Supercritical Fluid Carbon Dioxide Research Articles

Graphene exfoliation with supercritical fluids

Graphene is an unconventional material with a two-dimensional hexagonal crystalline array of elemental carbon atoms and outstanding properties; accordingly, a desirable objective in the line of research of graphene is the development of novel and more productive methods of synthesis, validating its properties and applications. In our exploratory research, we have effectively exfoliated graphene from graphite using supercritical fluids (water, ethanol and carbon dioxide). The exfoliated graphene was properly characterized; via scanning electron microscopy, the morphology of graphene was observed; Raman spectra confirmed the exfoliation of graphene depicting the characteristic shift towards smaller Raman number in the 2D band (2676 cm−1) compared to that of graphite (≈ 2700 cm−1); transmission electron microscopy analysis exhibited the crystalline structure of graphene attesting also the expected transparency of exfoliated layers. Graphene exfoliation from graphite by supercritical fluids promises to be a simple large-scale method for graphene production.

Optimization of Supercritical Fluid Extraction of Paprika (cv. Reshampatti) Oil, Capsaicin and Pigments

AbstractPaprika (Capsicum annuum L.) is a spice, utilized in culinary across the globe for its colour and pungency. A study was conducted to optimize the supercritical fluid extraction (SFE) process individually for selective extraction of paprika oil, capsaicin and pigments. Paprika oil was extracted by supercritical fluid—carbon dioxide at different process parameters: temperature (35‐75°C), pressure (100‐500 bar), extraction time (60‐180 minutes) and particle size (0.25‐1.25 mm) using central composite rotatable design (CCRD). The ANOVA results showed that yields of paprika oil, capsaicin and pigments were significantly (P ≤ .05) affected by the extraction process variables. Optimized SFE conditions, 65, 65 and 57.04°C temperature; 357.8, 200.62 and 400 bar pressure; 90, 90 and 100.89 minutes extraction time; and 0.78, 0.50 and 0.89 mm particle size, were obtained for optimum yield of paprika oil, capsaicin and pigments, respectively. Experimental yield of paprika oil, capsaicin and pigments at the optimized condition for respective compounds was 4.91% (w/w), 2.10% (w/w) and 16 319.9 NCV, and had good agreement with the predicted values. Antimicrobial activity of extracted paprika oil was found against E. coli, B. subtilus and S. aureus.

Determination of Polyphenols and Vitamins in Wine-Making by-Products by Supercritical Fluid Extraction (SFE)

Fruits, vegetables, cereals and their derivatives are associated with the prevention or delay of chronic degenerative diseases, being a source of important constituents able to reduce oxidative cellular stress. Vitaceae (e.g., Vitis vinifera L.) are very rich in polyphenols, sterols and vitamins that are partially transferred to wine by-products during winemaking practices. As a result, the solid waste generated by the wine industry may represent a valuable source of these active biological compounds. In this paper, in order to ennoble grape waste, high-value extracts were obtained from pomace, skins and seeds employing a simple, green and inexpensive protocol involving carbon dioxide supercritical fluid extraction (SFE). The comparison with a conventional approach based on a solid-liquid extraction, in terms of the extract antioxidant capacity and total polyphenol content, as well as extraction yield of trans-resveratrol, β-sitosterol, α-tocopherol and ascorbic acid, was carried out.

Fabrication of Poly(vinylidene fluoride)/Multiwalled carbon nanotube nanocomposite foam via supercritical fluid carbon dioxide: Synergistic enhancement of piezoelectric and mechanical properties

The fabrication of poly(vinylidene fluoride) (PVDF) based foam with complicated three-dimensional (3D) geometry and excellent piezoelectric property remains great challenge worldwide. In this study, microcellular PVDF/multiwalled carbon nanotube (MWCNT) nanocomposite foaming part was fabricated by supercritical carbon dioxide (scCO2) bead foaming technology. With the assistance of the ball milling, the good dispersion of MWCNT particles in PVDF matrix was achieved, which promoted the heterogeneous nucleation and enhancement effects of MWCNT on PVDF, resulting in the formation of more unique and denser cells, e.g. from 3.4 × 105 cells/cm3 of pure foam to 1.7 × 106 cells/cm3 of the composite foam when MWCNT content was 1.5%, and high compression strength, i.e. 3.1 MPa with 1.5% MWCNT at 10% compressive strain, about 1.1 MPa higher than that of pure foam. During the bead foaming process, the induced crystallization effect of MWCNT as well as the plasticizing and squeezing effect of scCO2 on PVDF matrix contributed to the increase of the β-phase crystal in PVDF matrix, thus endowing the composite foaming part with good piezoelectric property, i.e. 6.5 V of output voltage under periodic compression, which lightened 4 LEDs and made the foaming part had wide potential application in smart electronic field.

