Endset Temperature Research Articles

ZnO-NaNO3 nanocomposites for solar thermal energy storage systems

High-temperature phase change materials (PCMs) with good energy storage density and thermal conductivity are needed to utilize solar thermal energy effectively to meet industrial thermal energy demands. Composite PCMs containing a material of higher thermal conductivity and an inorganic high-temperature PCM can be explored to meet these requirements. Accordingly, a high-temperature, composite inorganic PCM (ZnO-NaNO3) with enhanced thermophysical properties was prepared, and its energy storage potential was investigated experimentally. A maximum thermal conductivity enhancement of 22.7% was achieved at 200 °C for 2 wt% ZnO-NaNO3 nanocomposite. The increase in thermal conductivity at higher temperatures may be attributed to the formation of ordered sodium nitrate layers on the nanoparticle surfaces. The increase in surface area and surface energy due to the addition of ZnO nanoparticles increased the specific heat of the nanocomposite in both the solid and liquid phases (43.5% in the liquid phase for 2 wt% ZnO-NaNO3). Thus, the addition of ZnO nanoparticles to NaNO3 increased its energy storage capacity. The addition of ZnO nanoparticles to NaNO3 did not affect the onset, peak or endset temperature during melting and freezing. Moreover, 2 wt% ZnO-NaNO3 exhibited cyclic stability even after 500 cycles and thus has potential as an energy storage medium.

Influence of drought stress and growth temperature during kernel development on physical and chemical starch characteristics of malting barley

AbstractBackground and ObjectivesStarch is the main component of malting barley (Hordeum vulgare L.), and its physical and chemical characteristics are particularly important in further processing in the beverage industry. This study investigates how the parameters (i) growing temperature (high/low) and (ii) water deficit (drought stress) during grain filling affect starch characteristics by cultivating nine different commonly used malting barley varieties in greenhouses under defined conditions. Particle size distribution of the starch granules, their phase transition characteristics (DSC), the pasting temperature (RVA), and the amylose/amylopectin (AM/AP) ratio were examined to assess starch characteristics.FindingsTwo‐way ANOVA analyses revealed that drought stress during the grain‐filling phase resulted in significantly smaller starch granules, lower onset, peak, and endset temperatures (DSC), and increased pasting temperature (PT) while not affecting the AM/AP ratio. High growth temperature during grain filling resulted in significantly higher onset, peak, and endset temperatures (DSC), lower phase transition enthalpies, significantly higher PTs, and lower AM/AP ratios.ConclusionsGrowth temperature during kernel development affected starch phase transition characteristics the most, while water availability was significantly associated with starch granule sizes.Significance and NoveltyClimate change is increasing the events and severity of heat and drought in Europe. Agricultural practices and modern barley varieties must be adapted to these requirements to maintain processability for food production.

Physicochemical Properties of Wild Yam (Dioscorea villosa) Starch.

Native starch extracted from wild yam (Dioscorea villosa) was evaluated for its intrinsic physicochemical properties. From the results, essential metals such as K, Ca, P, and Fe were detected along with some nonessential heavy metals below the WHO permissible limits. Bulk density was 0.13-0.63 g/mL. The water absorption capacity, oil absorption capacity, swelling power, and solubility of the starch were pH-responsive. Thermal profiles showed onset temperature, To (59.21 °C), peak temperature, Tp (60.22 °C), endset temperature, Tc (63.12 °C), gelatinization enthalpy, ΔHgel (0.54 J/g), temperature range of gelatinization, R (3.91 °C), and peak height index, PHI (1.87 J/g °C). Exhibiting a crystallite size of 0.03 nm, absorption peaks of 15.3119°, 24.4120°, and 18.4170°, corresponding to interplanar d-spacings of 3.7500 Ǻ, 5.14000 Ǻ, and 4.954610 Ǻ, were obtained. Evidence of C-H at 1338.1 cm-1, C-O at 640.0 cm-1, C-H stretch at 2829.7 cm-1, and a strong and broad O-H group at 3291.2 cm-1 were obtained. The starch granules had low particle sizes, were homogeneous, and were aggregates of irregular shapes. At a lower pH (2-4), the wild yam starch studied could be a potential absorbent material in the production of disposable diapers and female napkins and as biodegradable films due to its high hydrophobicity at a high pH (8-12).

