Thermal Properties (thermal + property)

Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Kinds of Thermal Properties

  • good thermal property

  • Selected Abstracts


    ABSTRACT Tensile strength (TS), elongation at break (EAB) and elastic modulus (EM) of edible films prepared from 5, 7 and 9% whey protein isolate (WPI) plasticized with different levels of glycerol (Gly) (WPI : Gly = 3.6:1, 3:1 and 2:1) were investigated in order to completely characterize WPI-Gly films. On increasing protein concentration an increase in TS and EAB was observed. On the other hand, increasing Gly led to a decrease in TS and EM, while EAB increased. The addition of pullulan (Pul) into the film forming solution (FFS) increased EAB while TS, EM and thermal properties were reduced. This suggested that Pul had a similar effect as plasticizers. Films with higher Pul content showed lighter protein bands on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Fourier transform infrared spectroscopy showed that hydrogen bonding was high in WPI : Pul films as compared with the control. This is attributed to the protein-polysaccharide interactions brought about by the dominance of Pul in the FFS. PRACTICAL APPLICATIONS This work describes some physical properties of films based on blends of whey protein isolate (WPI) and pullulan (Pul), made after a previous study on some characteristics of films based on pure WPI plasticized by glycerol. The most studied proteins in the edible films technology being gluten and WPI, the use of Pul in mixture with WPI is considered as a new investigation to explore the utilization of WPI-Pul in edible film and coating materials applied to food products. Furthermore, the use of WPI-Pul films and coatings could potentially extend the shelf life and improve the stability of the coated products as shown by the resultant properties in this investigation and previous works. [source]


    M.O. NGADI
    ABSTRACT Thermal properties of fried products namely butterfly and popcorn shrimp, French toast and breading were determined for a wide range of temperature (20 to 140C), moisture content (3.3 to 87.4% w.b.) and fat content (0.005 to 0.618 kg/kg dry weight) typically encountered during deep-fat frying. Solid density of the products ranged from 1034 to 1508 kg/m3. Solid density increased with decreasing moisture content of product. Thermal conductivity ranged from 0.03 to 0.85 W/mC. Specific heat ranged from 1.51 to 4.67 kJ/kgC. The results were in the range of published data for similar products. Temperature, moisture and fat content affected variations of thermal conductivity and specific heat. Regression equations were used to fit experimental data. [source]


    ABSTRACT Eight trained assessors evaluated one visual, eight texture and four gustative attributes of 15 commercial spreads. In addition, 100 consumers evaluated the acceptability of the spreads. Rheological behavior of the samples was evaluated in transient (stress,relaxation test) and dynamic (strain and frequency sweep test) shear mode. Thermal measurements were also performed. Finally, the microstructure of the samples was analyzed by scanning electron microscopy. Partial least squares regression was used to predict acceptability from sensory attributes and texture from instrumental data. Scanning electron micrographs indicated that spreads differed in morphology, size and distribution of hazelnut particles. Overall liking of the spreads was found to be related to hazelnut flavor and texture attributes. Prediction of the most important texture properties from instrumental measurements was quite successful, especially for spreadability which was found negatively related to the consistency and flow indices and, secondly, for meltability which was found to be strongly dependent on measured thermal parameters. PRACTICAL APPLICATIONS This study contributes to knowledge development in the research area of acceptability, sensory and instrumental correlation for semi-solid foods. The results confirm that texture properties of spreadable foods play a most important role in consumer acceptability. The research also allows better understanding as to why no single measurement is able to predict all texture attributes adequately and why more appropriate tests need to be developed for an accurate prediction of some sensory attributes as perceived by the human senses. [source]

    Minerals as Model Compounds for Cu/ZnO Catalyst Precursors: Structural and Thermal Properties and IR Spectra of Mineral and Synthetic (Zincian) Malachite, Rosasite and Aurichalcite and a Catalyst Precursor Mixture

