Influence of intercalated organoclay on the phase structure and physical properties of PTT–PTMO block copolymers (original) (raw)
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Poly(trimethylene terephthalate-block-tetramethylene oxide) (PTT-PTMO) copolymer/ graphene oxide nanocomposites were prepared by in situ polymerization. From the SEM and TEM images of PTT-PTMO/GO nanocomposite, it can be seen that GO sheets are clearly well-dispersed in the PTT-PTMO matrix. TEM images also showed that graphene was well exfoliated into individual sheets, suggesting that in situ polymerization is a highly efficient method for preparing nanocomposites. The influence of GO on the two-phase structure, melt viscosity and mechanical properties of PTT-PTMO block copolymer was examined by using DSC, ARES rheometer and tensile tests. The DSC results imply that the introduction of GO did not affect the glass transition temperature of PTMO-rich soft phase, melting temperature of PTT hard phase and degree of crystallinity of the nanocomposites. As the graphene oxide loading in the nanocomposites increase, the enhanced Young's modulus and yield stress was observed. The tensile strength slightly increased with the increase of GO from 0 to 0.5 wt% when elongation at break was higher or comparable to the value of neat PTT-PTMO copolymer.
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A series of poly(ethylene terephthalate-co-1,4-cyclohexanedimethanol terephthalate)-blockpoly(tetramethylene oxide) (PETG-block-PTMO) copolymers were synthesized by means of a polycondensation process and characterized using 1 H nuclear magnetic resonance (H NMR) and Fourier transform infrared spectroscopy (FTIR), that confirm the successful synthesis of the material. Differential scanning calorimetry (DSC), smalland wide-angle X-ray diffraction (SAXS and WAXS), and thermogravimetric analysis (TGA) were used in order to evaluate the influence of the block copolymers' composition and microstructure on the phase transition temperatures, thermal properties, as well as the thermooxidative and thermal stability of the PETG-block-PTMO copolymers, respectively. The mechanical properties were investigated by tensile testing and dynamic mechanical measurements (DMTA). We found that along with an increase in PTMO weight fraction, both number-average molecular weights and intrinsic visocisities increase. Moreover, an increase in the flexible segments content in PETG-block-PTMO resulted in shifting the values of glass transition temperatures toward lower ones, which was confirmed by DSC and DMTA analyses, thus affirming the miscibility of both phases. At the same time, along with an increase of PTMO flexible segments amount in the PETG-block-PTMO copolymers, the values of Young's modulus, tensile strength at yield and weight losses in lower temperatures range, i.e. 280-390 C, decrease.
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A series of poly(trimethylene terephthalate)-block-poly(ethylene oxide) (PTT-b-PEOT) copolymers with different compositions of rigid PTT and flexible PEOT segments were synthesized via condensation in the melt. The influence of the block length and the block ratio on the micro-separated phase structure and elastic properties of the synthesized multiblock copolymers was studied. The PEOT segments in these copolymers were kept constant at 1130, 2130 or 3130 g/mol, whereas the PTT content varied from 30 up to 50 wt %. The phase separation was assessed using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The crystal structure of the synthesised block copolymers and their microstructure on the manometer scale was evaluated by using WAXS and SAXS analysis. Depending on the PTT/PEOT ratio, but also on the rigid and flexible segment length in PTT-b-PEO copolymers, four different domains were observed i.e.,: a crystalline PTT phase, a crystalline PEO phase (which exists for the whole series based on three types of PEOT segments), an amorphous PTT phase (only at 50 wt % content of PTT rigid segments) and an amorphous PEO phase. Moreover, the elastic deformability and reversibility of PTT-b-PEOT block copolymers were studied during a cyclic tensile test. Determined values of permanent set resultant from maximum attained stain (100% and 200%) for copolymers were used to evaluate their elastic properties.
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Nanocomposites based on poly(trimethylene terephthalate)-block-poly(tetramethylene oxide) (PTT-PTMO)-segmented copolymer and COOH-functionalized single-walled carbon nanotubes (SWCNTs) were prepared by in situ polymerization method. The obtained nanocomposites were characterized by thermogravimetric analysis, scanning electron microscopy, differential scanning calorimetry (DSC), DMTA, wide-angle x-ray scattering (WAXS), small-angle X-ray scattering, and tensile testing. The nanocomposites with low SWCNTs loading (<0.5 wt %) shows uniform dispersion of CNT in polymer matrix. As the SWCNTs loading in the nanocomposites increase, the significant improvement of thermo-oxidative stability was observed. It was found that the nanocomposites have slightly higher degree of crystallinity (determined by DSC and WAXS) of poly(trimethylene terephthalate) (PTT) hard phase than neat PTT-PTMO copolymer. The melting point of PTT hard phase and glass transition temperature of poly(tetramethylene oxide)-rich phase were not affected by the presence of CNTs in polymer matrix. The SWCNTs played a role as nucleating agent in PTT-PTMO matrix, which led to increase in the crystallization rate. Tensile tests showed that the tensile strength of the nanocomposites with 0.05-0.3 wt % loading of SWCNTs have improved tensile strength in comparison to the neat PTT-PTMO copolymer without reduction elongation at break.
