Home > Application library > Articles
Articles
Results 1 to 20 of 3432 articles
| Pages |
1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 . 9 . 10 . 11 . 12 . 13 . 14 . 15 . 16 . 17 . 18 . 19 . 20 . 21 .   |
T0048 - Weak solid-solid transitions in pharmaceutical crystalline solids detected via thermally stimulated current
To demonstrate the ability of thermally stimulated current (TSC), normally used to study amorphous systems, in detecting weak solid-solid transitions in crystalline pharmaceutical compound. Methods: Polymorphs of a new chemical entity, LAU254, were generated and characterized using conventional and hot plate X-ray diffraction, DSC and TSC. Equilibration of 50:50 mixtures of the different polymorphs and solubility studies were conducted in aqueous and organic solvent at 25 and 50 ?C and then analyzed by X-ray and DSC. Results: Four crystalline forms (A-D) were isolated. formBshowed one single endotherm at 180 ?Cwhile the other forms showed lower melting endotherms, a crystallization exotherm and eventually a final melting endotherm corresponding to that of form B (180 ?C). The heat of fusion of form B was the highest. In contrast, solubility as well as mixture equilibration studies resulted in all forms converting to form A. TSC analysis revealed a well-defined reproducible peak with a maximum at ?130 ?C which was suspected to be a solid-solid transition. This was confirmed by hot plate X-ray diffraction where careful probing around 120-130 ?C revealed three different forms; form A (the initial form), a second form that appears above 150 ?C, melts, crystallizes and produces form B. Careful inspection of larger sample sizes in DSC showed a small endotherm at ?130 ?C. Conclusions: TSC, normally used to study amorphous systems, proved to be useful in detecting weak solid-solid transitions in crystalline pharmaceuticals, an application that has never been explored or reported previously. This resulted in identifying a form, obtainable only at temperatures above the transition temperature (related enantiotropically to the form that is most stable at ambient temperatures) and in reconciling the DSC and solubility data. TSC can be very useful in detecting and probing those transitions that occur in the solid state due to subtle dipolar motion and are not associated with large changes in global motion and heat capacity that is needed for detection by DSC and therefore can be complementary to DSC in obtaining a more complete assessment of the polymorphism behavior of crystalline solids.
Rama A. Shmeis, Steven L. Krill Thermochimica acta (2004) article in press
T0047 - Thermal analysis of complex relaxation processes in poly(desaminotyrosyl-tyrosine arylates)
The goal of this study is to better understand the thermal characteristics and molecular behavior of two poly(desaminotyrosyl-tyrosine arylates). These two polymers were chosen from a combinatorial library of polymers developed by changing the type and size of the two substitutable chain locations. The objective of this work was to describe the origin of the complex relaxation processes that have been observed by thermal analysis methods. DSC, TMA and TSC studies were conducted on poly(desaminotyrosyl-tyrosine dodecyl dodecanedioate), poly(DT 12,10), and poly(desaminotyrosyl-tyrosine ethyl succinate), poly(DT 2,2), in film and fiber form. DSC experiments on poly(DT 2,2) show only a glass transition at about 80°C which is characteristic of an amorphous polymer. The DSC of poly(DT 12,10) shows multiple thermal events indicative of a more complex internal structure. The thermally stimulated current (TSC) analysis results for poly(DT 2,2) indicate a region of molecular mobility at about 80°C consistent with the Tg from DSC. For poly(DT 12,10) there is a dipole relaxation process observed at about 40°C. An additional region of mobility at 60°C for poly(DT 12,10) fibers is observed. The comparison of conventional TSC with a modified TSC procedure suggests that this process represents a spontaneous reorganization of the internal structure of the solid. The comparison of DSC and TSC results suggests that poly(DT 12,10) has two distinct modes of organization with a transition between these modes at about 60°C. Previously published results indicate that solid state structure formation is related to two different modes of hydrogen bonding in the internal structure of the solid.
G. Collins, S-U. Yoo, A. Recber, M. Jaffe, Polymer 48 (2007) 975-988
T0046 - Process-structure-property relationships of erodable polymeric biomaterials: II--long range order in poly(desaminotyrosyl arylates)
The long-range order of some bioerodable polyesteramides based on a desaminotyrosyl [Thermochim Acta 396 (2003) 141; Polym Adv Technol 13 (2002) 926; J Am Chem Soc 119 (1997) 4553] diol monomer has been investigated. The order is mesogenic, best described as a 'condis crystal' or smectic-like. In all cases where long-range order is present, ordered H bonds between amide groups are observed. The order stabilizes the polymer to dimensional change and mechanical relaxation under biorelevant conditions.
