Authors:Julen Ibarretxe, Gabriël Groeninckx, and Vincent B. F. Mathot
pan measurements were subtracted from the actual measurements of the dispersions to remove the curvature of the heatflowrate signal as induced by the instrument itself.
Dynamic light scattering (DLS) measurements were performed on a back
Authors:S. Sarge, W. Hemminger, E. Gmelin, G. Höhne, H. Cammenga, and W. Eysel
Metrologically based measuring procedures and evaluation methods are recommended as guidance for practical temperature, heat
and heat flow rate calibration of DSC instruments which are largely independent of instrumental, test and sample parameters.
The relevant terms are defined, the measuring procedures and evaluation methods described, calibration materials and their
characteristic data stated and guidance for the sample handling provided. Reference is made to three extended papers on calibration.
The recommendations were developed by the working group ‘Calibration of Scanning Calorimeters’ of the German Society of Thermal
The response of temperature-modulated differential scanning calorimetry (TMDSC) to irreversible crystallization of linear polymers was investigated by model calculations and compared to a number of measurements. Four different exotherms were added to a typical modulated, reversible heat-flow rate in order to simulate irreversible crystallization. It was found that the reversing heat-flow rate of the TMDSC in response to such irreversible crystallization exotherms is strongly affected by tbe shape of the transition and the phase-angle where the exotherm occurs. A comparison with the experimental data gave valuable insight into the transitions, as well as the nature of the TMDSC response which is usually limited to an analysis of the first harmonic term of the Fourier series that describes the heat-flow rate.
Authors:Dumitru Oancea, Valentin Munteanu, and Domnina Razus
reaction heatflowrate and of the related surface reaction rate in isothermal conditions can be accomplished during both transient ignition and subsequent steady state combustion. As long as no other additional heat producing or consuming processes occur
heat-flowrate (in J s −1 or W) at the measured T . From this description, it is clear that the precision depends critically on the construction of the instrument and its calibration [ 2 ]. The heat-flowrate and time can be computed from Δ T and T
The modulated temperature differential scanning calorimetric method (MT-DSC) yields three temperature dependent signals, an underlying heat capacity curve from the underlying heat flow rate (corresponding to the conventional DSC signal), and a complex heat capacity curve with a real part (storage heat capacity) and an imaginary part (loss heat capacity). These curves have been measured in the cold crystallization region for poly(ethylene terephtalate) with a modified Perkin-Elmer DSC-7. The underlying curve shows the well known large exothermic crystallization peak. The storage heat capacity shows a step change which reproduces the change in heat capacity during crystallization. This curve may be used as baseline, to separate the crystallization heat flow rate from the underlying heat flow rate curve. The loss heat capacity curve exhibits a small exothermic peak at the temperature of the step change of the storage curve. It could be caused by changes of the molecular mobility during crystallization.
Authors:L. Ruan, Y. Liu, Z. Gao, P. Shen, and Q. Sheng
The thermogenic curves of the aerobic metabolism of the three strains of Bacillus thuringiensisB.t. A, B.t. B and B.t. C have been determined by using an LKB-2277 BioActivity Monitor. B.t. A was the host bacterium without foreign gene. B.t. B and B.t. C were constructed by transforming different foreign genes into the host B.t. A, respectively. B.t. B expressed erythromycin resistant gene, while B.t. C expressed both erythromycin resistant gene and tyrosinase gene. The heat flow rate of these strains is B.t. A> B.t. B >B.t. C. These results indicated that there is obvious interrelation between expression of foreign genes and heat flow rate of
Authors:N. Eckardt, H. Flammersheim, and H. Cammenga
Contrary to the situation in the field of temperature, heat and heat flow rate calibration, so far no generally accepted and easily practicable chemical reaction exists with regard to a kinetic evaluation. A possible reaction would be the well-known first-order cis-trans isomerization of subcooled liquid azobenzene. Surprisingly, the evaluation of measurements performed with a power compensated calorimeter yields activation parameters, which are dependent on the heating rate. The desmearing of the curves does not produce any improvements. However, constant activation parameters are obtained, if a small self-heating of the sample during the exothermic reaction is taken into account.
Microcalorimeters to monitor the heat dissipation of bench-scale animal cell cultures on line and in real time require a continuous
circuit between the vessel measuring heat flow rate and the bioreactor. The modifications to the transmission lines and calorimetric
heat exchanger were to: (i) reverse the usual upward direction of the cell suspension in the flow vessel to downwards; (ii)
install an in situ washing/cleaning facility; (iii) use low diffusivity PEEK material; and (iv) maintain thermal equilibration
by water-jacketing the transmission tubing. Chemical calibration showed that there was more than a 20% difference between
the physical volume and the effective thermal volume. An appropriate thermodynamic system was defined in order to permit enthalpy