Differential Scanning Calorimeter Method Research Articles

Rice gelatinization temperature prediction using the rapid visco analyzer vis‐à‐vis the traditional DSC method

AbstractBackground and ObjectivesThe measurement of gelatinization temperatures (GTs) of rice using the Rapid Visco Analyzer (RVA) can be a more rapid and efficient method as compared to the traditional method of using Differential Scanning Calorimeter (DSC). The objective of this research was to determine the accuracy and precision of the RVA technique in comparison to the DSC method for measuring GTs of contemporary rice cultivars produced in Arkansas.FindingsRice samples analyzed using the RVA had GT that ranged from 70.48 ± 0.18°C to 75.72 ± 0.11°C, while the DSC‐analyzed samples had GT that ranged from 67.25 ± 0.18°C to 74.72 ± 0.64°C. The values of RVA GT consistently overestimated the values of the DSC‐GT, with the RVA GT values demonstrating higher precision. A calibration equation was developed to correct the overestimation of RVA GT values, and its validity was confirmed through data obtained from both laboratory‐scale tests and industry‐based analysis.ConclusionsThe method of using RVA can serve as a standalone approach for determining the GT of rice from various cultivars.Significance and NoveltyThis technique of using RVA can be beneficial to industrial and educational applications because it is less expensive, easier to follow, and more rapid in analysis as compared to DSC.

The effects of interfacial thermal contact resistance between yarns and matrixes on the thermophysical property of the plain woven C/SiC composite

The plain woven C/SiC composites with high thermal shock resistance are widely used in aerospace applications. For this composite, thermal contact resistance (TCR) has an unneglectable contribution to the thermophysical property. In this work, the influence of the TCR on the thermophysical property of a real 2D plain woven C/SiC composite is studied. X-ray CT scanning is used to obtain the microstructures of the C/SiC composite, and the complex structures are restructured and transformed into standard cube grids based on the theory of the intersection of rays and triangles. Combining with finite difference method (FDM) and multiple GPUs acceleration, an efficient approach for numerically predicting the thermophysical property of the real C/SiC composite is established. Based on the Laser Flash Method (LFM) and Differential Scanning Calorimeter (DSC) method, the effective thermal conductivities (ETCs) of the C/SiC composite at different temperatures are obtained experimentally. The results show that ETCs predicted by our numerical method are closer to the measured ones when TCR is considered. Through the numerical simulation and theoretical analysis, the correlation between the ETC and TCR is obtained, which is proved to be a typical Logistic function, and the physical meanings of various constants in the correlation are determined and discussed. Besides, the thermal response time increases with the TCR increasing, simultaneously, the distributions of isotherms and heat-flux trajectories more approach the distributions of fiber yarns in the material.

The melting performance blast furnace slags with high alumina content

With a view to understanding the performance of the blast furnace slag with high Al2O3 content, the effects of w(MgO)/w(Al2O3), w(CaO)/w(SiO2), and w(Al2O3) on the melting performance (melting characteristic temperature and melting heat) of the blast furnace slag with high Al2O3 content were investigated by the differential scanning calorimeter (DSC) method. Experimental results indicate that melting end temperature (Tend) for almost all the slags has no obvious change with the increase of w(MgO)/w(Al2O3), w(CaO)/w(SiO2) and w(Al2O3) of the slag will raise Tend of the slag. When (w(MgO)/w(Al2O3), R, and w(Al2O3) are high, the melting onset temperature (Tonset) of the slag increases with the increase of any variables. When w(CaO)/w(SiO2) is low, Tonset of the slag decreases with the increase of w(Al2O3). w(MgO)/w(Al2O3), w(CaO)/w(SiO2), and w(Al2O3) within the scope of this study and all these factors lead to the increase of the slag melting heat.

