Differential scanning calorimeters DSCs

Fig. 1. Differential scanning calorimeter (dsc) curves of three grades of low melting syndiotactic 1,2-polybutadiene. A, 90% 1,2 = 71° C B, 92% 1,2 ...

In a testing context, it refers to the first detection of exothermic-activity on the thermogram. The differential scanning calorimeter (DSC) has a scan rate of I0°C/min, whereas the accelerating rate calorimeter (ARC) has a sensitivity of 0.02°C/min. Consequently, the temperature at which thermal activity is detected by the DSC can be as much as 50°C different from ARC data. 

Differential Scanning Calorimeter (DSC) thermograms were obtained on a Perkin Elmer DSC-2 run at 10°C per minutes. Dynamic Mechanical Thermal Analysis (DMTA) spectra were obtained on a Polymer Labs DMTA at a frequency of 1Hz with a temperature range from -150°C to +150°C at a scan rate of 5°C per minute. 

Thermal Properties. The glass transition temperature (Tg) and the decomposition temperature (Td) were measured with a DuPont 910 Differential Scanning Calorimeter (DSC) calibrated with indium. The standard heating rate for all polymers was 10 °C/min. Thermogravimetric analysis (TGA) was performed on a DuPont 951 Thermogravimetric Analyzer at a heating rate of 20 °C/min. 

Safety studies of the graphite anode samples were performed using a Perkin-Elmer Differential Scanning Calorimeter (DSC, model Pyris 1) instrument. The temperature scanning rate was 10 C/min over a temperature range of 50 to 375°C. 

A DuPont 910 differential scanning calorimeter (DSC) and a DuPont 951 thermogravimetric analyzer (TGA) connected to a DuPont 1090 thermal analyzer 3ftre used to study the transition data, thermal stability, and char yield, respectively, for all the polymers. The DSC was run under a nitrogen stream at a flow rate of 80 c.c./min. and at a heating rate of 20°C/min.. 

Adiabatic calorimeters are complex home-made instruments, and the measurements are time-consuming. Less accurate but easy to use commercial differential scanning calorimeters (DSCs) [18, 19] are a frequently used alternative. The method involves measurement of the temperature of both a sample and a reference sample and the differential emphasizes the difference between the sample and the reference. The two main types of DSC are heat flux and power-compensated instruments. In a heat flux DSC, as in the older differential thermal analyzers (DTA), the... 

Figure 2.6C shows the temperature difference between reference and sample as recorded by differential thermal analysis (DTA). Note also the similar differential scanning calorimeter (DSC) curve later in Figure 2.13. 

Fig. 1. Differential Scanning Calorimeter (DSC). Ts=sample temperature, Tr=reference temperature, T0=oven temperature.

Glass transition temperatures of the uv-hardened films were measured with a Perkin Elmer Model DSC-4 differential scanning calorimeter (DSC) that was calibrated with an indium standard. The films were scraped from silicon substrates and placed in DSC sample pans. Temperature scans were run from -40 to 100-200 °C at a rate of 20 ° C/min and the temperature at the midpoint of the transition was assigned to Tg. 

Experimental Methods Measurements of specific heat and enthalpies of transition are now usually carried out on quite small samples in a Differential scanning calorimeter (DSC). DSC is applied to two different moles of analysis, of these the one is more closely related to traditional calorimetry and is described here. In DSC an average-temperature circuit measures and controls the temperature of sample and reference holders to conform to a Organisation and Qualities... 

A number of sophisticated tools can be of assistance in these areas. Two of the more common tools are the Differential Scanning Calorimeter (DSC) and the Accelerating Rate Calorimeter (ARC). 

In this study, mechaiucal properties of emulsion copolymers of VAc and BuA were determined by differential scanning calorimeter (DSC). 

The heat capacity is the amount of energy required to increase the temperature of a unit mass of material. It is commonly measured using a differential scanning calorimeter (DSC). The heat capacity depends on the resin type, additives such as fillers and blowing agents, degree of crystallinity, and temperature. A temperature scan for the resin will reveal the Tg for amorphous resins and the peak melting temperature and heat of fusion for semicrystalline resins. The heat capacities for LDPE and PS resins are shown in Fig. 4.15. 

A differential scanning calorimeter (DSC), Dupont Instrument, Model DSC2910, was used to determine the glass transition temperatures. Thermo-gravimetric analyses were carried on a thermogravimetric analyzer (TGA), TA Instruments, Model Hi-Res TGA 2950. 

The reactivity value is obtained by using the peak temperature of the lowest differential thermal analysis (DTA) or differential scanning calorimeter (DSC) exotherm value as shown in column 2 of Table VI. Alternatively, it can be obtained from a qualitative description of the instability (or... 

