Butylene Terephthalate Research Articles

Preparation and Characterization of Flame-Retarded Poly(butylene terephthalate)/Poly(ethylene terephthalate) Blends: Effect of Content and Type of Flame Retardant.

A flame retardant named TAD was synthesized by the reaction of 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and triallyl isocyanurate at first. Then, novel flameretarded materials based on PBT and PET resin were formulated via melt blending with TAD, expandable graphite (EG), and a mixture of both. The effect of flame retardant type and TAD content on the flame behavior of PBT/PET blend was carefully investigated. TAD contributed towards higher LOI value and better UL-94 performance than EG. However, the best V-0 rating in the UL-94 test was achieved by the incorporation of TAD/EG mixture into the resin matrix. TAD/EG combination exhibited clear synergistic effect on both reducing the flaming intensity and increasing the residual char layer, as confirmed by cone calorimeter tests and TGA results. SEM images combined with XPS analysis revealed that expansion and migration of EG locked the P-containing radicals from decomposing TAD into the condensed phase, which led to the formation of compact and continuous char layers. All the results in our studies demonstrate that incorporation of TAD with a charring agent EG is an effective and promising technique to develop flame-retarded PBT/PET material, which has high potential for applications in the areas of electronic devices, household products, and automotive parts.

Coalescence efficiency of surface modified PBT meltblown nonwovens in the separation of water from diesel fuel containing surfactants

Abstract Removal of water from diesel fuel is essential to ensure efficient operation of High-Pressure Common-Rail (HPCR) fuel injection systems used in modern diesel engines. The presence of surfactants in modern fuels (including biofuels) can create conditions in which the interfacial tension between water and fuel is reduced, leading to coalescing media being “disarmed” and less effective in separation. To elucidate this phenomenon in industrially available depth coalescing media, the coalescence efficiency of surface-modified poly (butylene terephthalate) (PBT) meltblown nonwoven fabrics possessing a wide range of wetting behaviours was studied. Tuning of the wettability was accomplished by alkaline hydrolysis of the medium. Using reference grade diesel fuel with and without added surfactants, the coalescence efficiency and quality factor were studied by means of a purpose-built coalescence test rig. The coalescence efficiency was found to depend on both the fuel composition and the wettability of the treated PBT and the optimum efficiency for each test fuel required a difference in wettability of the PBT. For reference grade diesel, increasing the wettability to ‘intermediate’ level improved coalescence efficiency, but the quality factor can be negatively affected by water droplet retention within the medium. The reduced quality factor associated with hydrophilic media was even more pronounced in fuels containing surfactants due to increased pressure drop and re-emulsification of the fuel in water. These findings highlight the practical challenges that exist in engineering a “universal” coalescing medium suitable for removing water from diesel fuels containing surfactants, based solely on the modulation of fibre wettability and hydrophilicity.

Simulation of dynamic mechanical and viscoelastic behavior in polymer/clay nanocomposites

AbstractViscoelastic behavior of a polymer‐based composite displays the energy storage and damping capabilities of the composite. Simulation and numerical modeling of viscoelastic behavior can aid to estimate the viscoelastic data and optimize the formulations of composites. It is possible to simulate the viscoelastic behavior of a polymeric composite by using the dynamic mechanical analysis (DMA) data of pure polymeric matrix and elastic properties of reinforcement. In this study, three‐dimensional FE analysis was performed to study the viscoelastic behavior of poly(butylene terephthalate)(PBT)/polyurethane/clay nanocomposite by employing representative volumetric element and explicit dynamic analysis. A modified generalized Maxwell model was employed to express the viscoelastic behavior of polymer matrix. Experimental results of DMA for PBT/polyurethane and also elastic data of nanoclay were used in the finite element modeling, and subsequently, the storage and loss moduli of nanocomposite were predicted. The results of simulations were close to those of experiments particularly at low clay content (2 wt%). The aggregation of clays at higher content (4 wt%), increased the differences between experimental and FEM results.