Polymer-Based Nano-Adsorbent for the Removal of Lead Ions: Kinetics Studies and Optimization by Response Surface Methodology

This work successfully created a polypyrrole-polyethyleneimine (PPy-PEI) nano adsorbent for the elimination of the lead ion Pb2+ from an aqueous solution. An efficient conducting polymer-based adsorbent called as was created using ammonium persulfate (NH4)2S2O8 as an oxidant (PPy-PEI). The PEI hyper-branched polymer with terminal amino groups was added to the PPy adsorbent to offer heavy metals more effective chelating sites. Pb2+ removal from aqueous solution using polyethyleneimine micro adsorbent was successfully accomplished using a batch equilibrium technique (PPy-PEI). The generated water-insoluble polymer nanoadsorbent had enough nitrogen atoms; therefore, an effort was made to link PEI, a water-soluble PPy, with PPy, a conjugated polymer, for lead ion adsorption from an aqueous solution. The generated PPy-PEI nanoadsorbents were discovered to have average particle sizes of 18–34 nm and a Brunauer-Emmet-Teller surface area of 17 m2/g, respectively. The thermal behavior of the composites was investigated using thermo gravimetric and differential scanning calorimetric methods. The lead ion adsorption efficacy of pure polypyrrole was found to be 38%; however, a batch equilibrium technique employing nanoadsorbent revealed with the maximum adsorption capacity of 75.60 mg g−1. At pH 10 and 30 min of contact time at 50 °C, 0.2 g of adsorption was shown to be the ideal dosage. X-ray diffraction analysis, energy-dispersive ray spectroscopy, and Fourier transform infrared ray spectrum support the lead ion adsorption by PPy-PEI nanoadsorbents. The cauli-like structure was visible using field emission scanning electron microscopy. Studying the thermodynamic showed that the adsorption was endothermic as illustrated from the positive value of value of ΔH° is 1.439 kJ/mol which indicates that the uptake of Pb2+ onto nanoadsorbent PPy-PEI could be attributed to a physical adsorption process. According to the values of ΔG°, the adsorption process was spontaneous at all selected temperatures. The positive value of ΔS° value (43.52 j/mol) suggested an increase in the randomness at the solid/solution interface during the adsorption process. The adsorption data meet the pseudo-second-order kinetic model and suited the Langumuir isothermal model effectively.

Synthesis, thermal property and antifungal evaluation of pyrazine esters

Synthesis, thermal properties, as well as antifungal assessment of pyrazine esters were handed in this work. The metal-free esterification of pyrazinyl methanol and acid chloride derivatives in a stoichiometric ratio yielded the following compounds: pyrazin-2-ylmethyl benzoate (3a), (5-methylpyrazin-2-yl) methyl benzoate (3b), 1-(pyrazin-2-yl) ethyl benzoate (3c), 2-(pyrazin-2-yl) ethyl benzoate (3d), pyrazin-2-ylmethyl pivalate (3e). The spectral results totally showed that the synthesis conditions used permitted the compounds to be produced with great yield. The characterization included 1H NMR, 13C NMR, IR, HRMS and organoleptic tests. Their thermal degradation process was examined by using the TG (thermogravimetry) and DSC (differential scanning calorimeter) methods. The pyrolysis products of the pyrazine esters in inert and oxidative atmospheres were analyzed by the Py-GC/MS (pyrolysis–gas chromatography/mass spectrometry) method. It revealed that 3a–3e were totally evaporated throughout the pyrolysis experiments at low temperatures. And they evaporated with high relative contents in pure nitrogen (86.12%–94.17%) and oxidative (75.01%–88.85%) atmospheres, with only a small amount decomposing into a series of substances. Additionally, the in vitro antifungal effects of compounds 3a–3e against R. solani, P. nicotianae, F. oxysporum, F. graminearum, and F. moniliforme were further investigated using the mycelial growth rate methodology. The findings shown that compound 3c has 94% and 80% inhibitor rates at 0.5 mg/ml against R. solani and P. nicotianae, respectively, with an EC50 value (half maximum effective concentration) of 0.0191 mg/ml and 0.1870 mg/ml, respectively. Similarly, that of compounds 3a and 3b exhibited 82% and 91% at 0.5 mg/ml against R. solani, with an EC50 value of 0.0209 mg/ml and 0.0218 mg/ml, respectively. The molecular docking of compound 3c with SDH (Succinate dehydrogenase) was preliminarily performed to reveal the binding modes in active pocket and analyze the interactions between the molecules and the protein.

