TNF is the abbreviation for temperature nuclei free, which can be further defined as the temperature at which no crystals are present in a polymer melt. Even at temperatures above melting temperature persistent crystals may be present which can disturb processing techniques such as melt spinning.

This measurement is also useful for other (delegate) processing techniques such as film blowing or film casting.

With a TNF measurement the lowest temperature of a polymer melt is determined in which no persistent crystals are present. The TNF measurement contains a series of DSC measurements of which a graph can be constructed.