Differential Scanning Calorimetry Characterization Research Articles

Insight into the micro-mechanism of hydrate-based methane storage from active ice

Gas hydrate formation in active ice holds significant potential for solidified natural gas storage, while the deep understanding of its micro-mechanism is required for the futural application of such a technology. In this study, the kinetics and micro-properties of methane hydrate formation enhanced by active ice (porous ice containing an unfrozen solution layer of sodium dodecyl sulfate) were investigated via experiments and molecular dynamics (MD) simulations. Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray diffraction (XRD) differential scanning calorimetry (DSC) characterization, and in-situ visual observation confirmed the formation of sI methane hydrate in the active ice system and the occurrence of single-crystal hydrate, and also indicated the occurrence of active water near the surface of porous active ice during the active ice formation. A sensitivity analysis of the hydrate kinetics experiments suggested that temperature is the primary driver of rapid methane hydrate formation in the active ice system. The shortest induction time and t90 for hydrate formation were recorded at 5 s and 5.5 min, respectively. Furthermore, MD simulations indicated that the direct hydrate nucleation and growth in the active water, heat transfer from gas hydrate to ice, and the diffusion of active water (1.24 × 10-9 m2/s) and methane (7.10 × 10-8 m2/s) into the porous ice structure are the primary mechanism that enhances hydrate formation kinetics and methane storage capacity. This work provides an essential microscopic mechanism of the “active ice → active water → gas hydrate” circulation that contributes to the deep understanding and futural application of the efficient hydrate-based solidified methane storage in active ice system.

Efficient Recycling and Utilization Strategy for Steel Spent Pickling Solution

Before steel can be utilized, pickling is necessary to remove surface oxidation products. However, as the ferrous ion concentration in the pickling solution increases, the pickling rate significantly diminishes, necessitating the treatment of spent pickling solution (SPS) to mitigate its hazardous effects prior to disposal. Current industrial methods predominantly rely on neutralization and precipitation techniques, which are cost-prohibitive and generate substantial by-products, thus failing to meet environmental protection standards. In this study, a new method, which is based on the formation of FeC2O4·2H2O precipitate in a strong acid solution, is proposed to treat the SPS. Initially, the SPS undergoes a two-step impurity removal process, followed by the controlled addition of oxalic acid dihydrate (H2C2O4·2H2O) to precipitate iron. The resulting precipitate is filtered, washed, and vacuum-dried, and the regenerated acid is recycled back into the pickling tank. When 1 g/10 mL of H2C2O4·2H2O is used, the iron removal rate achieves 60%, and the acidity of the regenerated acid increases by 11.3%. X-ray diffraction pattern (XRD) and thermogravimetric–differential scanning calorimetry (TG-DSC) characterization showed that the precipitate was α-FeC2O4·2H2O, with an average particle size of about 3.19 μm and a purity of 95.24%. This process innovatively achieves efficient recycling of acid and iron resources, offering a potential solution to the industrial challenge of difficult SPS treatment in the steel industry and meeting the urgent need for sustainable development.

Vat photopolymerization additive manufacturing process modeling: a thermal-chemical coupling approach informed by in-situ and ex-situ characterization data

Vat photopolymerization (VPP) is one of the most widely used additive manufacturing methods. The VPP process temperature and material curing reaction interplay with each other to critically determine the final product quality. Insights about the time-varying process temperature and degree of conversion (DoC) is desired for VPP process control but difficult to attain due to lacking effective operando characterization technologies. This work reports a new method to create a thermal-chemical model of the VPP process by solving an inverse heat conduction problem (IHCP) based on in-situ observable temperature measurement to estimate the chemistry reaction-induced heat source that is a function of DoC. Ex-situ photo differential scanning calorimetry (Photo-DSC) characterization is used to initialize the chemistry reaction model parameters so that DoC can be calculated. Specifically, vat substrate temperature is measured using an in-situ infrared thermal camera and used as input to solve an IHCP for estimating exothermic heat generation rate for the internal heat generation component at the curing part. Overall, the newly developed VPP modeling framework combines an IHCP that is optimized by in-situ thermal monitoring with a chemical reaction heat generation and conduction model that is educated by Photo-DSC characterization. The model predictions of temperature and DoC are experimentally validated by comparing against in-situ temperature measurement and ex-situ spectroscopy measurement of prints at different exposure times.