    Malte Behrens
    Abstract The Cu/ZnO system is a model for Cu/ZnO/Al2O3 catalysts, which are employed industrially for the synthesis of methanol. These catalysts are usually prepared from mixed basic carbonate precursors. A complex phase mixture, with constituents structurally related to the minerals rosasite andaurichalcite, is present at the industrially applied composition (Cu/Zn , 70:30). Using minerals and phase-pure synthetic samples as references, a comprehensive characterisation of such a phase mixture, including the determination of the individual compositions of the different phases, has been attempted by complementary analytical laboratory techniques (XRD, TGA, IR). The results are critically discussed in light of the complexity of the system. A thermally very stable carbonate species , well-known for mixed synthetic systems , is also detected for the mineral reference samples. Significant amounts of amorphous phases are found to be present in the synthetic zincian malachite sample but not in synthetic aurichalcite or the catalyst precursor. A simplified explanation for the shift of the characteristic 20 reflection of the malachite structure as a function of Zn incorporation based on the varying average Jahn,Teller distortion of the MO6 octahedra is proposed. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

    Substituent Effects on Crosslike Packing of 2,,7,-Diaryl- spiro(cyclopropane-1,9,-fluorene) Derivatives: Synthesis and Crystallographic, Optical, and Thermal Properties,

    Z. Wang
    Abstract A series of 2,,7,-diarylspiro(cyclopropane-1,9,-fluorene) derivatives are efficiently synthesized and characterized to determine the reason for the "green-light" emission of these compounds. These compounds exhibit bright-violet to blue photoluminescence (PL) (,PLmax,=,353,419,nm) with excellent PL quantum efficiencies (,PL,=,83,100,%) in solution and show high thermal stabilities (Td,=,267,474,C). The variation of the optical properties of these molecules in the solid state depends on the different stacking modes of these compounds containing different substituents, which are revealed by crystallographic analysis. CH,, hydrogen bonds instead of intermolecular ,,, interactions act as the driving force between adjacent fluorenes, even though a very small dialkyl group (cyclopropane) is introduced at the C-9 position of fluorene. The crosslike molecular stacking efficiently reduces the energy transfer between the herring-like aggregates and therefore results in the absence of a "green-light" emission tail. In order to determine the cause of the "green-light" emission tails, the fluorescence spectra of the films annealed in N2 or in air are recorded. Broad green-light emission tails were observed for the films annealed in air, which might be caused by fluorenone defects generated during processing or during the course of the photophysical analysis by reaction with residual oxygen. [source]

    Rheological and Thermal Properties of Polylactide/Silicate Nanocomposites Films

    Jasim Ahmed
    ABSTRACT:, Polylactide (DL)/polyethylene glycol/silicate nanocomposite blended biodegradable films have been prepared by solvent casting method. Rheological and thermal properties were investigated for both neat amorphous polylactide (PLA-DL form) and blend of montmorillonite (clay) and poly (ethylene glycol) (PEG). Melt rheology of the PLA individually and blends (PLA/clay; PLA/PEG; PLA/PEG/clay) were performed by small amplitude oscillation shear (SAOS) measurement. Individually, PLA showed an improvement in the viscoelastic properties in the temperature range from 180 to 190 C. Incorporation of nanoclay (3% to 9% wt) was attributed by significant improvements in the elastic modulus (G,) of PLA/clay blend due to intercalation at higher temperature. Both dynamic modulii of PLA/PEG blend were significantly reduced with addition of 10% PEG. Rheometric measurement could not be conducted while PLA/PEG blends containing 25% PEG. A blend of PLA/PEG/clay (68/23/9) showed liquid-like properties with excellent flexibility. Thermal analysis of different clay loading films indicated that the glass transition temperatures (Tg) remained unaffected irrespective of clay concentration due to immobilization of polymer chain in the clay nanocomposite. PEG incorporation reduced the,Tg of the blend (PLA/PEG and PLA/PEG/clay) significantly. Both rheological and thermal analysis data supported plasticization and flexibility of the blended films. It is also interesting to study competition between PLA and PEG for the intercalation into the interlayer spacing of the clay. This study indicates that PLA/montmorillonite blend could serve as effective nano-composite for packaging and other applications. [source]

