Effects of filler type on the nonisothermal crystallization kinetics of poly(butylene terephthalate) (PBT) composites

AgNPs@ZnO hybride nanoparticles infused thermoplastic polyester elastomer and their biocide effect

This paper presents research results of biocidal effect of thermoplastic- polyester-elastomer (TPE-E) with incorporation of hybrid Ag/ZnO/SiO2 NPs (silver/Zinc oxide/SiO2 nanoparticles). These results were compared with various gamma-irradiated doses and processing techniques including extrusion, injection molding and compression molding. In all these processing techniques the TPE-E was mixed with mineral oil and Ag/ZnO/SiO2 nanoparticles. The TPE-E nanocomposites were characterized by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), Infrared FT spectroscopy (FTIR), surface enhanced Raman technique (SERS), FESEM (Field emission scanning electron microscopy), Energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), TEM (transmission electronic microscopy) and antimicrobial test. Antibacterial activity against E. coli and S. aureus, are reported and these results showed potential application in health care products.

Insights into the Bead Fusion Mechanism of Expanded Polybutylene Terephthalate (E-PBT)

Expandable polystyrene (EPS) and expanded polypropylene (EPP) dominate the bead foam market. As the low thermal performance of EPS and EPP limits application at elevated temperatures novel solutions such as expanded polybutylene terephthalate (E-PBT) are gaining importance. To produce parts, individual beads are typically molded by hot steam. While molding of EPP is well-understood and related to two distinct melting temperatures, the mechanisms of E-PBT are different. E-PBT shows only one melting peak and can surprisingly only be molded when adding chain extender (CE). This publication therefore aims to understand the impact of thermal properties of E-PBT on its molding behavior. Detailed differential scanning calorimetry was performed on neat and chain extended E-PBT. The crystallinity of the outer layer and center of the bead was similar. Thus, a former hypothesis that a completely amorphous bead layer enables molding, was discarded. However, the incorporation of CE remarkably reduces the crystallization and re-crystallization rate. As a consequence, the time available for interdiffusion of chains across neighboring beads increases and facilitates crystallization across the bead interface. For E-PBT bead foams, it is concluded that sufficient time for polymer interdiffusion during molding is crucial and requires adjusted crystallization kinetics.

Studies on the effects of 4,4′-dihydroxyphenyl on crystallization and melting behavior of poly (butylene terephthalate)

The blends of poly (butylene terephthalate) (PBT) and 4,4′-dihydroxyphenyl (DHP) were prepared by melt blending, and the effects of DHP on the crystallization and melting behaviors of PBT were investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and polarized optical microscopy (POM). The results showed that crystallization temperature and crystallinity of PBT apparently decreased with the addition of DHP. A remarkably decline in crystallization rate of PBT was achieved, and the blends had higher σe and q values than that of pure PBT as analyzed based on the Avrami equation and Lauritzen-Hoffman equation. The crystal structure of PBT did not change by the addition of DHP, while the spherulite size of PBT decreased.

Deformation-induced structure evolution of poly(butylene terephthalate)/poly(carbonate) blends during uniaxial stretching

Phase separation occurs during deformation for all the PBT/PC samples. At large strains, microfibril slippage plays a leading role in the macroscopic strain.

Preparation of poly(butylene terephthalate)/modified organoclay nanocomposite via in-situ polymerization

Nanocomposites of poly(butylene terephthalate) (PBT)/modified montmorillonite organoclay were prepared via in-situ polymerization of terephthalic acid and butanediol in the presence of different clay content. Cloisite 30B, a commercially available amino modified montmorillonite, was modified with 3-aminopropytriethoxysilane (APS) through a silylation reaction. Morphology and properties of all samples were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1HNMR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The extent of clay layers in samples was confirmed by XRD. Results of XRD and TEM showed that an exfoliation structure was produced in nanocomposites. Studies of crystallization showed that the presence of nanoclay leads to an increase in the crystallization rate and enhances the thermal stability of nanocomposites. Crystallization kinetics were described by the Avrami equation. Crystal growth was spherulitic. According to dynamic mechanical analysis (DMA), storage modulus of nanocomposites was remarkably improved compared with homo PBT. Moreover, a shrinkage test was carried out. Results showed a reduction in shrinkages along and across the flow direction that means a decrease in free volume. Flammability based on the UL-94 test was applied to study the flame retardancy effect of nanoclay on the samples.