Foaming Conditions Research Articles

Impact of foaming conditions on quality for foam-mat drying of Butterfly pea flower by multiple regression analysis

In recent years, the Butterfly pea flower has been increasingly interested in its color and function. However, the preservation of the extract faced many difficulties; therefore, foam drying technology was applied to solve this problem. The study was conducted to determine the effect of foaming conditions, including albumin ratio, carboxymethyl cellulose (CMC) ratio, and whipping time on foam characteristics. At the same time, the multi-dimensional regression method was also used to determine the most suitable foaming conditions for the following process. The research results showed that all 3 factors strongly influenced the foaming process of pea flower extract. It could be concluded that the most suitable condition for foaming is to use 9.3% albumin, 0.79% CMC and stir for 19 min. Under these conditions, the foam expansion and stability were 584.79% and 96.44% respectively. The powder obtained from the foam drying of Butterfly pea flower extract was also analyzed for quality. The temperature of 65 oC for 4 hrs gave relatively high-quality powder with protein content, anthocyanin and antioxidant activity of 9.89 g/100g, 1.15 mg/g and 87.34% respectively. In conclusion, the foam-mat dried powder from butterfly pea flower extract is suitable for other processing processes, especially in the processing of folk cakes, pasta and bread industry.

Inertial Sensor-Based Assessment of Static Balance in Athletes with Chronic Ankle Instability.

The Balance Error Scoring System (BESS), a subjective examiner-based assessment, is often employed to assess postural balance in individuals with chronic ankle instability (CAI); however, inertial sensors may enhance the detection of balance deficits. This study aimed to compare the BESS results between the CAI and healthy groups using conventional BESS scores and inertial sensor data. The BESS test (six conditions: double-leg, single-leg, and tandem stances on firm and foam surfaces, respectively) was performed for the CAI (n = 16) and healthy control (n = 16) groups with inertial sensors mounted on the sacrum and anterior shank. The BESS score was calculated visually by the examiner by counting postural sway as an error based on the recorded video. The root mean square for resultant acceleration (RMSacc) in the anteroposterior, mediolateral, and vertical directions was calculated from each inertial sensor affixed to the sacral and shank surfaces during the BESS test. The mixed-effects analysis of variance and unpaired t-test were used to assess the effects of group and condition on the BESS scores and RMSacc. No significant between-group differences were found in the RMSacc of the sacral and shank surfaces, and the BESS scores (P > 0.05), except for the total BESS score in the foam condition (CAI: 14.4 ± 3.7, control: 11.7 ± 3.4; P = 0.039). Significant main effects of the conditions were found with respect to the BESS scores and RMSacc for the sacral and anterior shank (P < 0.05). The BESS test with inertial sensors can detect differences in the BESS conditions for athletes with CAI. However, our method could not detect any differences between the CAI and healthy groups.

Experimental investigation on the influencing factors of preparing three-phase foam

A three-phase foam is considered one of the promising advanced materials for fighting fires. However, the preparation conditions, cost and effect are key factors for industrial applications. In this study, new three-phase foam systems with fly ash and a complex surfactant are proposed. Five types of surfactants alcohol polyoxyethylene ether sodium sulfate, coconut oil diethanolamine, sodium lauryl sulfate, polyacrylamide and polyether-modified silicone resin emulsion were selected as foaming agents. Through laboratory experiments, the effect on the expansion ratio and foam stability of the surfactant type/concentration, fly ash particle concentration/size and pH were investigated. The foaming condition was determined by numerical optimization. The results of this study may serve as a reference for understanding the preparation of a novel threephase foam. It is hoped that this work could provide useful guidance for the preparation of efficient three-phase fire-extinguishing foam for the safe guarding of process safety in the field of chemical production, transportation, and storage suitable for drug delivery than Al12P12 and Al12N12 based on their recovery times.

Sensory Interaction and Balancing Ability Evaluation of the Elderly Using a Simplified Force Plate System.