    Thermal Properties, Heat Sealability and Seal Attributes of Whey Protein Isolate/ Lipid Emulsion Edible Films

    S-J. Kim
    ABSTRACT: From 5% w/v whey protein isolate (WPI), whey protein/lipid emulsion edible films were produced that were sorbitol- or glycerol-plasticized, containing butterfat (0.2% w/v) or candelilla wax (0.8% w/v). Thermal properties of the films determined by Differential Scanning Calorimetry (DSC) showed onset temperatures (To) of 126 to 127 C for sorbitol- and 108 to 122 C for glycerol-plasticized films. To values were used as the basis for heat sealing temperatures. Temperature (110, 120, 130 C), pressure (296,445 kPa), and dwell time (1,3 s) affected seal strength. Optimum heat sealing temperature was 130 C for sorbitol- and 110 C for glycerol-plasticized films. All films were heat sealable with an impulse heat-sealer. Electron Spectroscopy for Chemical Analysis (ESCA) of the surfaces of both sealed and unsealed films showed increase in hydrogen and covalent bonds involving C-O-H and N-C, which may be the main forces responsible for the sealed joint formation of the films. [source]

    Effect of the Starting Microstructure on the Thermal Properties of As-Sprayed and Thermally Exposed Plasma-Sprayed YSZ Coatings

    Yang Tan
    Thermal barrier coatings (TBCs) experience thermal gradients, excessive temperature, and high heat flux from hot gases in turbines during service. These extended thermal effects induce sintering and significant microstructure changes, which alter the resulting thermal conductivity of the TBCs. To study the effects of different starting microstructures on the sintering behavior, plasma-sprayed yttria-stabilized zirconia (YSZ) TBCs produced from different starting powders and process parameters were subjected to thermal aging at several temperatures and time intervals, after which their thermal conductivity was measured at room temperature. The thermal conductivity results were analyzed by introducing the Larson,Miller parameter, that describes the creep-like behavior of thermal conductivity increase with annealing temperature and time. One set of coatings was also annealed under the same conditions and the thermal conductivities were measured at elevated temperatures. The temperature-dependent thermal conductivity data were analyzed and used to predict the long-term thermal property behavior for a general YSZ coating design. [source]

    Spectroscopic and Thermal Properties of Ga2S3,Na2S,CsCl Glasses

    Luiz C. Barbosa
    The synthesis and properties of the vitreous system (0.75,x)Ga2S3,0.25Na2S,xCsCl, with x varying from 0.1 to 0.2, are presented. Thermal, optical, and structural properties such as density, viscosity, thermal expansion coefficient, glass transition temperature, softening point temperature, refractive index, and absorption coefficient were measured using several techniques: X-ray diffraction, Raman scattering, differential thermal analysis, thermal mechanical analysis, and absorption spectroscopy. This glass system presents a high third-order non-linear optical susceptibility that can be significantly increased by increasing the CsCl content without affecting the low phonon frequency. [source]

    Structural, Dielectric, and Thermal Properties of Strontium Barium Niobate-Doped Fused Silica Nanocomposites

    Sheng-Guo Lu
    Ferroelectric strontium barium niobate (SBN)-doped Na2O,B2O3,SiO2 (NBS) glass nanocomposites were prepared by dispersing sol,gel-derived SBN powder into fused NBS glass. Their structures were characterized by X-ray diffractometry and Raman spectroscopy. The dielectric constants were measured as functions of frequency and temperature using an impedance analyzer. The ferroelectric-to-paraelectric-phase transition was studied by differential scanning calorimetric analysis. Our results revealed that the embedded SBN has lower phase transition temperature and phase transition heat than those of SBN bulk materials. Their activation energy, however, is larger than that of SBN ultra-fine powders. Pure tetragonal-phase SBN nanocomposites can be obtained at annealing temperatures of 750,1000C. Their dielectric constants are ,32,46 and ,20,25 at low frequencies and radio frequencies, respectively, and the loss tangent is <0.1 at room temperature in the radio frequencies range. Our studies suggested that additional reduction in the loss properties must be made before these systems can be considered for application as microwave dielectric materials. [source]

