Linear low-density polyethylene (LLDPE) is one of the most commercially successful packaging materials; however, to be used for active packaging purpose functionality must be crafted. In this work, ...LLDPE surface was chemically modified by chromic acid (CA) treatment and coated with clove essential oil (CLO); afterwards, the films were tested for antimicrobial properties. The optical, mechanical, barrier, thermal, and morphological properties of the films were characterized. FTIR spectroscopy confirmed the infusion of CLO in the film, and coating of CLO influenced the yellow color value of the films. The tensile stress and elongation at break of acid-treated and CLO coated films differed significantly from the control sample. CLO coating improved the UV-barrier property of LLDPE film. The melting point, Tm of the composite films dropped significantly from 122 to 117 °C when CLO was coated on the etched film surfaces. The morphology of the LLDPE/CA films exhibited pitting and roughness of the surface. LLDPE/CA/CLO films exhibited strong antimicrobial activity against Salmonella Typhimurium and Listeria monocytogenes in a packed chicken sample for 21 days of refrigerated storage. Thus, the developed film could be used as active packaging for fresh chicken.
•Antimicrobial film was prepared by clove oil infusion on surface treated LLDPE.•Clove oil coating improved the UV-barrier property of LLDPE film.•The melting temperature of blended film was significantly dropped.•SEM micrographs revealed pitting and roughness of the treated film surface.
Dynamic evolution of CaO solidification at 2720 K (a)-(c), solid–liquid coexistence at 2730 K (d)-(f), and liquidation at 2740 K (g)-(i) using DPMD simulations. The region represented by the green ...shadow indicates the presence of the molten phase. The initial configuration consists of a liquid phase at 3300 K and a solid phase at 3000 K.
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Although the physical properties of CaO have been extensively discussed as a crucial component of the Earth’s mantle, there remains a significant discrepancy between the theoretically predicted melting temperature (Tm) and experimental measurements. Therefore, further investigation of the melting properties of CaO is required to clarify these discrepancies. In this study, a deep learning potential (DP) model is used to perform large-scale molecular dynamics simulations with greater accuracy. The DP model accurately reproduces the lattice constants, elastic parameters and equations of state of CaO, in contrast to empirical potentials. The atomic structures of the solid and liquid states are also discussed using radial distribution functions. Using the DP model, the Tm of CaO were obtained to be 3140, 2915, and 2730 K by single-phase method, void method, and solid–liquid coexistence method. This study discusses possible reasons for the discrepancy in the Tm of CaO. Despite agreement with first-principles calculations, inherent defects in the pseudopotential lead to discrepancies between the simulation results and the experimental measurements in the DP model. In addition, the relative strength of atomic bonding can be assessed by comparing the Vickers hardness and the cohesive energy of MgO and CaO. It is evident that MgO has the lowest energy and is the most stable, suggesting a higher theoretical Tm than CaO.
The enthalpy and melting characteristics (onset melting temperature, endset melting temperature, peak melting temperature and enthalpy of melting) of 12 vegetable oils were experimentally determined ...within a temperature range of −60 and 25
°C by means of a differential scanning calorimeter. Data obtained showed that vegetable oils melt over a wide temperature range (19–44
°C). The enthalpy required to increase the temperature of the vegetable oil samples from −60 to 25
°C was between 241.1 and 325.7
kJ/kg. Results from fatty acid composition indicate that the amount of the monounsaturated or polyunsaturated is highly correlated (
R
2>0.91) with the onset melting temperature, peak melting temperature and enthalpy of melting for the 12 vegetable oil samples. Poor correlation (
R
2<0.27) was obtained between the melting characteristics and the amount of saturated or unsaturated fatty acid. A linear equation was therefore used to relate each of the melting characteristics of a vegetable oil sample to the amount of monounsaturated or polyunsaturated fatty acid. The models developed are valuable for predicting material behavior and for modeling processing operations for vegetable oils.
In this paper, the authors propose a highly conductive die attach material based on Ag@Sn powder for power devices operating at high temperatures or in other harsh environments. The preform can be ...reflowed at 250 °C (18 °C above the Tm of Sn, 232 °C), but the resulting bondline can sustain high temperatures up to 400 °C with a high shear strength due to the high re‐melting temperature of the formed Ag3Sn (Tm = 480 °C) after the complete consumption of the outer Sn layers. In addition, the formed bondline exhibits excellent electrical and thermal conductivities due to the embedded Ag particles in the interconnections. The interconnections also exhibit excellent reliability under thermal shock cycling from −55 to 200 °C because of the increased bondline thickness and inherent ductility of the Ag particles embedded in the Ag3Sn.
