engleski

Crystallization kinetic of TPU/PP blends

The effect of talc on thermal properties especially on crystallization behaviour of blends consisting of thermoplastic polyurethane (TPU) and an isotactic polypropylene (i-PP) were studied under isothermal and no isothermal condition by differential scanning calorimetry (DSC). Blends of different ratios of TPU/PP and TPU/T/PP were produced by melt mixing using a Haake Record 90 twin –screw extruder. Crystallization studies under isothermal condition were carried out in the temperature range of 116°C to 132°C. Isothermal and no isothermal crystallization kinetics were described by means of the Avrami equation. The effects of different isothermal temperature were studied comparing the values of kinetic parameters such as the Avrami exponent, n, the kinetic constant of the crystallization rate, K, and the half-time of crystallization, t1/2. The Avrami exponent was evaluated to be in the range of 1, 18 - 2, 31. These results indicated the two-dimensional growth of crystalline units. The isothermal crystallization kinetics showed that the addition of talc increased the isothermal crystallization temperature and increased the crystallization rate, K, of TPU/PP blends because of nucleating effect of talc particles. For a given crystallization temperature, the crystallization half-time, t1/2, in the TPU/PP/T blends was lower than the corresponding value for TPU/PP blends. The kinetic of crystallization from the melt state under no isothermal condition of the neat PP and all investigated blends was also studied by the Avrami model. It is found that the Avrami exponent for i-PP is around 2 indicating a two- dimensional growth of the PP crystals.

Crystallization kinetic ; Non-isothermal crystallization ; Isothermal crystallization ; Avrami's model ; Polymer blends

nije evidentirano