    On the Interrelationship of Transreactions with Thermal Properties and Dynamic Mechanical Analysis of PTT/PEN Blends

    Seyed-Hassan Jafari
    Abstract An attempt was made to explore the effects of interchange reactions on the crystallization, melting, and dynamic mechanical behavior of binary blends based on poly(trimethylene terephthalate) (PTT)/poly(ethylene 2,6-naphthalate) (PEN). 1H NMR spectroscopy is used to verify the occurrence of interchange reactions at the interface, which are increased upon an increase in the melt processing time and temperature. The crystallinity of PTT was reduced while that of PEN was increased on blending. In addition, the crystallization temperatures of both phases showed depression. A single composition-dependent glass transition temperature (Tg) was detected in the second and subsequent heating thermograms of the blends, which is indicative of miscibility. The cold crystallization of the PTT phase was observed to increase while that of PEN was suppressed on blending. Each phase crystallized individually and a melting point depression was evident, which suggests a certain level of miscibility. Dynamic mechanical thermal analysis corroborated differential scanning calorimetry results. A constructive synergism was observed in the glassy state storage moduli of the blends, which is suggestive of a reduced specific volume of the system because of enhanced interactions and crystallinity. [source]

    Cellulose Acetate- graft -Poly(hydroxyalkanoate)s: Synthesis and Dependence of the Thermal Properties on Copolymer Composition

    Yoshikuni Teramoto
    Abstract Summary: Several different series of cellulose acetate- graft -poly(hydroxyalkanoate)s (CA- g -PHAs) were synthesized over a wide range of compositions by the graft copolymerization of lactic acid, L -lactide, (R,S)- , -butyrolactone, , -valerolactone and , -caprolactone onto the residual hydroxyl positions of CA, by virtue of a suitable catalyst, solvent and procedure for each individual case. To achieve a diversity of molecular architectures of the respective graft copolymer series, the degree of acetyl substitution (acetyl DS) of the CA starting material was also varied, resulting in different levels of the intramolecular density of grafts. The CA- g -PHAs thus obtained were subjected to differential scanning calorimetric measurements and the relationship between their molecular structure and thermal transition behavior was estimated, in comparison with some semi-empirical equations available for polymer blends or comb-like polymers. In particular, the composition dependence of the Tgs of the graft copolymers was represented well in terms of a formula proposed by Reimschuessel for comb-like polymers, when CAs of acetyl DS ,2 were employed as a trunk polymer. The deviation of the glass transition data from the model function was discussed in connection with the manner of graft modification. [source]

    Structural, Electrical, Mechanical, and Thermal Properties of Electrospun Poly(lactic acid)/Polyaniline Blend Fibers

    Paulo H. S. Picciani
    Abstract Conducting electrospun fiber mats based on PLA and PAni blends were obtained with average diameter values between 87 and 1 006,nm with PAni quantities from 0 to 5.6 wt.-%. Structural characteristics of fiber mats were compared to cast films with the same amount of PAni and studied by SEM, SAXS, and AFM. Thermal properties of fiber mats and cast films were compared by DSC analyses. Mechanical properties of fiber mats were also evaluated. It was found that electrospinning process governs the crystal structure of the fibers and strongly affects fiber properties. New properties of PLA/PAni blends are reported due to the size fiber reduction. [source]

    Polyurethanes Based on Castor Oil: Kinetics, Chemical, Mechanical and Thermal Properties