Clever use of PCL as kinetic controller in PBT/PCL blends

This work investigated the melting and nonisothermal melt crystallization of poly (butylene terephthalate) (PBT) and poly (ε-caprolactone) (PCL) blends with PCL content ranging from 3 to 10% of the weight. Thermal stability and morphology analyses were performed by thermogravimetry (TG) and scanning electron microscopy (SEM), whereas the nonisothermal crystallization of PBT/PCL blends carried out by differential scanning calorimetry (DSC), and the kinetic parameters were determined using Pseudo-Avrami, Ozawa and Mo models. PCL improved thermal stability by decreasing the degradation rate of PBT. From SEM images the brittle fracture of PBT was modified through PCL addition with absorption energy mechanisms developed in PBT/PCL blends. PCL delayed the melt crystallization of PBT, most due to its fluid viscous state during PBT crystallization. Ozawa model failed to provide an effective description of the blends, while Pseudo-Avrami and Mo models successfully described the nonisothermal melt crystallization, and linearity deviations were observed only at the beginning and at the end of crystallization, probably due to nucleation and spherulite impingement during secondary crystallization.

Hybrid Polyester-Hydrogel Electrospun Scaffolds for Tissue Engineering Applications.

Electrospinning is an attractive fabrication process providing a cost-effective and straightforward technic to make extra-cellular matrix (ECM) mimicking scaffolds that can be used to replace or repair injured tissues and organs. Synthetic polymers as poly (ε-caprolactone) (PCL) and poly (ethylene oxide terephthalate)-poly(butylene terephthalate) (PEOT/PBT) have been often used to produce scaffolds due to their good processability, mechanical properties, and suitable biocompatibility. While synthetic polymers can mimic the physical features of native ECM, natural polymers like alginate are better suited to recapitulate its hydrated state or introduce functional groups that are recognized by cells (e.g., –NH2). Thus, this study aims at creating electrospun meshes made of blended synthetic and natural polymers for tissue engineering applications. Polyethylene oxide (PEO), PCL, and PEOT/PBT were used as a carrier of Alginate. Scaffolds were electrospun at different flow rates and distances between spinneret and collector (air gap), and the resulting meshes were characterized in terms of fiber morphology, diameter, and mesh inter-fiber pore size. The fiber diameter increased with increasing flow rate, while there was no substantial influence of the air gap. On the other hand, the mesh pore size increased with increasing air gap, while the effect of flow rate was not significant. Cross-linking and washing of alginate electrospun scaffolds resulted in smaller fiber diameter. These newly developed scaffolds may find useful applications for tissue engineering strategies as they resemble physical and chemical properties of tissue ECM. Human Dermal Fibroblasts were cultured on PCL and PCL/Alginate scaffolds in order to create a dermal substitute.

Swarm intelligence integrated micromechanical model to investigate thermal conductivity of multi-walled carbon nanotube-embedded cyclic butylene terephthalate thermoplastic nanocomposites

With the recent demand for miniaturization and integration of electronic devices, there has been a growing interest in device malfunction due to high temperature. In this study, a experimental and theoretical study on the composites with improved thermal conductivity by dispersing multi-walled carbon nanotubes (MWCNTs) in the thermoplastic resin was carried out. A micromechanical model was derived based on the ensemble volume-averaging method and the modified Eshelby’s tensor reflecting the interface properties. The effects of the waviness, interface, and orientation of fillers on the thermal conductivity of composites were numerically analyzed. A computational intelligence-based particle swarm optimization (PSO) algorithm was adopted to the proposed model for optimizing the model constants. The thermal conductivity of the polymerized cyclic butylene terephthalate (pCBT)/MWCNT composites was experimentally measured according to the content of MWCNT. Finally, the experimentally measured data were utilized in the PSO to improve the predictive capability of the proposed model.

