Isothermal crystallization studies of poly(butylene terephthalate) composites

Abstract

Different crystallization kinetic models (Avrami and Tobin) have been applied to study the crystallization kinetics of virgin poly(butylene terephthalate) (PBT) and filled PBT systems under isothermal experimental conditions. The experimental data have been analyzed with a nonlinear, multivariable regression program. The kinetic parameters for the isothermal crystallization have been determined. The analysis results indicate that both models satisfactorily represent the isothermal crystallization kinetics. PBT crystallizes most slowly. The presence of nanoclays or nanofibers, added as fillers, enhances the crystallization rate of PBT composites. An analysis of the kinetic data with the Avrami and Tobin models has shown little change in the crystallization exponent compared with that of virgin PBT. The crystallization rate constant decreases with a rise in the temperature for the two models. This trend has been observed for similar polyester systems reported in the literature. The dispersion of the clay layers in the PBT nanocomposites has been characterized with wide-angle X-ray diffraction and transmission electron microscopy.

Isothermal crystallization kinetics of poly(butylene terephthalate‐co‐sebacate) copolymer

“…It is needed to point out that Marrs et al found the crystallization rate of PBTS decreased as sebacate content increased. On the other hand, the chain of poly(butylene sebacate) (PBS) is more flexible than that of PBT, and the crystallization rate of PBS is larger than that of PBT 11, 14–16. Generally, the addition of the minor segment with high crystallization rate into a polymer backbones with low crystallization rate results in an enhanced crystallization of the polymer segment in the copolymer 17, 18.…”

High performance PP/SEBS/CNF composites: Evaluation of mechanical, thermal degradation, and crystallization properties

“…Sandler et al studied crystallization of CNT/PP and CNF/PP composites and observed that carbon nanomaterials act as nucleation sites in bulk samples and highly oriented composite films. Al‐Mulla et al have reported that CNF enhanced the rate of crystallization and lowered the onset and peak crystallization temperatures of composites; however these effects were influenced the concentration of reinforcement and on the cooling rate. Tjong et al have found that CNF were dispersed uniformly in amorphous PS and less crystalline LDPE matrices, but agglomerated in more crystalline HDPE.…”

“…where DH f is the normalized enthalpy of fusion, DH max is the enthalpy of fusion of 100% crystalline PP (207.1 J/g) and W poly is the weight fraction of PP in the blend. Effect of CNF on the crystallization process of polymers has been studied by various researchers [35][36][37][38][39][40][41][42][43][44]. Sandler et al [35] studied crystallization of CNT/PP and CNF/PP composites and observed that carbon nanomaterials act as nucleation sites in bulk samples and highly oriented composite films.…”

Crystallization in Polymer Nanocomposites

“…The crystallization of polybutylene terephthalate ( PBT ) -based nanocomposites has been reported for nanofi llers such as clay [45 -47] , attapulgite [48] , and carbon nanofi bers [49] .…”

“…The fold surface free energy of polymer chains in the nanocomposites was less than that in the neat PBT, which suggested that attapulgite acted as a good nucleating agent for the crystallization of PBT. When the nanocomposites of PBT with carbon nanofi bers and organoclay were prepared by melt compounding, isothermal crystallization studies showed that the presence of nanoclays or nanofi bers had enhanced the crystallization rate of the PBT [49] .…”