /N 2 and O 2 /N 2 .

Flexible Ultra-Thin Nanocomposite Based Piezoresistive Pressure Sensors for Foot Pressure Distribution Measurement

“…It can be modeled as three-dimensional resistor networks based on tunneling effect [ 51 ]. Theoretically, two types of resistance can be seen in MWCNT–PDMS nanocomposite films such as R is intrinsic resistance of MWCNT [ 52 ]. The second type is R , which is further divided into contact resistance between MWCNT ( R ) and tunneling resistance ( R ) between MWCNT, which can be seen below: where d is the distance between MWCNT, h is the Planck constant, e is the quantum of electricity, l is the barrier height of energy, m is the electron mass, and A is the cross-sectional area of the tunnel [ 52 ].…”

“…Theoretically, two types of resistance can be seen in MWCNT–PDMS nanocomposite films such as R is intrinsic resistance of MWCNT [ 52 ]. The second type is R , which is further divided into contact resistance between MWCNT ( R ) and tunneling resistance ( R ) between MWCNT, which can be seen below: where d is the distance between MWCNT, h is the Planck constant, e is the quantum of electricity, l is the barrier height of energy, m is the electron mass, and A is the cross-sectional area of the tunnel [ 52 ]. During the initial applied force of 1 N, the nanocomposite thin film comes in contact with the underlying electrode, resulting in an abrupt decrease in resistance of the sensor.…”

Functionalised Multi-walled Carbon Nanotubes/Cellulose Acetate Butyrate Mixed Matrix Membrane for CO2/N2 Separation

“…With low MWCNT loadings of 0.2 wt% and 0.7 wt%, the free volume cavities increased thereby causing an increment of the N 2 permeance. 33 Meanwhile, the loading of 1.0 wt% caused the reduction in the permeance of N 2 gas due to the control amount of MWCNTs-F, which dispersed homogenously within the polymeric membrane structure as schematically described by Ahmad et al 18 However, at a higher MWCNTs concentration of 1.2 wt%, the MWCNTs tended to agglomerate and caused the permeance of N 2 to decrease due to van der Waals forces. 32 Based on this figure, the highest CO 2 /N 2 selectivity of 1.9740 was achieved for the MMM with MWCNTs content of 1.0 wt%.…”

“…The changes in the membrane thickness were due to the amount of suspensions used to prepare the MMM. 33 The amount of the MWCNT loading had also a significant effect on the membrane thickness. Based on Figure 19, the thickness of the membrane decreased when the loading increased up to 0.7 wt% (MMM-0.7F) due to the increase in the viscosity of the solution.…”

Blend Cellulose Acetate/Multi-Walled Carbon Nanotubes Mixed Matrix Membrane for CO2 /N2 Separation

“…In this case, the strong interactions between the MWCNTs particles induced by the Van der Waals forces led to the agglomeration which in turn, caused large 0.1F exhibited a thinner dense layer as compared to the CA polymer and MMM-0.1P. The change in membrane thickness was due to the alteration towards the original CA polymer packing from the integration of nanofillers (MWCNTs) within the polymer matrix (Silva et al 2017;Wang 1998). The thinner dense skin layer of MMM-0.1F was due to the existence of a relatively shorter permeation pathway in the membrane from the superior synergistic relationship of the functionalized CNTs and the polymer matrix (Sarfraz and Ba-Shammakh 2018).…”