Physico‐mechanical, and thermal properties of sisal/hemp/Kevlar fibers, fly ash and Titanium Carbide nanoparticles reinforced bioepoxy composites

AbstractIn the present investigation, the chemically treated and untreated sisal/hemp fibers, fly ash or titanium carbide (TiC) nanofillers, and Kevlar fabrics reinforced bio epoxy (Sr 56) polymer matrix were manufactured using the wet layup method. Experimentation was performed to study the physical, mechanical and thermal properties. This investigation also includes determining the influence of accelerated weathering on the specimen surface for 5 months. The tensile fracture of the sample before and after the accelerated weathering from scanning electron microscope (SEM) pictures exhibited that the extensive failure principles in the laminates in terms of matrix cracking, fiber breakage, delamination, and fiber pull out. The thermal analysis examined the onset, endset temperature, transition loss, and carbon residue which were also reduced after the accelerated weathering. It exhibits that adding fly ash or TiC nanoparticles as an altered inhibitor against the weathering in the bio epoxy hybrid composite scheme can reduce the undesirable impacts from moisture and Ultra‐violet light exposure.Highlights Sisal/hemp fibers were chemically treated to reduce hydrophilicity. Contact angle of KSCHCTBE56 improved to 84.04°. SEM confirmed uniform dispersion of fillers and enhance mechanical strength. Mechanical and thermal characteristics reduced after accelerated weathering.

Dynamic Rheological, Thermal, and Structural Properties of Starch from Modified Cassava Flour (MOCAF) with Two Cultivars of Cassava

The objectives of this study were to investigate alteration in the starch properties of modified cassava flour from two different local cassava cultivars from Indonesia at different fermentation times, provide structural information for starch molecules, and characterize the dynamic rheological and thermal properties. Resistant starch, non-resistant starch, and total starch levels in the cassava cultivars were also evaluated. Changes in the starch properties of Cimanggu and Kaspro (local cultivars of cassavas from Indonesia) were compared following different fermentation times (0, 12, and 24 hours). The properties of starch from modified cassava flour were influenced by the fermentation time, although both cassava varieties showed the same general characteristics. Their levels of resistant starch, non-resistant starch, and total starch were 33.28% to 51.74%, 20.51% to 23.72%, and 53.81% to 72.25% (g/100 g dry sample), respectively. The starch granules for the non-fermented samples were oval, polygonal, and round shapes; however, during fermentation, the starch granules became more porous and developed cracks of various sizes. The starches of both varieties showed an onset temperature between 67.85 and 70.17 °C, a peak temperature of 69.33 °C to 71.62 °C, and an end set temperature of 68.62 °C to 70.95 °C, with enthalpy values ranging from 1.25 mJ/mg to 1.74 mJ/mg.

Evaluation of volatile and thermal properties of boza, a traditional fermented beverage

Although boza is widely preferred and consumed, there is no detailed study on volatile and thermal characteristics. A liquid–liquidextraction (LLE) method has been proposed for the volatile extraction of boza using GC-MS. DB-Wax column from 50 °C to 250 °C at a rate of 4 °C/min with a final hold at 250 °C for 10 min. A helium gas was selected as a carrier gas with a 3.2 ml/min linear velocity. The retention time of the internal standard (4-nonanol) used in our study, was detected in the middle of the chromatogram, and the peak response was relatively stable. The odor activity values (OAVs) were utilized to elucidate the aroma and key odorant substances. Based on OAVs, the most important aroma compounds identified in boza were hexanoic acid [25.1, cheesy goat], 4-vinyl phenol [12.1, phenolic/burnt], acetoin [9.1, buttery/creamy], acetic acid [6.7, vinegary/irritant] and octan-2-ol [3.5, coconut]. The high-performance liquid chromatography (HPLC) system was used to determine the organic acids in boza. The quality parameters of the method were established in terms of the linearity of the calibration, the limit of quantification, the limit of detection, and recovery experiments. The proposed method showed a good recovery from 79.47 to 109.96%. The proposed method was found to be specific as no interference peaks were observed for blank samples. Regarding thermal properties, onset temperature (To), peak temperature (Tp), and end set temperature (Te) increase with the heating rate. In contrast, with increasing temperature, there was a slight decrease in the endothermic peak width (EPW) and peak height index (PHI) values. The level of alcohol was 0.06% below the criteria of the Turkish Boza Standard (TSE 9778).