The Wii balance board (WBB) is a simplified force plate system used to evaluate the balancing ability of the elderly via a sensory interaction task to confirm a significant standing balance index. The accuracy of this system has been verified in previous studies. In this study, an instrumented and modified clinical test of sensory interaction on balance (i-mCTSIB) was performed on 84 elderly subjects, and the variables for center of pressure (CoP) were calculated using WBB for each task condition. The results indicate that the visual condition has a significant effect on the sway proprioceptive sensory variables with a foam condition as their complexity increases. In addition, the correlation between the variable and Berg Balance Scale was not confirmed since CTSIB is a sensory interaction on balance ability. Therefore, WBB can be used to evaluate balancing ability based on sensory interactions consisting of the surface condition.

Multidimensional evaluation of structural properties of ovalbumin at the air-water interface: Spectroscopy and molecular dynamics simulations

The structural transitions and molecular properties of the most abundant ovalbumin in eggs at the air-water (foam) interface were investigated by spectroscopic and molecular dynamics (MD) simulation techniques. The results of UV–Vis, second-derivative and CD spectra demonstrated that the alkaline environment and the air-water interface promoted the structural stretching of ovalbumin and the increase of polarity especially for tryptophan. The higher zeta potential detected in foam and high pH conditions meant that electrostatic repulsion due to negative surface charges provided the driving force for the unfolding of ovalbumin. Moreover, MD analysis illustrated that the second half of the ovalbumin structure possessed more complex interactions and that non-hydrogen bonding forces played an essential role in protein migration. Both the protein skeleton and protein-water interactions were strongly disturbed by the air-water interface. Amino acids at positions 110, 136, 168 and 318 might be critical in the structural rearrangement. This work would provide new insights into protein interface properties and provide theoretical support for the targeted regulation of egg white foam capacity and stability.

Effects of goat milk addition on physicochemical characteristics and conditioning performance of shampoo

ABSTRACT Goat milk, per se, has very interesting technological and nutritive features, and could be used in shampoo formulations and improve their properties. The aim of this study was to compare the physicochemical characteristics and conditioning performance of shampoo made with 0, 10, 20 and 30% content of goat milk. pH, surface tension, solids content, wetting time, foaming ability and foam stability, dirt dispersion, viscosity, instrumental colour, and conditioning performance were evaluated during 60 days of storage. pH ranged between 5.55 and 6.73. Goat milk addition decreased the surface tension and viscosity, as well as provided good conditioning performance, good cleaning capacity, foaming stability, wetting time, luminosity and blueish to the shampoos. The best shampoos were those that used 10–20% of goat milk, because they kept their features and did not present flocculation of milk proteins or acidification. The stability of the product with goat milk was established at one month.

Influence of pressure-induced temperature drop on the foaming behavior of amorphous polylactide (PLA) during autoclave foaming with supercritical CO2

Autoclave technology is widely used for the fabrication of cellular structures based on thermoplastic polymers. In this work, the autoclave process is investigated focusing on thermodynamic phenomena during the expansion of supercritical fluids. The depressurization with supercritical carbon dioxide (scCO2) leads to rapid adiabatic expansion, which affects pressure drop rate (PDR) and temperature inside the vessel. Analysis of density versus saturation temperature and pressure allows identification of a "valley" bounded by three limits to low densities. First two are caused by (i) low viscosity for stabilization and (ii) thermodynamically suppressed nucleation and expansion at low pressures. At high pressures and low temperatures, the expansion of the medium leads to a temperature drop (iii), which increases resistance of the polymer to stretching. Morphological examination showed significant influence of the initial pressure drop rate on the nucleation density. Size and integrity of cells can be adjusted by selective modification of foaming conditions.