    Elodie Hablot
    Abstract Polyurethanes based on vegetable oil were synthesized with castor oil and toluene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate, using dibutyltin dilaurate as a catalyst. The effects of the nature of the diisocyanate on the evolution of the kinetics, as well as the physical and mechanical properties and the thermal stability, of the different synthesized polyurethanes were investigated, and these complement data from the literature on equivalent systems. The polymerization kinetics, degree of swelling and mechanical properties were greatly affected by the diisocyanate nature, whereas the rheological properties and thermal stability were found to be similar for all polyurethanes. [source]

    Fully Crosslinked Poly[cyclotriphosphazene- co -(4,4,-sulfonyldiphenol)] Microspheres via Precipitation Polymerization and Their Superior Thermal Properties

    Lu Zhu
    Abstract Fully crosslinked, stable poly[cyclotriphosphazene- co -(4,4,-sulfonyldiphenol)] (PZS) microspheres have been prepared via the polycondensation between hexachlorocyclotriphosphazene and 4,4,-sulfonyldiphenol by precipitation polymerization. The diameter of the PZS microspheres ranged from 0.6 to 1.0 m with the specific surface area of the microspheres ranging from 11.7 to 10.1 m2,,g,1. The formation of the non-porous microspheres was observed to obey an oligomeric species absorbing mechanism. The fully crosslinked chemical structure of the PZS microspheres were determined by IR, CP/MAS NMR, XRD, and EDX. No glass-transition temperature was observed and the onset of the thermal-degradation temperature was 542,C. Thermal stability of the PZS microspheres by the precipitation polycondensation was significantly improved as compared with crosslinked microspheres produced by addition polymerizations. [source]

    A Study on the Metal Organic CVD of Pure Copper Films from Low Cost Copper(II) Dialkylamino-2-propoxides: Tuning the Thermal Properties of the Precursor by Small Variations of the Ligand,

    R. Becker
    Abstract Pure copper metal thin films were grown on SiO2/Si(100) substrates by metal,organic (MO) CVD in a horizontal cold-wall reactor employing the two metal,organic compounds, Cu(OCHMeCH2NR2)2, where R,=,Et (1) and R,=,Me (2) as precursors. Thermogravimetric analyses proved them to be convenient compounds for the deposition of copper without a reducing agent. Depositions were carried out at various substrate temperatures in the range 230,350,C. X-ray diffraction (XRD) indicated that the resulting films were highly crystalline and showed a strong (111) preferred orientation, which increased with increasing deposition temperature. Photoelectron spectroscopy (XPS) revealed that copper films deposited at 230,C and 260,C consisted solely of metallic copper with no detectable carbon, nitrogen, or oxygen contamination. Copper films obtained from 1 at 260,C had a resistivity of 2.16,,,,cm. [source]

    Crystal Structure and Thermal Properties of La1-xCaxCoO3-, (0 , x , 0.4).

    CHEMINFORM, Issue 23 2006
    Johann Mastin
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

    Template-Assisted Solvothermal Synthesis of Five Copper(I)-Thioantimonate(III) Composites: Crystal Structures and Optical and Thermal Properties of (C6N2H18) 0.5Cu2SbS3, (C4N3H15) 0.5Cu2SbS3, (C8N4H22) 0.5Cu2SbS3, (C4N3H14) Cu3Sb2S5, and (C6N4H20) 0.5Cu3Sb2S5.

    CHEMINFORM, Issue 43 2005
    V. Spetzler
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Solvothermal Syntheses, Crystal Structures, and Thermal Properties of New Manganese Thioantimonates(III): The First Example of the Thermal Transformation of an Amine-Rich Thioantimonate into an Amine-Poorer Thioantimonate.

