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Here, we present a detailed description of the in situ isothermal crystallization of poly(trimethylene 2,5-furandicarboxylate)(PTF) as revealed by real-time Fourier transform infrared spectroscopy (FTIR) and grazing incidence wide-angle X-ray scattering (GIWAXS). From FTIR experiments, the evolution of hydrogen bonding with crystallization time can be monitored in real time, while from GIWAXS, crystal formation can be followed. Density functional theory (DFT) calculations have been used to simulate FTIR spectra for different theoretical structures, enabling a precise band assignment. In addition, based on DFT ab initio calculations, the influence of hydrogen bonding on the evolution with crystallization time can be understood. Moreover, from DFT calculations and comparison with both FTIR and GIWAXS experiments, a crystalline structure of poly(trimethylene 2,5-furandicarboxylate) is proposed. Our results demonstrate that hydrogen bonding is present in both the crystalline and the amorphous phases and its rearrangement can be considered as a significant driving force for crystallization of poly(alkylene 2,5-furanoate)s.

This article presents an experimental study on the relaxation dynamics of a series of random copolymers based on bio-friendly comonomers with interesting gas barrier properties. We analyze the relaxation response in the glassy and ultraviscous regime of poly (trimethylene furanoate/sebacate) random copolymers via dielectric spectroscopy. We report lower values of dynamic fragility [a dimensionless index introduced in 1985 (Angell, Relaxations in Complex Systems, 1985)] in comparison to popular polyesters widely used in industry, such as poly (ethylene terephthalate), suggesting that the amorphous phase of these furanoate-based polyesters adopt an efficient chain packing. This is consistent with their low permeability to gases. We also discuss on different equations (phenomenological and theory-based approaches) for fitting the temperature-evolution of the alpha relaxation time.

A series of aliphatic-aromatic copolyesters based on poly(butylene terephthalate) (PBT) and poly(lactic acid) (PLA) have been synthesized by means of a novel reactive blending procedure coupled with polycondensation in melt. The obtained copolymers were further compared with PBT and PLA homopolymers and PBT/PLA non-compatibilized physical blends in order to investigate the effect of transesterification reactions on the structural, morphological, thermal and mechanical performance. Properties of the obtained materials have been found strictly dependent on the preparation process and blend/copolymer composition. The PBT/PLA physical blends appeared as highly crystalline, phase separated systems that exhibit brittle behavior. On the other hand, the applied method of reactive blending enhanced interfacial adhesion and promoted the arrangement of PBT and PLA in blocks of different lengths. Although the PBT-b-PLA copolyesters were found to be miscible in amorphous phase, the phase separation that has arisen from PBT crystalline domains occurs. Along with an increase in PLA weight fraction in copolymers, the length of aromatic sequences decreased which in turn resulted in shifting the values of melting temperatures (T) toward lower ones and decreased the degree of crystallinity (x). Moreover, PBT-b-PLA copolymer with 30 wt% of PLA units has been demonstrated as a promising thermoplastic shape memory polymer (SMP) with a switching temperature of 35°C.

In this article, postconsumer poly (ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) (PET-G) foils have been modified with three types of carbon nanofillers that differ in size and shape, ie, multiwalled carbon nanotubes (MWCNTs), graphene nanoplatelets (GNP), and nanosized carbon black (nCB), thus enabling the reusage of recyclate in receiving new functional materials. The series of polymer hybrid nanocomposites have been prepared via a two-stage polycondensation process, be means of glycolysis of postconsumer PET-G foil, followed by polycondensation in the presence of carbon nanofillers. The scanning electron microscopy revealed that nanoadditives were uniformly dispersed into the whole volume of polymer matrix. The results present the synergistic effect of hybrid system of nanofillers in improving tensile properties of PET-G. It has been found that the incorporation of three types of carbon nanofillers has not affected the glass transition temperature of the polymer matrix. Moreover, the incorporation of carbon nanofillers, and the mixture of two, or even three of those, caused an improvement in thermal conductivity and thermal stability.

