Chip calorimetry

Figure 3. Temperature dependence of the specific heat capacities of a Polyamide 6 and of a (PS/SMA2)/PA6 (62/13) 5 blend, measured by thin-film chip calorimetry at different heating rates, after crystallization from the melt at 85 C.

In order to obtain data at lower temperature, specifically designed nudeation experiments were recently performed by fast scanning chip calorimetry in a wide temperature range between 40 and 110 °C [51, 52]. The PLA melt was rapidly cooled to the analysis temperature and then annealed for different periods of time to permit nuclei formation. The number of formed crystal nuclei was then probed by measurement of the crystallization rate at 120 °C, which accelerates according to the progress of earlier nuclei formation at the annealing temperature. 

In this laboratory investigation, you will use the methods of calorimetry to approximate the amount of energy contained in a potato chip. The burning of a potato chip releases heat stored in the substances contained in the chip. The heat will be absorbed by a mass of water. 

Keywords Multi-analyte biosensor Microelectrode-array Enzyme immobilization Enzyme stability Differential scanning calorimetry (DSC) Chip-calorimeter... 

Kohler JM, Zieren M, and Willnauer R (1999) Chip sensors for reaction, scanning, and ac-calorimetry in stationary and moving samples using thermoelectric transduction. Proceedings of the Electrochemical Society 99(23) 429 39. 

Spalik conducted a study to determine whether flux or the oxidation of Pb° in the solder caused the decrease in tin concentration observed with flip chip solder joints (C4) that experienced multiple reflows. Differential scanning calorimetry analyses made on 90Pb l0Sn solder samples both before and after heating to about 350°C in the presence of a rosin flux for more than 24 hr showed no detectable change in the tin content. This result was consistent with the requirement that in order for a metal to dissolve in an acid, H2 must be evolved. In other words, the following reaction must occur ... 

Differential scanning calorimetry (DSC) has proven to be a very reliable technique to obtain heat capacity at elevated temperatirres in a reasonably short time. DSC also allows the study of the kinetics of nonequilibrium transitions in a wide dynamic range. Because of its simplicity and ease of use, DSC is widely applied in polymer science and is the focus of this chapter. Recent additions such as temperature modulation and fast scanning, both making additional use of chip-based calorimeters, are also discussed in detail. 

Figure 1 Different types of differential scanning calorimeters, (a) Three-dimensional cylindrical calorimeter (Tian-Calvet). (b) Three-dimensional calorimeter with power compensation, (c) Two-dimensional plate-like calorimeter, (d) Scheme of a twin-chip sensor (Mettler Toledo Flash 1 DSC ) for fast scanning calorimetry.

Data in Figure 21 cover more than 5 orders of magnimde in time. At high crystallization temperatures (above 40 °C), the acceleration of crystallization due to addition of a nucleating agent is seen in DSC and chip-based calorimetry data. Below 40 ° C, additional nuclei do not speed up crystallization... 

Figure 21, DSC and chip-based calorimetry data coincide, indicating similar crystallization kinetics for the milligram-sized DSC and the nanogram-sized chip-based calorimetry samples. For PBT, this is not the case (see Figure 22).

Figure 22 Crystallization halftime (time of peak maximum) of PBT as a function of crystallization temperature. Data from DFSC, AC chip-based calorimeter after quick cooling from the melt inside the DFSC, and DSC. The data are extended to slow crystallization measurements by using AC calorimetry and DSC at low and high temperatures, respectively. The dynamic glass-transition temperature from AC calorimetry at 40 Hz is also indicated (see Section 2.31.4.4).

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