Design and preparation of a biomedical titanium alloy with low elastic modulus and high antibacterial property based on Ti-Mo-Ag system

Titanium and titanium alloys have been widely used as biomedical materials as a result of low density, high specific strength, good biological propertise, good mechanical compatibility and easy processing. However, problems such as stress shielding and bacterial infection often occur in the clinical application. In this paper, Ti-15Mo-xAg (x = 10, 12) alloys were designed and prepared to obtain low elastic modulus and excellent antibacterial ability. We studied the microstructure, mechanical properties, antibacterial properties and cytocompatibility by scanning electron microscopy, differential scanning calorimeter, X-ray diffraction, micro-hardness instrument and plate counting method. The calculated results indicated that Ti-15Mo alloys with different Ag contents could be β-type or near β-type alloy with potential of a low elastic modulus. Microstructure results demonstrated that the increasing Ag content from 10 wt% to 12 wt% increased the phase transformation temperature and resisted the formation of ω phase in Ti-Mo-Ag system. Both the elastic modulus and the antibacterial ability were significantly influenced by the ageing treatment and Ag content due to the phase constitution, and high Ag content and the precipitation of Ti 2 Ag were beneficial to the antibacterial performance but increased the elastic modulus. Cell assessment showed that Ti-Mo-Ag alloys did not have cytotoxicity to MC3T3. Ti-15Mo-10Ag alloy exhibited strong antibacterial rate of 99.5%, good cellular compatibility and low elastic modulus of 85 GPa, which suggests that this alloy might be a highly competitive medical material. • The effects of Ag content and heat treatment process on elastic modulus and antibacterial properties were studied. • Ti-15Mo-10Ag and Ti-15Mo-12Ag alloy had no cytotoxicity to MC3T3 cell. • Ti-15Mo-10Ag exhibited low elastic modulus and good antibacterial ability after the ageing treatment of 650 ℃.

Effects of maltodextrin on physicochemical properties of freeze-dried avocado powder

The effect of maltodextrin on the moisture sorption isotherm, glass transition temperature (Tg), and degree of caking of freeze-dried avocado samples at room temperature (25°C) was investigated. The incorporation of maltodextrin reduced the water sorption capacity of the powder due to its less hygroscopic nature. Parameters derived from the Guggenheim, Anderson, and de Boer (GAB) model describing the properties of absorbed water are discussed. The water absorption isotherm possessed the characteristic sigmoid-shaped type II isotherm curves and the model gave the best fit over the whole range of aw tested. The differential scanning calorimetric method was used to measure the Tg of freeze-dried avocado samples. Increasing the water content decreased the Tg, and Tg was increased with increasing maltodextrin content. Increased maltodextrin content to solid material in the freeze-dried sample was associated with less sensitivity to caking as evidenced by Tg values. In addition, increased maltodextrin content in the powders caused brighter, less yellowish, and more greenish coloration and protected color change including browning index. The antioxidant capacity was significantly decreased with increasing maltodextrin content. Thus, the effect of maltodextrin concentration on physicochemical properties was a promising way to preserve the physical property and chemical compounds in freezedried avocado powder.

