Expansion coefficients, hydrogen bond

As a consequence, the overall penetrant uptake cannot be used to get direct informations on the degree of plasticization, due to the multiplicity of the polymer-diluent interactions. The same amount of sorbed water may differently depress the glass transition temperature of systems having different thermal expansion coefficients, hydrogen bond capacity or characterized by a nodular structure that can be easily crazed in presence of sorbed water. The sorption modes, the models used to describe them and the mechanisms of plasticization are presented in the following discussion. 

Similarly, thermal stresses can be produced if a temperature differential exists across an element of a low-temperature system or if materials with unlike expansion coefficients are bonded together Sagata has presented an interesting summary of the problems associated with the thermal stresses created by liquid hydrogen in insulated tanks. 

The expansions, Eqs. (5.36) and (5.37), of IT(p) can be used to reduce dimensionality by focusing on the radial coefficients [157]. Thakkar and coworkers [157] formulated empirical mles to help understand the smaU-p behavior of II( p) for linear molecules using only the first four n p) terms. This technique was subsequently used to analyze bonding in 14-electron diatomics [337], strong hydrogen bonding [338], substiment effects in alkynes and cyanides [339], and bonding in alkaline-earth oxides [340,341]. 

Kamlet-Taft) hydrogen bond donation ability ultrasound absorption coefficient isobaric expansibility... 

Figure 3.14 shows the relationship between the crystal modulus, the FIP of cellulose I, and temperature. The FIP is almost constant from room temperature up to 200 °C. This reveals that the cellulose molecule does not show any thermal expansion or contraction. This is in contrast to any other solids, including metals, polymers, and even diamond. For example, an iron crystal expands about 0.275% from 0 to 200 °C, diamond expands with a linear thermal expansion coefficient of 1.1 X 10 K a much larger expansion than that of the cellulose skeleton. The crystal modulus is also temperature independent, which shows that the cellulose skeleton, including intramolecular hydrogen bonds, is intrinsically thermally stable. 

---