Inhibition of melanin production and promotion of collagen production by the extract of Kuji amber.

Kuji amber is fossilized tree resin of the Late Cretaceous in Japan. In this study, new biological activities of ethanol extract of Kuji amber (EtOH ext.) and supercritical carbon dioxide fluid extract of Kuji amber (scCO2 ext.) were examined. Both EtOH ext. and scCO2 ext. inhibited melanin production in B16 mouse melanoma cells and promoted collagen production in human skin fibroblast SF-TY cells. The scCO2 ext. had more potent activity than that of EtOH ext. and may depend on the efficiency of the extraction. The main new biologically active compound in Kuji amber, kujigamberol had no activities against melanin production, however, it promoted collagen production at low concentrations. A biologically active compound having a different structure, spirolactone norditerpenoid, showed both the inhibition activity against melanin production and the promotion activity of collagen production in a dose dependent manner. EtOH ext. and scCO2 ext., which include both kujigamberol and spirolactone norditerpenoid, have not only anti-allergy activity, but also inhibit melanin production and promote collagen production.

Depigmented Centella asiatica Extraction by Pretreated with Supercritical Carbon Dioxide Fluid for Wound Healing Application

Centella asiatica has been included in Thai traditional medicinal plants and recipes, as a well-established historical use as a vegetable and tonic. However, when applied in modern formulations, the progressive degradation of the plant pigments occurs, causing color-fading and color variation in the products. Depigmentation of the comminuted sample using supercritical carbon dioxide (scCO2) fluid extraction with a cosolvent was introduced as a pretreatment to solve the color-fading problem. The contents of compounds with known biological activities and the wound healing activities (antioxidant screening by DPPH and ABTS+ scavenging activities; cell migration assay; matrix metallopeptidase [MMP]-2 inhibition on human skin fibroblast; endothelial cell tube formation assay) of the C. asiatica leaf extracts obtained by conventional ethanolic extraction (CV) and pretreatment using scCO2 extraction, were determined. Total triterpenoids (madecassoside, asiaticoside B, asiaticoside, madecassic acid, terminolic acid and asiatic acid) and total triterpenoid glucosides (madecassoside, asiaticoside B and asiaticoside) were notably more abundant in the extract that had been pretreated using scCO2 than the extract obtained by CV. Moreover, the scCO2 pretreatment not only caused greater relative MMP-2 inhibition (58.48 ± 7.50% of the control), but also exhibited a higher cell migration (59.83 ± 1.85% of the initial) and number of vessels (18.25 ± 4.58) of angiogenesis in the wound healing process. Additionally, positive correlations were observed between the DPPH antioxidant activity and madecassoside content (r = 0.914, p < 0.01), as well as between the cell migration activity and asiaticoside content (r = 0.854, p < 0.05). It can be concluded that the scCO2 pretreatment of C. asiatica can eliminate color pigments from the extract and improve its in vitro wound healing activity.

Solubility and loading ability of benzene derivative drugs onto viscose substrate in supercritical carbon dioxide and their release behavior in solvent

An investigation of the solubility and loading ability (LA) of nine benzene derivative drugs with different chemical structures onto viscose substrate in supercritical carbon dioxide fluid (SCF–CO2) was performed, in order to construct some bases at the first time for manufacturing drug-loaded cosmetic textiles by employing an ecofriendly, sustainable supercritical methodology. Moreover, a release behavior of each of the loaded drugs from viscose substrate in a solvent of ethanol was also disclosed. The results show that a more hydrophobicity of the substituent group linked on the benzene ring readily led to a higher solubility in SCF-CO2, while an overlong aliphatic tail and its molar mass also brought some effects on its dissolving behavior. As for the isomer drugs, the locations of a methoxy group (-O-CH3) at the ortho-position to the carboxyl group (-(CO)–OH) in the benzene ring resulted in the highest solubility, while a para-position showed the lowest solubility in SCF-CO2. The loading ability (LA) for most of the tested drugs mainly depended on their solubilities in SCF-CO2, and was also affected by the interactions between the drug and viscose substrate. The investigation of drug release reveals that the LA played a predominant role in the release behaviors of the tested drugs with different substituent groups, molar mass or aliphatic chains and isomer structures. Moreover, the drug molecular size and its interaction with viscose substrate also presented effects on the subsequent release behaviors in the utilized release system and conditions.