The effect of inoculum and glucose addition on polyhydroxyalkanoate production by Brevibacterium sp. B45

Petroleum-based plastics are the major cause of environmental pollution because the plastics need years to be degraded. The difficulties in handling waste of petroleum-based plastic have motivated researchers to produce environmentally friendly plastic materials that are biologically degradable; one of them is polyhydroxyalkanoate (PHA). Polyhydroxyalkanoate is natural biodegradable biopolymers produced by bacteria as an intracellular carbon and energy storage. This polymer is an alternative source of plastics with similar physical properties to petroleum-based plastic.It can be easily biodegraded aerobically and anaerobically. This study examined the potential of one superior isolate as PHA producers, i.e.,Brevibacterium sp. B45. Brevibacterium sp. B45 was cultivated in Ramsay’s minimal medium with inoculum concentrations were 1, 2, and 3% (v/v)and glucose concentrations were 1, 3, and 5% (w/v). The cultivation of Brevibacterium sp. B45 was carried out in a 500 mL Erlenmeyer flask on a shaker incubator with 150 rpm and 30 oC for 72 hours. PHA recovery was carried out by chloroform extraction and characterized by scanning electron microscopy (SEM), Fourier transformed infrared (FTIR), and differential scanning calorimetric (DSC) methods. The highest yield of dried biomass (2.92%) was obtained using 3% inoculum and 3% glucose. The melting temperature (Tm), enthalpy (ΔHf), and crystallinity (Xc) of the PHA product were 172.1 °C, 61.04 J g-1, and 41.08%, respectively. Data of SEM show that a porous surface characterized morphological of purified PHA grains. The functional units of purified PHA grains were C=O, CH3, C-O, C-O-C, C-C, C-H, and -OH. The purified PHA grains show a similar spectrum to the standard Poly-3-hydroxybutyrate (PHB). Therefore, it could be assumed that PHA produced by Brevibacterium sp. B45 was most likely PHB.

Facile preparation of Metal/Metal-organic frameworks decorated phase change composite materials for thermal energy storage

New types of metal or metal-organic frameworks (MOFs) decorated and porous carboxymethyl chitosan (CMCS) shape-stabilized phase change material (PCM), which are referred to as Metal-PCM@CMCS or MOFs/PCM@CMCS, respectively, were designed and synthesized with a very simple way in this study. The porous CMCS was constructed by the cross-linking of metal ions with the inherent active groups (for example, -COOH, -NH2, and -OH) within the CMCS molecules. This not only encapsulated the PCM, but also provided active sites (metal ions) for further building the MOFs structures by post-treating the coordination processes between the metal ions and the organic ligand to obtain MOFs/PCM@CMCS. The effects of different metal ions, as well as various drying techniques, on the microstructural morphology, performance, and stability of the composites were discussed. Scanning electron microscope (SEM) and differential scanning calorimeter (DSC) methods were employed to study and analyses the microstructures and thermal energy storage performances of the composites. The obtained results indicated that the inherent three-dimensional network structures of the porous CMCS could effectively provide support carriers for solving the issues of PCM leakage. It was found that both the products of Metal-PCM@CMCS and MOFs/PCM@CMCS which had been treated with freeze-drying and vacuum drying processes had similar phase change enthalpy with the maximum value 90 J/g, which successfully met the requirements of phase change energy storage applications. This work firstly provides a simple and quick method for the preparation of shape-stabilized phase change composite materials, and at the same time, this result will also lay an experimental basis for the study of the mechanism of synergistic action between MOFs and PCM, expands the application of MOFs and PCM, and provide new ideas for the development of multifunctional composite materials with anti-temperature property.

Thermal Properties of 3D-Printed Sand Molds

Specific heat capacity (Cp), density (ρ), and thermal conductivity (λ) of phenolic-bonded 3D-printed sand (3DPS) molds have been determined in the temperature range of 20–1400 °C using differential scanning calorimeter (DSC), dilatometer, and hot wire method. The results have been used to simulate the thermal gradient in a sand mold during casting aluminum using a commercial simulation software. The simulated results have been compared with laboratory-measured results and simulated results using the software’s database for conventional mold making. Our results show that available database for sand thermal properties cannot explain the thermal gradient in 3DPS molds and this manufacturing process affects the thermal properties of the mold compared to traditional mold making. It is necessary to collect data for a variety of 3D-printed sand molds to ensure accurate modeling simulation in the foundry industry.