Preparation and Supercritical CO2 Foaming of Modified Nanocrystalline Cellulose Reinforced Polylactic Acid Bionanocomposites

The solution casting method was used to prepare polylactic acid/modified nanocrystalline cellulose (PLA/mNCC) composites, and the effects of the mNCC content on the morphology, thermal characteristics, and rheological properties of the PLA nanocomposite were examined. The PLA microcellular foaming nanocomposite was prepared using supercritical CO2 foaming. Furthermore, the foaming conditions were optimized, and the effect of NCC surface modification, as well as the content and interfacial force of nanoparticles, on the foaming efficiency and cell pattern of composites was examined. The results suggested that a sufficient number of nanoparticles increased the nucleation site for foaming and played a vital role in heterogeneous nucleation in the foaming system. An ideal microcellular foaming material with an average cell diameter of 6.97 μm and a cell density of 6.05 × 109 cells/cm3 was prepared when the foaming temperature was 110°C, the foaming pressure was 18 MPa, the incubation period was 2 h, and the mNCC content was 6%.

Numerical simulation of polymethyl‐methacrylate supercritical fluid foaming process: Bubble growth dynamics

AbstractControl of cell structure is an important factor of fabricating polymer foam, which is related to technological design and product performance. In this article, a multibubble growth model of polymethyl‐methacrylate (PMMA) is established based on supercritical fluid foaming method and fluid simulation, aiming to analyze and predict the effects of foaming conditions (foaming temperature and foaming pressure) on the cell structures of PMMA foams. The bubble growth process is endothermic, resulting in a drop of temperature in PMMA/CO2 system, a decrease in diffusion coefficient and an increase in surface tension and viscosity, thereby preventing bubble growth. The pressure in the outer cells decreases faster than the pressure in the inner cells, causing the outer cells preferentially grow and deform, and will limit the growth of the inner cells. An empirical formula for the average cell size and foaming conditions is obtained.

Effect of foaming parameters on the physical and phytochemical properties of tomato powder

The objective of this work was to study the effect of foaming parameters on the physical and phytochemical properties of tomato powder. A central composite rotatable design of experiments was defined with two parameters (concentration of soy protein isolate [SPI]: 1–5% and whipping time: 2–14 min) with 5 levels for each parameter. The foam was prepared by whipping tomato puree after adding SPI and dried in a thin layer (4 mm ± 1) at 50 °C. The obtained results showed the predominant effect of the concentration of SPI on the physical and phytochemical properties compared to whipping time. The powder prepared under foaming conditions of 5% SPI and whipping time of 8 min showed an increase of 97, 39, 62, and 46% in the total phenolics, total flavonoids, antioxidant activity, and porosity, respectively, while the bulk density decreased by about 25%.

Effect of Foaming Conditions on Foam Properties and Drying Behavior of Powder from Magenta (Peristropheroxburghiana) Leaves Extracts

In manufacturing food powders, foam-mat drying provides a cost-effective alternative to traditional drying methods. This study aimed to select the foaming conditions which support the subsequent drying of Magenta leaves extract. In the initial stage, concentrations of egg albumin (5 to 15%) as a foaming agent, xanthan gum as foam stabilizer (0.1 to 0.5%), and whipping time (2 to 8 min) were designed. Multiple regression analysis was applied to analyze the relationship between the dependent variables (Foam expansion volume and foam density) and three independent variables as an indicator of foaming capacity and foam stability. The multiple response optimization was applied to optimize the foam density and foam expansion. The optimum foam density (0.25 g/mL) and foam expansion volume (298.12%) were obtained at the optimum egg albumin and xanthan gum concentrations, and whipping time at 12.21%, 0.24%, and 5.8 min, respectively, indicating a stable foam structure. Experimental moisture loss data are fitted for five selected drying models. The mathematical models were compared according to three statistical parameters, such as coefficient of determination (R2), chi-square (χ2), and root mean square error (RMSE). Among the five mathematical models tested with experimental data, the Page model could be applied to describe the foam-mat drying process of magenta leaves extract. The highest value of R2 (99.54%), the lowest value of χ2 (0.0007), and RMSE (0.0253) were observed for a air drying temperature of 60 °C. The effect of temperature on diffusion is described by the Arrhenius equation with an activation energy of 100.21 kJ/mol. Effective moisture diffusion values ranged from 2.27 × 10−10 to 6.71 × 10−10 m2/s as the temperature increased. The effect of drying conditions on anthocyanin changes of magenta leaves powder was compared. The results showed that the highest quality of the sample was observed when the sample was dried at 60 °C.