Fabrication of Piezoelectric Composites Using High-Temperature Dielectrophoresis

In this paper, we present a method to create a highly sensitive piezoelectric quasi 1–3 composite using a thermoplastic material filled with a piezoelectric powder. An up-scalable high-temperature dielectrophoresis (DEP) process is used to manufacture the quasi 1–3 piezoelectric polymer-ceramic composites. For this work, thermoplastic cyclic butylene terephthalate (CBT) is used as a polymer matrix and PZT (lead zirconium titanate) ceramic powder is chosen as the piezoelectric active filler material. At high temperatures, the polymer is melted to provide a liquid medium to align the piezoelectric particles using the DEP process inside the molten matrix. The resulting distribution of aligned particles is frozen upon cooling the composite down to room temperature in as little as 10 min. A maximum piezoelectric voltage sensitivity (g33) value of 54 ± 4 mV·m/N is reported for the composite with 10 vol% PZT, which is twice the value calculated for PZT based ceramics.

Preparation, structure and flame retardancy of poly(butylene terephthalate) with gradient intumescent flame retardant distribution

In this manuscript, the content-gradient distributions of an intumescent flame retardant (IFR) island-shaped structure in poly(butylene terephthalate) (PBT) were prepared using compression sintering processing technology inspired by powder metallurgy, to achieve efficient flame retardancy and mechanical properties with low flame retardant dosage. The PBT/IFR master-batch was first prepared by extrusion and then pulverized into powder. At low temperature (20 °C below the melting temperature) and high pressure (≥ 50 MPa) sintering processing conditions, two PBT/IFR powders with different levels of IFR content were fabricated into restricted island-like structure composites. The island with a higher IFR content exhibited flame retardancy, while the island with lower IFR content maintained the mechanics of the matrix. Compared with the uniform dispersion PBT/20 wt% IFR composite, the combustion of the PBT/IFR (25 wt%:15 wt% = 1:1) gradient content composite improved from V-1 to V-0 using a UL-94 test, while the tensile strength increased by 10%. The performance of the flame retardant was improved by periodically changing its distribution in the polymer matrix via restricted island-like structures fabricated using compression sintering processing technology inspired by powder metallurgy.

High-Speed Melt Spinning of Polylactide/Poly(Butyleneterephthalate) Bicomponent Fibers: Mechanism of Fiber Structure Development and Dyeing Behavior

Bicomponent fibers consisting of polylactide (PLA) as the sheath and poly(butylene terephthalate) (PBT) as the core were produced by high-speed spinning to obtain materials suitable for medical clothing. The higher-order structure of the PLA fiber component appeared to exhibit simple, alternately stacked, uniaxially oriented amorphous and crystalline regions. Therefore, fairly large tanδ peaks were observed for single-component PLA fibers, even when the orientation-induced crystallization was achieved by high-speed spinning. By conjugating PLA with PBT, although limited mutual interference with the crystallization of each component occurred, both the PLA (Mw = 170,000, L-lactide content = 98.7%) and PBT (intrinsic viscosity = 0.835-0.865 dL/g) could crystallize on a high-speed spinning line, and the proposed formation of a shish-kebab-like structure in the PBT component enhanced the thermal stability of the bicomponent fibers, particularly resulting in shrink-proof properties. The bicomponent fibers developed herein could be deeply dyed at 98 °C, with results comparable to those of industrial polyester, and peeling of the PLA skin layer was rarely observed, even when the dyed fibers were flattened by a rubbing force.

Bio-Based PBT-DLA Copolyester as an Alternative Compatibilizer of PP/PBT Blends.