A novel numerical approach for measuring phase change temperature range of Phase Change Material in real building conditions

Phase change materials (PCMs) integrated into the building envelope offer a significant interest in regulating indoor temperatures. They allow them to approach, reach or maintain thermal comfort conditions for the occupants. The efficiency of the PCM depends on its intrinsic parameters, such as latent heat or phase change times. These parameters are usually obtained from expensive differential scanning calorimetry (DSC) or Heat Flux Meter Apparatus (HFMA) measurements. This paper proposes an innovative numerical method to provide the same information from simple measurements of temperature and heat flux at their surface. The Latent Heat Detection Method (LHDM) allows the detection of the duration of the transition zones and calculates the latent heat of the phase change. The LHDM method is applied to the annual data of a full-scale platform, and a PCM performance indicator is proposed. Comparing the DSC results allows concluding of the accuracy of the proposed method. The maximum associated relative errors remained below 6%, with an average relative error close to 2.5% for the onset temperatures and 1.61% for the endset temperatures. These results offer promising prospects for increasing the accessibility of experimental PCM research.

Effects of Plasma Treatment on Chemical and Physical Properties of Pigmented Rice Flour

Abstract The objective of this research was to study the effects of plasma treatment at different power levels (100, 120, and 140 W) and exposure times (5, 10, and 15 min) on the physical and chemical properties of pigmented rice flours from Kum Doi Saket cultivar. An increase in plasma power and exposure time resulted in decreases of moisture contents, solubility, and swelling power of the rice flour, while the resistant starch content was increased. The amylose content tended to decrease when plasma power and exposure time was increased. In this study, plasma treatment at 140 W for 10 min maintained the highest anthocyanin content in Kum Doi Saket rice flour (68.35 – 98.63 mg/100 g). Pasting property analysis by RVA revealed decreases in peak viscosity, breakdown and setback viscosities. The pasting temperature of Kum Doi Saket rice flour was significantly decreased (P ≤0.05) after plasma treatment. Plasma treatment did not affect the onset temperature (To) and ΔH of starch gelatinization as analyzed by a DSC, while peak temperature (Tp) and end set temperature (Te) of flour sample were increased (P ≤0.05). Plasma effects on size, shape and surface roughness of flours were observed by SEM. Higher plasma power and treatment time caused more micro-pores on the surface of flour particles, especially after being treated at 140 W for 15 min. Keywords: Pigmented rice flour, Cold plasma technology, Flour properties, Cross-linking

Enhancement of thermal properties of Kevlar 29 coated by SiC and TiO2 nanoparticles and their binding energy analysis

In the fields of military research, aerospace, and vehicle technology, the thermal stability of Kevlar fiber is critical for improving its flame resistance. In this work, the pad mangle machine was used to improve the thermal properties of Kevlar 29 in order to expand the range of applications for thermal aspects. Silicon carbide and titanium oxide nanoparticles provide thermal stability on the fiber surface through intermolecular adhesion. Here, 5 wt% and 10 wt% of nanoparticles with various mass ratios (1:1) have been chosen. Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) analysis, and X-ray Photoelectron Spectroscopy (XPS) analysis have all been used to measure different thermal properties. The surface morphology of samples is represented by FESEM analysis, while the active organic groups are represented by FTIR analysis. The greater crystallization of epoxy and nanoparticles is linked to post-heat treatment of the material. The glass transition temperature of the coated samples shifted maximum from 559.13 °C to 580.51 °C, the end set temperature increased by 30.67 °C compared to the uncoated sample, and the residual weight changed from 29.77 percent to 4.06 percent, according to the findings (i.e., lightweight). When compared to the uncoated sample, the coated sample's enthalpy increased significantly (i.e., the samples can absorb more heat). The smaller the positive binding energy, the higher the activation energy, and hence the slower the chemical reaction, which is especially important in high-temperature applications. Finally, this research reveals a 4.5–5.2 percent increase in thermal characteristics.

