Additivity group contributions

Van Krevelen DW (1990) Properties of Polymers. Their correlation with chemical structure, their numerical estimation and prediction from additive group contributions, 3rd ed. Elsevier, Amsterdam. 

Van Krevelen, D. W. Properties of Polymers Their Correlation with Chemical Structure Their Numerical Estimation and Prediction from Additive Group Contributions. New York Elsevier, 1997. 

Discovery of Additive Functions and Derivation of Additive Group Contributions (=Group Increments)... 

It will be shown that the molar volumetric properties can be calculated with a remarkable accuracy from additive group contributions. Furthermore there exist interesting correlations with the Van der Waals volume. 

Richards et al. (1955,1958) measured line widths at low temperatures (90 K) and found that the second moment (S2) depended very much on the inter-hydrogen distance. Since the hydrogen atoms in an aromatic ring are more widely spaced than those in aliphatic groups, the variation in the line widths can be associated with variation of the ratio aromatic/aliphatic components. Richards et al. derived additive group contributions to the second moment from the resonance spectra of a number of model substances they are shown in Table 12.7. Because of the differences in mobility it is also possible to determine, e.g. the plasticizer content in Polyvinyl chloride. 

The mechanical properties of polymers are controlled by the elastic parameters the three moduli and the Poisson ratio these four parameters are theoretically interrelated. If two of them are known, the other two can be calculated. The moduli are also related to the different sound velocities. Since the latter are again correlated with additive molar functions (the molar elastic wave velocity functions, to be treated in Chap. 14), the elastic part of the mechanical properties can be estimated or predicted by means of the additive group contribution technique. 

U is called Molar Elastic Wave Function it is independent of temperature or polymeric phase state and can be calculated from additive group contributions. In this way the elastic parameters can be estimated or predicted. 

If the additive group contributions of these molar functions are known, the moduli can be calculated ... 

A set of additive group contributions for UR valid for liquids was derived by Sakiades and Coates (1955). 

In this chapter it will be demonstrated that the free enthalpy of reactions can be calculated by means of additive group contributions. 

Their Correlation with Chemical Structure their Numerical Estimation and Prediction from Additive Group Contributions... 

THEIR CORRELATION WITH CHEMICAL STRUCTURE THEIR NUMERICAL ESTIMATION AND PREDICTION FROM ADDITIVE GROUP CONTRIBUTIONS... 

As the limitations of the additive group-contribution techniques become more apparent, new representational models will be required to solve the product design problem. These models must maintain some simplicity in the structure-property relationships, which can be inverted in an efficient and explicit manner to yield the structure(s) of the feasible molecule(s). Such models have yet to be invented, but it is important to keep in mind the needs of the product design, as new theories and techniques are being written for the estimation of physical properties. 

The development of new polymeric structures for different technological applications usually requires knowledge about properties of this material. The prediction of properties using additive group contribution method is a valuable procedure adopted during the developments presented here. The group contribution method concept was applied to obtain viscosity data versus temperature, an intermediate step of the free-volume parameters estimation procedure (equation (2) inputs). Detailed concepts about prediction of polymer properties were studied and applied as presented in specific literature (Van Krevelen, 1992 Bicerano, 2002). Equations (4) and (5) are the key equations of the procedure to obtain zero shear viscosity predicted data. The references adopted in this section also allows to predict many others polymer properties. 

Additive (group contribution) methods have a long tradition of successful use in predicting the properties of both ordinary molecules and macromolecules (polymers). They have formed the backbone of the quantitative structure-activity relationships (QSAR) [1,2] used to predict the chemical reactivity and the biological activity of molecules in medicinal and agricultural chemistry. They have also been used extensively in many quantitative structure-property relationships (QSPR) developed for the physical and chemical properties of polymers. 

Additive Property) = X("additive" group contributions) + X("constitutivc" structural terms) (1.3)... 

Empirical additive group contributions to the experimental phosphorus chemical shift, originally suggested by Van Wazer et were moderately successful, as were attempts to rationalize the shift data for several tertiary, secondary phosphines.More recently Grim et al. showed that the observed chemical shift for 1209 tertiary and secondary phosphines and quaternary phosphonium salts could be predicted with reasonable certainty using nine empirical group contributions (a ) for organic substituents. 

Bacaloglu, R., Fisch, M. Degradation and stabilization of poly(vinyl chloride). V. Reaction mechanism of poly(vinyl chloride) degradation. Polym. Degrad. Stabil. 47(1), 33-57 (1995) van Krevelen, D.W. Properties of Polymers. Their Correlation with Chemictil Structure. Their Numerical Estimation and Prediction from Additive Group Contributions, 3rd edn., pp. 627-639. Elsevier, Amsterdam (1990)... 

Even a property as sensitive as the energy can exhibit additive group contributions as was once again first demonstrated in the experimentally determined heats of formation of the normal hydrocarbons . Benson has demonstrated how this and other thermodynamic properties of molecules and the changes in these properties upon chemical reaction can be usefully tabulated and predicted in terms of group contributions. 

Fedderly, J., Compton, E., and Hartmaim, B. Additive group contributions to density and glass transition temperature in polyurethanes. Polymer Engineering and Science, 38(12), 2072-2076 (1998). 

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