Characterization and applications of a newly formulated ferroelectric liquid crystal mixture W315

In this article, we present the formulation, characterization, and application of a newly prepared ferroelectric liquid crystal (FLC) mixture namely W315 composed of pyrimidine compounds. The characterization of FLC material under investigation has been performed through polarizing optical microscopic, dielectric spectroscopic, differential scanning calorimetric and other electro-optical methods. The temperature dependence of the dielectric loss factor of the homogeneously aligned FLC sample shows a phase change from Smectic C* to Smectic A that further confirms the transition temperature of FLC material. From electro-optical observations, the values of spontaneous polarization, rotational viscosity, and response time of W315 were found to be 8.03 nC/cm2, 86.56 mPa s, and 890 µs respectively. The material constants of FLC material under investigation can be utilized in various FLC based faster displays and non-display devices.

Phase equilibria in binary blends of a flexible liquid crystal polymer and rigid-rod monomers

In this study, we report on the phase equilibria in binary blends of a flexible liquid crystal polymer with non-mesogenic rigid-rod monomers. We utilized a combination of Optical Microscopic (OM) and Differential Scanning Calorimetric (DSC) methods to determine the transition temperatures, enthalpies and entropies within the total compositions of the phase diagrams. We verified the effect of molecular geometry of rigid-rod monomers on transition temperatures, enthalpies and entropies of blends and evaluated the apparent axial ratio of polymer and entropy values of nematic-isotropic phase transition. In addition, we compared our experimental nematic-isotropic phase transition data with few early lattice model theories.

Comparative Study of Vegetable Oils Oxidative Stability using DSC and Rancimat Methods

A comparative study was carried out to evaluate and compare the oxidative stability of vegetable oils (olive, corn and sunflower) in Egypt, through evaluation of accelerated oxidation at four different isothermal temperatures (110, 120, 130, 140 °C) using two different instruments: a differential scanning calorimeter (DSC) and a Rancimat instrument, taking into account the physicochemical quality characteristics and relationships between oxidative stability and fatty acid composition of oils. The Rancimat instrument was set at the four different isothermal temperatures with an air flow 20 L/h and measures the induction period (IP) of the selected oils. The differential scanning calorimetry (DSC) technique involved accelerated oxidation of oil samples in an air flow of 60 ml/min in DSC cell set at four different isothermal temperatures. A rapid increase in evolved heat was observed with the appearance of a sharp exothermic curve during initiation of the oxidation reaction. From the resulting exothermic curve, the onset of oxidation time (To) was determined graphically by the DSC instrument. There was an excellent correlation (p 0.98) between the two methods with coefficient of determination (R2 >0.89) for DSC independent of the vegetable oil source, imply that DSC can be recommended as an alternative appropriate objective method for assessing the oxidative stability of vegetable oils because of its simplicity, absence of toxic chemicals, small amount of sample and time-saving nature and could be easily used for routine analysis in oils and fats industry.

Fabrication and Characterization of a Modified Conjugated Molecule-Based Moderate-Temperature Curing Epoxy Resin System

2-methylimidazole derivative (EGE-2MI) was synthesized through the reaction of ethyl glycidyl ether (EGE) with conjugated molecule 2-methylimidazole (2-MI). The structure was confirmed by Fourier transform infrared spectroscopy (FTIR)、1H-nuclear magnetic resonance spectroscopy (1H-NMR) and differential scanning calorimeter (DSC). The synthesized EGE-2MI was applied in epoxy resin E-51 as latent curing agent. Kinetics of the curing reaction were studied by DSC method, optimum curing process parameters were determined, storage life of the resin system at room temperature was evaluated, mechanical properties of the moderate-temperature cured products were also tested and analyzed. The results revealed that epoxy resin system using EGE-2MI as curing agent can be efficiently cured at 110~120 °C, with an activation energy of 86.34 kJ/mol. The storage period of EGE-2MI/ Cyanate resin (CE) system can reach 14 days under ambient temperature. In addition, the cured mixture with EGE-2MI/CE has a tensile strength of 40 MPa and an Al-Al adhesion shear strength of 20.11 MPa.