Injection molded discontinuous and continuous rattan fiber reinforced polypropylene composite: Development, experimental and analytical investigations

Because of the superabundant accessibility and availability of natural fiber, the research field of natural fiber-reinforced composites is becoming an emerging interest in sustainable technology. In this present study, injection molded rattan fiber inreinforced polypropylene composites were prepared, where maleic anhydride grafted polypropylene (MAPP) was used as compatibilizer. The extreme amount of lignin percentage in rattan fiber was the primary motive for fabricating the rattan-based polypropylene composite with MAPP compatibilizer. Three different fiber volume percentages (10, 20 and 30%) were considered for preparing the composites. The mechanical characterizations, such as tensile behavior, flexural behavior, impact strength, hardness, and thermal characterization, such as thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were investigated. Several thermal properties, such as onset temperature, endset temperature, melting temperature, heat capacity, melting enthalpy, decomposition behavior of these composites were observed from these TGA and DSC curves. As well, the wet absorption characteristics of the composites were examined to investigate hydrophilic behavior. Furthermore, continuous rattan fiber reinforced polypropylene composites with indistinguishable fiber volume percentages and compatibilizer were prepared by partial injection molding technique for comparing the mechanical and wet absorption behaviors and validating elastic modulus by the analytical findings. The tensile strength, flexural strength and impact toughness of discontinuous fiber composites were enhanced up to 23, 25, 153% respectively within the fiber content. The improvement of mechanical properties was higher when polypropylene was reinforced by continuous rattan fiber. Nevertheless, the continuous fiber composites were more hydrophilic than discontinuous fiber composites.

Processing of carbon-polymer porous composite from expanded graphite addition on poly(furfuryl alcohol)

The addition of expanded graphite (EG) on environmentally friendly polymer matrix was systematically studied to produce carbon-polymer porous composite. Firstly, an appropriate EG was produced by monitoring the time and temperature of intercalated graphite thermal expansion while poly(furfuryl alcohol) (PFA) resin was obtained from the furfuryl alcohol polymerization. After PFA synthesis, different EG amounts of 0.2, 0.5, and 1.0 wt% were added in the resin and evaluated by viscosimetry and differential scanning calorimetry that showed EG helped in the crosslink formations decreasing the onset and endset temperatures. PFA resin kept a good fluidity, even for 1.0 wt% EG ensuring its homogeneous impregnation on the polyurethane foams. FTIR analyses confirmed the presence of functional groups on EG, which would contribute to the resin impregnation on the foam porous structure without changing the thermal resistance of the final product.

Effect of TiC nanoparticles on accelerated weathering of coir fiber filler and basalt fabric reinforced bio/synthetic epoxy hybrid composites: Physicomechanical and thermal characteristics

AbstractIn the present research, the physical, mechanical, and thermal characteristics of bio and synthetic basalt fabric epoxy composites reinforced with coir microparticles and TiC nanofillers under before and after exposure of accelerated weathering were investigated. All the bio and synthetic epoxy hybrid composites were exposed to humidity, elevated temperature, and ultraviolet radiation. It has been examined that both bio and synthetic epoxy composites exhibited reduced mechanical characteristics after the exposure of accelerated weathering when compared with before exposure. The wettability experiment was performed from the contact angle evaluation method and found that all the fabricated samples before and after the exposure of accelerated weathering have contact angle value lower than 90° that is assigned with the hydrophilic surface characteristics of the laminate. The water absorption capacity showed that all the bio and synthetic epoxy composites reacted for water absorption up to 45 days and then endured constant in both conditions. After the exposure of accelerated weathering, epoxy hybrid composites absorbed more water than before exposure. The chemical modifications possessed on the surface were evaluated from Fourier transform infrared spectra. The intensity of hydroxyl and carbonyl functional groups of bio and synthetic epoxy hybrid composites decreased compared with the original samples, which tends to decrement in tensile, flexural, and impact characteristics of the laminate. The production of more fracture lines on the cross‐sectional surface of epoxy hybrid composites has been observed from scanning electron microscope micrographs after the exposure of accelerated weathering. The onset, end set, and glass transition temperature of bio and synthetic epoxy composites in the thermal examination were reduced after the disclosure of accelerated weathering for all fabricated specimens. The reason may be assigned to the weaker bonding between the coir microparticles and TiC nanofillers. The undesirable impact emerged from ultraviolet radiation, elevating the temperature and humidity. The test results showed that the accelerated weathering has negative impact on physicomechanical characteristics of bio/synthetic epoxy hybrid polymer composites. The overall thermal characteristics were not considerably affected with 570 h of the weathering exposure.