Exploring the caveats associated with estimating the properties of amorphous glassy thermoset

Structural-thermal-mechanical properties are examined for various cross-linked amorphous SU-8 samples via Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and nanoindentation, respectively. It is found that room temperature FTIR spectra provide less cross-linking (%) estimation than baking temperature spectra due to the mobility effect of polymer chains. DSC results show that glass transition temperature (Tg) is increasing with the extent of cross-linking (%). However, the correlation of Tg with FTIR measured cross-linking (%) will not be accurate because during DSC characterization sample will undergo cross-linking. From nanoindentation, counter-intuitive results are obtained by the conventional method for reduced elastic modulus (Er) and hardness (H), i.e., decrease with an increase in cross-linking (%). The possible errors, i.e., physical phenomena and methodology, have been analyzed thoroughly for these trends. After minimization/elimination of physical phenomena errors, it is found that current analysis methods are not accurate to estimate Er and H for glassy polymers.

Ribociclib Hybrid Lipid-Polymer Nanoparticle Preparation and Characterization for Cancer Treatment.

Ribociclib is a newly approved orally administered drug for breast cancer. This study aimed to prepare, characterize, and evaluate hybrid lipid-polymer nanoparticles (PLNs) of ribociclib to enhance its in vitro dissolution rate, pharmacokinetics, and anticancer efficacy. Ribociclib-loaded PLNs were prepared by solvent evaporation using the Box-Behnken design to optimize formulation variables. Particle size, entrapment efficiency, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), in vitro release cytotoxicity, molecular modeling, and pharmacokinetic studies were examined. The ribociclib-loaded PLN (formula 1, F1) was optimized in terms of particle size (266.9 ± 4.61 nm) and encapsulation efficiency (59.1 ± 2.57 mg/mL). DSC and thermogravimetric characterization showed the absence of a crystalline structure in the prepared PLNs, confirmed by FTIR, and showed no interactions between the components and the drug. AFM showed well-dispersed heterogeneously shaped nanoparticles. The in vitro release profile exhibited significant results for the optimized formula, reaching 100% at 600 and 90 min at pH 6.8 and 1.2, respectively. The low IC50 obtained by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay suggests that optimized PLN might serve as an effective delivery vehicle for cancer treatment, especially breast and lung cancer. Molecular modeling revealed several hydrogen bonds. A pharmacokinetic study in rats showed that the ribociclib formula had a 6.5-fold increase in maximum concentration (Cmax) and a 5.6-fold increase in area under the curve (AUC). Regarding the everted intestinal sac absorption, formula 1 increased ribociclib penetration relative to the physical combination and pure medication. In conclusion, optimized PLNs with enhanced physicochemical and cytotoxic properties and improved pharmacokinetic parameters were successfully prepared.

Thermal Characterization of Phase Change Materials by Differential Scanning Calorimetry: A Review

The use of phase change materials (PCMs) in thermal energy storage (TES) applications as a system that can fill the gap between the energy supply and demand has sharply increased over recent years. Due to the dependence of the storage capacity in a TES on the transition (mostly solid/liquid) of PCMs, knowing the thermal properties of PCMs is of high importance. Calorimetric methods have an inevitable role in PCMs’ characterization methods. The most important properties of PCMs that lead us to integrate them in a specific application can be determined by the calorimetric method. These properties are transition temperatures, the enthalpy of transition and the heat capacity. Among the calorimetric methods, differential scanning calorimetry (DSC) is widely available and accurate results can be obtained at a reasonable cost. Furthermore, the thermal stability of PCMs can be determined after a hundred cycles of melting and solidification. The present work proposes an extensive and comprehensive review on calorimetric measurements of PCMs via the DSC method. The objective is to highlight the relevant research with a focus on DSC characterization of PCMs. This review includes studies from 1999 to 2022 and provides a summary of the methods, results and recommendations for future measurements.

Improving the Mechanical Properties of Damaged Hair Using Low-Molecular Weight Hyaluronate.