    CHEMINFORM, Issue 29 2004
    Michael Schaefer
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Preparation of LLDPE/MgAl-LDH Exfoliation Nanocomposites with Enhanced Thermal Properties by Melt Intercalation

    Long-Chao Du
    Abstract The interlayer surface of MgAl layered double hydroxide (MgAl-LDH) was modified by exchanging about half of the interlayer nitrate anions by dodecyl sulfate anions (DS) to get MgAl(H-DS) LDH, and then the MgAl(H-DS) was melt intercalated by LLDPE to get the LLDPE/MgAl-LDH exfoliation nanocomposites. The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), ion chromatography, transmission electron microscopy (TEM), and thermogravimetry analysis (TGA). The nanoscale dispersion of MgAl-LDH layers in the LLDPE matrix was verified by the disappearance of (00l) XRD reflection of the modified MgAl-LDH and by the TEM observation. The TGA profiles of LLDPE/MgAl-LDH nanocomposites show a faster charring process between 210 and 370 C and a higher thermal stability above 370 C than LLDPE. The decomposition temperature of the nanocomposites with 10 wt% MgAl(H-DS) can be 42 C higher than that of LLDPE at 40% weight loss. [source]

    Nitrogen-rich 6-(3,5-Dimethylpyrazol-1-yl)-3-(2,4,6-trinitro-anilino)-1,2,4,5-tetrazin: Synthesis, Crystal Structure and Thermal Property

    Wan-Long PAN
    Abstract 6-(3,5-Dimethylpyrazol-1-yl)-3-(2,4,6-trinitroanilino)-1,2,4,5-tetrazin (1) has been synthesized and characterized by 1H NMR, MS, elemental analysis, infrared spectra and thermal analyses. The crystal structure was determined by X-ray diffraction method. 1 is crystallized in P21/c space group of monoclinic crystal system, and exhibits good physical properties, such as high densities (>1.55 gcm,3) and good thermal stabilities (Td>220 C). The intrermolecular hydrogen bonds construct the P - and M -helices from organic molecules and may contribute to the high melting points. [source]

    Thermal properties of conduction current and carrier behavior in an organic electroluminescent device

    Masahiro Minagawa
    Abstract Organic electroluminescent device (OLED) was fabricated using a vacuum evaporation method and thermal properties were investigated. The OLED has an indium tin oxide (ITO)/N,N,-diphenyl- N,N,-bis(3-methylphenyl)-1,1,-biphenyl-4,4,-diamine (TPD)/tris(8-hydroxyquinoline) aluminum (Alq)/lithium fluoride (LiF)/aluminum (Al) structure. An electron-dominant device of Al/Alq/LiF/Al structure, or a hole-dominant device of ITO/TPD/Al structure was also fabricated in order to study the carrier behavior in the OLEDs. The current density versus voltage (J,V) properties with various thickness of organic layers were investigated in both electron- and hole-dominant devices, and the thermal dependence of J,V properties was observed in the devices. At room temperature, conductions in a wide current region were considered to be due to space-charge-limited current for all of the devices. Especially for the Al/Alq/LiF/Al device and the OLED, relationships were observed across a wide current region. At low temperature, tunnel currents were estimated for the ITO/TPD/Al device. For the Al/Alq/LiF/Al device and the OLED, relationships were observed across a wide current region at low temperature. 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(3): 24,31, 2009; Published online in Wiley InterScience ( DOI 10.1002/ecj.10048 [source]

    Thermal properties of lightweight-framed construction components at elevated temperatures

    FIRE AND MATERIALS, Issue 3 2005
    Noureddine Bnichou
    Abstract Fire resistance behaviour of lightweight-framed assemblies is determined by defining the thermal and structural performances of the assembly when exposed to fire. To adequately model thermal behaviour in a lightweight wood-framed assembly, thermal properties of the components of the assembly at elevated temperatures must be well defined. This paper presents results of measurements of thermal properties at elevated temperatures of construction materials commonly used to build lightweight wood-framed assemblies that were conducted at the National Research Council of Canada since 1990. The test results, in graphical form, are given as a function of temperature for thermal conductivity, specific heat, mass loss and thermal expansion/contraction for wood, gypsum and insulation. In addition, the effects of temperature on the thermal conductivity, specific heat, mass loss and thermal expansion/contraction of these materials are discussed. Finally, in addition to providing a resource of information, this paper also identifies the additional thermal property tests required to complete the matrix of information. Copyright 2005 Crown in the right of Canada. Published by John Wiley & Sons, Ltd. [source]