Foaming of PCL-Based Composites Using scCO2-Biocompatibility and Evaluation for Biomedical Applications.

The process of foaming poly(caprolactone)-based composite materials using supercritical carbon dioxide was analyzed, especially in terms of the biocompatibility of the resultant materials. The influence of foaming process conditions and composite material properties on the functional properties of polymer solid foams, intended for artificial scaffolds for bone cell culture, was investigated. The relationship between wettability (contact angle) and water absorption rate as a result of the application of variable conditions for the production of porous structures was presented. For the evaluation of potential cytotoxicity, the MTT and PrestoBlue tests were carried out, and animal cells (mouse fibroblasts) were cultured on the materials for nine days. There was no toxic effect of composite materials made of poly(caprolactone) containing porogen particles: hydroxyapatite, crystalline nanocellulose, and graphene oxide on cells. The desired effect of the porogens used in the foaming process on the affinity of cells to the resultant material was demonstrated. The tested materials have been shown to be biocompatible and suitable for applications in biomedical engineering.

Operational Performance of a Thermosiphon Reboiler under Foaming Conditions

AbstractThe evaporation of aqueous solutions with varying surfactant concentrations was investigated with regard to foam formation and performance impairment of the reboiler. Foam formation was induced by partial evaporation in the reboiler and increased with rising driving temperature difference and decreasing operating pressure. Compared to the evaporation of pure water, the addition of surfactants resulted in a reduction in circulation velocity at higher heat fluxes. Temperature profiles in the reboiler tube and area‐averaged heat transfer coefficients were determined to characterize the thermal performance. Only at the lowest surfactant concentration a slight decrease in heat transfer was observed.

Supercritical CO2 Foaming of Poly(3-hydroxybutyrate-co-4-hydroxybutyrate).

The supercritical carbon dioxide foaming characteristics of the biodegradable polymer poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) are studied for environmentally friendly packaging materials. The effect of the 4HB composition of the P(3HB-co-4HB) copolymers on the foaming conditions such as pressure and temperature is studied and the density and the expansion ratio of the resulting P(3HB-co-4HB) foam are together evaluated. The increase in the 4HB content reduces the crystallinity and tan δ value of P(3HB-co-4HB) required for the growth of the foam cells. Therefore, the foaming temperature needs to be lower to retain a suitable tan δ value of P(3HB-co-4HB) for foaming. It was found that P(3HB-co-4HB) with less crystallinity showed better formability and cell uniformity. However, foaming is not possible regardless of the foaming temperature when the 4HB content of P(3HB-co-4HB) is over 50%, due to the high tan δ value. A lower foam density and higher expansion ratio can be obtained with crystalline P(3HB-co-4HB) of low 4HB content, compared with non-crystalline P(3HB-co-4HB) of high 4HB content. The expansion ratio of P(3HB-co-4HB) foams can be increased slightly by using a chain extender, due to the lowing of crystallinity and tan δ. This is most effective in the case of P(3HB-co-4HB), whose 4HB content is 16%.