Study on the Crystallization Behavior of PAN Fibers during Hot-Drawing Process in Supercritical Carbon Dioxide Fluid with Different Strain

Hot-drawing of polyacrylonitrile (PAN) fibers is an important step in the production of carbon fibers. In this article, we investigated the effect of strain on the crystallization behavior and mechanical properties of PAN fibers treated in supercritical carbon dioxide (Sc-CO2) fluid. We mainly used the methods of X-ray diffraction (XRD), monofilament strength analysis and differential scanning calorimeter (DSC) to study the crystallization behavior, mechanical properties and thermal behavior of PAN fibers during hot-drawing process. The experimental results showed that the crystallinity and mechanical properties of PAN fibers both increased a lot under the action of strain during hot-drawing in Sc-CO2 fluid. This provides an important method for preparation of higher performance PAN precursor for PAN-based carbon fibers.

Измерение растворимости веществ в сверхкритических флюидных средах динамическим методом

The study of currently known methods and devices for processing plant materials has shown that during the study period, the greatest interest (about 31%) of patent holders is manifested in increasing the yield of extractive substances. If we take as an example a tea leaf, then indeed, the formation of conditions for a more complete release of the target components into the aqueous phase during brewing can provide a more profitable and economical consumption of tea raw materials. The study of the thermodynamic principles of the use of supercritical fluid media and carbon dioxide, in particular, in the processing of plant materials and the processing of tea raw materials, as well as the development of methods for intensifying mass transfer to the aqueous phase when “brewing” tea leaves, are uniquely relevant tasks. An important section of thermodynamics is the concept of phase equilibria in systems of different composition. And one of the key characteristics of phase equilibria is such a thing as the solubility of a substance, including in supercritical fluid media. Since solutions of substances in supercritical fluids are diluted, the dependence of the solubility of substances on temperature, pressure, and density of a pure solvent near its critical point is of practical interest. The results of experimental studies of measuring the solubility of tannin in supercritical carbon dioxide by the dynamic method at a temperature of 308 and 333 K, in the pressure range from 8 to 26 MPa, are presented. The data obtained, firstly, indicate a low solubility of tannin in supercritical carbon dioxide, which is a positive moment for the implementation of the tea leaf pretreatment process in order to improve its biological potential, and secondly, a clear suppression of isolines is observed, which in turn indicates the presence of crossover behavior on solubility isotherms. Based on the results of the obtained experimental data on the solubility of tannin in supercritical carbon dioxide, a mathematical description of the solubility of tannin was carried out by the Peng-Robinson equation of state.

Solubility Measurements of Chloramphenicol in Supercritical Fluid CO2 Using Static Solubility Apparatus Interfaced with Online Supercritical Fluid Chromatography

The solubility of chloramphenicol in pure supercritical fluid carbon dioxide (SF-CO2) has been determined using a continuously stirred supercritical solubility vessel (SSV) directly interfaced with...

Efficacy of Neem Kernel Bioactives Extracted using Supercritical Fluid Carbon Dioxide on Selected Dermatophytes and Foodborne Pathogens

