Solubilities of sub- and supercritical carbon dioxide in polyester resins

In supercritical carbon dioxide (CO2) assisted polymer processes the solubility of CO2 in a polymer plays a vital role. The higher the amount of CO2 dissolved in a polymer the higher is the viscosity reduction of the polymer. Solubilities Of CO2 in polyester resins based on propoxylated bisphenol (PPB) and ethoxylated bisphenol (PEB) have been measured using a magnetic suspension balance at temperatures ranging from 333 to 420 K and pressures up to 30 MPa. An optical cell has been used to independently determine the swelling of the polymers, which has been incorporated in the buoyancy correction. In both polyester resins, the solubility of CO, increases with increasing pressure and decreasing temperature as a result of variations in CO, density. The experimental solubility has been correlated to the Sanchez-Lacombe equation of state.</p

Sustainable polymer foaming using high pressure carbon dioxide: A review on fundamentals, processes and applications

In recent years, carbon dioxide (CO2) has proven to be an environmentally friendly foaming agent for the production of polymeric foams. Until now, extrusion is used to scale-up the CO2-based foaming process. Once the production of large foamed blocks is also possible using the CO2-based foaming process, it has the potential to completely replace the currently used foam production process, thus making the world-wide foam production more sustainable. This review focuses on the polymer–CO2-foaming process, by first addressing the principles of the process, followed by an overview of papers on nucleation and cell growth of CO2 in polymers. The last part will focus on application of the process for various purposes, including bulk polymer foaming, the production of bioscaffolds and polymer blends

Polymerisation of olefins catalysed by a palladium complex in supercritical carbon dioxide

A late transition metal catalyst has been used to polymerise hex-1-ene and ethene in supercritical carbon dioxide, yielding high molecular weight polymers; a comparison with polymerisations in CH2Cl2 reveal that polymers with identical molecular weight and polydispersity are formed

Calorimetric study of the energy efficiency for ultrasound-induced radical formation

Energy conversion in sonochemistry is known to be an important factor for the development of industrial applications, however, the strong influence of the physical properties of the liquid on the ultrasound characteristics usually prevents an accurate determination of the chemical effects. In this study, the energy efficiency of the ultrasound-induced radical formation from methyl methacrylate has been investigated. The energy yield can be quantified by comparison of the ultrasonic power that is transferred to the liquid and the radical formation kinetics. Based on this method the influence of temperature and amplitude of the ultrasound horn on the energy efficiency has been determined. The energy yield for the formation of radicals from ultrasonic waves appears to be in the order of 5×10-6 J/J. The energy conversion is the highest at low temperatures and at low amplitudes

Foam processing of poly(ethylene-co-vinyl acetate) rubber using supercritical carbon dioxide

Soft rubber foams like poly(ethylene-co-vinyl acetate) (EVA) are industrially applied in a broad range of products, including sports gear, insulation materials and drug delivery systems. In contrast to glassy polymers, few studies in literature concern the foaming of soft rubbers using supercritical carbon dioxide. In this study, open microporous matrices of EVA have been formed with CO2. Prior to the foam expansion, sorption and swelling isotherms of CO2 in EVA have been measured and the obtained isotherms have been correlated using the Sanchez–Lacombe equation of state. Additionally, a pressure-independent diffusion coefficient of CO2 in EVA has been obtained from these experiments. The microporous foams have been formed by a pressure quench of the CO2-swollen polymer matrix. Sorption pressure as well as temperature and decompression times appear to determine the pore size and bulk density of the foam. These parameters allow for a control of the foam structure of EVA rubbers

Polymerisation of olefins catalysed by a palladium complex in supercritical carbon dioxide

A late transition metal catalyst has been used to polymerise hex-1-ene and ethene in supercritical carbon dioxide, yielding high molecular weight polymers; a comparison with polymerisations in CH2Cl2 reveal that polymers with identical molecular weight and polydispersity are formed

Preparation of Amberlyst-coated pervaporation membranes and their application in the esterification of acetic acid and butanol

Catalytic Amberlyst 15 layers were deposited on composite ceramic/poly(vinyl)alc. membranes by the dip-coat technique using Aculyn as a rheol. modifier. Tuning of the catalytic layer thickness is possible by varying the no. of dip-coat steps. The obtained \ dried-mud like\ Amberlyst 15 layers are stable during pervaporation and reaction expts. The catalytic activity of the Amberlyst-coated pervaporation membrane equals the activity of the unsupported catalyst. In the pervaporation-assisted esterification reaction between acetic acid and 1-butanol the catalytic membrane is able to couple catalytic activity and water removal. Due to the high activity of the Amberlyst catalyst the conversion of the esterification reaction is limited by the removal rate of water through the membrane. This is in contrast to zeolite-coated pervaporation membranes, for which the conversion of the esterification reaction between acetic acid and 1-butanol is limited by the catalytic activity

