AbstractThe isothermal and non‐isothermal crystallization of isotactic polypropylene coloured with selected organic pigments was examined by differential scanning calorimetry. It was found that the nucleating ability of pigments is connected with their chemical nature and with the reduction of the free energy for critical nucleus formation. The experimental data were analysed in terms of the well known Avrami equation.Blue pigment and Red lake are substances which accelerate the crystallization of isotactic polypropylene, while Orange pigment decreases the crystallization rate slightly.

AbstractThe dependence of glass temperature on the heating rate and the composition for styrene‐zinc acrylate copolymers has been investigated by differential scanning calorimetry. Thermogravimetry was used in order to examine these copolymers undergoing pyrolysis in an atmosphere of air at three different heating rates. Thermal decomposition of ionomers is a three‐stage process. The orders and activation energies have been determined for each stage of decomposition using the computer programs based on the methods of Kissinger, Freeman‐Carrol, and Ozawa. It was found that the heat stability is lowered by the ionic groups.

AbstractThermogravimetry was used to investigate petroleum and coal tar pitches undergoing pyrolysis in an atmosphere of air and nitrogen at three different heating rates.Pyrolysis of pitches in air is a three‐stage process, whereas in nitrogen two stages were found.A kinetic analysis of the thermogravimetric data has been made. The orders and activation energies have been determined for each stage of decomposition using the methods of Kissinger, Freeman, and Hüttinger.

AbstractThe dependence of glass temperature on the heating rate for styrene‐divinylbenzene solvent modified network copolymers has been investigated by differential scanning calorimetry. The McMillan equation has been utilized to determine apparent activation energies of vitrification. Values of glass temperature do not show a linear function of the degree of crosslinking.

Differential scanning calorimetry (d.s.c.) data on non-isothermal crystallization of isotactic polypropylene and high-density polyethylene from the melt at different cooling rates were treated in terms of the Ozawa equation. It was found that the crystallization of polypropylene follows the Ozawa equation but in the case of polyethylene the Ozawa theory is not valid.

Impact-resistant polypropylene copolymer (IPC) samples with various pre-shear histories were prepared by a Brabender Rheometer. The influence of pre-shearing on crystallization of IPC, including isothermal and nonisothermal crystallization behaviors was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The results of nonisothermal crystallization showed that compared with as-received IPC, the temperatures referred to the peak of crystallization exotherm, Tp, were prominently elevated for pre-sheared IPC. In isothermal crystallization experiment, combining Avrami Method and Hoffman–Lauritzen Model, it was found that the half-time of crystallization (t1/2) of pre-sheared IPC was greatly shortened and the calculated fold surface free energy (σe) within the isothermal temperatures investigated showed a large reduction. Morphological development during isothermal crystallization observed by POM clearly confirmed that the enhancement in crystallization is mainly due to the fast formation of nuclei during crystallization. Besides, using successive self-nucleation and annealing (SSA) thermal fractionation technique, changes in chain structures induced by pre-shearing were obtained. The relaxation behavior of pre-sheared IPC was also evaluated and it was found that the shear-induced enhancement in crystallization could be relaxed to various extents under annealing conditions.