Thermal Effect and Mechanism Analysis of Flame-Retardant Modified Polymer Electrolyte for Lithium-Ion Battery.

In recent years, the prosperous electric vehicle industry has contributed to the rapid development of lithium-ion batteries. However, the increase in the energy density of lithium-ion batteries has also created more pressing safety concerns. The emergence of a new flame-retardant material with the additive ethoxy (pentafluoro) cyclotriphosphazene can ameliorate the performance of lithium-ion batteries while ensuring their safety. The present study proposes a new polymer composite flame-retardant electrolyte and adopts differential scanning calorimetry (DSC) and accelerating rate calorimetry to investigate its thermal effect. The study found that the heating rate is positively correlated with the onset temperature, peak temperature, and endset temperature of the endothermic peak. The flame-retardant modified polymer electrolyte for new lithium-ion batteries has better thermal stability than traditional lithium-ion battery electrolytes. Three non-isothermal methods (Kissinger; Kissinger–Akahira–Sunose; and Flynn–Wall–Ozawa) were also used to calculate the kinetic parameters based on the DSC experimental data. The apparent activation energy results of the three non-isothermal methods were averaged as 54.16 kJ/mol. The research results can provide valuable references for the selection and preparation of flame-retardant additives in lithium-ion batteries.

Potential of Gum Arabic Functionalized Iron Hydroxide Nanoparticles Embedded Cellulose Paper for Packaging of Paneer

Recently, the interest of scientists has turned towards eco-friendly metal nanoparticles due to their distinctive physicochemical properties that have been used in several biochemical and food applications, including drug and bioactive component delivery, sensing of food pathogenic bacteria, imaging techniques, and theranostics. Therefore, this study aimed to fabricate gum arabic stabilized iron hydroxide nanoparticles (IHNPs) using the co-precipitation process and to develop nanoparticles decorated antimicrobial cellulose paper. The agglomeration of IHNPs is a major concern, therefore, the varied concentration (0.25–2.0%) of gum arabic was used to functionalize and stabilize the nanoparticles, and based on UV-visible spectroscopy and particle size analysis, 1% gum arabic concentration was screened out. Scanning electron microscopy displayed polygonal disc shapes of IHNPs that had sides of approximately equal lengths. Energy dispersive spectroscopy was used to determine the purity of the IHNPs and results illustrated the elemental iron peak at 0.8 keV and 6.34 keV. For thermal stability, differential scanning calorimetry (DSC) was employed, and the glass transition temperature was observed at 138.50 °C with 138.31 °C onset and 147.14 °C endset temperature, respectively. Functionalized IHNPs showed a significantly (p < 0.05) higher zone of inhibition against S. aureus (29.63 mm) than that of E. coli and were found to be non-toxic to Caco-2 cells during cell viability assay. Time-kill kinetics showed that cellulose paper embedded with nanoparticles possessed excellent antibacterial activity against S. aureus. To explore the food application of developed cellulose paper, citric acid coagulated dairy product (Paneer), similar to cottage cheese was formulated, and it was evaluated for its microbial shelf life. The unwrapped sample showed higher microbial load during the fourth day of the storage. However, both wrapped samples were acceptable till the 10th of storage.

