BS 7034-8:1988

This standard BS 7034-8:1988 Viscosity and viscometric fixed points of glass is classified in these ICS categories:

• 81.040.01 Glass in general

This part of ISO 7884 specifies a method of determining the (dilatometric) transformation temperature t_g of a glass by means of the thermal expansion method. This temperature characterizes a certain glass transition range from the elastic brittle (low temperature) state to the viscous (high temperature) state of glass. The transformation temperature has been found useful for specifying cooling programmes and estimating the upper temperature limit of applicability of the respective glassware.

NOTE The more direct viscometric method of annealing point and strain point determination (see ISO 7884-7) serves similar purposes. The determination of the transformation temperature t_g might be convenient if a suitable device for determining the coefficient of thermal expansion is available in the laboratory.

Thermal expansion method.