Measurement of entrainer effects of water and ethanol on solubility of caffeine in supercritical carbon dioxide by FT-IR spectroscopy

2006 ◽  
Vol 38 (3) ◽  
pp. 312-318 ◽  
Author(s):  
Yoshio Iwai ◽  
Hirotaka Nagano ◽  
Gil Sun Lee ◽  
Machiko Uno ◽  
Yasuhiko Arai
Keyword(s):  
Carbon Dioxide ◽  
Ir Spectroscopy ◽  
Supercritical Carbon Dioxide ◽  
Ft Ir ◽  
Ft Ir Spectroscopy ◽  
Supercritical Carbon

FT-IR study on interactions between solutes and entrainers in supercritical carbon dioxide

2002 ◽  
Vol 193 (1-2) ◽  
pp. 203-216 ◽  
Author(s):  
Yoshio Iwai ◽  
Daisaku Tanabe ◽  
Morio Yamamoto ◽  
Taro Nakajima ◽  
Machiko Uno ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Ft Ir ◽  
Ir Study ◽  
Supercritical Carbon

scholarly journals Study on the Changes of Structures and Properties of PAN Fibers during the Cyclic Reaction in Supercritical Carbon Dioxide

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 402 ◽  
Author(s):  
Mengmeng Qiao ◽  
Haijuan Kong ◽  
Xiaoma Ding ◽  
Zhifeng Hu ◽  
Luwei Zhang ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Heating Temperature ◽  
Cyclization Reaction ◽  
Effect Of Temperature ◽  
High Heat Transfer ◽  
Structures And Properties ◽  
Ft Ir ◽  
Pan Fibers ◽  
Supercritical Carbon

Thermal pre-oxidation of polyacrylonitrile (PAN) fibers is a time-consuming and energy-consuming step in the production of PAN-based carbon fibers. In this paper, the effect of temperature on the structures and properties of PAN fibers cyclized in the supercritical carbon dioxide (Sc-CO2) medium was studied. The thermal behaviors of the PAN fibers were investigated by Fourier transform infrared spectra (FT-IR), X-ray diffraction (XRD), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The cyclization reaction was sensitive to the heating temperature and gas atmosphere. The FT-IR results of the PAN fibers treated in the Sc-CO2 confirmed that the degree of cyclization increased with the increase of the cyclization temperature. Compared with the PAN fibers treated in the air, the PAN fibers treated in the Sc-CO2 showed a higher degree of cyclization even at the same temperature. These findings might be related to the osmotic action of Sc-CO2 causing the fibers to be further arranged in a regular manner, which was favorable for the cyclization reaction. Moreover, as one kind of high diffusion and high heat transfer media, the heat release during the cyclization of PAN fibers could be quickly removed by Sc-CO2, which achieved the progress of the rapid-entry cyclization reaction.

scholarly journals Environmentally Friendly Surface Modification Treatment of Flax Fibers by Supercritical Carbon Dioxide

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 438 ◽  
Author(s):  
Maria Carolina Seghini ◽  
Fabienne Touchard ◽  
Laurence Chocinski-Arnault ◽  
Vincent Placet ◽  
Camille François ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Fragment Length ◽  
Interfacial Adhesion ◽  
Environmentally Friendly ◽  
Flax Fibers ◽  
Fragmentation Test ◽  
Ft Ir ◽  
Single Yarn ◽  
Supercritical Carbon

The present work investigates the effects of an environmentally friendly treatment based on supercritical carbon dioxide (scCO2) on the interfacial adhesion of flax fibers with thermoset matrices. In particular, the influence of this green treatment on the mechanical (by single yarn tensile test), thermal (by TGA), and chemical (by FT-IR) properties of commercially available flax yarns was preliminary addressed. Results showed that scCO2 can significantly modify the biochemical composition of flax fibers, by selectively removing lignin and hemicellulose, without altering their thermal stability and, most importantly, their mechanical properties. Single yarn fragmentation test results highlighted an increased interfacial adhesion after scCO2 treatment, especially for the vinylester matrix, in terms of reduced debonding and critical fragment length values compared to the untreated yarns by 18.9% and 15.1%, respectively. The treatment was less effective for epoxy matrix, for which debonding and critical fragment length values were reduced to a lesser extent, by 3.4% and 3.7%, respectively.

