Standard semicrystalline state

For many years, the thermodynamic description of macromolecules lagged behind other materials because of the unique tendency of pol5nneric systems to assume nonequilibrium states. Most standard sources of thermodynamic data are, thus, almost devoid of polymer information (1-7). Much of the aversion to include polymer data in standard reference sources can be traced to their nonequilibrium nature. In the meantime, polymer scientists have learned to recognize equilibrium states and utilize nonequilibrium states to explore the history of samples. For a nonequilibrium sample it is possible, for example, to thermally establish how it was transferred into the solid state (determination of the thermal and mechanical history). More recently, it was discovered with the use of temperature-modulated differential scanning calorimetry (TMDSC) that within the global, nonequilibrium structure of semicrystalline polymers, locally reversible melting and crystallization processes are possible on a nanophase level (8). 

The tables in Chapter 6 provide specific volumes neither at or below the melting transition of semicrystalline materials nor at or below the glass transition of amorphous samples, since PVT data of solid polymer samples are non-equilibrium data and depend on sample history and experimental procedure (which will not be discussed here). Therefore, only equilibrium data for the liquid/molten state are tabulated. Their common accuracy (standard deviation) is about 0.001 cm /g in specific volume, 0.1 K in temperature and 0.005 P in pressure (95ZOL). 

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