M. Jaffe, Z. Ophir, G. Collins, A. Recber, S-U. Yoo, J.J. Rafalko, Polymer 44 (2003) 6033-6042
T0045 - Characterisation of EVA encapsulant material by thermally stimulated current technique
The purpose of this investigation is to better define the thermal behaviour of EVA-based encapsulant during photovoltaic module encapsulation process and also in field exposure in desert climate using the thermally stimulated current (TSC) technique. TSC experiments were conducted on EVA in the temperature range from -150°C to 70°C, the measurements were carried out on uncured and cured specimens of EVA and on EVA samples especially prepared using the laminator equipment. When performing the measurements with the TSC instrument it was noted that the EVA exhibits two peaks assigned to dipole relaxation processes. The peak maximum current and the area under the TSC current peak were used for the determination of the glass transition temperature, activation energy and relaxation frequency. For original EVA, we found that glass transition temperature at constant polarisation voltage and under different polarisation temperatures remain unchanged and is located around -38°C. Also, the activation energy has been determined using initial rise method to be about 0.32 eV. At gel content of 70%, the cured EVA shows a reduced integrated area under the depolarisation peak, especially for the high temperature. The combined change in TSC peak parameters of EVA encapsulant is correlated with the degree of curing.
K. Agroui, G. Collins, Solar Energy Materials & Solar Cells 80 (2003) 33-45
T0044 - A mechanistic investigation of an amorphous pharmaceutical and its solid dispersions. Part II: Molecular mobility and activation thermodynamic parameters
The ability of TSDC to characterize further amorphous materials beyond that possible with DSC was presented in part I (16) of this work. The purpose of part II presented here is to detect and quantitatively characterize time-scales of molecular motions (relaxation times) in amorphous solids at and below the glass transition temperature, to determine distributions of relaxation times associated with different modes of molecular mobility and their temperature dependence, and to determine experimentally the impact upon these parameters of combining the drug with excipients (i.e., solid dispersions at different drug to polymer ratios). The knowledge gleaned may be applied toward a more realistic correlation with physical stability of an amorphous drug within a formulation during storage. Methods. Preparation of amorphous drug and its solid dispersions with PVPK-30 was described in part I (16). Molecular mobility and dynamics of glass transition for these systems were studied using TSDC in the thermal windowing mode. Results. Relaxation maps and thermodynamic activation parameters show the effect of formulating the drug in a solid dispersion on converting the system (drug alone) from one with a wide distribution of motional processes extending over a wide temperature range at and below Tg to one that is homogeneous with very few modes of motion (20% dispersion) that becomes increasingly less homogeneous as the drug load increases (40% dispersion). This is confirmed by the high activation enthalpy (due to extensive intra- and intermolecular interactions) as well as high activation entropy (due to higher extent of freedom) for the drug alone vs. a close to an ideal system (lower enthalpy), with less extent of freedom (low entropy) especially for the 20% dispersion. The polymer PVPK-30 exhibited two distinct modes of motion, one with higher values of activation enthalpies and entropy corresponding to -relaxations, the other with lower values corresponding to -relaxations characterized by local noncooperative motional processes. Conclusions. Using thermal windowing, a distribution of temperature- dependent relaxation times encountered in real systems was obtained as opposed to a single average value routinely acquired by other techniques. Relevant kinetic parameters were obtained and used in mechanistically delineating the effects on molecular mobility of temperature and incorporating the drug in a polymer. This allows for appropriate choices to be made regarding drug loading, storage temperature, and type of polymer that would realistically correlate to physical stability.
R.A. Shmeis, Z. Wang and S.L. Krill, Pharmaceutical Research 21 (2004) 2031-2039
T0043 - A mechanistic investigation of an amorphous pharmaceutical and its solid dispersions. Part I: A comparative analysis by Thermally Stimulated Depolarization Current and Differential Scanning Calorimetry
To explore using thermally stimulated depolarization current (TSDC), in comparison to differential scanning calorimetry (DSC), for the characterization of molecular mobility of an amorphous pharmaceutical new chemical entity (LAB687), an amorphous polymer (PVPK-30), and their combination as solid dispersions at different % drug loadings. Methods. Amorphous drug was prepared by quenching from the melt. Solid dispersions containing 10-60% of drug in polymer were prepared by solvent evaporation method. Glass transition temperatures (Tg) were determined by DSC and TSDC. Results. In comparison to a single Tg obtained from DSC for the drug substance, TSDC shows two overlapping relaxations. Both peaks correspond to -relaxations that are associated with the glass transition, with the second peak corresponding to the rigid fraction that is difficult to be detected by DSC because it is associated with only small changes in heat capacity. Two overlapping relaxations were also observed for the polymer vs. one Tg by DSC. The lower temperature relaxation is believed to be a beta-relaxation, whereas the higher temperature transition corresponds to an alpha-relaxation. For the solid dispersions, one single peak was obtained for each of the 20% and 30% dispersions in excellent agreement with the DSC results. However, at the 40% drug load, a small shoulder was observed by TSDC at the low temperature of the main peak. This shoulder becomes more pronounced and overlaps with the main peak as the drug load increases to 50% and 60%. Agreement between the Tg values calculated by the Gordon-Taylor equation and the DSC and TSDC experimental data, especially for the 20% and 30% drug loading, indicate ideal miscibility. At higher drug loads, only by TSDC was it possible to detect the saturation level of the drug in the polymer. Conclusions. TSDC proved to be very sensitive in detecting small reorientational motions in solids and in separating overlapping events with only slight differences in molecular motion exhibited as broad events in DSC. This allowed for detection of the rigid fraction of the amorphous drug, the sub-glass transition beta-relaxation in the polymer, and the limit of miscibility between the drug and the polymer in the solid dispersions.
