Polyester yarn spun over a range of wind-up speeds has been characterized using differential scanning calorimetry. Samples prohibited from shrinking during the thermal analysis show slightly smaller heats of fusion and crystallization and reduced cold crystallization temperatures than samples that are free-to-shrink, particularly in the intermediate wind-up speed region. One critical observation made is that the cold crystallization temperature reaches a minimum at some relatively low overall molecular orientation (Δn ∼ 0.020) and fails to decrease further. A likely explanation is that crystallization continuously removes polymer from the melt in the spinline in regions where the local orientation reaches some critically high value.
Polyester yarn spun over a range of wind-up speeds and subsequently drawn at 373 K has been characterized by differential scanning calorimetry. Samples that are constrained from shrinking during the thermal scan respond differently than samples that are free-to-shrink. In the region of intermediate orientation, the constrained samples typically show a lower cold crystallization temperature: In the region of high orientation, the constrained samples typically show a higher melting temperature. The results are quantitatively similar to those based on fibers in which the orientation is imparted directly by high speed spinning.
The technique of heat flow calorimetry was used to study the thermal behaviour of different carbohydrates between 20°C and 270°C. The samples were analyzed by heating in sealed cells. The temperature range in which exothermic reactions, due to thermal decomposition, occurred varied widely depending on the type of carbohydrate investigated. Reaction enthalpies of 44 sugars and polysaccharides are given. Endothermic phenomena, such as fusion or vaporization of crystallized water, were also observed: fusion temperatures and enthalpies of 34 sugars and sugar alcohols are listed. Calorimetric curves showing crystallization of amorphous sucrose, cellobiose and lactose are also presented.
Thermal investigations were performed on a colony of the Colombian stingless bee Trigona (Frieseomelitta) nigra paupera by means of thermometry and direct calorimetry.
A nest with about 2000 individuals was transferred to a twin calorimeter, where the bees continued their normal life and development.
Two camping boxes (‘Poor Man’s Calorimeter, PMC’) with Peltier elements as cooling systems were used as a differential system.
Each box had a volume of 8 L and a sensitivity of 19.2 mV W−1. The colony was monitored calorimetrically and thermometrically with resistors distributed in the nest. Signals were recorded
continuously by a four-channel data logger.
The calorimetric cells of a Setaram BT 2.15 flux calorimeter have been modified, in order to measure the heat production associated with microbial growth, with a continuous flow of gas and liquid through the sample. Good conditions for the growth of the microorganisms present in a polluted soil were determined and the possibility of the bioremediation examined. It was shown that the biodegradation of hydrocarbons adsorbed for a long time in the soil is a very slow process difficult to study with calorimetry. On the contrary, sodium succinate and different C14 hydrocarbons were easily biodegradated, producing a large quantity of heat.
Authors:J. Botelho, A. Souza, L. Nunes, A. Chagas, I. Garcia dos Santos, M. da Conceição, and P. Dunstan
The standard molar enthalpies of formation of crystalline dialkyldithiocarbamates chelates, [Pd(S2CNR2)2], with R=C2H5, n-C3H7, n-C4H9 and i-C4H9, were determined through reaction-solution calorimetry in acetone, at 298.15 K. From the standard molar enthalpies of formation
of the gaseous chelates, the homolytic (172.43.8, 182.53.2,150.93.1 and 162.63.1 kJ mol−1) and heterolytic (745.03.8, 803.73.3,834.33.1 and 735.23.0 kJ mol−1) mean palladium-sulphur bond-dissociation enthalpies were calculated.
Authors:Urs von Stockar, Ian Marison, Marcel Janssen, and Rodrigo Patiño
biological processes will be an important issue. Calorimetry is a convenient experimental tool to explore these characteristics, because it permits measuring experimentally one of these energy exchanges, namely heat dissipation.
Authors:N. Smirnova, B. Lebedev, T. Bykova, A. Markin, and D. Tur
By adiabatic vacuum and dynamic calorimetry, heat capacity for poly[bis(trifluoroethoxy)phosphazene] has been determined over the 6–620 K range. Physical transformations of the polymer on its heating
and cooling have been detected and characterized. Smoothed heat capacity Cp0(T) and standard thermodynamic functions (H0(T)-H0(0), S0(T) and G0(T)-H0(0)) of poly[bis(trifluoroethoxy)phosphazene] have been evaluated for the temperature range from T→0 to 560 K. The standard entropy of formation ΔfS0 at T=298.15 K has been also determined. Fractal dimensions D in the heat capacity function of the multifractal variant of Debye’s theory of heat capacity of solids characterizing the
heterodynamics of the tested polymer have been determined.
A calorimetric procedure is developed to study the effect on the soil of the effluents resulting for the anaerobic digestion
of slaughtering houses residues. DSC was used to study the pyrolysis properties of the effluent and the soil while isothermal
calorimetry is applied to study the microbial activity in the effluent and to assess on its effect on the microbial activity
of the soil where the industrial digester will be situated. The calorimetric data were studied together with the chemical
and biological properties of that residue. Results showed that effluent is constituted by low levels of carbon and high levels
of nitrogen. The power-time curves of the effluent have the typical shape of microbial growth yielding microbial growth rate
constants between 0.37 and 0.53 h−1 for about 4 and 11 h. The addition of the effluent to the soil decreases the heat of pyrolysis with time and stimulates the
heat flow rate of the microbial metabolism.
Authors:P.-J. Zhou, H.-T. Zhou, Y. Liu, S.-S. Qu, and Y.-G. Zhu
In this paper, the thermogenesis and differential scanning calorimetry (DSC) curves of energy release of the mitochondria
isolated from variant strains of cytoplasmic male sterile lines of rices have been determined by using an LKB2277 Bioactivity
Monitor and a DuPont 910 differential scanning calorimeter. The regularity and characteristics of the energy release of the
mitochondria at constant and changing temperature were investigated, the differences in shape of the curves and the thermodynamic
and kinetic characteristics of the thermogenesis of the mitochondria were compared, the thermodynamic and kinetic parameters
of energy release of the mitochondria in the thermogenesis increasing stage were calculated, and the experimental thermokinetic
equations describing the different thermogenesis processes were established.