Neem seed kernel was subjected to supercritical fluid carbon dioxide (SCF) process and evaluated for the inhibition of selected dermatophytes such as Candida albicans, Candida tropicalis, Candida parapsilosis, Trichophyton rubrum, Trichophyton mentagrophytes. The extraction was carried out by SCF-CO2 at 300 bar 50 °C with and without entrainer (30 % methanol and acidified methanol). Results showed that the inhibition of the growth of all the dermatophytes is maximum in the extract obtained at 300 bar 50 °C with methanol (SCF-Me) followed by 300 bar 50 °C without methanol (SCF). The acidified SCF (SCF-MeA) extract did not show any remarkable inhibition. Of the dermatophytes, SCF-Me showed the inhibition against Candida parapsilosis of 18.46±0.25 mm compared to Candida albicans 16±0.26 mm, whereas the methanol control exhibited 10±0.3 mm inhibition. Out of the two fungal organisms, SCF-Me inhibited the growth of Trichophyton rubrum and Trichophyton mentagrophytes at 21.53±0.23 mm and 18.1±0.1 mm respectively. The extracts were also evaluated for its inhibition against the foodborne pathogens (bacteria, fungi, and yeast). The SCF-Me extract showed maximum inhibition against Pseudomonus aeroginosa (27.26±0.25) compared to Bacillus subtilis (24.36±0.35) at the concentration of 70mg. In fungus, Aspergillus ochraceus (16.7±0.60) was maximum when compared to Aspergillus niger (15.2±0.43) and yeast exhibited the inhibition of 15.93±0.20 at the concentration of 80mg. The dermatophytic and antimicrobial activity of the SCF-Me extract is due to the presence of higher amount of triterpenoinds such as Azadirachtin (50.7 %), 6-deacetyl nimbin (0.14 %), Nimbin (0.08 %), Salannin (1.83 %) and Epoxy azadiradione (1.58 %) which were confirmed by liquid chromatography and mass spectroscopy (LC-MS).

Cytotoxicity of Triterpene Seco-Acids from Betula pubescens Buds.

The present study investigated the magnitude and mechanism of the cytotoxic effect on selected cancer cell lines of 3,4-seco-urs-4(23),20(30)-dien-3-oic acid (1), 3,4-seco-olean-4(24)-en-19-oxo-3-oic acid (2), and 3,4-seco-urs-4(23),20(30)-dien-19-ol-3-oic acid (3) isolated from downy birch (Betula pubescens) buds by carbon dioxide supercritical fluid extraction and gradient column chromatography. Cell viability in six human cancer lines exposed to these compounds was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was quantified by annexin V/propidium iodide staining of gastric cancer AGS and colorectal cancer DLD-1 cells. To evaluate the mechanism of apoptosis, the expression of apoptosis-related proteins was analyzed by Western blot. Compound 1 exhibited non-specific toxicity, while compounds 2 and 3 were specifically toxic to colon and stomach cancer cells. The toxicity of compounds 2 and 3 against these two cell lines was greater than for compound 1. Cleavage of caspase-8, -9, and -3 was found in AGS and DLD-1 cells treated with all three seco-acids, indicating the induction of apoptosis via extrinsic and intrinsic pathways. Therefore, triterpene seco-acids (1–3) decreased cell viability by apoptosis induction. AGS and DLD-1 cells were more susceptible to seco-acids with an oxidized C19 than normal fibroblasts. Hence, it made them a new group of triterpenes with potential anticancer activity.

Sequential Green Extraction of Caffeine and Catechins from Green Tea

Separation of caffeine and catechins from tea extracts usually requires conventional liquid-liquid extraction employing chloroform. This work was planned to improve a green extraction technique to distunguish these important chemicals from green tea. Extraction of caffeine and catechins from Turkish green tea firstly employing MAE, and then to separate these compounds from each other using a SFE method were purpose of this study. Microwave assisted extraction was applied to extract tea components from green tea then i) conventional liquid-liquid extraction or ii) supercritical carbon dioxide fluid extraction (SFE) method was charged with the effective separation of caffeine and catechins. Initially, an ethanol: water mixture was used in a close microwave system under the particuler extraction situations of green tea samples (fresh, frozen or dried) picked up in three collection periods (first, second and third collection periods). MAE of tea samples was exerted under a controlled 600 W microwave power for 4 min irradiation time at 80 oC temperature. Then MAE crude aqueous extract was divided in to two portions. The first portion was fractionated first with chloroform to distunguish caffeine then ethyl acetate for catechins. Caffeine and catechins were successfully separated. Second portion was freeze-dried and obtained lyophilized solid was used for SFE. Caffeine (3.68% extract yield) was successfully separated from catechins with SFE at 250 bar and 60°C for 180 min. Constituents of the extracts were determined (caffeine and four catechins namely EGC, EC, C, EGCG) by HPLC to evaluate the effectiveness of the separation.