    Full scale experiments for evaluating theoretical fire wall models

    FIRE AND MATERIALS, Issue 6 2004
    P. Clancy
    Abstract The aim of the research described in this paper was to provide experimental results for the evaluation of theoretical models for predicting the behaviour and time-to-failure of loadbearing and non-loadbearing wood framed walls in fire. References for thermal and mechanical properties of wood and gypsum board are given to provide comprehensive input for the evaluation of theoretical wall models. The scope of the research involved full-scale uninsulated cavity walls with well-controlled clearly known conditions including initial ambient vertical load capacity for benchmarking the reduction in capacity and stiffness, rotational stiffness of supports, eccentricity of vertical load, elastic moduli of wood and gypsum board in compression, stiffness of slip between gypsum board and studs and end stud effects. The experiments were repeated and they demonstrated that the controls led to high consistency in the results despite the inherent large variability of the mechanical properties of wood. The results include temperature distributions, initial vertical load capacity, load-deflection plots and times-to-failure. The results show that the temperatures in the studs are approximately uniform until all the moisture is vaporized. Thermal properties of wood will not vary significantly for consistent density, moisture content and species of wood. The main structural actions that should be modelled for different loading regimes are deduced. Copyright 2004 John Wiley & Sons, Ltd. [source]

    Thermal properties of gypsum plasterboard at high temperatures

    FIRE AND MATERIALS, Issue 1 2002
    Geoff Thomas
    Light timber frame wall and floor assemblies typically use gypsum-based boards as a lining to provide fire resistance. In order to model the thermal behaviour of such assemblies, the thermo-physical properties of gypsum plasterboard must be determined. The relevant literature and the chemistry of the two consecutive endothermic dehydration reactions that gypsum undergoes when heated are reviewed. The values determined for the thermo-physical properties are modified to create smooth enthalpy and thermal conductivity curves suitable for input into a finite element heat transfer model. These values are calibrated within a reasonable range and then validated using furnace and fire test data. The type of plasterboard used in these tests is an engineered product similar to the North American type C board. The temperature at which the second dehydration reaction occurs is altered to be consistent with later research with little apparent affect on the comparison with test results. Values for specific heat, mass loss rates and thermal conductivity for gypsum plasterboard that are suitable for use in finite element heat transfer modelling of light timber frame wall and floor assemblies are recommended. Copyright 2002 John Wiley & Sons, Ltd. [source]

    Antimicrobial activity studies of the metal complexes derived from cyclobutane-substituted thiazole carbamate ligands

    Alaaddin ukuroval
    Two novel monodentate carbamate ligands derived mainly from 4-(1-methyl-1-phenylcyclobutyl-3-yl)-2-aminothiazole and 4-(1-phenyl-1-methylcyclobutane-3-yl)-2-(N -methyl)aminothiazole, have been prepared. The ligands and their metal complexes have been characterized by elemental analyses, IR, 13C, and 1H NMR spectra, as well as UV,Vis, and magnetic susceptibility measurements. Both ligands contain 1 mole of water of crystallization and all complexes are mononuclear. Antimicrobial activities of the ligands and their complexes have been screened against the Bacillus subtitis IMG 22 (bacteria), Micrococcus luteus LA 2971 (bacteria), Escherichia coli DM (bacteria), Staphylococcus aureus COWAN I (bacteria), Saccharamyces cerevisiae UGA 102 (yeast), and Candida albicans CCM 314 (yeast). Thermal properties of the ligands and their complexes have been studied by thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC). 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:665,670, 2001 [source]