R.A. Shmeis, Z. Wang and S.L. Krill, Pharmaceutical Research 21 (2004) 2025-2030
T0042 - Correlation between Calorimetric and Thermally Stimulated Depolarization Current. Spectroscopy relaxation times below Tg with Dielectric Relaxation times above Tg
x
C. Bhugra, R. Shmeis, S.L. Krill, M.J. Pikal
T0041 - Detection of low levels of the amorphous phase in crystalline pharmaceutical materials by Thermally Stimulated Current Spectrometry
To demonstrate the applicability of thermally stimulated current (TSC) spectrometry for the detection of low levels of the amorphous phase in crystalline pharmaceutical materials. Methods. A crystalline drug substance was melt quenched to produce an amorphous material. Blends of the crystalline and amorphous phases in different ratios (from 75:25 to 99:01) were prepared by serial dilution. TSC studies were performed by applying an electric field at a temperature above the glass transition temperature (Tg) to orient the dipoles, rapidly cooling to 0°C, short circuiting for 1 min, and scanning at 7°C/min to measure the depolarization current. The temperature of the peak in the spectrum corresponds to the Tg of the amorphous phase. Modulated differential scanning calorimtery (DSC) studies were performed using three different test protocols (varying linear heating rate, modulation amplitude, and time period). Powder X-ray diffraction (XRD) studies were performed using a Siemens D500 diffractometer. Results. The ability to detect the amorphous phase by powder XRD is beset with problems due to indirect inference, orientation effects, and instrument-related intensity variations. Even using a consistent sampling procedure and an internal standard, the XRD could quantify the amorphous phase at a level of 5%. In the conventional or modulated DSC, the amorphous phase manifests itself as a shift in the baseline. Using modulated DSC it was possible to detect the amorphous phase at a level of 5% when tested at a heating rate of 2°C/min and an amplitude of ±1.0°C with a period of 30 s. The moisture sorption method appears to have a similar detection capability. In TSC scans, the glass transition event due to molecular/segmental mobility in the amorphous phase was manifested as a peak/shoulder on the low-temperature side of the depolarization peak of the crystalline phase. The amorphous phase was unambiguously detected at 2% with a lower detection limit of ~1%. Conclusions. On the basis of the results of this preliminary investigation, TSC appears to be capable of detecting the amorphous phase at as low as ~1% in crystalline pharmaceuticals, thus offering a much needed capability in discerning factors.
G.M. Venkatesh, M.E. Barnett, C. Owusu-Fordjour, and M. Galop, Pharmaceutical Research 18 (2001) 98-103
T0040 - The thermal analysis of films in the 21st century: Relevance to cell culture, biochips and roll-to-roll circuits
Films may be considered as wide fibers, or as unique material geometry possessing two dimensional symmetry (X, Y, Z). Potentially different uniformity issues along the machine (long) and transverse directions of the film, characterization of Z-axis performance-especially as films become "thin" and the characterization/identification of surface modification, introduce the need for careful sampling strategies if the resulting thermal analysis data is to be reflective of either process history or end-use performance or both. Two dimensional imaging by a combination of techniques-i.e., DSC-WAXS-FTIR-AFM exploit the convenience of the sample geometry, while aiding in the definition of structural complexity. Molecular spectroscopy techniques (DMA, TSC) provide a sensitive and instructive tool for examining novel surface or interface chemistry. Characterization under biorelevant conditions (37°C, aqueous, standard saline, presence of adhesive and other proteins, presence of cells) is critical for the generation of meaningful data on films to be utilized biologically (cell culture, tissue engineering substrates, biochips). Of special interest are strategies for accelerated aging that allow prediction of biological or biorelevant performance.
