Continuous Heating Method

Heat the rubber sample in a nitrogen atmosphere to about 600 °C, where the all orgarric compounds except the carbon black completely decompose. 

The content of carbon black in other polymeric materials can also be determined in the same way. This method gives a repeatability of about 2%. 

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CONTINUOUS HEATING METHOD OF CALORIMETRY AND ITS APPLICATION TO THE STUDY OF LOW-TEMPERATURE SPECIFIC HEAT ANOMALIES IN METHYLAMMONIUM ALUM. 

The first is a stairstep method where the sample temperature is raised in 5°C increments and allowed to equihhrate at each temperature for 3.5 minutes before performing the measurements. Since the sample thermocouple is typically 1 mm away from the face of the material, and the sample will have some thickness that may vary from 0.5—5 mm, this method is designed to overcome the problems associated with thermal lag between the measured temperature and the actual bulk temperature of the material. However, the method has the disadvantage of only providing a data point every 5°C. This may be adequate for instances where the objective of the test is an approximate storage modulus value, since interpolation is possible for applications where the temperature of interest falls between measurement points. However, for identifying exact transition temperatures, which appear as peaks in the loss modulus and tan delta curves, this method is less satisfactory than a continuous heating method. 

Both batch and continuous furnaces maybe employed. The maximum temperature that can be reached in a sintering furnace depends on the furnace and the heating methods (Table 7) (23). 

Heating of the adsorbent in the thermal desorption method can be performed either in a continuous or in a stepwise manner. Most usually a continuous heating is applied. 

Milton et al. [1.136] used this methods and refer to it as manometric temperature measurement. They used times of pressure rises of up to 30 s. During this time, the ice temperature will increase, mainly due to continued heat flow. Therefore, an equation has been developed to transform the experimental pressure data, including three other corrections, into the true vapor pressure of the ice. If the valve is closed for only a very short time, < 3 s, and the pressure is measured and documented 60 to 100 times/s, these data can be recorded as shown in Fig. 1.78.1. The automatic pressure rise measurements (1) can then be plotted... 

A typical procedure calls for reaction of the hemiacetal donor with dicydohexyl carbodiimide and copper(I) chloride (0.1 equiv) at 80 °C, followed by an addition of the acceptor and continued heating. As an early demonstration of this protocol, oc-riboside 86 was prepared in moderate yield but with exclusive stereoselectivity [141]. Further measures were required for the glycosylation of monosaccharide acceptors, such as addition of p-toluenesulfonic add (0.1 equiv) to promote the formation of disaccharide 87 [144]. The method was more suitably applied to the synthesis of O-acyl glycopeptides, as evidenced by the formation of 88 in 60% yield [143,144]. Various peptides with non-nudeophilic side chains were found to be amenable to this stereoselective reaction. The [3-selectivity was suggested to arise from a preponderance of the a-isourea intermediate 85 in the activation step. 

ESI has become the most commonly used interface for LC/MS. It was recognized by John Fenn and co-workers as an important interface for LC/MS immediately after they developed it as an ionization technique for MS. ESI transforms ions in solution to ions in the gas phase and may be used to analyze any polar molecule that makes a preformed ion in solution. The technique has facilitated the ionization of heat-labile compounds and high-molecular-weight molecules such as proteins and peptides. ESI is a continuous ionization method that is particularly suitable for use as an interface with FiPLC. It is the most widely accepted soft-ionization technique for the determination of molecular weights of a wide variety of analytes and, has made a significant impact on drug discovery and development since the late 1980s. 

When using the continuous flow method, however, some additional versatility is available in chemisorption measurements. For example, when data is required at an adsorbate pressure of 0.1 atm, a 10 % mixture of adsorbate, mixed with an inert carrier gas, is passed through the apparatus with the sample cooled to a temperature at which no chemisorption can occur. Upon warming the sample to the required temperature, adsorption occurs producing an adsorbate-deficient peak that is calibrated by injecting carrier gas into the flow stream. Equation (15.9) is then used to calculate the quantity adsorbed. This process is repeated for each concentration required. Caution must be exercised to avoid physical adsorption when the sample is cooled to prevent chemisorption. Should this occur, the adsorption peak due to chemisorption can be obscured by the desorption peak of physically bound adsorbate when the sample is heated. 

Hands and Horsfall58 developed a method based on the continuous heating principle. Their improvements to this apparatus were not published but further development was reported by Smith59. The apparatus allowed measurements of molten polymers and accuracy was helped by measuring the change in thickness of the sample during the test. 

ASTM F 1939 Standard Test Method for Radiant Heat Resistance of Flame Resistant Clothing Materials with Continuous Heating... 

This batch was not prepared by continuous feed method. Instead, a 50% solution of all reactants in xylene was placed into the flask, and the reaction mixture was heated to 138 °C. and stirred under N2 till full conversion was achieved. 

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