PRODUCTION OF BIOETHANOL FROM RICE AND MILLET HUSKS

This study was based on the production of bioethanol as an alternative source of fuel using rice and millet husks. Proximate, elemental and thermogravimetric analysis (TGA) were conducted of the biomass. The proximate analysis revealed that millet husk had the highest moisture content of 26.67±0.58% when compared with rice husk 8.17±0.29%. The TGA of rice husk had a high endset temperature of 355.510C and a weight loss of -48.23%, millet husk had low endset temperature of 349.210C and a weight loss of -44.25%. When thirty grams (30g) of the substrates was used, rice husk revealed the highest reducing sugar content of 2.59±1.24mol/dm3 when compared to millet husk that had 1.63±0.68 mol/dm3. Rice husk indicated low yield after 7 days of fermentation period but showed a significantly high yield in the volume of ethanol produced 68.67±17.69g/l and millet husk had a yield of 79.80±0.93g/l. This indicated that both rice and millet husks were potent for bioethanol production with millet husk having the highest yield.

Antioxidant, Nutritional, Structural, Thermal and Physico-Chemical Properties of Psyllium (Plantago Ovata) Seeds

The present investigation was carried out to characterize four different types of psyllium seeds including one landrace for their nutritional, structural, antioxidant profile and biological active compounds. DSC analysis showed the highest peak temperature (TP) of 107.57 ºC in RI-89 and end set temperature (TE) of 130.2 ºC for HI-5 cultivar. FT-IR analysis displayed strong absorption bands at frequencies 960, 1380, 1740, 2280 and 3280cm-1. SEM micrographs of each cultivar showed compact and irregular mass of fiber at various magnifications. Protein, fat, ash and total carbohydrate content of psyllium seed flour were recorded up to 13.33, 0.38, 5.0 and 77.88 %, respectively. Ethanol was found to be a suitable solvent than methanol to extract the phytonutrients from psyllium seed flour. DPPH free radical scavenging activity (FRSA) of methanolic and ethanolic extract varied between 31 to 39 % and 38.9 to 43 %, respectively. However, ABTS-FRSA varied between 31.7 to 32.9 % and 33.2 to 34.3 %, for methanolic and ethanolic extract, respectively. Total flavonoids and total phenolic content was recorded up to 2.92 mg RE/g and 4.37 mg GAE/g, in ethanolic extract. The reducing power (RP) and Metal chelating activity (MCA) also varied significantly (p≤0.05) among the cultivars. The MCA ranged from 33.20 to 34.81 % in methanolic extracts and 34.62 to 36.07 % in ethanolic extracts. The lowest absorbance for reducing power was found in methanolic extract of landrace (0.16), whereas, the highest was found in ethanolic extract of RI-89 (0.37). Physico-chemical properties including oil and water absorption capacity of both seed and flour did not vary significantly among the cultivars, whereas significant difference was observed in seed hydration capacity among cultivars evaluated. Among the physical properties, L/W ratio ranged from 1.80 to 199, whereas porosity and angle of repose were of 59.2 to 67.7 % and 23.20 to 27.02º, respectively. Static coefficient of friction was found less using steel (0.484 to 0.667) as a test surface compared to wood (0.679 to 0.744) and plastic (0.536 to 0.560). Bulk density, true density and porosity of various psyllium seed cultivars varied between 0.57 to 0.63 g/cm3 and 1.50 to 1.77 g/cm3 and 58.2 to 67.7%, respectively. Geometric mean diameter (Dg), Arithmetic mean diameter (Da) and surface area of seeds (A) varied from 1.49 to 1.60 mm and 1.68 to 1.79 mm and 5.91 to 6.78 mm2, respectively.

Relationship between the Surface Morphology of Thin YBa2Cu3O7 – x Films Obtained by Pulsed Laser Deposition and the Endset Temperature of Superconducting Transition