Preparation and Electro-thermal Properties of Low Voltage DC Driven Graphene Electro-thermal Film

Exfoliated graphene were prepared by supercritical carbon dioxide fluid stripping and electro-thermal film with graphite and exfoliated graphene ware prepared and then studied by SEM and Raman spectroscopy. The results show the graphene sheets are exfoliated from the graphite blocks with a size of 3-10μm after stripping. The graphene existed in sheet in the electro-thermal film while graphite was blocks, which caused the graphene oriented and the conductive network more abundant and effective. The power of graphene electro-thermal film reduced by 22.5% compared with graphite electro-thermal film to reach the same space temperature under 12V, and the film temperature decreased by 9.623 °C, the comprehensive heat transfer coefficient is 2.60×10-3 W·cm-2·°C-1, And the heating rate of the graphene electro-thermal film rapidly increase and the temperature rise time greatly decrease. The initial heating rate of graphene electro-thermal film is 19.3 times of that of the graphite electro-thermal film, and the temperature rise time decreased to 24.7%.

Selective Extraction of ω-3 Fatty Acids from Nannochloropsis sp. Using Supercritical CO2 Extraction.

In this article, microalgae Nannochloropsis sp. was used for fatty acid (FA) extraction, using a supercritical fluid-carbon dioxide (SF-CO2) extraction method. This study investigated the influence of different pre-treatment conditions by varying the grinding speed (200–600 rpm), pre-treatment time (2.5–10 min), and mixing ratio of diatomaceous earth (DE) and Nannochloropsis sp. biomass (0.5–2.0 DE/biomass) on FAs extraction. In addition, the effect of different operating conditions, such as pressure (100–550 bar), temperature (50–75 °C), and CO2 flow rate (7.24 and 14.48 g/min) on eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) recovery, was analyzed. Experimental data evidenced that, keeping constant the extraction conditions, the pre-treatment step enhanced the FAs extraction yield up to 3.4 fold, thereby the maximum extracted amount of FAs (61.19 mg/g) was attained with the pre-treatment with a ratio of DE/biomass of 1 at 600 rpm for 5 min. Moreover, by increasing both SF-CO2 pressure and temperature, the selectivity towards EPA was enhanced, while intermediate pressure and lower pressure promoted DHA recovery. The highest amount of extracted EPA, i.e., 5.69 mg/g, corresponding to 15.59%, was obtained at 75 °C and 550 bar with a CO2 flow rate of 14.48 g/min, while the maximum amount of extracted DHA, i.e., ~0.12 mg/g, equal to 79.63%, was registered at 50 °C and 400 bar with a CO2 flow rate of 14.48 g/min. Moreover, the increased CO2 flow rate from 7.24 to 14.48 g/min enhanced both EPA and DHA recovery.

Characterization of polystyrene nanocomposites and expanded nanocomposites reinforced with cellulose nanofibers and nanocrystals

Expanded nanocomposite production is an evolutionary and emerging technology in the field of porous materials, because it’s characterized by combining the structural characteristics of the nanocomposites with the lightness of the polymeric foams. Three different processes were used in the present study: (1) extraction of two types of nanocellulose: cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs), both from curaua fibers. CNFs were obtained by mechanical defibrillation method and CNCs by 2,2,6,6-tetramethylpiperidine-1-oxyl (T.E.M.P.O.)-mediated oxidation method. (2) incorporation of reinforcement in a polystyrene matrix, producing nanocomposites in the following concentrations: 0.25%, 0.50% and 1.00% (w/w). (3) nanocomposite expansion with supercritical carbon dioxide fluid (scCO2), a new expander agent trend. The nanocomposites all had increased storage and loss moduli in relation to neat PS. In the expanded nanocomposites, the incorporation of CNFs promoted an increase in the compressive strength and a decrease in the cell size in comparison to the samples reinforced with CNCs and polystyrene foam. In the nanocomposites produced with CNCs, no significant variations were observed when compared to pure polystyrene foam.

Potent Anti-Proliferation on the Colon Cancer Cell Line (HT-29) of Liposomal Formulations Entrapped with Semi-Purified Job's Tears (Coix lacryma-jobi Linn.) Fractions.