Ag@Sn Core‐shell Powder Preforms is successfully prepared, the preforms required only a short time (5 min) reflow processing at 250 °C, but the resulting interconnections can withstand a high temperature up to 480 °C and exhibit excellent electrical and thermal conductivities due to the high density and the embedded Ag particles in the interconnections.
•The convention void method has been improved.•Nonequilibrium thermodynamic integration method displays the highest accuracy for melting temperature.•The melting temperature of Ni-Zr compound system ...were investigated with five different methods.
Finding the efficient and accurate schemes to calculate the melting temperature is important for molecular dynamics simulation. We propose a modified void method based on heterogeneous nucleation to validly calculate the melting temperature from solid-liquid coexistence state. It decreases the degree of superheating in the conventional voids method. The efficiency and accuracy of five methods (i.e., hysteresis method, two phase coexistence method, the interface pinning method, the Frenkel-Ladd path method and the modified void method) have been discussed in detail. The calculated results of hysteresis method strongly depend on heating/cooling rate. For the nonequilibrium thermodynamic integration method, the calculated accuracy is consistent with the interface pinning method for monoatomic Cu. For the modified void method the calculated results agree with the nonequilibrium thermodynamic integration method.
We perform an assessment of the Li2O${\rm Li}_2{\rm O}$‐La2O3${\rm La}_2 {\rm O}_3$═ZrO2${\rm ZrO}_2$ phase diagram using an array of computational methods to address significant gaps in available ...experimental data at high‐temperatures, due to lithium loss and high reactivity with most materials, which poses significant containment challenges. Free energies of the solids are calculated via the quasi‐harmonic approximation (QHA) and thermodynamic integration, based on the density functional theory (DFT) simulations. Free energies of the liquids are modeled as regular solutions, with enthalpies of mixing calculated from DFT molecular dynamics simulations. The melting temperatures of Li2O${\rm Li}_2{\rm O}$, LiLaO2${\rm LiLaO}_2$, La2Zr2O7${\rm La}_2 {\rm Zr}_2 {\rm O}_7$, and Li7La3Zr2O12${\rm Li}_7 {\rm La}_3 {\rm Zr}_2 {\rm O}_{12}$ (LLZO) are calculated using the small‐size coexistence method. Free energies from prior experimental assessments are combined with our computational results to generate a CALculation of PHAse Diagram (CALPHAD) model and phase diagrams.
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The increasing societal concerns about the environmental impact of plastic waste, together with the depletion of petroleum resources, makes it imperative to develop environmentally ...friendly products that would potentially replace conventional petroleum based materials. Due to their inherent thermomechanical behaviour and biodegradability, biodegradable polyesters have shown explosive growth and underpin the global shift towards sustainability. In fact, the potential of ester groups to undergo hydrolytic chain scissions has brought biodegradable polyesters to the forefront of polymer science, both in fundamental research and industry level. Although the field of biodegradable polymers has been traditionally limited to aliphatic polyesters, recently, the introduction of aromatic rings into the polymer structure has allowed obtaining aliphatic/aromatic polyesters with much broader thermal, mechanical and biodegradation properties.
The discovery of new synthetic approaches has boosted the development of novel biodegradable polyesters, with reported properties equivalent or even superior to conventional polymers. As polymer chemistry is a property driven science, the thermomechanical properties are often the most relevant aspects that determine product performance specifications and play a pivotal role towards the definition of the specific end-use applications of polymeric materials. Coupled with an understanding of polymer biodegradability, including hydrolytic and enzymatic degradation behaviour, the stage is set for a broadening impact of these systems on global sustainable polymer challenges. Accordingly, this review establishes an up-to-date state-of-the-art in the field of biodegradable polyesters, thoroughly analyzing and comparing their thermal, mechanical and biodegradation properties.