The removal of fatty acids from edible oil : removal of the dispersed phase of a water-in-oil dispersion by a hydrophilic membrane

Fatty acids can be extracted from an oil phase by forming a dispersed phase of saponified fatty acids/water/isopropanol in oil. This dispersion can be separated in the two phases by two membranes of opposite polarity in series. In this study the separation of the water phase from the dispersion by a hydrophilic membrane and the mechanisms underlying the flux characteristics are investigated. The permeation flux through a PAN ultrafiltration membrane is optimized with respect to the fatty acid/water/isopropanol ratio. It appears that a 1:6.5:3 (v/v) ratio gives the highest flux [95 L/(m2-h-bar)]. The dispersion at these conditions consists of a continuous oil phase as well as a continuous water phase between 20 and 65% water phase hold up. The flux/pressure curve shows a linear increase of the flux with pressure at low pressures (determined by the membrane resistance), followed by a maximum flux value for the case where the volume of the water phase present in the inflow is limiting. It is not possible to remove the water phase with membranes below a water phase hold up of 20%. At this hold up value the transition between a bicontinuous and a discrete dispersion also occurs

Comparison of commercial solid acid catalysts for the esterification of acetic acid with butanol

Esterification of acetic acid with butanol has been studied in a heterogeneous reaction system, using a variety of solid acid catalysts. Comparative esterification experiments have been carried out using the homogeneous catalysts sulphuric acid, p toluenesulphuric acid, and a heteropolyacid. The catalysts have been characterised using gas adsorption analysis (BET), X ray diffraction (XRD), scanning electron microscopy (SEM) and temperature programmed decomposition (TPD) techniques. The weight based activity of the heterogeneous catalysts decreases in the following order: Smopex 101 &gt; Amberlyst 15 &gt; sulphated ZrO2 &gt; H USY 20 &gt; H BETA 12.5 &gt; H MOR 45 &gt; Nb?2O5 &gt; H ZSM 5 12.5. The low activity of ZSM 5 is a result of internal diffusion limitations in the medium sized pores of this zeolite type material. For H MOR the low activity can be explained by pore blocking in the one-dimensional H MOR channels. For the H USY type zeolites, the influence of the Si/Al ratio on catalytic activity has been examined. Although the amount of acid sites decreases with an increase in the Si/Al ratio, an optimum Si/Al ratio of 20 has been found. The activity of sulphated zirconia shows an optimum calcination temperature, even though both the amount and acidity of the acid sites increase monotonically with calcination temperature. Most likely, at higher calcination temperatures Lewis acid sites are formed and Br?d acid sites are removed. As Br?d acid sites are essential for catalysis of esterification reactions this explains the decrease in activit

Surfactant-aided size-exclusion chromatography for the purification of immunoglobulin G

In the production of monoclonal antibodies, separate chains of the antibody are often present in the product mixture as well as other contaminating proteins. These fragments should be removed from the whole antibodies. This paper shows the purification of monoclonal immunoglobulin G (IgG) from its heavy chain contaminant. The heavy chain fragment is simulated experimentally using bovine serum albumin (BSA), which has approximately the same molecular weight. The purification is performed using traditional size-exclusion chromatography (SEC) and using surfactant-aided SEC (SASEC), testing two different surfactants (C12E23 and Tween20) and two different gels (Sephacryl S200HR and Sephacryl S300 HR). Pulse experiments show that with SASEC both BSA and IgG are more distributed towards the solid phase than compared to using SEC. This effect is larger on IgG, the largest component than on BSA. As a consequence, azeotropes will be formed at a specific surfactant concentration. Above this concentration the selectivity is reversed and increased to values higher than obtained with conventional SEC. At 7.5% (w/w) of C12E23, BSA actually elutes before IgG. These experiments further show that when using SASEC larger productivity, higher yields and lower solvent consumption can be achieved without loss of purity of IgG when compared to conventional SEC. Mathematical simulation of the separation of BSA and IgG using simulated moving bed (SMB) chromatography indicates a large increase in productivity when applying a surfactant gradient in SASEC SMB compared to conventional isocratic SEC-SMB. Furthermore, solvent consumption reductions with a factor 15 prove possible as well as concentrating the IgG by a factor 2