In this article, we have studied thermal and dielectric conductivity and morphology of polycarbonate (PC)/ethylene–propylene copolymer (EPC)/multiwalled carbon nanotubes (MWCNTs) nanocomposites. Transmission electron microscopy has been used to investigate the localization and migration of MWCNTs within the matrix. The MWCNTs were located in the PC phase and at the interface of PC and EPC. The results showed that the thermal conductivity of the PC decreased with the increasing content of EPC elastomeric particles. However, at the same time, one could observe an increase of the thermal conductivity in the polymer blends along with an addition of MWCNT. The electrical conductivity of the PC/EPC blends containing 10 wt% of EPC increased with the incorporation of MWCNTs, and the conducting paths were formed at additive content less than 0.5 wt% of MWCNT.

We report on the formation of Laser Induced Periodic Surface Structures in poly (ethylene terephthalate) and poly (ethylene terephthalate)/Expanded Graphite films by laser irradiation with nanosecond pulses at 266 nm. The characterization studies show that the quality of the ripples depends strongly on the irradiation time and fluence and the optimal conditions for obtaining LIPSS are affected by the amount of the expanded graphite present in the film due to the differences in crystallinity, thermal conductivity and thermal diffusivity of the nanocomposites. Physicochemical modifications in the materials were inspected by Raman spectroscopy, the colloidal probe technique and contact angle measurements using different liquids. Results show that there is an increase of the hydrophilicity of the surfaces after laser irradiation together with an increase of the surface free energy and in particular of its polar component. Additionally, the adhesion force estimated by the colloidal probe technique increases after laser nanostructuring.

Laser induced periodic surface structures (LIPSS) are formed on poly(trimethylene terephthalate) and its composites with single-walled carbon nanotubes (SWCNT) and with both SWCNT and expanded graphite (EG) upon irradiation with a Q-Switched Nd:YAG laser (266 nm, 8 ns). The morphology of the polymer films was characterized by atomic force microscopy. A cantilever with a colloidal probe was used to obtain information about surface adhesion. Surface energies were estimated by contact angle measurements using different liquids. Chemical modification in the materials upon irradiation was assessed by Raman spectroscopy. Results show a dependence of the number of pulses required for LIPSS formation as a consequence of the presence of the carbon nanoadditive and an increase of the hydrophilic character of surfaces after irradiation. Moreover, the polar component of the surface free energy changes significantly and surface adhesion increases by the addition of the additive to the polymer matrix. Additionally, the adhesion force decreases after laser nanostructuring as a consequence of a lower contact area in the nanostructured material.

Design and experiment of polymeric nanocomposites (NCs) for photovoltaic applications with outstanding electrical and thermal properties has been investigated with the introduction of SiC nanofibers (NFs) into the poly(trimethylene terephthalate)-block-poly(tetramethylene oxide) (PTT-PTMO) copolymers. In order to enhance the electrical and thermal conductivity, different concentrations of SiC NFs, ranging from 0.1 to 3.0 wt %, have been selected to mix with PTT-PTMO via in situ polymerization method. This reaction method is an excellent choice for incorporation of high amount of SiC NFs (3 wt %) into the polymer that was confirmed by morphological studies. From dielectric spectroscopy studies a percolating behavior was confirmed at low percolation threshold (less than 2% wt %). Furthermore, the 15% increment for thermal conductivity appeared with combination of 0.5 wt % SiC NFs with PTT-PTMO copolymers, which can be affected by manufacturing process of NCs, state of nanofillers dispersion and aspect ratio of nanofillers.

Multi-walled carbon (MWCNT) and tungsten disulfide (INT-WS) nanotubes are materials with excellent mechanical properties, high electrical and thermal conductivity. These special properties make them excellent candidates for high strength and electrically conductive polymer nanocomposite applications. In this work, the possibility of the improvement of mechanical, thermal and electrical properties of poly(trimethylene terephthalate) (PTT) by the introduction of MWCNT and INT-WS nanotubes was investigated. The PTT nanocomposites with low loading of nanotubes were prepared by in situ polymerization method. Analysis of the nanocomposites' morphology carried out by SEM and TEM has confirmed that well-dispersed nanotubes in the PTT matrix were obtained at low loading (<0.5 wt%). Thermal and thermo-oxidative stability of nanocomposites was not affected by the presence of nanotubes in PTT matrix. Loading with INT-WS up to 0.5 wt% was insufficient to ensure electrical conductivity of PTT nanocomposite films. In the case of nanocomposites filled with MWCNT, it was found that nanotube incorporation leads to increase of electrical conductivity of PTT films by 10 orders of magnitude, approaching a value of 10 S/cm at loading of 0.3 wt%. Tensile properties of amorphous and semicrystalline (annealed samples) nanocomposites were affected by the presence of nanotubes. Moreover, the increase in the brittleness of semicrystalline nanocomposites with the increase in MWCNT loading was observed, while the nanocomposites filled with INT-WS were less brittle than neat PTT. Copyright © 2016 John Wiley & Sons, Ltd.

