Differential colorimeter

For many commercial purposes all that is required is to assess small variations from a standard pattern and differential colorimeters are designed for this purpose. Such an instrument is shown diagrammatically in Fig. 26.28. 

The Differential Colorimeter reads in terms of per cent reflectance of the tristimulus filter, which may be converted toX YZ tristimulus values, or directly to Adams s chromatic value system. As with other tristimulus colorimeters this instrument performs best if it is used as a difference meter, i.e., to compare colors which are close together in color space. 

Figu re 10.4. Differential scanning colorimeter traces showing the melting endotherms for a pure HDPE sample and a 43 wt % polystyrene/HDPE sample. Integration of the endotherms provides the heat of fusion of the samples. 

Differential thermal analysis was carried out on a Perkin-Elmer differential scanning colorimeter, model DSC-2C, at a heating rate of 10°/min, in an atmosphere of nitrogen. It gave a single sharp melting endothermic peak at 298.2cC, followed by decomposition (Figure 5).23... 

Use a differential scanning colorimeter (DSC) or differential thermal analysis (DTA) apparatus 1 with aluminium oxide ( a - alumina) as the reference substance. 

Differential scanning colorimeter, Perkin-Elmer DSC-1B, was used to deter-... 

In order to eliminate problems assoeiated with the differenees in surface properties and shapes of coimnercially available dehydrated vermicelli, Andre and Pauli (1978) ground the samples down to powders, then formed tablets from the powders using a hydraulic press. The 40 mm diameter by 10 mm thick tablets could be measured directly on the head of the colorimeter. Good correlations were found between colour co-ordinate values and the / -carotene content derived from the egg component of the pastas. Pastas made from different flours could also be differentiated in terms of colour values. 

In such cases the use of different filters in a colorimeter will often suffice to differentiate the component colors. A spectrophotometer is particularly useful because it permits making a separate calculation for each wave length whose transmission is affected by the treatment with activated carbon. 

McClain, P.E. and Wiley, E.R. (1972) Differential scanning colorimeter. studies of the thermal transition.s of collagen. Implications on structure and stabilift-./. Biol. Chem., 247, 692-697. 

The melting and polymerization temperatures of the monomers were analyzed by differential scanning colorimeter (DSC) under nitrogen atmosphere and the results are summarized in Table 1. Monomer IC with 3 wt % of diamine (ODA) curing agent shows that the onset and completion temperatures of polymerization reaction are 256 and 300°C, respectively (1260-315°C and the reaction time of 32-36 hr) The same... 

DSC, differential scanning colorimeter GC, gel chromatography TM, thermomechanical analysis. These techniques do not specifically identify materials. Materials can be identified by matching the instrument s test carves with those of known polymers or compounds. Otherwise, other analytical procedures must be used. 

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