M. Jaffe, G. Collins and J. Menczel, Thermochimica Acta 442 (226) 87-91
T0039 - Thermal behaviour and slow molecular mobility in two isomers of biphenylmethanol DSC and TSDC study
The thermal behaviour of 2- and 4-biphenylmethanol were studied by differential scanning calorimetry (DSC). It was found that the 2-isomer shows a relatively strong resistance to crystallisation, and that it easily vitrifies on cooling. Oppositely, 4-biphenylmethanol readily crystallizes on cooling. The slow molecular mobility of 2-biphenylmethanol in the amorphous solid state was studied by DSC and by thermally stimulated depolarisation currents (TSDC). Both techniques indicate that 2-biphenylmethanol is a relatively strong glass-former, with a fragility index of ~50 in the Angell's scale.
H.P. Diogo, S.S. Pinto and J.J. Moura Ramos, Journal of Thermal Analysis and Calorimetry 83 (2006) 361-366
T0038 - Intrinsic compensation phenomenon in thermally stimulated depolarisation studies
The compensation behaviour as observed in thermally stimulated depolarisation currents (TSDC) corresponds to the linear relationship found between the Arrhenius (or Eyring) apparent thermokinetic parameters obtained in a series of thermal sampling (TS) experiments performed in the region of cooperative relaxation processes, particularly around the glass transition of glass forming materials. The compensation effect exhibits the same features of the intrinsic compensation found for any given TS curve, where the values of Ea and t0, in the region where the sum of square residues is low, are highly correlated, being this correlation similar to the conventional compensation. This intrinsic compensation is a result, and exhibits the same features, of the compensation found in the description of a given set of points obtained with the Arrhenius equation with the own Arrhenius equation. This compensation is transmitted directly to the equation that describes the temperature dependence of the depolarisation currents, J(T), as a nearly direct relationship exists between J(T) and t(T). In fact, it was shown that J(T) for an elementary process could be approximated by P0 exp[-c/t(T)]/t(T), c being a constant.
J.F. Mano, Thermochimica Acta 430 (2005) 135-141
T0037 - Weak solid-solid transitions in pharmaceutical crystalline solids detected via thermally stimulated current
To demonstrate the ability of thermally stimulated current (TSC), normally used to study amorphous systems, in detecting weak solid-solid transitions in crystalline pharmaceutical compound. Methods: Polymorphs of a new chemical entity, LAU254, were generated and characterized using conventional and hot plate X-ray diffraction, DSC and TSC. Equilibration of 50:50 mixtures of the different polymorphs and solubility studies were conducted in aqueous and organic solvent at 25 and 50°C and then analyzed by X-ray and DSC. Results: Four crystalline forms (A-D) were isolated. Form B showed one single endotherm at 180°C while the other forms showed lower melting endotherms, a crystallization exotherm and eventually a final melting endotherm corresponding to that of form B (180°C). The heat of fusion of form B was the highest. In contrast, solubility as well as mixture equilibration studies resulted in all forms converting to form A. TSC analysis revealed a well-defined reproducible peak with a maximum at 130°C which was suspected to be a solid-solid transition. This was confirmed by hot plate X-ray diffraction where careful probing around 120-130°C revealed three different forms; form A (the initial form), a second form that appears above 150°C, melts, crystallizes and produces form B. Careful inspection of larger sample sizes in DSC showed a small endotherm at 130°C. Conclusions: TSC, normally used to study amorphous systems, proved to be useful in detecting weak solid-solid transitions in crystalline pharmaceuticals, an application that has never been explored or reported previously. This resulted in identifying a form, obtainable only at temperatures above the transition temperature (related enantiotropically to the form that is most stable at ambient temperatures) and in reconciling the DSC and solubility data. TSC can be very useful in detecting and probing those transitions that occur in the solid state due to subtle dipolar motion and are not associated with large changes in global motion and heat capacity that is needed for detection by DSC and therefore can be complementary to DSC in obtaining a more complete assessment of the polymorphism behavior of crystalline solids.
R.A. Shmeis and S.L. Krill, Thermochimica Acta 427(2005) 61-68
T0036 - The determination of the activation energy of a relaxational process from thermally stimulated depolarisation currents (TSDC) data: an illustration with the beta-relaxation of maltitol
Three different and independent procedures to obtain the activation energy of a motional process from thermally stimulated depolarisation currents (TSDC) data are reported. One of the procedures requires a single thermal sampling (TS) experiment: the activation energy is calculated from the temperature dependence of the relaxation time associated with this TS peak. The other two procedures are based on the influence of the heating rate on the features of the TS peak namely, on the temperature location Tm and on the intensity of the maximum I(Tm) of the peak. The illustration with the case of an elementary component of the beta-relaxation of maltitol shows that the values of the activation energy provided by these procedures are in good mutual agreement. The fact that the TSDC technique provides different and independent procedures to obtain the kinetic parameters of a motional process is a unique feature in the context of the experimental techniques most often used to study molecular mobility.
