Study of the Effect of Pressure on Melting Behavior of Saturated Fatty Acids in Liquid or Supercritical Carbon Dioxide

Abstract

The melting point depression of saturated fatty acids (C 12 −C 18 ) was investigated in liquid or supercritical carbon dioxide. The pressure and temperature melting point ranges were determined for each excipient in liquid or supercritical CO 2 . Additionally, the effect of pressure on the melting point of fatty acids was also more closely studied in the (7.0 to 50.0) MPa range. Untreated and CO 2 -treated samples were analyzed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). A melting point depression in the range (10.8 to 19.5) K was observed for the fatty acids studied in this work. The melting behavior of fatty acids in CO 2 was found to be dependent on pressure and carbon chain length. Melting temperature curves for each of the fatty acids in CO 2 exhibited a minimum as a function of pressure. Analysis by DSC and XRD indicated that CO 2 treatment had no impact on the morphological or crystallographic properties of these excipients under the selected experimental conditions.

Effect of Pressure on the Melting Point of Pluronics in Pressurized Carbon Dioxide

“…A similar melting point depression trend has been reported for polycaprolactone and poly(butylene succinate) in the pressure range of 0.1 to 27.6 MPa and 0.1 to 20.7, respectively 31 . On the other hand, compounds such as fatty acids, octacosane and naphthalene show an initial decrease followed by an increase in the melting point with the increase in pressure 12,32 . The initial decrease in melting point is attributed to the solubility effect and the increase in melting point at higher pressures is due to the pressure effect.…”

“…The depression in melting point (T m ) or glass transition (T g ) temperature in polymers due to the sorption of CO 2 is a well-known phenomenon which is dependent on various factors such as crystallinity and presence of CO 2 -philic moieties [9][10][11][12][13][14] . Amorphous polymers are reported to show higher interactions with CO 2 than crystalline polymers 15,16 .…”

Myristic Acid Coated Protein Immobilised Mesoporous Silica Particles as pH Induced Oral Delivery System for the Delivery of Biomolecules

“…The protein-adsorbed particles were separated from the media via centrifugation at 3700 rpm (Centrifuge 5430, Eppendorf, Stevenage, UK) for 10 min and freeze-dried at −55 • C under deep vacuum using a ScanVac CoolSafe freeze dryer (LaboGene ApS, Lillerød, Denmark). The dried particles were coated by SCF processing with MA at a temperature and pressure reported elsewhere (43 • C and 100 bar) [27,48]. The instrumental set up is detailed in Figure 12, which consists of a temperaturecontrolled 150 mL and 3.5-cm-thick stainless steel cylinder with sapphire windows to monitor the experiments.…”

Conversion of phenylacetonitrile in supercritical alcohols within a system containing small volume of water

“…However, supercritical alcohol was one of the most promising due to milder reaction conditions, such as its higher solubility and high ionic product, which was commonly used in the alcoholysis reaction. Researchers have paid increasing attention to supercritical alcohol and a series of studies have been conducted (Demirbaş, 2002;Kusdiana & Saka, 2004;Bicker et al, 2005;Minami & Saka, 2006;Song et al, 2008;Kamitanaka et al, 2008;Goto et al, 2009;Šk-erget et al, 2011;Trivedi et al, 2013). Kamitanaka et al (2008) investigated the non-catalytic alcoholysis of benzonitrile in supercritical methanol.…”