Cubical coefficients

This table lists values of /3, the cubical coefficient of thermal expansion, taken from Essentials of Quantitative Analysis, by Benedetti-Pichler, and from various other sources. The value of /3 represents the relative increases in volume for a change in temperature of 1°C at temperatures in the vicinity of 25°C, and is equal to 3 a, where a is the linear coefficient of thermal expansion. Data are given for the types of glass from which volumetic apparatus is most commonly made, and also for some other materials which have been or may be used in the fabrication of apparatus employed in analytical work. 

The general equation which is applicable to linear, superficial or cubical coefficients of expansion, may be expressed as mt m (I + t + /3d2 + yt3 + where mt = length, area or volume at t°C m0 = same at temp 0°C a fit y = empirically detd coefficients For solids, if. a linear coeff 0O is known, the superficial coeff is approx (2fO and the cubical (W... 

The linear coefficient of expansion of a bar of polymer may be determined by measuring the difference in its length at two different temperatures and dividing by the temperature difference. The cubical coefficient of expansion may be measured in a dilatometer such as that used for measuring Tr... 

THERMAL EXPANSION COEFFICIENT. The change in volume per unit volume per degree change in temperature (cubical coefficient). For isotropic solids the expansion is equal in all directions, and the cubical coefficient is about three times the linear coefficient of expansion. These coefficients vary with temperature, but for gases at constant pressure the coefficient of volume expansion is nearly constant and equals 0.00367 for each degree Celsius at any temperature. 

NIST has specified 20°C as the normal temperature for volumetric work. The cubical coefficient of expansion of Pyrex is about 0.9 X 10 K that of water at 20°C is about 21 X 10 K. The expansion of glass will be of importance only in very precise work that of water however will affect molar concentrations and will be of significance if the actual temperature is more than about 5°C removed from 20°C. 

Its cubical coefficient of expansion with rise of temperature is 0 00004.1... 

Problem 2.24 A new polymer is found to have glass transition at 90°C and its cubic coefficient of thermal expansion is 5.6xlO"" at 120°C. Can this polymer be used in an application which requires the cubic coefficient of thermal expansion to be less than 4xl0 °K at 60° C ... 

Tabie 3.35. PTFE Resins Cubical Coefficients of Expansion ... 

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