Crystallization and spherulitic growth kinetics of poly(trimethylene terephthalate)/polycarbonate blends (original) (raw)
Related papers
2004
Various macrokinetic models, namely the Avrami, Ozawa, and Ziabicki models, were applied to describe the nonisothermal melt crystallization process of poly(trimethylene terephthalate) (PTT), poly(butylene terephthalate) (PBT), and their blends. Both the Avrami and the Ozawa models were found to describe the experimental data fairly well. Among the blend compositions studied, Ziabicki's kinetic crystallizability parameter was found to decrease with increasing PTT content. The effective energy barrier for non-isothermal crystallization process of these blends, analyzed based on the differential iso-conversional method of Friedman, was found to be an increasing function of the relative degree of melt conversion. Within the relative degree of melt conversion range of less than ca. 0.5, the effective energy barrier was found to increase with increasing PTT content.
Journal of Polymer Science Part B: Polymer Physics, 2004
Blends of poly(trimethylene terephthalate) (PTT) and poly(ethylene terephthalate) in the amorphous state were miscible in all of the blend compositions studied, as evidenced by a single, composition-dependent glass-transition temperature observed for each blend composition. The variation in the glass-transition temperature with the blend composition was well predicted by the Gordon-Taylor equation, with the fitting parameter being 0.91. The cold-crystallization (peak) temperature decreased with an increasing PTT content, whereas the melt-crystallization (peak) temperature decreased with an increasing amount of the minor component. The subsequent melting behavior after both cold and melt crystallizations exhibited melting point depression behavior in which the observed melting temperatures decreased with an increasing amount of the minor component of the blends. During crystallization, the pure components crystallized simultaneously just to form their own crystals. The blend having 50 wt % of PTT showed the lowest apparent degree of crystallinity and the lowest tensile-strength values. The steady shear viscosity values for the pure components and the blends decreased slightly with an increasing shear rate (within the shear rate range of 0.25-25 s Ϫ1 ); those of the blends were lower than those of the pure components. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 676 -686, 2004
Polymer Testing, 2004
Blends of poly(trimethylene terephthalate) (PTT) and poly(butylene terephthalate) (PBT) were miscible in all of the blend compositions studied, as evidenced by an observed single and composition-dependent glass transition temperature for each blend composition. The variation of the glass transition temperature with the blend composition was well predicted by the Gordon-Taylor equation, with fitting parameter being ca. 6.9. The cold crystallization (peak) temperature was found to increase, while the melt crystallization (peak) temperature was found to decrease, with increasing PTT content. The subsequent melting behavior for these blends (after cold crystallization) showed the melting point depression behavior, in that the melting (peak) temperature for each component was lowered with increasing content of the other component. During crystallization, the pure components crystallized simultaneously to form their own crystals. The blend having 60 percent by weight of PTT showed the lowest apparent degree of crystallinity. The steady shear viscosities for the pure components and the blends showed slight decrease with increasing shear rate (within the shear rate range of 0.25-25 s Ϫ1 ), with those of the blends lying in between those of the pure components.
Miscibility and crystallisation behaviour of poly(ethylene terephthalate)/polycarbonate blends
Polymer, 2002
Poly(ethylene terephthalate)/polycarbonate blends were produced in a twin-screw extruder with and without added transesteri®cation catalyst, lanthanum acetyl acetonate. The miscibility of the blends was studied from their crystallisation behaviour and variation in glass transition temperature with composition using differential scanning calorimetry, scanning electron microscopy and change in mechanical properties. The blends prepared without the catalyst showed completely immiscible over all compositions, while those prepared in the presence of the catalyst showed some limited miscible. The presence of PC inhibited the crystallisation of PET but this was much greater in the blends prepared in the presence of catalyst suggesting that some reaction had taken place between the two polyesters. The tensile properties showed little differences between the two types of blends. q
Journal of Thermal Analysis and Calorimetry, 2019
The role of bisphenol-A diglycidyl ether (BADGE)-a weakly interacting, low molecular weight additive on crystallization kinetics, morphology and spherulite growth of semi-crystalline thermoplastic-poly(trimethylene terephthalate) (PTT) is quantitatively evaluated. Blends of PTT with different loadings of BADGE were prepared by melt blending. Weak secondary interactions between BADGE and PTT influenced the crystallization kinetics of PTT. This gives rise to concentrationdependent changes in spherulite morphology, crystallization kinetics and stereochemical conformation of PTT. BADGE behaved as a nucleating agent/plasticizer for PTT depending on its loading and changed the conformational distribution of PTT thereby facilitating chain mobility, along with diffusion and attachment of chain segments to crystal nuclei and growth faces. Crystallization kinetics and glass transition studies were carried out using differential scanning calorimetry, while spherulite growth rate was followed using polarized optical microscope equipped with hot stage, and the microphase structure evaluated using small-angle X-ray scattering studies.