Chemical treatments of hair such as dyeing, perming and bleaching could cause mechanical damage to the hair, which weakens the hair fibers and makes the hair break more easily. In this work, hyaluronate (HA) with different molecular weight (MW) was investigated for its effects on restoring the mechanical properties of damaged hair. It was found that low-MW HA (average MW~42 k) could significantly improve the mechanical properties, specifically the elastic modulus, of overbleached hair. The fluorescent-labeling experiments verified that the low-MW HA was able to penetrate into the cortex of the hair fiber, while high-MW HA was hindered. Fourier transform infrared spectrometry (FT-IR) results implied the formation of additional intermolecular hydrogen bonds in the HA-treated hair. Thermos gravimetric analysis (TGA) indicated that the HA-treated hair exhibited decreased content of loosely bonded water, and differential scanning calorimetry (DSC) characterizations suggested stronger water bonding inside the HA-treated hair, which could alleviate the weakening effect of loosely bonded water on the hydrogen bond networks within keratin. Therefore, the improved elastic modulus and mechanical strength of the HA-treated hair could be attributed to the enhanced formation of hydrogen bond networks within keratin. This study illustrates the capability of low-MW HA in hair damage repair, implying an enormous potential for other moisturizers to be used in hair care products.

Coupling effects of gamma irradiation and moisture on the properties of SiO2 and TiO2 filled silicone rubber

This work mainly includes the effects of gamma irradiation and absorbed moisture on the properties of silicone rubber. The coupling effects have been analyzed by characterization of tensile, creep, and differential scanning calorimetry (DSC). With the same absorbed dose, the elongation at break, creep elongation, melting temperature, melting enthalpy and crosslinking density of the dewatered silicone rubber after irradiation show more obvious change than the pristine samples (the content of absorbed moisture is 0.3%), which means that the absorbed moisture is an important factor in the coupling aging of silicone rubber. The moisture is likely to reduce the chain mobility and restrain crosslinking reactions even with quite low absorbed moisture content.

Structural Study of a Eutectic Solvent Reveals Hydrophobic Segregation and Lack of Hydrogen Bonding between the Components

An in-depth study of the hydrophobic eutectic solvent formed by butylated hydroxytoluene (BHT) and l-menthol (MEN) in a 1:3 molar ratio has been carried out using an integrated approach that combines differential scanning calorimetry (DSC), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, small- and wide-angle X-ray scattering (SWAXS), and molecular dynamics (MD) simulations. The obtained data have been step-by-step compared to those collected on the eutectic formed by 3,5-di-tert-butyltoluene (TBT) and MEN in the same molar ratio, where TBT is analogous to the BHT without the hydroxyl group. The DSC characterization showed comparable results between the two systems, evidencing that the hydroxyl group of the BHT has little or no impact on the thermal behavior of the BHT:MEN eutectic. Both the FTIR and MD results agree in finding that no hydrogen bond (H-bond) interactions are played by the BHT because of the high steric hindrance suffered by its hydroxyl group so that the only established H-bonds are those between MEN molecules. The incompatibility between the components in terms of H-bonds formation results in hydrophobic segregation promoting the MEN–MEN interactions, which are even more intense than in the pure compound. The three-dimensional arrangement between the components showed a remarkable degree of structural order among the alkyl functional groups, suggesting that the apolar–apolar attraction might be the driving force of the eutectic formation. This picture is translated into the establishment of an intermediate-range organization in solution, as evidenced by the SWAXS data. The overall impact of this study is that of pushing a little bit further the definition of these eutectics, indicated until now as extensively H-bonded systems.

Functional Unit Construction for Heat Storage by Using Biomass-Based Composite.

How to construct a functional unit for heat storage by using biomass materials is significant for the exploration of phase change materials (PCMs). In this work, we try to design and construct a functional unit for heat storage by employing a vacuum impregnation method to prepare sugarcane-based shape stabilized phase change materials (SSPCMs) for improving the thermal conductivity of phase change materials (PCMs) and preventing the liquid state leakage of PCMs. The morphologies of the prepared materials are characterized by Scanning electron microscope (SEM) as containing a unique channel structure which is viewed as the key factor for heat storage. X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA) were used to characterize the prepared materials. The results indicated that no chemical reaction occurred between PEG and sugarcane-based biomass during the preparation process and SSPCMs showed great thermal stability. Their thermal properties are measured by using the differential scanning calorimetry (DSC) characterization and show a high melting enthalpy of 140.04 J/g and 94.84% of the relative enthalpy efficiency, illustrating the excellent shape stabilized phase change behavior. Moreover, the highest thermal conductivity of SSPCMs is up to 0.297 W/(mK), which is 28.02% higher than that of the pristine PEG. The excellent capability for thermal energy storage is attributed to the directional thermal conduction skeletons and perfect open channels and the unique anisotropic three-dimensional structure of the SSPCMs. Hence, the unique structure with PEG is testified as the functional unit for heat storage. Comprehensively considering the excellent properties of sugarcane-based materials—providing cheap raw materials via green preparation—it is conceived that sugarcane-based materials could be applied in many energy-related devices with reasonable function unit design.