Journal of Applied Polymer Science, 2009
Layered-silicate-based polymer–clay nanocomposite materials were prepared depending on the surface modification of montmorillonite (MMT). Nanocomposites consisting of poly(butylene terephthalate) (PBT) as a matrix and dispersed inorganic clay modified with cetyl pyridinium chloride (CPC), benzyl dimethyl N-hexadecyl ammonium chloride, and hexadecyl trimethyl ammonium bromide by direct melt intercalation were studied. The organoclay loading was varied from 1 to 5 wt %. The organoclays were characterized with X-ray diffraction (XRD) to compute the crystallographic spacing and with thermogravimetric analysis to study the thermal stability. Detailed investigations of the mechanical and thermal properties as well as a dispersion study by XRD of the PBT/clay nanocomposites were conducted. X-ray scattering showed that the layers of organoclay were intercalated with intercalating agents. According to the results of a differential scanning calorimetry analysis, clay acted as a nucleating agent, affecting the crystallization. The PBT nanocomposites containing clay treated with CPC showed good mechanical properties because of intercalation into the polymer matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Journal of Applied Polymer Science, 2013
Thermal, rheological, and physical properties of amorphous poly(ethylene terephthalate) (PET)/organoclay nanocomposite films which were successfully prepared with melt processing method using a PET/organoclay masterbatch were studied in detail. Structural and physical properties of the films were characterized by the UV-Vis spectroscopy, XRD and SEM analysis, DSC, DMA, and rheological tests and gas permeability measurements. Cold-crystallization behavior of the samples was analyzed by the DSC and DMA methods. Aspect ratio of the organoclay layers were determined with the Nielsen and Halpin-Tsai models based on the gas permeability and DMA data, respectively. It was found that the organoclay reduced the nonisothermal cold-crystallization rate of PET chains by restricting the segmental motion of the polymer in the solid state. On the other hand, the organoclay enhanced the nonisothermal melt-crystallization of PET due to the nucleation effect. Aspect ratio (A f) of the clay layers were found to be about 20 by using the gas permeability and DMA data. Aspect ratio value was also confirmed by the analysis of SEM images of the samples. A physical model for the sample microstructure was offered that the stacks with the thickness of 20-30 nm and the lateral size of 400-600 nm, probably consisting of 5-8 layers, were uniformly dispersed in the PET structure. V
Thermo-mechanical behavior of poly(butylene terephthalate)/silica nanocomposites
Journal of Applied Polymer Science, 2017
In this work, experimental results about poly(butylene terephthalate) (PBT) based nanocomposites filled with various amounts of silica nanoparticles (NPs) are reported. Two different types of filler are used: silica gel NPs, produced through the St€ ober method, and a commercial fumed silica, both coated by a PBT shell. Melt-mixed samples have been thoroughly investigated by scanning and transmission electron microscopy, infrared Fourier transform spectroscopy (FTIR), thermal gravimetric analysis, differential scanning calorimetry, wide and small angle X-ray diffraction, and dynamic mechanical analysis. A fine and very good dispersion of NPs into the polymeric matrix is revealed through the morphological analysis when St€ ober NPs were used as filler with respect to systems including commercial fumed silica particles. This evidence, combined with matrix-filler interactions revealed by FTIR spectroscopy, justifies the enhancement of both storage modulus and glass transition temperature of the former samples in comparison with reference pristine PBT.
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Poly(ethylene-co-isosorbide terephthalate) (PEIT) copolyesters could be used in various applications depending on their ability to crystallize. Moreover, the possibility to carry out solid-state post-condensation (SSP) is conditioned by its ability to sufficiently crystallize. The present study, thus, gives a systematic investigation of isothermal crystallization of these statistical copolyesters with isosorbide contents ranging from 4.8 to 20.8 mol.%. For each copolyester composition, the lowest isothermal half crystallization times and the highest Avrami constant (K) were obtained around 170 • C. Over the range of composition that was studied, both melting points and melting enthalpies decreased with increasing amounts of isosorbide (from 250 to 207 • C and from 55 to 28 J/g, respectively). On the contrary, half crystallization time displayed an exponential increase when increasing isosorbide contents in the studied range. Finally, structural and thermal analysis of PIT homopolyester are reported for the first time, showing that only ET moieties crystallized when PEIT was subjected to isothermal crystallization at 170 • C.