E. Kaisersberger et al., THE INFLUENCE OF RECYCLED MATERIAL ON THE CRYSTALLIZATION KINETICS OFTHERMOPLASTIC POLYMERS, Journal of thermal analysis, 40(2), 1993, pp. 821-829
The injection moulding of semi-crystalline thermoplastic polymers requ
ires an exact knowledge of the thermodynamic data and of the crystalli
zation kinetics. The behaviour of the polymer melt during rapid coolin
g in the mould determines, to a great extent, the quality and usabilit
y of a final product. Technical raw materials are often equipped with
nucleating agents in order to obtain crystallization within the desire
d temperature range and at the required rate. The use of recycled mate
rial (regranulate) shows an analogous effect such as the addition of n
ucleating agents, i.e. crystallization begins at a higher temperature
and a higher crystallization rate is detected compared to materials wi
thout added regranulate. Heat flux DSC was used to study the crystalli
zation of polyamides, polyolefins and polyoxymethylene during cooling
at various cooling rates. Although the temperature gradients and press
ures which occur in the processing machine cannot be realised in DSC t
ests, the DSC results reproduce the direction of influence of the regr
anulate additive very clearly.