The aim of this work was to assess whether synthesized random copolyester, poly(butylene terephthalate-r-butylene dilinoleate) (PBT–DLA), containing bio-based components, can effectively compatibilize polypropylene/poly(butylene terephthalate) (PP/PBT) blends. For comparison, a commercial petrochemical triblock copolymer, poly(styrene-b-ethylene/butylene-b-styrene) (SEBS) was used. The chemical structure and block distribution of PBT–DLA was determined using nuclear magnetic resonance spectroscopy and gel permeation chromatography. PP/PBT blends with different mass ratios were prepared via twin-screw extrusion with 5 wt% of each compatibilizer. Thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis were used to assess changes in phase structure of PP/PBT blends. Static tensile testing demonstrated marked improvement in elongation at break, to ~18% and ~21% for PBT–DLA and SEBS, respectively. Importantly, the morphology of PP/PBT blends compatibilized with PBT–DLA copolymer showed that it is able to act as interphase modifier, being preferentially located at the interface. Therefore, we conclude that by using polycondensation and monomers from renewable resources, it is possible to obtain copolymers that efficiently modify blend miscibility, offering an alternative to widely used, rubber-like petrochemical styrene compatibilizers.

Trastuzumab-conjugated nanoparticles composed of poly(butylene adipate-co-butylene terephthalate) prepared by electrospraying technique for targeted delivery of docetaxel.

Human epidermal growth factor receptor 2 (HER-2) is overexpressed in 20-30% of human breast cancers, associated with poor prognosis and tumour aggression. The aim of this study was the production of trastuzumab-targeted Ecoflex nanoparticles (NPs) loaded with docetaxel and in vitro evaluation of their cytotoxicity and cellular uptake. The NPs were manufactured by electrospraying and characterised regarding size, zeta potential, drug loading, and release behaviour. Then their cytotoxicity was evaluated by MTT assay against an HER-2-positive cell line, BT-474, and an HER-2-negative cell line, MDA-MB-468. The cellular uptake was studied by flow cytometry and fluorescent microscope. The particle size of NPs was in an appropriate range, with relatively high drug entrapment and acceptable release efficiency. The results showed no cytotoxicity for the polymer, but the significant increment of cytotoxicity was observed by treatment with docetaxel-loaded NPs in both HER-2-positive and HER-2-negative cell lines, in comparison with the free drug. The trastuzumab-targeted NPs also significantly enhanced cytotoxicity against BT-474 cells, compared with non-targeted NPs.

Dielectric spectroscopy of novel bio-based aliphatic-aromatic block copolymers: Poly(butylene terephthalate)-b-poly(lactic acid).

Broadband dielectric spectroscopy has been used to characterize in deep the relaxation behavior of novel bio-based aliphatic-aromatic block copolymers based on poly(butylene terephthalate) (PBT) and poly(lactic acid) (PLA). The results indicate that the copolymerization decreases the ability to crystallize of the resulting block copolymer. The [Formula: see text] relaxation of the block copolymers is consistent with this fact exhibiting initially the characteristics features of an amorphous polymeric material cold crystallizing upon heating. The cold crystallization can be easily visualized by dielectric spectroscopy by a discontinuous and abrupt change of the shape parameters of the [Formula: see text] relaxation. The sub-glass dynamics of the block copolymers is complex and be ascribed to a [Formula: see text] relaxation composed of two local modes, [Formula: see text] and [Formula: see text], which can be assigned to the relaxation in PBT of the bond between the ester oxygen and the aliphatic carbon and to the bond between the aromatic ring carbon to the ester carbon, respectively. With increasing amount of the PLA block the crystallinity decreases as well as the activation energy of the [Formula: see text] mode approaching the expected value for amorphous PBT. On the contrary, the activation energy for the [Formula: see text] exhibits an unexpected increase as the amount of PLA increases. This effect has been explained by considering that at lower temperatures the [Formula: see text] mode of PBT is the more significant while at higher temperatures the [Formula: see text] relaxation of the PLA block becomes the dominant one.