In the CSM laboratory, Rueff et al. (1988) used a Perkin-Elmer differential scanning calorimeter (DSC-2), with sample containers modified for high pressure, to obtain methane hydrate heat capacity (245-259 K) and heat of dissociation (285 K), which were accurate to within 20%. Rueff (1985) was able to analyze his data to account for the portion of the sample that was ice, in an extension of work done earlier (Rueff and Sloan, 1985) to measure the thermal properties of hydrates in sediments. At Rice University, Lievois (1987) developed a twin-cell heat flux calorimeter and made AH measurements at 278.15 and 283.15 K to within 2.6%. More recently, at CSM a method was developed using the Setaram high pressure (heat-flux) micro-DSC VII (Gupta, 2007) to determine the heat capacity and heats of dissociation of methane hydrate at 277-283 K and at pressures of 5-20 MPa to within 2%. See Section 6.3.2 for gas hydrate heat capacity and heats of dissociation data. Figure 6.6 shows a schematic of the heat flux DSC system. In heat flux DSC, the heat flow necessary to achieve a zero temperature difference between the reference and sample cells is measured through the thermocouples linked to each of the cells. For more details on the principles of calorimetry the reader is referred to Hohne et al. (2003) and Brown (1998). 

The differential scanning calorimeter (DSC) works on a technique that detects physicochemical transition in a system by measuring the amount of heat absorbed or released as the sample is heat across its suspected transition range. The heat absorbed or released from a sample of known mass compared with that of an empty reference pan. Modulated differential scanning calorimeter (mDSC) works on an advanced technology version of DSC, where the signal quality has been improved using... 

The compositions of the composites were determined simply by weighing the tared solid sample. Melting endotherms and glass transition temperatures were determined using a TA Instruments 2910 modulated differential scanning calorimeter (DSC) operated with a 3°C/min ramp rate, a 0.75 °C oscillation amplitude, and a 60-s oscillation period. 

An impressive number of papers on the polymerization kinetics of thermosets have been published since the 1970s. This kind of sport of reporting kinetic results is possibly based on the simplicity with which they can usually be obtained. All one needs is a differential scanning calorimeter (DSC) and some centigrams of a commercial formulation. The task is even facilitated if the software for kinetic calculations, provided by most commercial DSC devices, is used to fit a phenomenological rate expression. 

A further positive reaction to this dramatic incident took place in the central research department of the company. A physico-chemist had the idea of using his differential scanning calorimeter (DSC) to look at the energy involved in this reaction. He performed an experiment with the initial concentration and a second with a higher concentration. The thermograms he obtained were different and he realized that he could have predicted the incident (see Exercise 11.1). As a consequence, it was decided to create a laboratory dedicated to this type of experiment. This was the beginning of the scientific approach of safety assessments using thermo-analytic and calorimetric methods. From this time on, many different methods were developed in different chemical companies and became commercially distributed, often by scientific instrument companies. 

In this category of calorimeters, we find the isothermal calorimeters and the dynamic calorimeters where the temperature is scanned using a constant temperature scan rate. The instrument must be designed in such a way that any departure from the set temperature is avoided and the heat of reaction must flow to the heat exchange system where it can be measured. The instrument acts as a heat sink. In this family we find the reaction calorimeters, the Calvet calorimeters [7], and the Differential scanning calorimeter (DSC) [8],... 

In order to obtain the degree of cure and rate of curing, we must first measure the reaction. This is typically done using a differential scanning calorimeter (DSC) as explained in Chapter 2. Typically, several dynamic tests are performed, where the temperature is increased at a constant rate and heat release rate (Q) is measured until the conversion is finished. To obtain Qt we must calculate the area under the curve Q versus t. Figure 7.17 shows four dynamic tests for a liquid silicone rubber at heating rates of 10, 5, 2.5 and 1 K/min. The trapezoidal rule was used to integrate the four curves. As expected, the total heat Qt is the same (more or less) for all four tests. This is to be expected, since each curve was represented with approximately 400 data points. 

Here, R is the gas constant and b, b2, ai and a2 are constants that can be obtained by fitting the above equations to data measured with a differential scanning calorimeter (DSC) [9, 17],... 

Differential Scanning Calorimetry (DSC) Studies. Hairless mouse abdomen stratum corneum, extracted lipids and protein residues were studied with a Perkin Elmer 4 differential scanning calorimeter (DSC) equipped with a thermal analysis data system (TADS). Scanning rates were 10°C per minute over the temperature region -10 to 237°C. Stratum corneum, extracted lipid and protein residue samples obtained from the abdomen of the hairless mice (average 10 mg/sample) were studied in the desiccated state following evaporation of any residue water or solvents by vacuum drying at 10 4 Torr. 

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