Porosity manipulation to boost piezoelectric output via supercritical carbon dioxide foaming and surface modification

Flexible piezoelectric devices for energy harvesting have long been attractive in the field of collecting distributed mechanical sources. However, the piezoelectric performance of the state-of-art piezoelectric devices were still limited by poor strain accumulation effect of traditional film or fiber based piezoelectric energy harvesters. Herein, flexible poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF)/barium titanate (BT) three-dimensional (3D) porous composite foam with perfected interface and controlled porosity was prepared via supercritical carbon dioxide (scCO2) foaming technology and surface modification. By manipulating foaming conditions, PVDF foams with uniform cellular structures were successfully obtained. The further introduction of surface coating of polydopamine (PDA) onto BT optimized distribution of BT and foaming behaviors of the composites, and thus by synergetic effect of BT and modulated 3D porous structure, the piezoelectric output was finally improved to ∼12.5 V and ∼150 nA with a peak output power density of ∼0.15 μW/cm2, which was ∼25 times of that of flat-film. Taking advantages of the comprehensive electromechanical performance, the integrated piezoelectric devices can be applied to collect micro sources from use of keyboard and power micro-electronics. Our work provides a simple microstructure design strategy for modulating the porosity to boost the piezoelectric output.

A novel drift eliminator enhanced by Voronoi-based porous foam applied to liquid desiccant system: Separation performance and preliminary design

A novel drift eliminator enhanced by Voronoi-based porous foam (VPF-enhanced drift eliminator) is proposed for the control of salt-spray aerosol in liquid desiccant systems. The gas-liquid flow characteristics though VPF-enhanced drift eliminator under different conditions are examined numerically and verified by the experimental results in the literature. Additionally, a new prediction model of separation efficiency is obtained based on response surface methodology. The results show that 3-D modeling of porous foam based on Voronoi technology can well characterize the structure properties of actual porous foam in terms of meso-scale (i.e. pore shape, strut orientation and cell topology) and macro-scale (i.e. strut diameter and porosity), which provides support for more accurate analysis of separation performance from the microscopic aspect of droplet. Separation performance exhibits a strong dependence on the structure properties of porous foam and operating conditions. Moreover, the interaction of thickness and porosity has a significant impact on separation efficiency. For porous foams with relatively low resistance (i.e. smaller thickness and higher porosity), separation efficiency can be simply quantified by the specific surface area of the porous foam. For relatively high resistance, it is jointly determined by the specific surface area and resistance. It is concluded that prediction model combined with multi-objective optimization can provide guidance for the structural design and selection of VPF-enhanced drift eliminator. Meanwhile, Voronoi-based porous foam can be conveniently processed by the additive manufacturing techniques, which provides engineering significance for the development of VPF-enhanced drift eliminator under specific needs.

High‐strength and antistatic PET/CNTs bead foams prepared by scCO2 foaming and microwave sintering

AbstractThis paper reported the high strength and antistatic polyethylene terephthalate (PET) bead foam with a typical segregated structure prepared by supercritical carbon dioxide (scCO2) foaming and microwave selective sintering. Firstly, carbon nanotubes (CNTs) were coated on the surface of PET pellets, and then the composite foam with segregated structure was prepared via scCO2 foaming in a confined mold. The interfaces among PET foamed beads were further sintered by utilizing the selective heating behaviors of microwave, which greatly enhanced the interfacial strength and thus the overall mechanical strength of bead foam. The final composite foam showed an electrical conductivity of 0.004 S/m with an extremely low CNTs loading of 0.138 vol%, and its mechanical strength reached as high as 10.44 MPa, far superior to the composite without microwave treatment. Thus, the problem in the welding of PET bead foams and antistatic properties could be solved. The effect of the foaming conditions on the structure and properties of PET foam were systematically investigated, providing a novel method for the preparation of high strength and antistatic engineering plastics composite foam.

Foaming characteristics and impact of ethanol pretreatment in drying behavior and physical characteristics for avocado pulp powder obtained by foam mat drying.