Liposomes, entrapped with Job's Tears fractions, were prepared by the supercritical carbon dioxide fluid (scCO₂) technique with and without sonication. Physical characteristics, which were the particle size, zeta potential, vesicular morphology, microviscosity and bioactivities including anti-proliferative, apoptotic and antioxidative activities of the S1L-S5L liposomal systems, were investigated. The potent anti-proliferative activity with the IC50 value of 4.44±2.31 ug/ml in a colon cancer cell (HT-29) was observed in the S5L. S5L also showed the apoptotic activity of 4.45±0.92% in an HT-29 cell. For antioxidative activities, the S3L showed the highest free radical scavenging activity and lipid peroxidation inhibition, whereas the S4L gave the highest metal chelating activity. This study has demonstrated the potent anti-proliferative activity on an HT-29 cell of the S5L liposomal formulation prepared by the scCO₂ technique which can be further developed towards a novel anticancer drug.

Supercritical CO₂ Fluid Extraction of Elaeagnus mollis Diels Seed Oil and Its Antioxidant Ability.

Supercritical fluid carbon dioxide (SF-CO2) was used to extract oil from Elaeagnus mollis Diels (E. mollis Diels) seed and its antioxidant ability was also investigated. The effect of extraction pressure (20–35 MPa), extraction temperature (35–65 °C), extraction time (90–180 min) and seed particle size (40–100 mesh) on the oil yield were studied. An orthogonal experiment was conducted to determine the best operating conditions for the maximum extraction oil yield. Based on the optimum conditions, the maximum yield reached 29.35% at 30 MPa, 50 °C, 150 min, 80 mesh seed particle size and 40 g/min SF-CO2 flow rate. The E. mollis Diels seed (EDS) oil obtained under optimal SF-CO2 extraction conditions had higher unsaturated fatty acid content (91.89%), higher vitamin E content (96.24 ± 3.01 mg/100 g) and higher total phytosterols content (364.34 ± 4.86 mg/100 g) than that extracted by Soxhlet extraction (SE) and cold pressing (CP) methods. The antioxidant activity of the EDS oil was measured by DPPH and hydroxyl radical scavenging test. EDS oil extracted by different methods exhibited a dose-dependent antioxidant ability, with IC50 values of no significant differences. Based on the results of correlation between bioactive compounds, lupeol and γ-tocopherol was the most important antioxidant in EDS oil.

Determination of multi-class antibiotic residues in compost by microwave-enhanced accelerated solvent extraction and ultra performance convergence chromatography with tandem mass spectrometry.

This work reports the development and application of a multi-class compound analysis method for the determination of 20 antibiotic residues in compost. Samples were processed by microwave-enhanced accelerated solvent extraction at 120°C for 7.5min. Salting-out homogeneous liquid-liquid extraction was used to remove water and water-soluble impurities from the extract before ultra performance convergence chromatography with tandem mass spectrometry analysis. By using the supercritical fluid (carbon dioxide) and organic solvent (methanol) as the mobile phase, the 20 antibiotics and the internal standard were well separated in 8.2 min without obvious matrix effect. Method validation was performed and good trueness (relative error in the range of ±5.0%) and precision (inter- and intraday relative standard deviations<10.8%) were obtained. Method detection and quantitation limits were 0.8-1.9 and 2.7-7.1ng/g, respectively. Recoveries were assessed at three concentration levels (10, 60, and 400ng/g) and acceptable mean values (70.4-111.9%) were found. This method has also been used to analyze real samples, and the average concentrations of antibiotics (excepting the concentrations<method quantitation limits) were determined up to 123.6ng/g. The results showed the method could be helpful for the analysis of multi-class antibiotics in environmental samples.

Effect of Different Pressures on Microstructure and Mechanical Performance of F-III Fibers in Supercritical Carbon Dioxide Fluid.

F-III fibers were treated at different pressures in supercritical carbon dioxide fluid and all samples including untreated and treated F-III fibers were characterized by a mechanical performance tester, wide-angle X-ray scattering and small-angle X-ray scattering. By studying the relationship between mechanical performance and microstructural changes of the samples, it was found that microstructural change was the main cause of variation in mechanical performance. Results revealed that the maximum tensile strength and modulus of F-III fibers were acquired at 14 MPa within the pressure range of 8 MPa to 16 MPa when the temperature, tension and time were 250 °C, 6 g·d−1 and 40 min, respectively. Correspondingly, the microstructures of the samples, including the phase fraction, crystal size, orientation factor, fibril radius, fibril length and misorientation angle, have been investigated. It was fortunate that the supercritical carbon dioxide fluid could be used as a medium during the hot-stretch process to improve the mechanical performance of F-III fibers, although the treatment temperature was lower than the glass transition temperature of the F-III fibers.