J.J. Moura Ramos and N.T. Correia, Thermochimica Acta 426 (2005) 185-190
T0035 - Low frequency chain dynamic of cross-linked poly(acrylic acid)
Cross-linked poly(acrylic acid) (PAA) synthesized by radical polymerization in inverse suspension is a swelling gel. The physical structure of PAA has been analyzed using low frequency chain dynamic given by the analysis of thermo stimulated currents (TSC). The alpha primary dielectric relaxation mode observed around the glass transition temperature (Tg=+38°C) corresponds to the slowest dynamic. The relaxation times of the constituting processes show that it is due to a delocalized cooperative molecular mobility involving nanometric sequences of the hydrocarbon skeleton. The beta secondary dielectric relaxation mode observed at lower temperature (Tbeta=-35°C) corresponds to a higher frequency molecular mobility. It has been assigned to the cooperative mobility of hydrogen bonded COOH groups. In fact, the hydrogen bonded side chains behave as an hydrophilic matrix in which nanometric domains constituted by sequences of the main chain are embedded. Such a picture might explain the specific swelling properties of cross-linked PAA.
Ch. Mayoux, J. Dandurand and C. Lacabanne, Thermochimica Acta 421 (2004) 43-49.
T0034 - Analysis of Thermally Stimulated Current and effect of rubbery annealing around glass-rubber transition temperature in polyethylene terephtalate
Thermally stimulated currents (TSC) in amorphous polyethylene terephthalate films have been investigated in the temperature range of -180 to 140°C. This material shows a very weak intensity peak at approximately -95°C and another around 80°C originated from dipolar process (alpha-peak), as evidenced from the variation of polarizing conditions such as applied electric field and polarizing time. The effect of isochronal rubbery annealing starts to appear from a temperature of annealing of 90°C, it then appears in a TSC spectrum two components around 88 and 108°C allotted, respectively to the true and rigid amorphous phases. The first component tends to disappear in an irreversible way to the detriment of the second which implies the establishment of an order within material during annealing by the formation and growth of nodules. The thermostimulated currents technique allowed to calculate with good precision the activation parameters of each process as well as the evaluation of the crystallinity rate by an established empirical formula.
N. Benrekaa , A. Gourari, M. Bendaoud and K. Ait-hamouda, Thermochimica Acta 413 (2004) 39-46
T0033 - The use of thermal methods for predicting glass-former fragility
Glass-former fragility describes the changing dynamics of a supercooled liquid with temperature and so dictates the temperature of glass transition as well as the dynamics of the non-equilibrium glassy state. Fragility parameters can be calculated from either experimental relaxation time or viscosity data. Predictions of fragility can also be made using thermal methods. The objectives of this manuscript are to evaluate three thermal methods of fragility prediction and, using these methods, to predict the fragility of a number of pharmaceutical glass-formers. Using differential scanning calorimetry, fragility predictions were performed by extrapolating configurational entropy to zero and by calculating an activation enthalpy of structural relaxation at the glass transition (?ETg) from the scanning rate dependency of the glass transition temperature, and glass transition width. On comparison with experimental Vogel-Tammann-Fulcher (VTF) fragility parameters for four glass-formers, all thermal methods were found to have reasonable predictive ability. Characterisation of pharmaceutical glass-formers by all thermal methods yielded predicted VTF D parameters in the range of 7-15. Predictions for a further 10 pharmaceutical glass-formers using only the configurational entropy method were within this range suggesting that moderately 'fragile' behaviour may be a common feature of such materials.
K.J. Crowley and G.Zografi, Thermochimica Acta 380 (2001) 79-93
T0032 - Characterization of structural heterogeneity of polyurethane coatings
The thermal analysis techniques - Differential Scanning Calorimetry and ThermoStimulated Current - have been used to characterize a polyurethane high solid coating. The glass transition temperature, as determined by DSC, is 60°C. Below this glass transition temperature, an sub dielectric relaxation mode has been observed; it corresponds to cooperative movements precursor of the glass transition. The ss dielectric relaxation mode, located at Tg has been attributed to movements of soft sequences of the amorphous phase liberated at the glass transition temperature. The analysis of the fine structure shows that they are constituted of elementary processes characterized by relaxation times following a compensation law. Above Tg, the hs dielectric relaxation of hard sequences has been shown. It corresponds to hard sequences hydrogen bonded in polyurethane
P. Paolpi, C. Lacabanne, Journal of Applied Polymer Science 81 (2001) 2786 - 2790
T0031 - Study of molecular mobility at the secondary relaxations range in polyamide 66 and polyamide 66/EPR blends by thermally stimulatde creep and current
Thermally stimulated creep with fractional loading technique and thermally stimulated current have been used to investigate the relaxation processes of polyamide 66 and polyamide 66/EPR blends over temperature range covering y, beta and alpha-EPR. Absorbed water decreases the thermally stimulated creep and the thermally stimulated current height of y-relaxation. The thermally stimulated creep mechanical beta-relaxation in PA66 is characterized by a broad peak, while the thermally stimulated current dielectric one is composed of two separate processes beta1 and beta2 according to the maximum temperature decrease. The peak height of the beta1 component is increased by moisture while the beta2 component is not modified. According to the criteria of Starkweather for sample and complex relaxations, the y- and low temperature part of beta-relaxations have been assigned to localized non-cooperative motions. The high temperature part of beta-process and alpha-EPR-relaxation have positive activation entropies and result from high cooperative motions. These interpretations from thermal sampling analysis is in close aggrement with the predictions of Ngai's coupling model.