The objective of this study was to optimize the production of powdered avocado using foam mat drying. In order to achieve this, the effect of Emustab® (4, 6, and 8% w/w), goat's milk (10, 15, and 20% w/w), and whipping time (15, 20, and 25min) on the foam physical properties of avocado pulp were evaluated. In addition, the influence of ethanol pretreatment on the drying kinetics, thermodynamic properties, and physicochemical characteristics of the powders was also assessed. An experimental design 23 with three central points was used in this study and optimized foam conditions were dried at 50, 60, and 70°C, with a fixed air speed of 1.5m/s. Empirical and diffusive models (boundary conditions of the third type) were adjusted to the experimental data to describe the drying kinetics and to determine the process activation energy and thermodynamic properties. The final products were characterized regarding their physical properties. Optimized foam mat drying conditions were achieved when avocado pulp was whipped for 15 min and 8% of Emustab® and 20% of powdered goat milk were used as foaming agents. The use of an ethanol pretreatment and higher drying temperature (70°C) resulted in higher drying rate (1.6×102 /min) and shorter processing time (270min). The ethanol pretreatment reduced the activation energy and Biot number and led to more uniform moisture distribution. The physical properties, such as water content, water activity, bulk, and tapped densities decreased with an increase in drying temperature and pretreatment with ethanol, whereas water absorption capacity increased. PRACTICAL APPLICATION: In this work, new information about the drying kinetics and mass transfer of the foam mat avocado pulp using ethanol as pretreatment is obtained. The results will contribute to the optimization production avocado foaming and powder. Ethanol pretreatment can represent an alternative to minimize the negative impacts on drying process and can be surely suggested as an industrial application.

Achieving low‐thermal conductivity and high β phase in PVDF/PMMA blend foams via low‐pressure microcellular foaming

AbstractPolyvinylidene fluoride (PVDF) foam exhibits wider applications than traditional foams such as polyethylene and polystyrene foams due to its good corrosion resistance, flame retardant and wide operating temperature range. However, PVDF is difficult to foam and rigorous operating conditions including high pressure and high temperature were unavoidably adopted to prepare PVDF foams. Herein, microcellular PVDF foam was successfully fabricated with the combination of adding polymethylmethacrylate (PMMA) and batch foaming at mild processing condition. Compared to the pure PVDF foam with a low‐expansion‐ratio of 1.1 times, the PVDF/PMMA (70/30) blend foam showed an expansion ratio as high as 20 times together with a small cell size of approximately 5 μm. Additionally, the prepared PVDF/PMMA blend foam exhibited a low‐thermal conductivity (0.039 w m−1 k−1) and high content of β‐phase crystal (95%), which shows promising application in areas like electronic devices, thermal insulation and packaging materials.

Developing the Positional Characteristics of a Dance-Specific Star Excursion Balance Test (dsSEBT).

Current dynamic balance tests do not sufficiently test all aspects of balance required for dancers in everyday training and performances. The aim of this study was to examine alterations to the Star Excursion Balance Test (SEBT) to ensure a more dance-specific protocol. Twenty-four healthy ballet and contemporary dancers (age: 22.21 ± 6.47 years) participated in completing five different variations of the SEBT. This research implemented upper-body restrictions commonly used in dance settings and tested the effects of two different foot positions, parallel and turned out, as well as two alternate balance surfaces, a foam balance pad and a firm yoga block. Reach distances (percent of limb length), center of pressure (COP, cm²), error scores, and time to completion were measured. Overall, the dance-specific upper body restrictions did not affect the dancer's ability to reach maximally and achieve a successful trial as there were no significant differences between the original SEBT and the dance-specific SEBT parallel condition (p = 1.00). The foam and block conditions were found to be significantly more difficult due to lower reach distance values, higher COP values, and higher error score values when compared to the original, parallel, and turnout positions (p < 0.05). Lastly, it was discovered that 62.61% of all errors made were in the crossed side and crossed front spokes, suggesting these are the most difficult reach directions to accomplish. The variations used in the study will aid in developing a reliable dance-specific dynamic balance test.