In this paper, both a novel experiment and simulation model was presented to evaluate the performance of a solar still by applying a new shape-stabilized phase change material (SSPCM). The SSPCM was ...characterized with stable shape, high thermal conductivity and high solar absorption. Firstly, an experiment for solar still with SSPCM was carried out, and the SSPCM used in the experiment got thermal conductivity 1.50 W/m K and solar absorption around 0.94, which can replace the conventional metal absorber plate. Then, a comprehensive heat transfer model for the solar still was built to analyze the effect of melting temperature and thermal conductivity of the SSPCM on the performance of the solar still. The experimental results revealed that the daily productivity of solar still with SSPCM was 3.41 L/m2, 43.3% higher than that of conventional solar still without SSPCM. The simulation results showed that the daily productivity increased from 42% to 53% compared with that of conventional solar still when thermal conductivity of SSPCM increased from 0.2 W/m K to 4.0 W/m K. And increasing the melting temperature of SSPCM from 34 °C to 50 °C improved the percentage of enhancing productivity from 21.5% to 57.5%. Finally, the cost analysis was performed.
•Shape-stabilized PCM has the high solar absorption and thermal conductivity.•Problems in the application of paraffin wax are solved by SSPCM.•A comparison between solar stills with and without SSPCM is carried out.•Effect of thermophysical properties of SSPCM on yield is analyzed.•The temperature gradient of SSPCM is considered to analyze process of charge/discharge heat.
In order to improve the thermal performance of Trombe wall, the mixture of 55% decanoic acid and 45% lauric acid as a kind of PCM was chosen to integrate with Trombe wall. The article presents a test ...of properties of the PCM and an experimental study on a small-scale integrated PCM Trombe wall. Two periodic heat input modes simulate the periodically varying solar radiation absorbed by the absorber. Its melting temperature and latent heat are 21.33 °C and 133.4 kJ/kg, respectively and its volume expansion rate is 7.94%. The experimental results show that the integrated PCM Trombe wall can increase indoor air temperature by 0.82 °C–1.88 °C for low heat input mode and 1.75 °C–3.27 °C for high heat input mode. Besides, two-dimensional heat transfer along the height and thickness directions of PCM wall results in large temperature difference in these two directions even if the absorber surface is heated evenly. There exists the irregular-shape liquid/solid interface. The PCM above the liquid/solid interface can be completely melted while that below the liquid/solid interface is always in the solid state. Therefore, it is suggested that the PCM with the suitable melting temperature, a wide range of phase change temperature and high latent heat should be chosen.
•The properties of the mixture of 55% decanoic acid and 45% lauric acid are studied.•Only the PCM in the upper region of PCM wall melts in two investigated cases.•The maximum temperature difference in the height direction of PCM wall is 21.5 °C.•The highest temperature rise in the air gap and is 19.33 °C.•The highest laboratory temperature rise is 3.27 °C.
•The role of increasing amount of molten phase on corrosion of stainless steel was studied.•A certain critical percentage of molten phase was required before observing severe corrosion.•This is ...believed to be caused by the increased steel/salt-melt contact.•Thecriticalamount of molten phaseat T0for severe corrosion is steel specific.
In biomass combustion, the presence of alkali chlorides will lower the ash deposit melting temperature. It is also known that aggressive corrosion of superheater materials may occur in the presence of melt in contact with the steel. Therefore, the first melting temperature (T0) has been used as a guideline for the maximum superheater temperature. However, the impact of the share – or percentage - of molten phase in the salt deposit on corrosion has not been systematically investigated. In this work, the role of the share of molten phase on the corrosion of two stainless steel qualities, AISI 347 and 310, was studied. The salt mixtures used (NaCl-Na2SO4 and KCl-K2CO3) were prepared to produce different amounts of melt at the higher test temperature. The steels were exposed for one week to a salt mixture in a tube furnace, at temperatures both below and above T0. After the exposure, the samples were cut to reveal the cross-sections. The cross-sections were analysed by means of SEM-EDX. Remarkable differences in the corrosion tendencies of the materials were observed depending on the percentage of molten phase. The work revealed that for a certain steel quality a given minimum percentage of molten phase was required before observing severe corrosion. For the NaCl-Na2SO4 salt mixtures, around 3 wt% molten phase was sufficient to significantly accelerate the corrosion rate for AISI 347, while the corresponding value was 14 wt% for AISI 310. The criterion of first melting temperature T0 being the critical limit for severe superheater corrosion requires modification. The amount of liquid phase at T0 is also essential.Thecriticalamount of liquid phaseat T0for severe corrosion is steel specific.