The formation of Laser Induced Periodic Surface Structures (LIPSS) is a process commonly used to nanostructure polymer surfaces. Forming of LIPSS is possible because of the irradiation of the polymer surface with polarized laser pulses at fluences below the ablation threshold. This leads to a modulation of the depth of the surface, resulting from an inhomogeneous intensity distribution, due to the interference between the incoming and the surface-scattered waves, reinforced with a positive feedback process. Such structures have a spatial period close to the laser wavelength, aligned parallel to the polarization of the laser beam

En este trabajo, se presenta un estudio sobre la generación de estructuras periódicas inducidas por irradiación láser (LIPSS, por sus siglas en inglés) en superficies poliméricas de poli (etilén tereftalato) (PET), PET reforzado con grafito expandido, poli (trimetilén tereftalato) (PTT) y PTT reforzado con nanotubos de carbono de pared simple. La irradiación de las muestras se llevó a cabo usando un láser Nd:YAG (266 nm, 8 ns, 1-10 Hz). Se adquirieron imágenes topográficas de las superficies de las muestras irradiadas mediante el uso de microscopía de fuerza atómica (AFM, por sus siglas en inglés). En todos los casos, se consiguieron estructuras periódicas con periodos cercanos a la longitud de onda de irradiación, las cuales son paralelas al vector de polarización de la radiación incidente. Se encontró que la formación de LIPSS depende considerablemente de los parámetros de irradiación utilizados. Se llevó a cabo la caracterización de las muestras irradiadas y no irradiadas con el propósito de analizar los posibles cambios en las propiedades superficiales inducidos por la irradiación láser. Por un lado, se midieron las propiedades nanomecánicas usando la técnica de mapeo nanomecánico cuantitativo mediante AFM (PF-QNM, por sus siglas en inglés) y se realizaron medidas de adhesión con AFM y una punta coloidal. Por otra parte, se obtuvieron medidas de ángulo de contacto con diferentes líquidos para evaluar la mojabilidad y calcular las energías superficiales de las muestras. Finalmente, se usó la espectroscopia Raman para inspeccionar los posibles cambios químicos en los materiales tras la irradiación láser

© 2015 Elsevier Ltd. A synergetic effect between graphene nanoplatelets (GNP) and single-walled carbon nanotubes (SWCNT) leading to an improvement of the electrical conductivity of poly(trimethylene terephthalate-. block-poly(tetramethylene oxide) (PTT-PTMO) based nanocomposites is demonstrated. PTT-PTMO based nanocomposites were prepared with varying concentration of SWCNT and GNP as conducting fillers, and their electrical conductivity and morphology were evaluated using Dielectric and Raman spectroscopies respectively. It has been shown that the addition of SWCNT and GNP enhanced the electrical conductivity of composites, particularly in the case of composites with 0.3 wt. % SWCNT and 0.1 wt. % GNP nanoparticles. These results suggest the existence of synergy arising from the combination of two conducting fillers with different geometrical shapes and aspect ratios as well as different dispersion characteristics in the PTT-PTMO thermoplastic elastomer matrix.

Nanocomposites based on poly(ethylene terephthalate) (PET) and expanded graphite (EG) have been prepared by in situ polymerization. Morphology of the nanocomposites has been examined by electronic microscopy. The relationship between the preparation method, morphology, and electrical conductivity was studied. Electronic microscopy images reveal that the nanocomposites exhibit well dispersed graphene platelets. The incorporation of EG to the PET results in a sharp insulator-to-conductor transition with a percolation threshold (φ c) as low as 0.05 wt %. An electrical conductivity of 10 -3 S/cm was achieved for 0.4 wt % of EG. The low percolation threshold and relatively high electrical conductivity are attributed to the high aspect ratio, large surface area, and uniform dispersion of the EG sheets in PET matrix. © 2012 Wiley Periodicals, Inc.