    Ground water level influence on thermal response test in Adana, Turkey

    . Bozda
    Abstract For optimum design of borehole thermal energy storage (BTES) and ground sources heat pump (GSHP) applications, determination of underground thermal properties is required. The design and economic feasibility (number and depth of boreholes) of these systems need thermal conductivity of geological structure, , (W,m,1,K,1), and thermal resistance of ground heat exchanger, R (K,W,1,m). Thermal properties measured in laboratory experiments do not coincide with data of in situ conditions. Therefore, in situ thermal response test equipment has been developed and used in Canada, England, Germany, Norway, U.K., U.S.A. and Sweden to ensure precise designing of BTES systems. This paper describes the results and evaluations of the Adana continual thermal response test measurements. Copyright 2007 John Wiley & Sons, Ltd. [source]

    Surface modification of PHBV films with different functional groups: Thermal properties and in vitro degradation

    Yu Ke
    Abstract Polyacrylamide was photografted on solution-cast poly(3-hydroxybutyric acid- co -3-hydroxyvaleric acid) (PHBV) films (amide-PHBV), on which amide groups were transformed into amine groups through Hofmann degradation reaction (amine-PHBV), followed by collagen coupling reaction to prepare collagen-modified PHBV (collagen-PHBV). Amide-, amine-, and collagen-PHBV had higher water absorption and d -spacing values than PHBV, and melting temperatures and enthalpies decreased in the order of collagen-PHBV < amine-PHBV < amide-PHBV < PHBV. Thermal decomposition kinetics of PHBV component in the films has been investigated by means of nonisothermal thermogravimetric and derivative thermogravimetric studies. Applying the Avrami-Erofeev equation with index of 2/5 as the probable kinetic function, the suitable activation energy was calculated by the Friedman method through linear fitting (correlation coefficient > 0.98). The activation energy of PHBV was lower than that of amide-PHBV but higher than that of amine- and collagen-PHBV. Being incubated in phosphate-buffered saline at 37C, the modified PHBV films showed more weight loss than PHBV during 360 days; however, pH of degradation fluids was nearly neutral as the initial pH was recorded at 7.2. The modified PHBV films with different functional groups may provide an improved biodegradation rate for various cytocompatible biomaterials constructs. 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Thermal properties and flame retardancy of polyglycidyloxypropyl silsesquioxane/layered titanate nanocomposites

    Miyuki Harada
    Abstract Polyglycidyloxypropyl silsesquioxane, which has an excellent heat resistance, was combined with sheet-like and spherical titanate as nano-fillers. The burning property of the composites was related to the shape of the dispersed titanate. A burning test was carried out according to the UL-94 test method. As a result, though the test specimen burned from one end to the other in the spherical titanate filled composite system, a fire extinguishing property was observed in the sheet-like titanate filled composite system. The extinguishing time of the latter system classified V-0 in the specification test. 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Direct fluorination of Twaron fiber and investigation of mechanical thermal and morphological properties of high density polyethylene and Twaron fiber composites

    J. Maity
    Abstract Composites consisting of high density polyethylene (HDPE) reinforced with randomly oriented chopped Twaron fibers (both fluorinated and nonfluorinated) show a significant increase in mechanical and thermal properties. To increase the better fiber matrix adhesion, the Twaron fiber is surface fluorinated using elemental fluorine. The surface of the Twaron fiber becomes very rough and the diameter of Twaron fiber increases from , 12 to 14 ,m after fluorination. The composites were prepared using solution method to overcome the damage of the fiber. The tensile strength and the Young's modulus increases with increasing fiber content. The tensile strength and modulus of modified fiber (fluorinated Twaron fiber) composites is much higher than nonmodified fiber composites indicating that there is better mechanical interlocking between the modified fiber and the matrix. Thermal properties obtained from DSC and DTA-TG analysis of the fluorinated fiber composites are also improved. Contact angle measurements, as well as the surface energy measurements, indicate that the composites are more wettable and is maximum for fluorinated fiber composites i.e., surface energy for fluorinated fiber composites is highest. Crystallinity is also higher for fluorinated fiber composites. 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source]