Improved repeatability of DSC characterization of TPU by means of supportive use of heat-transfer agents

The characterization of materials by means of differential scanning calorimetry (DSC) may contain measurement artefacts originating from the undefined contact area between the material sample and the pan surface. Especially in cases where low thermal conducting materials are investigated, this contact area strongly determines the heat transfer towards the material sample and, thus, the obtained results. As a remedy, the supportive use of heat-transfer agents (HTA) in DSC characterization is proposed in this paper. The beneficial effect of HTA is demonstrated for thermoplastic polyurethane (TPU) with its original DSC data showing significant variation of measurement data, most notably in the temperature range where softening of the material occurs. In the course of an experimental study, covering a temperature range from −40 °C to 270 °C, TPU specimens are analysed with and without HTA considering different heating rates, showing an improved reproducibility of DSC results by the supportive use of HTA, especially in case of higher heating rates.

Influence of moisture/water absorption on mechanical and thermal properties of polyamide6/boric oxide composites

PurposeThis paper aims to investigate the mechanical and thermal behavior, i.e. tensile strength, hardness, impact strength and glass transition temperatures of water-treated polyamide6/boric oxide (PA) composites.Design/methodology/approachThe PA6 and PA6/boric oxide composites were exposed to an open environment and immersed in water for 15 days to analyze the effect of environmental humidity and frequent water immersion conditions on the composite’s mechanical and thermal properties. The tensile strength, elastic modulus, hardness and impact strength of materials were measured to identify the mechanical properties. The scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) characterizations were used to see the effect of humidity/water absorption on microstructure, crystallinity and glass transition temperatures.FindingsThe testing results revealed the loss in strength, elastic modulus and hardness, while the impact resistance was improved after exposure of materials to humidity/water. SEM images clearly show the formation of voids and XRD graphs revealed the loss in crystallinity after water immersion. The DSC plots of water immersed materials revealed the loss of glass transition temperatures up to 15°C.Originality/valueThe mechanical and thermal behavior of PA composites varies according to the surrounding atmosphere. Experiments were performed to investigate the influence of water treatment on the PA6/B2O3 composite’s mechanical and thermal properties. Water treatment resulted in the bonding between PA and water molecules, which generated voids in the materials. These voids generations are found the main reason for the low strength and hardness of water-treated materials.

Effect of plastic deformation on the precipitation reaction in 2024 alloys

The plastic deformation effect on activation energy, transformed volume fraction, and Avrami exponent for the phase precipitation in a 2024 aluminum alloy was evaluated in this study. Differential scanning calorimetry characterization was carried out in deformed and non-deformed samples, focusing on the study of S phase precipitation (Al2CuMg precipitates with orthorhombic structure, space group Cmcm, and lattice parameters a = 4.03 Å, b = 9.3 Å, c = 7.08 Å). The results show that the solid-state reactions were activated, kinetically controlled, and modified by the plastic deformation. The enthalpy changes, activation energy, and peak temperature shifting confirm that the applied deformation alters the reaction sequence. Two different Avrami exponent values were found, one close to 1.7, which indicates that nucleation occurs in preexisting nucleation sites, and the other near 1.3, which corresponds to phase transformation driven by diffusion mechanisms.

Thermal performance of PEG-MWCNTs composites as shape-stabilised phase change materials for thermal energy storage