Non-isothermal melt-crystallization kinetics of poly(trimethylene terephthalate)
2004
Non-isothermal melt-crystallization kinetics and subsequent melting behavior of poly(trimethylene terephthalate) (PTT) have been investigated by differential scanning calorimetry (DSC). The Avrami, Tobin and Ozawa equations were applied to describe the kinetics of the crystallization process. Both of the Avrami and Tobin crystallization rate parameters (i.e. K A and K T , respectively) were found to increase with increasing cooling rate. The Ozawa crystallization rate K O was found to decrease with increasing temperature. The ability of PTT to crystallize from the melt under a unit cooling rate was determined by the Ziabicki's kinetic crystallizability index G Z , which was found to be ca. 0.98. The effective energy barrier describing the non-isothermal melt-crystallization process DE of PTT was estimated by the differential iso-conversional method of Friedman and was found to increase with an increase in the relative crystallinity. In its subsequent melting, PTT exhibited triple endothermic melting behavior when it was cooled at cooling rates lower than ca. 20 v C min À1 , while it exhibited double endothermic melting behavior when it was cooled at cooling rates greater than ca. 20 v C min À1 .
Journal of Applied Polymer Science, 1998
The isothermal and dynamic crystallization behaviors of polyethylene terephthalate (PET) blended with three types of liquid crystal polymers, i.e., PHB60-PET40, HBA73-HNA27, [(PHB60-PET40) -(HBA73-HNA27) 50 : 50], have been studied using differential scanning calorimetry (DSC). The kinetics were calculated using the slope of the crystallization versus time plot, the time for 50% reduced crystallinity, the time to attain maximum rate of crystallization, and the Avrami equation. All the liquid crystalline polymer reinforcements with 10 wt % added accelerated the rate of crystallization of PET; however, the order of the acceleration effect among the liquid crystalline polymers could not be defined from the isothermal crystallization kinetics. The order of the effect for liquid crystalline polymer on the crystallization of PET is as follows:
Journal of Applied Polymer Science, 2011
We investigated the reactive melt blending of poly(ethylene terephthalate) (PET) and poly(trimethylene terephthalate) (PTT) in terms of the thermal properties and structural features of the resultant materials. Our main objectives were (1) to investigate the effects of the processing conditions on the nonisothermal melt crystallization and subsequent melting behavior of the blends and (2) to assess the effects of the blending time on the structural characteristics of the transreaction products with a fixed composition. The melting parameters (e.g., the melting temperature, melting enthalpy, and crystallization temperature) decreased with the mixing time; the crystallization behavior was strongly affected by the composition and blending time. Moreover, a significant role was played by the final temperature of the heating treatment; this meant that interchange reactions occurred during blending and continued during thermal analysis. The wide-angle X-ray diffraction patterns obtained under moderate blending conditions showed the presence of crystalline peaks of PET and PTT; however, the profiles became flatter after blending. This effect was more and more evident as the mixing time increased. Transesterification reactions between the polyesters due to longer blending times with an intermediate composition led to a new copolymer material characterized by its own diffraction profile and a reduced melting temperature. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 698-705, 2011