Non-isothermal crystallization kinetics of wood-flour/polypropylene composites in the presence of b-nucleating agent

The influence of aryl amide compounds（TMB）as b-nucleating agents, on the non-isothermal crystallization of a wood-flour/polypropylene composite（WF/PP）prepared by compression molding was investigated by wide-angle X-ray diffraction and differential scanning calorimetry. TMB was proved to be an effective b-crystalline nucleating agent for WF/PP. The DSC data showed that the crystallization peak temperature（Tp） increased and the half-time（t1/2） decreased with the addition of TMB.Three theoretical models were used to analyze the nonisothermal crystallization process. The modified Avrami method and Mo method successfully explained the nonisothermal crystallization behavior of PP and its composites. Their activation energies for non-isothermal crystallization were determined basing on the Kissinger method.

Isothermal Crystallization Kinetics and Crystalline Morphologies of Poly(butylene adipate-co-butylene 1,4-cyclohexanedicarboxylate)Copolymers

In this study, the isothermal crystallization kinetics and crystalline morphology of poly（butylene adipate-co-butylene 1,4-cyclohexanedicarboxylate）（PBAC）, which refers to a copolyester containing a non-planar ring structure, were investigated by differential scanning calorimetry and polarized optical microscopy, and compared with those of neat poly（butylene 1,4-cyclohexanedicarboxylate）（PBC）. The results indicate that the introduction of butylene adipate（BA） unit into PBAC did not change the intrinsical crystallization mechanism. But, the crystallization rate and ability, and equilibrium melting temperature of PBAC copolymers were reduced. All PBC and PBAC copolymers could only form high density of nucleation from melt at given supercooling, while no Maltese cross or ring-banded spherulites could be observed. PBAC copolymers with a high amount of BA unit became amorphous after quenching with liquid nitrogen from melt, while PBC and PBAC copolymers with a low amount of BA unit could still form a large amount of nuclei under the same treatment.

The Effect of Self-nucleation on Isothermal Crystallization Kinetics of Poly(butylene succinate)(PBS) Investigated by Differential Fast Scanning Calorimetry

Differential fast scanning calorimetry（DFSC） was employed on the study of self-nucleation behavior of poly（butylene succinate）（PBS）.The ultra-fast cooling ability of DFSC allows investigating the effect of self-nucleation on the isothermal crystallization kinetics over a wide temperature range.Crystallization half-time,instead of crystallization peak temperature,was used to describe the self-nucleation behavior,and the self-nucleation domain for the samples crystallized at different temperatures was determined.Due to the competition between homogenous nucleation and self-nuclei,the effect of self-nucleation was less pronounced at high supercooling than that for the sample isothermally crystallized at higher temperature.An efficiency scale to judge the efficiency of nucleating agents from the crystallization half-time was also introduced in this work.