Effect of treatment temperature on structures and properties of flax rove in supercritical carbon dioxide

2016 ◽  
Vol 88 (2) ◽  
pp. 155-166 ◽  
Author(s):  
Juan Zhang ◽  
Huanda Zheng ◽  
Laijiu Zheng
Keyword(s):  
Carbon Dioxide ◽  
Thermal Properties ◽  
Supercritical Carbon Dioxide ◽  
Monosaccharide Composition ◽  
Treatment Temperature ◽  
Scanning Calorimetry ◽  
Flax Fibers ◽  
Ft Ir ◽  
Isolated Compound ◽  
Supercritical Carbon

In this study, flax rove was treated in supercritical carbon dioxide. The effect of different treatment temperatures on the surface morphology, chemical and crystal structures, and thermal properties, as well as isolated compounds of flax rove, were investigated by employing scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal analysis, and nuclear magnetic resonance (NMR), respectively. The results showed that more mild grooves and stripes appeared on the surface of the treated flax fibers after supercritical carbon dioxide treatment. FT-IR spectra showed that hydrolysis of macromolecule of flax fibers occurred, producing a C≡C group. XRD spectra confirmed that the crystallinity of the treated flax samples was gradually increased with the raising of treatment temperature. Simultaneously, thermo gravimetric analyzer (TGA), differential thermal gravity (DTG) and differential scanning calorimetry (DSC) analysis indicated that the thermal properties of flax rove were improved with the increase of treatment temperature. In addition, NMR analysis proved that lignin and the monosaccharide composition of isolated compound were extracted from flax rove. Moreover, a predominance of β–O–4’ arylether linkages, followed by β–5’ phenylcoumaran and β–β’ resinol-type linkages for lignins of isolated compound was shown in NMR. Therefore, the results confirmed that it is technically feasible to using supercritical carbon dioxide to conduct the scouring and bleaching of flax rove.

scholarly journals Supercritical Carbon Dioxide Isolation of Cellulose Nanofibre and Enhancement Properties in Biopolymer Composites

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5276
Author(s):  
Olaiya N. G. ◽  
Abdul Khalil H. P. S. ◽  
Salah M. El-Bahy ◽  
Mohd Rafatullah ◽  
Che K. Abdullah ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Zeta Potential ◽  
Physical Properties ◽  
Fibre Diameter ◽  
Crystallinity Index ◽  
Diameter Distribution ◽  
Fibre Size ◽  
Ft Ir ◽  
Supercritical Carbon

The physical properties, such as the fibre dimension and crystallinity, of cellulose nanofibre (CNF) are significant to its functional reinforcement ability in composites. This study used supercritical carbon dioxide as a fibre bundle defibrillation pretreatment for the isolation of CNF from bamboo, in order to enhance its physical properties. The isolated CNF was characterised through zeta potential, TEM, XRD, and FT-IR analysis. Commercial CNF was used as a reference to evaluate the effectiveness of the method. The physical, mechanical, thermal, and wettability properties of the bamboo and commercial CNF-reinforced PLA/chitin were also analysed. The TEM and FT-IR results showed the successful isolation of CNF from bamboo using this method, with good colloidal stability shown by the zeta potential results. The properties of the isolated bamboo CNF were similar to the commercial type. However, the fibre diameter distribution and the crystallinity index significantly differed between the bamboo and the commercial CNF. The bamboo CNF had a smaller fibre size and a higher crystallinity index than the commercial CNF. The results from the CNF-reinforced biocomposite showed that the physical, mechanical, thermal, and wettability properties were significantly different due to the variations in their fibre sizes and crystallinity indices. The properties of bamboo CNF biocomposites were significantly better than those of commercial CNF biocomposites. This indicates that the physical properties (fibre size and crystallinity) of an isolated CNF significantly affect its reinforcement ability in biocomposites. The physical properties of isolated CNFs are partly dependent on their source and production method, among other factors. These composites can be used for various industrial applications, including packaging.

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