When crystallization causes an increase of temperature for instance during cooling of a slab or an extruded tube or during sudden stress induced crystallization in fiber spinning, the

heat of crystallization is accounted for by an additional term in the heat transfer equation:

The

heat of crystallization of the polyolefin must be 40 J/g or less.

Equation of energy, taking into account dependence of thermophysical properties upon temperature and release of latent

heat of crystallization within the range of temperatures, is described by Fourier equation of heat conductivity.

By providing more nucleation sites, and, therefore, greater

heat of crystallization during solidification, undercooling is minimized and equilibrium solidification is aided.

The relative degree of crystallinity is calculated from the ratio of the heat evolved up to time t, the area under the curve, divided by the total

heat of crystallization, the total area, according to Eq.

The melting parameters were calculated from the reheating scans and

heat of crystallization from the cooling scans.

0]), which is the temperature where the thermogram initially departs from baseline on the high temperature side of the exotherm; and the

heat of crystallization ([[DELTA][H.

Numerical Prediction of the Temperature Rise and Latent

Heat of CrystallizationThe temperature plateau has its physical origin in the release of latent

heat of crystallization, which counterbalances the heat lost from the film by radiation and convection.

c] is the

heat of crystallization during the same heating scan.

The effect of different crystallization kinetics for different materials was approached by arbitrarily varying the degree of crystallinity by changing the latent

heat of crystallization in the calculation.

1/2], and the

heat of crystallization [DELTA]H of LDPE and LDPE/Al composites at various cooling rate [Q.