A correlation was found between the endset temperature of the superconducting transition T(R = 0) of YBa2Cu3O7 – x films 100–200 nm thick, obtained by pulsed laser deposition on SrTiO3(100) substrates with a temperature of ~740°C, and the regimes of high-speed filtering of the erosion plume formed upon ablation of the material the target. Under deposition conditions, we changed the width of the filtering window, the repetition rate of the atomized material passing through the filter onto the substrate, and the radiation energy density of the KrF excimer laser on the target surface. At deposition rates of less than 0.1 nm s–1, the values of T(R = 0) did not exceed 77 K, and pyramids were formed on the surface of the films up to 80 nm in height along the c axis in the form of spirals with rectangular bases and steps of 1–2 nm along the lateral faces. With an increase in the deposition rate from 0.1 to 0.6 nm s–1, T(R = 0) increased to 86 K. These regimes corresponded to a wavy pyramid surface up to 40 nm in height with rounded bases up to 1500 nm in diameter and irregular steps 1–4 nm on the side slopes. Faceted crystals with a width from 20–30 to 500 nm in the base grew along the boundaries between the pyramids during the deposition. This morphology of the growth surface was explained by the high flow rate of the sputtered material, which is determined by the frequency filtering of the erosion plume and the energy density in the pulse upon predominantly surface diffusion.

Degradation study of polyester fiber in swimming pool water

The disinfection of swimming pool water is vital to maintain water quality. The chemicals used in this practice can damage the fabrics of bathing suits and shorten the shelf life of the textile substrate. The degradation of polyester, a polymer that is widely used in bathing suits for swimming pools, was investigated. For this, a 23 factorial design was employed for the experimental methodology. The effect of several variables was analyzed in a simulated swimming pool batch, such as textile-exposure time, concentration of the used disinfection product, and batch temperature. The response variables were enthalpy of fusion ΔHm, melting temperature and crystallinity (obtained by differential scanning calorimetry), percentage of weight loss, temperature of maximum rate of weight loss, onset temperature and endset temperature (measured through thermogravimetric analysis), and Young's modulus values (measured in strain-stress tests in the row and column directions). The factors of temperature, time, and the concentration of disinfectant were significant for melting temperature, crystallinity, onset temperature, and Young's modulus for columns. The analyses of variance were obtained using software Design-Expert DX7. Attenuated total reflectance-Fourier transform infrared spectroscopy analysis showed changes in band intensities at 695 cm−1, which were attributed to ester groups, as well as a decrease of the carbonyl band at 1712 cm−1, which was attributed to the hydrolysis of the material. Analysis through scanning electronic microscopy images showed the appearance of stretch marks in the constituent filaments of the tested textiles, which suggests a surface degradation occurred.

Phase equilibrium for methane, ethane and carbon dioxide hydrates at pressures up to 100 MPa through high-pressure microcalorimetry: Experimental data, analysis and modeling

New experimental dissociation data for CH4, C2H6, and CO2 hydrates obtained by high-pressure microcalorimetry (HP-μDSC) up to 100 MPa are presented. Deviations of onset, peak, and endset temperatures from predictions and their representativeness as equilibrium values are evaluated. For these systems, the onset temperatures provided good reproducibility and more accurate results than peak and endset temperatures, when compared to literature data. Predictions from CSMGem and Multiflash software packages are compared to the experimental results. Dynamic effects on gas hydrates formation are also evaluated by varying the water-sample size and the cooling-heating rate. Enthalpies of dissociation are determined by applying the Clapeyron equation, and new approaches are applied for the calculation of the hydrate volume and the hydration number estimation. The enthalpy of dissociation at conditions above the upper quadruple point is obtained for ethane and carbon dioxide hydrates for the first time.

Effect of gamma-irradiation on the thermal, rheological and antioxidant properties of three wheat cultivars grown in temperate Indian climate

Health consciousness of consumers has shifted the trend from consumption of refined wheat flour to whole wheat flour. The aim of the present study was to evaluate the effect of gamma irradiation on thermal, rheological and antioxidant properties of whole wheat flours obtained from three cultivars namely, SW-1, SKW-355 & HS-240. The thermal and rheological properties were determined using Differential scanning calorimetry (DSC) and dynamic rheometry, respectively. Onset, peak and endset temperatures of the three wheat cultivars were found in the range of 35.36–45.86 °C, 67.59–86.98 °C and 82.64–112.8 °C, respectively. The rheological study revealed the dominance of storage modulus (G′) over loss modulus (G″) throughout the applied frequency sweep (0-100 s-1). Irradiation treatment of 0–5 kGy resulted in the decrease in thermal properties and in the dynamic moduli of all the flours. Antioxidant properties were significantly (p < 0.05) increased upon irradiation.