The development of phase change materials (PCM) for thermal energy storage is a promising technology. However, the liquid PCM leaks and low thermal conductivity limit the practical PCM applications. This article aims to solve these problems; it presents the preparation and thermal characterisation of PCM enhanced by carbon-based nanoparticles. The polyethene glycol 6000 (PEG 6000) is used as PCM and multi-walled carbon nanotubes (MWCNTs) as a shell matrix and thermal conductivity enhancer. The sample was prepared by the sonification method under vacuum conditions. Fourier transform infra-red spectroscopy (FT-IR) and thermo-gravimetric analysis (TGA) tested the chemical and thermal compatibility of the prepared samples. The storage performances are tested by modulated differential scanning calorimetry characterisation. The nano-enhanced-PCM (NPCM) with 1 wt% MWCNTs showed excellent shape stability without any liquid leakage when the temperature was about 110 °C for 30 minutes. Drying method has a significant effect on the thermal storage capacity of the NPCM. The melting, solidification points and the latent heats of the NPCM were measured as 61.75, 35.50 °C, and 174.24, 167.84 J g−1, respectively. Meanwhile, the specific heat is 2.63 J g−1°C−1 for the solid-state and 2.14 J g−1°C−1 for the liquid-state. The thermal conductivity of pristine PEG was improved by 49%. Highlights PEG-MWCNTs shape-stabilised phase change materials were prepared through ultrasound-assisted vacuum method for efficient thermal energy storage. The thermophysical properties and thermal stability of the proposed NPCM has been analysed and discussed. The drying method highly influences the phase change temperatures and latent heats of the prepared NPCM. PEG adsorption into MWCNTs reached 99 wt% without leakage, and 1 wt% of MWCNTs enhanced the thermal conductivity by 49% and maintained good latent heat of 175 J g−1. The developed NPCM is an excellent potential candidate for electronic devices cooling applications.

Phase-microstructure-mechanical properties relationship of carbon fiber reinforced ionic liquid epoxy composites

The effect of liquid phases on the mechanical properties of carbon fiber reinforced composites (CFRP) is still unclear. In this study, various mass percentages of ionic liquid have been incorporated into epoxy resins and used to fabricate CFRPs. A brittle-ductile transition is demonstrated in tensile behavior of the CFRPs, accompanied by the change of failure mechanisms among fiber breakage, a combination of fiber breakage, splitting and delamination, and delamination. These ionic liquid-induced behavior change arouses our enormous interest in investigating the microstructure change of CFRP. On one hand, ionic liquid leads to microstructural transformation of the epoxy-ionic liquid mixtures. Differential scanning calorimetry (DSC) characterizations help to confirm one transition from one phase (ionic liquid confined within epoxy network) to two phases (separate ionic liquid and epoxy phase) in the matrices at the critical mass percentage of 35 wt%. On the other hand, the interfacial bonding strength and effective bonding area of matrix to carbon fibers are decreased, as confirmed by the decrease of short beam strength with the increase of ionic liquid. This work presents a representative example of the systematic analysis of the modified CFRP, which lays good foundations for the optimization of structural electrolytes for structural power composites.

Quantitative Structure Activity Relationship Analysis of Polypropylene during Ultraviolet Aging Based on Tensile Strength

In order to improving ultraviolet radiation (UV) aging resistance of polypropylene (PP) and expanding its application range, it is necessary to research the rule and mechanism of PP in UV aging process. On the base of Fourier transform infrared spectroscopy and differential scanning calorimetry characterization, the variations of structure parameter (crystallinity and carbonyl index) of homo-PP corresponding to different UV aging time were calculated and analyzed. Combined with tensile strength testing, the influences of both crystallinity and carbonyl index on tensile strength in UV aging process of PP were researched. Then the relationship formula between tensile strength and structure parameter was constructed based on linear relationship, and the quantitative structure-activity relationship of PP during UV aging was analyzed. The results show that, with the extending of aging time, the influence of crystallinity on tensile strength of PP declines, while that of carbonyl index is on the contrary. During UV aging, the tensile strength of PP rises slightly with the increase of crystallinity first, then acceleratedly declines for the increase of carbonyl index. It should be noted that, although the crystallinity of PP begins to decline after 100 h UV aging, its effect to tensile strength can’t be ignored while aging time is less than about 300 h.

Novel sulphonic acid liquid crystal derivatives: experimental, computational and optoelectrical characterizations.

A novel liquid crystal homologous series based on the benzene sulphonic acid moiety, namely (E)-4-((4-((4-(alkoxy)benzoyl)oxy)benzylidene)amino)benzenesulfonic acid (Sn), was synthesized and examined via different experimental and theoretical measurements. The four synthesized members have terminally connected alkoxy chain groups, which vary between 6 and 12 carbons. FT-IR and NMR spectroscopy, as well as elemental analyses, were used to confirm their molecular structures. Mesomorphic and optical investigations of the prepared homologues were also conducted using differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The DSC and POM characterization revealed that all of the synthesized sulphonic acid members are monomorphic, exhibiting a pure smectic A (SmA) mesophase with enantiotropic properties. Moreover, all compounds in the group have high thermal transition temperatures. The terminal electron-withdrawing group –SO3H plays a considerable role in the stabilization of the molecule, which in return resulted in high thermal SmA stability. Furthermore, the experimental data relating to the mesophase behavior were substantiated via computational studies using the DFT approach. In addition, the terminal –SO3H moiety has an essential impact on the thermal and physical parameters of possible geometries. All members of the synthesized Sn series exhibit ohmic behavior with electrical resistance in the GΩ range, as revealed by electrical measurements. The S10 electrode had the highest electrical conductivity: 35.16 pS. It also showed two direct optical band gaps of 3.58 and 3.23 eV with Urbach energies of 1261.1 and 502.4 meV. Upon decreasing the number of carbon atoms to n = 6, the main bandgap for S6 reduced to 3.3 eV. The highest conductivity, good absorption, and two large bandgaps recorded for the chain derivative S10 make it suitable for investigations relating to energy-based applications.