P. Demont, M. Diffalah, J.J. Martinez-Vega and C. Lacabanne, Journal of Non-Crystalline Solids 172-174 (1994) 978-984
T0030 - Ultra low frequency study of dielectric relaxation in ferroelectric Polyamide 11
X
C. Maraval, A. Bernés, D. Chatain, C.Lacabanne and J. I. Scheinbeim, Journal of Electrostatics 40-41 (1997) 331-336
T0029 - Thermal behavior of ferroelectric polyamide 11 in a relation to pyroelectric properties
The pyroelectric properties of oriented thin films of ferroelectric Polyamide 11 have been studied in the temperature range of -100°C up to +140°C. The temperature dependence of the experimental pyroelectric coefficient has been analyzed. Three changes of slope of the pyroelectric coefficient are observed at -20, +50, and +100°C. The origin of the lower temperature event has not yet been defined. The upper transition is attributed to chain movements in crystalline regions, and more precisely, to a crystalline phase transition. The intermediate event is close to the glass transition temperature Tg observed by DSC. It is attributed to the manifestation of the glass transition. Below Tg, the variations of the pyroelectric coefficient are very small. For higher temperatures, it increases rapidly, attesting to a major contribution of secondary pyroelectricity and dimensional effects above Tg. The breaking of hydrogen bonds occurring at the glass transition temperature observed on DSC thermograms does not affect pyroelectric properties. Pyroelectric properties are mildly reduced after annealing at temperatures up to +140°C. A comparative study of oriented ferroelectric films prepared by quenching from the melt and nonoriented slowly cooled samples has been carried out by means of DSC
L. Ibos, C. Maraval, A. Bernès, G. Teyssèdre, C. Lacabanne, S-L. Wu and J.I. Scheinbeim, Journal of Polymer Sciences 37 (1999) 715-723
| Pages |
| 1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 . 9 . 10 . 11 . 12 . 13 . 14 . 15 . 16 . 17 . 18 . 19 . 20 . 21 . |
Registrer now
For full access to application library,
spare parts catalog and newsletters
Inscription
Login
Contact us
Contact us
Our news
NEW VOLUMETRY PRODUCT
A fully automated Sievert instrument for measuring Gas (CO2, CH4, C2H6, N2) Sorption properties of materials. PCTPro SOFTWARE UPDATES
Important PCTPro software updates
NEW AUTOMATED STA
Introduction of a new autosampling option for LABSYS, market leading TGA, STA and TG-DSC
Our agenda
- September 26, 2012 - September 28, 2012
International Conference
Darmstadt, GermanyInternational Conference on Chemical Looping 201226th to 28th of September 2012A Concept for Efficient and Clean Use of Fossil ResourcesThe Institute for Energy Systems and Technology (EST) at Technische Universität Darmstadt is pleased to announce the 2nd International Conference on Chemical Looping as „An Alternative Concept for Efficientand Clean Use of Fossil Resources”, to be held from Wednesday 26th to Friday 28th of September 2012 at Maritim Conference Hotel Darmstadt.
- September 16, 2012 - September 19, 2012
MOF 2012
Edinburgh, UKMOF20123rd International Conference on Metal-Organic Frameworks and Open Framework Compounds September 16, 2012 - September 19, 2012John McIntyre Conference Centre, Edinburgh Dechema and the IZA together with the local organising committee warmly invite you to attend MOF2012 in Edinburgh.The aim of MOF2012 is to address all questions concerning the community working with metal-organic frameworks, metal coordination compounds and related materials covering all aspects of MOFs from synthesis and characterization of new materials over properties of MOFs to all kinds of applications, e.g. in biology/medicine, catalysis, magnetism, luminescence and adsorption. We are looking forward to experimental, theoretical, and modelling contributions along with papers addressing key questions regarding potential industrial applications of this fascinating family of materials.