Physicochemical, antioxidant and sensory properties of chocolate spread fortified with jackfruit (Artocarpus heterophyllus) flour

Chocolate spread is often considered as an unhealthy product with low antioxidant activity and phenolic content since it does not contain cocoa liquor. This research aimed to investigate the potential on the physicochemical composition and antioxidant activity of jackfruit (Artocarpus heterophyllus) flour and red palm olein in the chocolate spread formulations. The effect of the jack fruit and red palm olein incorporation on the quality attributes and high nutritional value of chocolate spread was also examined. Physicochemical properties of the fortified chocolate spread, as well as the evaluation of physical parameters in the chocolate spread, were investigated. Melting points were analyzed by DSC (Differential scanning calorimeter) method, colour lightness was analyzed by chromameter hunter method, profile bioactive compound was analyzed by gas chromatography-mass spectrometry (GC-MS), and whilst for viscosity by Brookfield Viscometer method. The analysis results obtained that the sample code F5 (10% jackfruit flour: 26% sugar) contains of 43.47% fat, 0,88% free fatty acids, polyphenol 127 mg/g, 160.16 mg/g carotenoids, 42.75 μg/mL antioxidant activity IC50, and 6.19 degree of acidity per 100 g chocolate spreads and high panelists preference. However, the fortified chocolate spread had different characteristics from each other either in the chemical, physical or sensory properties. The best formulation code is F5 with 10% jackfruit flour, fortification significantly increased the antioxidant activity, carotenoid, polyphenols, viscosity, colour and melting points. Additionally, chocolate spread with 10% of jackfruit flour by-product presented the highest-ranking test rate of the three sensory attributes of aroma, taste and texture. Therefore, the use of jackfruit by-products in the development of chocolate spread is a viable alternative which can be explored for nutritional, technological and sensory purposes by the food industry.

Pressure-Gradient Sorption Calorimetry of Flexible Porous Materials: Implications for Intrinsic Thermal Management.

Thermal management is an important consideration for applications that involve gas sorption by flexible porous materials. A pressure-gradient differential scanning calorimetric method was developed to measure the energetics of adsorption and desorption both directly and continuously. The method was applied to the uptake and release of CO2 by the well-known flexible metal-organic frameworks MIL-53(Al) and MOF-508b. High-resolution differential enthalpy plots and total integral enthalpy values for sorption allow comprehensive assessment of the thermal behavior of the materials throughout the entire sorption process. During adsorption, the investigated materials display the ability to offset exothermic adsorption enthalpy against endothermic structural transition enthalpy, and vice versa during desorption. The results show that flexible materials offer reduced total integral heat over a working range when compared to rigid materials.

Study on the spontaneous combustion risk and thermal decomposition characteristics of nitrocellulose

Nitrocellulose (NC) is an important raw material for industrial products and is widely used in military and civilian industries. However, accidents of nitrocellulose burning and explosion are common. In order to test the thermal hazards of NC and guide its safe production, storage, transportation and use, an auto-ignition temperature tester was used to study the effects of different factors (quality, heating rate, nitrogen content) on NC spontaneous combustion. And differential scanning Calorimetric method was used to test the heat flow curve of nitrocellulose at a heating rate of 5 °C/min after adding different content of diphenylamine (DPA) to determine the thermal kinetic characteristics of the initial reaction exotherm temperature, maximum peak temperature, reaction enthalpy change, etc. The results show that after adding 1%, 2%, and 3% DPA, the ΔT of NC increases sequentially by 4, 3.12, and 3.10°. DPA as a stabilizer has good compatibility with NC, which can effectively slow down the thermal decomposition speed of NC and prolong the storage life of NC.

Tetrafunctional Epoxy Resin-Based Buoyancy Materials: Curing Kinetics and Properties.