Microscopic morphology, rheological behavior, and mechanical properties of polymers: Recycled acrylonitrile‐butadiene‐styrene/polybutylene terephthalate blends

ABSTRACTIn this study, styrene‐acrylonitrile‐glycidyl methacrylate (SAG) series copolymers were specially designed for producing the recycled acrylonitrile‐butadiene‐styrene (rABS)/poly(butylene terephthalate) (PBT)/SAG blends, which were prepared through the process of continuous melt blending and batch feeding. The effects of viscosity composition, SAG chemical composition, and SAG content on the morphology, and rheological and mechanical properties of the blends have been investigated. As demonstrated by morphological observation, the variety of viscosity composition of the blends affects the size of dispersed PBT droplets. Moreover, high viscosity of rABS matrix seems to facilitate the formation of smaller dispersed phase size of blends. Various SAG chemical compositions have different stabilities on the morphology of the blends, which affects the deformation, fragmentation, and coalescence of dispersed phase droplets. In addition, a finer phase morphology can be achieved when the density distribution of epoxy group is optimal in SAG copolymer. Rheological characterization manifested that the rheological properties of the blends depends strongly on its composition and structure, while the crosslinking degree is associated with the concentration of reactive groups and extent of reaction. Thereby, the rheological behavior of the blends during processing can be controlled by changing the reactive sequence and adding the quantity of epoxy group. The test on mechanical properties verified that a recycled product with excellent performance can be obtained by altering processing methods and the blends formula, which may be further applied to the 3D printing materials required by fused deposition modeling technology. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48310.

A Cascade Polymerization Method for the Property Modification of Poly(butylene terephthalate) by the Incorporation of Isosorbide

Poly(butylene terephthalate) (PBT) is an important engineering plastic with good mechanical properties. We report herein the incorporation of biobased isosorbide into PBT by a green in situ cascade...

Ultraviolet Functionalization of Electrospun Scaffolds to Activate Fibrous Runways for Targeting Cell Adhesion.

A critical challenge in scaffold design for tissue engineering is recapitulating the complex biochemical patterns that regulate cell behavior in vivo. In this work, we report the adaptation of a standard sterilization methodology—UV irradiation—for patterning the surfaces of two complementary polymeric electrospun scaffolds with oxygen cues able to efficiently immobilize biomolecules. Independently of the different polymer chain length of poly(ethylene oxide terephthalate)/poly(butylene terephthalate) (PEOT/PBT) copolymers and PEOT/PBT ratio, it was possible to easily functionalize specific regions of the scaffolds by inducing an optimized and spatially controlled adsorption of proteins capable of boosting the adhesion and spreading of cells along the activated fibrous runways. By allowing an efficient design of cell attachment patterns without inducing any noticeable change on cell morphology nor on the integrity of the electrospun fibers, this procedure offers an affordable and resourceful approach to generate complex biochemical patterns that can decisively complement the functionality of the next generation of tissue engineering scaffolds.

Effects of hybrid fillers on the electrical conductivity, EMI shielding effectiveness, and flame retardancy of PBT and PolyASA composites with carbon fiber and MWCNT

ABSTRACTThe effects of hybrid fillers of carbon fiber (CF) and multiwall carbon nanotube (MWCNT) on the electrical conductivity, electromagnetic interference shielding effectiveness (EMI SE), flame retardancy, and mechanical properties of poly(butylene terephthalate) (PBT)/poly(acrylonitrile‐co‐styrene‐co‐acrylate) (PolyASA) (70/30, wt %) with conductive filler composites were investigated. The CF was used as the main filler, and MWCNT was used as the secondary filler to investigate the hybrid filler effect. For the PBT/PolyASA/CF (8 vol %)/MWCNT (2 vol %) composite, a higher electrical conductivity (1.4 × 100 S cm−1) and EMI SE (33.7 dB) were observed than that of the composite prepared with the single filler of CF (10 vol %), which were 9.0 × 10−2 S cm−1 and 23.7 dB, respectively. This increase in the electrical properties might be due to the longer CF length and hybrid filler effect in the composites. From the results of aging test at 85 °C, 120 h, the electrical conductivity and EMI SE of the composites decreased slightly compared to that of the composite without aging. The results of electrical conductivity, EMI SE, and flame retardancy suggested that the composite with the hybrid fillers of CF and MWCNT showed a synergetic effect in the PBT/PolyASA/CF (8 vol %)/MWCNT (2 vol %) composite. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48162.