- August 20, 2012 - August 24, 2012
ICTAC 2012
Osaka, JapanICTAC 201215th International Congress on Thermal Analysis and CalorimetryAug. 20-24, 2012 Kinki UniversityInternational Congress on Thermal Analysis and Calorimetry (ICTAC) is held every four years, with an aim to promote international understanding and to exchange ideas and findings in the field of thermal analysis and calorimetry. In 2012, memorable 15th ICTAC is held in Osaka, Japan. Osaka is located virtually in the center of Japan, and is near to ancient and beautiful cities of Kyoto and Nara.
- August 12, 2012 - August 15, 2012
NATAS 2012
Orlando, Florida, USA40th Annual Conference of NATAS Technical ConferenceAugust 12-15, 2012Short CourseAugust 10-12, 2012Buena Vista Palace Hotel & SpaWith great pleasure, we invite you all to the 40th Annual Conference of NATAS that will take place in Orlando, Florida, 12-15 August 2012.
- August 05, 2012 - August 10, 2012
ICCT 2012 and CALCON 2012
Búzios, BrazilICCT 2012 and the 67th Calorimetry ConferenceWe are delighted to invite you to take part in an event that that is unique in every way: the association of ICCT 2012 and the 67th Calorimetry Conference, being held together, both for the first time in Latin America.
- July 15, 2012 - July 19, 2012
INMM
Orlando, Florida USAINMM 53rd Annual MeetingJuly 15-19, 2012Renaissance Orlando Resort at SeaWorldOrlando, Florida USAThe 53rd Annual Meeting will provide attendees with a professional forum for the exchange of the latest technical information in nuclear materials management. The meeting will address all aspects of nuclear materials management with papers and posters organized by the INMM Technical Program Committee.
- July 15, 2012 - July 20, 2012
BZA 2012
Chester, EnglandThe 35th Annual British Zeolite Association Meeting15th - 20th July 2012University of Chester in northwest EnglandThe 2012 meeting of the British Zeolite Association will be held at the University of Chester in northwest England. This triennial, Chislehurst-style BZA meeting, organised along the lines of a Gordon Conference, will be limited to 120 participants.The BZA welcomes contributions from all fields of zeolite, microporous and mesoporous materials science, including synthesis, structure, applications, characterisation, catalysis and computational studies.
- June 26, 2012 - June 29, 2012
CTEC 2012
Lyon, FranceCalorimetry and Thermal Effects in CatalysisCalorimetry and thermal analysis methods, alone or linked to other techniques, applied to the characterization of catalysts, supports and adsorbents, and to the study of catalytic reactions in various domains: air and wastewater treatment, clean and renewable energies, refining of hydrocarbons, green chemistry, hydrogen production and storage, CO2 capture...
- June 18, 2012 - June 22, 2012
EU BC&E 2012
Milano, Italy20th European Biomass Conference and Exhibition18 - 22 June 2012 at the Milano Convention Centre in Milano, ItalyWith this event, we will continue the biomass specialist's role as the leading technical platform covering all aspects of biomass from research to industry and markets.
- June 05, 2012 - June 08, 2012
AICAT 2012
Rome, ItalyAICAT 2012Sapienza University of RomeJune 5-8 2012AICAT 2012 is jointly organized by the Italian Association of Calorimetry and Thermal Analysis (AICAT) and by Interdivisional Group of Calorimetry and Thermal Analysis (GICAT) of the Italian Chemical Society (SCI) and represents the main scientific meeting of these Associations. The Congress aim is to provide to the scientists working in Calorimetry, Thermal Analysis and closely related topics an opportunity for an exchange of scientific information, critical discussion and advanced planning on fundamental and applied research aspects of interest in this field.
- May 28, 2012 - June 01, 2012
2012 Fiery Ice
Sapporo, Hokkaido, Japan2012 Fiery Ice8th International Workshop on Methane Hydrate Research & DevelopmentWith great pleasure, we announce that 8th International Workshop on Methane Hydrate Research & Development (Fiery Ice from the Seas) is being held in Sapporo, Japan at refreshing season, 28th of May to 1st of June, 2012.
- May 27, 2012 - May 31, 2012
BiPoCo 2012
Siófok, Lake Balaton - Hungary BiPoCo 2012,an International Conference onBio-Based Polymers and CompositesMay 27-31, 2012Siófok, Lake Balaton - HungaryDownload the First circular
- May 22, 2012 - May 24, 2012
JCAT 2012
Toulouse, FranceThe 43rd Calorimetry and Thermal Analysis DaysMore information coming soon
- May 20, 2012 - May 25, 2012
HTCPM 2012
Les Embiez, FranceHTCPM 20128th International Symposium on High-Temperature Corrosion and Protection of Materials20 - 25 May, 2012Les Embiez, France The goal of this international symposium is to reflect the interests of the major industries dependent on the successful application of high-temperature materials, providing a periodic updating on the current research and understanding in these areas.