In order to synthesize a new kind of buoyancy material with high-strength, low-density and low-water-absorption and to study the curing reaction of tetraglycidylamine epoxy resin with an aromatic amine curing agent, the non-isothermal differential scanning calorimeter (DSC) method is used to calculate the curing kinetics parameters of N,N,N′,N′-tetraepoxypropyl-4,4′-diaminodiphenylmethane epoxy resin (AG-80) and the m-xylylenediamine (m-XDA) curing process. Further, buoyancy materials with different volume fractions of hollow glass microsphere (HGM) compounded with a AG-80 epoxy resin matrix were prepared and characterized. The curing kinetics calculation results show that, for the curing reaction of the AG-80/m-XDA system, the apparent activation energy increases with the conversion rates increasing and the reaction model is the Jander equation (three-dimensional diffusion, 3D, n = 1/2). The experimental results show that the density, compressive strength, saturated water absorption and water absorption rate of the composite with 55 v % HGM are 0.668 g·cm−3, 107.07 MPa, 0.17% and 0.025 h−1/2, respectively. This kind of composite can probably be used as a deep-sea buoyancy material.

Highly conducting solid electrolyte films based on PVA and iron alum: Synthesis, characterization and electrical properties

Abstract Excellent conducting solid polymer electrolyte films were prepared by using Polyvinyl alcohol (PVA) and Iron alum through a reactive blending process. The effect of the concentration of the iron alum on the conducting behavior was studied in detail by varying the concentration of the alum in the PVA matrix. The functionality was studied using the Infrared (FT-IR) spectroscopic technique. A thermal analysis of the synthesized polymer blend was made using the differential scanning calorimetric (DSC) method, indicating that the material possesses an excellent thermal response. The FT-IR and X-ray photoelectron spectroscopy (XPS) analyses confirm that the hydroxyl group of PVA is involved in the chemical reaction with the added iron alum. An X-ray diffraction (XRD) analysis confirms that the crystallinity is enhanced upon increasing the alum content. Scanning electron microscopy (SEM) along with XPS analysis reveals the presence of the desired atoms in the polymer film. The highest AC conductivity of 1.09 × 10−1 Scm−1 at 100 °C is obtained with in this system and the AC conductivity obeys the Jonscher power law.

Structural and dynamical characterisation of intermediate water interacting polyvinyl pyrrolidone

Polyvinyl pyrrolidone (PVP) is well known as a biocompatible polymer used in the fields of medical devices and pharmaceuticals, and is associated with intermediate water, which is said to play an important role in developing the biocompatibility of medical materials. The states of water molecules interacting with PVP, i.e., the non-freezing water, slow and fast intermediate water are classified using 2H NMR. The non-freezing water is directly hydrogen-bonded to ca. 1.5 amide groups of PVP. The slow intermediate water interacts with PVP indirectly through non-freezing water. It then shows slow diffusion dynamics and forms cubic-form ice during cold crystallisation, while the fast intermediate water can diffuse as fast as free water, and can freeze to form normal hexagonal-form ice. Statement of significanceFor many of the medical materials, including artificial organs such as dialysis membranes and artificial blood vessels, polymers are used. Biocompatibility of polymer is an important property for materials used in medical devices and medicine. Although there are lots of studies about surface design of materials in terms of hydrophilicity, charge, or morphology, the unified expression factor of biocompatibility have not been clear. Recently, it is suggested that water molecules, especially intermediate water, on materials surface play important roles in the development of biocompatibility. However, the characteristics of the intermediate water have not been understood. It is important issues to be solved in the development of new and high-performance biocompatible polymer materials based on the concept of intermediate water.In present study, we have investigated the intermediate water on polyvinyl pyrrolidone (PVP), which is biocompatible polymer widely used in medical device and medicine. Differential scanning calorimeter (DSC), X-ray diffraction (XRD), and various nuclear magnetic resonance (NMR) methods for PVP aqueous solutions were performed in order to clarify the physical properties of the intermediate water. We found that the intermediate water has structural order and diffusive mobility just between free water and non-freezing water. These features of intermediate water are induced by structural interaction with polymer. The knowledge from present study expected to provide guidance for the design of biocompatible materials.