DSC and TGA characterization of free and surface water of colloidal unimolecular polymer (CUP) particles for coatings applications

Colloidal unimolecular polymer (CUP) particles are spheroidal nano-scale and 3–9 nm that can be easily designed and controlled. The formation of CUP involves simple synthesis and water reduction. These nanoparticles have charged hydrophilic groups on the surface and are surrounded by a layer of surface water that does not freeze until very low temperature. CUPs have very high surface area per gram, which gives them a high nonfreezing water content. The CUP system is free of surfactant and has zero VOC, exhibiting great potential for coatings applications. The amount and thickness of the surface water were determined by differential scanning calorimetry (DSC) using the heat of fusion. The solution density and knowledge of the resin density and the composition of the CUP solution were used to determine the density of surface water. The evaporation rate of free water and surface water in CUP solutions were investigated by thermogravimetric analysis (TGA) and showed the effect of CUP on the evaporation rate. CUP as an additive to give freeze thaw stability, wet edge retention and open time improvements were explored. Excellent performance in freeze thaw, wet edge time improvement and more open time was found. The CUP system offers an excellent alternative to form zero VOC waterborne coatings.

THERMAL, DYNAMIC MECHANICAL ANALYSIS AND MECHANICAL PROPERTIES OF POLYBUTYLENE TEREPHTHALATE/POLYETHYLENE TEREPHTHALATE BLENDS

Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and mechanical tests were conducted to characterize the properties of polybutylene terephthalate/polyethylene terephthalate (PBT/PET) blends. PBT and PET were blended at different PBT/PET ratios (80/20, 60/40, 40/60, 20/80) via twin screw extruder prior to injection molding. DSC characterization showed a single glass transition temperature for all PBT/PET blends indicating that the miscibility occurred in the amorphous region. From DMA results, loss modulus and tan δ also showed a single peak for all PBT/PET blends, confirming the DSC results. At room temperature, PBT/PET 20/80 has the highest storage modulus followed by PBT/PET 80/20 blend. PET has higher tensile strength, flexural strength, Young’s and flexural modulus than PBT but lower in elongation at break and impact strength. PBT/PET 80/20 blend has the highest tensile strength, flexural strength, elongation at break, and impact strength compared to other PBT/PET blends. PBT/PET 80/20 blend can be suggested as an optimum formulation with balanced mechanical properties in terms of stiffness and toughness.

Effect of grain boundary relaxation on the corrosion behaviour of nanocrystalline Ni-P alloy

Grain boundary relaxation (GBR) in nanocrystalline materials is an approach to reduce the excess free energy of the material without any change in the grain size of the material and is carried out through controlled heat treatments at relatively low temperatures. In this work, we are investigating the effect of grain boundary relaxation on the corrosion behaviour of nanocrystalline Ni-P, a topic which has not been explored before. Nanocrystalline Ni-P foils were produced using the pulsed electrodeposition route using the modified Watts bath and were characterized by X-Ray Diffraction and Transmission Electron Microscopy. Differential scanning calorimetry (DSC) characterization technique was used to establish the GBR regime, and the same was validated by measuring the grain size post the grain boundary relaxation treatment. Once the relaxation regime was established, systematic heat treatments at a temperature of 473 K were carried out, which enhanced the hardness of the nanocrystalline material without any change in the initial grain size. Corrosion studies using potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) test were performed to understand the effect of GBR. The corrosion studies revealed an improvement in corrosion resistance of the relaxed structure vis-à-vis the as deposited nanocrystalline Ni-P. An increase in Ecorr and a decrease in icorr and ip were found for the relaxed structure. The EIS tests too revealed an improvement in the polarization resistance for the relaxed structure.