- May 16, 2012 - May 18, 2012
INNOSTOCK 2012
Lleida, SpainINNOSTOCK 2012The 12th International Conference on Energy Storage16-18 May 2012Innostock 2012 is part of the Stock conference series sponsored by the ECES IA of the International Energy Agency.Innostock 2012 will gather the world’s leading specialists and academic researchers within the field of energy efficiency through energy storage. Energy storage will present in all its topics:• Underground thermal energy storage• Sensible, latent and thermochemical energy storage• Electrical storage
- May 14, 2012 - May 18, 2012
11th International Hydrocolloids Conference
Purdue University, USA11th International Hydrocolloids ConferenceBiofunctionality and Technofunctionality of Hydrocolloids14-18 May 2012, Whistler Center for Carbohydrate Research, Purdue University, USAThe 11th International Hydrocolloids Conference is organized by the world-renowned Whistler Center for Carbohydrate Research and will be held at The Stewart Center at Purdue University, Indiana, USA.
- April 30, 2012 - May 03, 2012
Carbon Capture Utilization & Sequestration
Pittsburgh, Pennsylvania - United States 11th Annual Conference on Carbon Capture Utilization & Sequestration April 30 - May 3, 2012Pittsburgh, Pennsylvania The 2012 Conference program follows in the footsteps of the past 10 events, with an added emphasis this year on potential utilization of anthropogenic carbon emissions that is reflected in the new name of the conference. The focus is on systems and technologies that are being or could be deployed in the U.S. and North America.
- April 17, 2012 - April 20, 2012
ANALYTICA 2012
Munich, GermanyANALYTICA 2012April 17 - 20, 2012New Munich Trade Fair Centre23rd International Trade Fair for Laboratory Technology, Analysis, Biotechnology and analytica Conference
- April 16, 2012 - April 18, 2012
Food Colloids 2012
Copenhagen, DenmarkFood Colloids 2012This conference is the fourteenth in the series of biennial European conferences dedicated to the area of food colloids. Food Colloids is a highly multidisciplinary topic that brings together scientists from many different areas. The aim of the conference is to present the state of the art on a number of fast evolving questions and to promote discussions and interactions between researchers involved in different fields of food colloids. This series aims to emphasise the importance of approaching the subject from different perspectives; from the fundamental physical-chemistry to the nutritional and consumer aspect of the food product.
- April 03, 2012 - April 04, 2012
TAC 2012
The Royal Society of ChemistryThermal Methods Group presentsTAC 20123 - 4 April 2012Food Sciences DivisionSchool of Biosciences, University of Nottingham, UK
- March 21, 2012 - March 23, 2012
- March 18, 2012 - March 23, 2012
Natural Gas Hydrate Systems
Ventura Beach MarriottVentura, CA, United StatesNatural Gas Hydrate Systems2012 marks the 2nd Gordon Research Conference on Natural Gas Hydrates. The Conference combines cutting-edge presentations on field, experimental, and modeling studies that enhance our understanding of gas hydrates and their interaction with sediments, pore fluids, and the biosphere on pore space to planetary spatial and temporal scales. The meeting emphasizes the occurrences and processes that influence the dynamic systems of present day and palaeo-hydrates, including marine and terrestrial and permafrost gas hydrate systems.
- February 27, 2012 - February 29, 2012
Applied Gas Hydrate Management
Doha, Qatar | W Doha HotelApplied Gas Hydrate Management (Challenges and Opportunities)27 – 29 February 2012This workshop has the objective of bringing together a range of industry, academic and government professionals into an environment where they can brainstorm, troubleshoot and discuss the fundamental understanding of all aspects of hydrate management. Part of the workshop will be discussions on hydrate management, including sweet and sour gas application, the impact of facilities design, removal of KHI from produced water, applications of treatment chemicals and the use of novel methods to control hydrate problems.
- January 31, 2012 - February 04, 2012
THERMANS 2012
Mumbai, IndiaTHERMANS-2012DAE – BRNSEighteenth International Symposium & Workshop on Thermal AnalysisThe Symposium and Workshop is sponsored by Board of Research in Nuclear Sciences(BRNS), Department of Atomic Energy (DAE) in association with the Indian ThermalAnalysis Society (ITAS). In this Symposium, it is planned to focus on “Thermochemical and Thermophysical Investigations of Materials Relevant to Nuclear Industry and Allied Areas”.Training School HostelHomi Bhabha National Institute, Mumbai, IndiaJanuary 31-February 2, 2012 (Symposium)February 3-4, 2012 (Workshop)
Useful Links