Synergistic thermo-oxidative maleation of PA11 as compatibilization strategy for PA6 and PBT blend

The compatibilization of polyamide (PA) 6 and poly(butylene terephthalate) (PBT) blends has been successively achieved by the design of a compatibilizer made from renewable biobased PA11, named PA11C. The synergistic action of maleation coupled with thermo-oxidation of the PA11 backbone allows both improvements of hydrophilic/hydrophobic balance and availability of functional groups that are able to react during the reactive extrusion. The nature of the functional groups was associated to maleic anhydride, terminal vinyl group as well as carbonyls such as aldehydes that come from the PA11 thermo-oxidation cascade reactions. Thermomechanical and morphological investigations corroborate in explaining the compatibilization mechanism probed by multiple reactions in between PA6 and PBT. The toughening effect was observed in the compatibilized PA6/PBT blends through the increase in the elongation at break. This strategy opens new perspectives in term of compatibilization for formulations containing polyester and PA tailored for specific applications.

Toughening of PBT by POE/POE-g-GMA Elastomer through Regulating Interfacial Adhesion and Toughening Mechanism

Supertough poly(butylene terephthalate) (PBT) blends were prepared by melting with poly(ethylene-octene) (POE) and glycidyl methacrylate grafted POE (POE-g-GMA), and the toughening mechanism was sy...

A green cascade polymerization method for the facile synthesis of sustainable poly(butylene-co-decylene terephthalate) copolymers

Typical semicrystalline aromatic polyesters are synthesized via the condensation polymerization of aromatic diacids with excess diols in vacuum. We demonstrate here a green cascade polycondensation-coupling ring-opening polymerization (PROP) method for the facile incorporation of diols into polyesters in N2, utilizing cyclic oligo(butylene terephthlate)s as monomer and bio-based 1,10-decanediol as initiator. Poly(butylene-co-decylene terephthalate) (PBDT) copolyesters are synthesized with high atom economy (87–99%), and their structures are characterized and confirmed by the 1H quantitative NMR, two dimensional 1H–1H gCOSY and DOSY NMR spectra. Property investigations reveal that with the increment of decanediol content, the glass transition temperature, melting temperature, storage modulus and Young's modulus for PBDT copolyesters decrease, while the toughness increases, respectively. Our results provide a high atom economy PROP method for the synthesis of sustainable PBDT copolyesters, which have lower processing temperatures and improved ductility than poly(butylene terephthalate) (PBT) homopolymers, and could draw attentions for further investigations on the green synthesis of other copolyesters.

Accelerated weathering parameters for some aromatic engineering thermoplastics

Samples of polycarbonate (PC), poly(butylene terephthalate) (PBT), a PC/PBT blend, and poly(styrene-co-acrylonitrile) (SAN), all containing 3% TiO2 (by mass), were exposed in the NIST (National Institutes of Standards and Technology) SPHERE (Simulated Photodegradation via High Energy Radiant Exposure) to determine the effects of UV intensity (irradiance), temperature, relative humidity (RH), and UV wavelength on yellowing and gloss loss. There was no effect of irradiance, such that the samples obeyed reciprocity and doubling the irradiance doubled the rate of degradation. The activation energy for yellowing was determined to be ≈ 20 kJ/mol for PC, PC/PBT, and SAN and ≈16 kJ/mol for PBT. The activation energy for gloss loss was determined to be 9–16 kJ/mol. Thus, a 10 °C increase in temperature results in a 20%–30% increase in degradation rate. There was no consistent effect of RH on PC or PC/PBT yellowing or gloss loss. SAN degraded rapidly under dry conditions but showed little effect for RH > 10%. PBT lost gloss more slowly under dry conditions but displayed no RH effect with yellowing. Shorter wavelength UV had a greater effect on PC/PBT compared to PC or PBT.