Butylene Terephthalate Research Articles

A hybrid construct with tailored 3D structure for directing pre-vascularization in engineered tissues

Hybrid 3D constructs combining different structural components afford unique opportunities to engineer functional tissues. Creating functional microvascular networks within these constructs is crucial for promoting integration with host vessels and ensuring successful engraftment. Here, we present a hybrid 3D system in which poly (ethylene oxide terephthalate)/poly (butylene terephthalate) fibrous scaffolds are combined with pectin hydrogels to provide internal topography and guide the formation of microvascular beds. The sequence/method of seeding human endothelial cells (EC) and mesenchymal stromal cells (MSC) into the system had a significant impact on microvessel formation. Optimal results were obtained when EC were directly seeded onto the fibrous scaffold, followed by the addition of hydrogel-embedded MSC. This approach facilitated the development of highly oriented microvascular networks along the fibers. These networks were lumenized, supported by a basement membrane, and stabilized by pericyte-like cells, persisting for at least 28 days in vitro. Furthermore, culture under pro-angiogenic and osteoinductive conditions induced MSC osteogenic differentiation without impairing microvessel formation. Upon subcutaneous implantation in mice, the pre-vascularized constructs were infiltrated by host vessels, and human microvessels were still present after 2 weeks. Overall, the proposed hybrid 3D system, combined with an optimized cell-seeding protocol, offers an effective approach for directing the formation of robust and geometrically oriented microvessels, making it promising for tissue engineering applications.

Unlocking interfacial synergies: In situ multi-step reaction-induced control for high-performance and functional polybutylene terephthalate/polyolefin blends from recycled sources

This investigation employed free radical melt grafting technology for the synthesis of (POE/R-LLDPE)-g-(GMA-co-St) graft copolymers. Subsequently, this graft copolymer was applied as a modifier for poly (butylene terephthalate) (PBT) resin. The effects of varying recycled linear low-density polyethylene (R-LLDPE) contents in the graft on the rheological behavior, thermal properties, mechanical properties, and toughening mechanism of PBT/(POE/R-LLDPE)-g-(GMA-co-St) blends were exhaustively explored. The findings revealed that glycidyl methacrylate (GMA) and styrene (St) were effectively grafted onto the poly (ethylene-octene) (POE) and R-LLDPE molecular chains. This process enabled the epoxy groups in the GMA of the graft to react with the terminal groups of the PBT resin, thereby enhancing its compatibility with PBT. The use of R-LLDPE-g-(GMA-co-St) or POE-g-(GMA-co-St) as singular modifiers did not produce optimal modification results. Conversely, the most effective modification of the PBT resin was observed when both were combined, indicating a pronounced synergistic modification effect. The optimal overall performance of the blend was noted when the R-LLDPE content in the graft copolymer was 50 wt%. This method significantly enhanced the toughness of the blend while preserving excellent thermal stability and mechanical strength, concurrently reducing the product cost. At this point, a high concentration of voids was observed in the stress-whitening area of the impact specimens. The PBT matrix displayed conspicuous shear yielding with a notably rough impact fracture surface, manifesting highly significant tough fracture characteristics.

Poly(butylene terephthalate) Copolyesters with Dilinoleic Derivatives: Solution Properties and Influence of Short‐Chain Branching

AbstractThe solution behavior of poly(butylene terephthalate) (PBT) copolyesters with dilinoleic monomer units (dilinoleic diol (LD) / dilinoleic diacid (LA)) is studied to understand the processing behavior from melt. NMR investigations show that the short‐chain branches are characterized by a distribution of different alkyl chain lengths, where n‐butyl (C4) and longer chains have the largest content (>55 mol%). High‐temperature size exclusion chromatography with threefold detection (multi‐angle light‐scattering, refractive index, and viscosity detector) in 1,2,4‐trichlorobenzene is performed to determine molar masses, hydrodynamic radii, viscosity radii, and Kuhn–Mark–Houwink–Sakurada (KMHS) exponents α in dependence of the molar amount of short‐chain branched comonomers. Low concentrations of dilinoleic comonomers in PBT copolyesters improve the solubility of the copolyesters significantly. Higher amounts cause contraction of the polymer coils as illustrated by smaller hydrodynamic radii as well as lower KMHS exponents. The α values decrease with increasing amount of short‐chain branched comonomer except for very low concentrations. The solution behavior of LA and LD copolyesters with a higher aliphatic content shows different trends of the influence of short‐chain branches on the melt behavior, which reflects the influence of intramolecular versus intermolecular entanglements in solution and in melt.

Synthesis and properties of biodegradable PBAT prepared from PBT chemically recycled resources

The production of synthetic polymer materials has engendered substantial environmental hazards stemming from waste generation. Employing chemical recycling methods constitutes a viable approach for attaining sustained recycling of synthetic raw materials. In the present study, bishydroxybutyl terephthalate (BHBT), a precursor for the synthesis of poly(butylene adipate-co-terephthalate) (PBAT), was created by chemically alcoholyzing polybutylene terephthalate (PBT). Further, bis(4-hydroxybutyl) adipate (BHAT), which was produced via esterification with adipic acid (AA) and 1,4-butanediol (BDO), and BHBT condensation polymerization were combined to create biodegradable PBAT. Additionally, the effects of the recycled BHBT and BHAT segment ratio on the structures and properties of biodegradable PBAT were investigated. The results indicate that the synthesis of repolymerized PBAT was accomplished successfully. As the proportion of butylene terephthalate (BT) segments increased, several notable improvements were observed: an increase in melting temperature, enhanced thermal stability, elevated tensile strength, and a reduction in the rate of biodegradation. The melting point was 139.51 °C, the tensile strength was 22.62 MPa, and the 30-day biodegradation rate was 23.32 % when the percentage of BT segments was 60 %. In the present study, a method for producing biodegradable polyesters through the process of alcoholysis and repolymerization of recalcitrant polyester waste was proposed. It provides a new solution for the efficient recycling of waste polymer materials.

Production and characterization of flame-retardant poly (butylene terephthalate) composites containing boron compounds

ABSTRACT Within the scope of this work, flame retardant polybutylene terephthalate (PBT) was produced using boron compounds, namely, anhydrous borax (BX), colemanite (C), and zinc borate (ZnB) in three different concentrations of 40, 50, and 60 wt%. The thermal, flame retardant, and tensile properties of PBT composites were systematically investigated using thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical UL 94 test (UL-94V), mass loss calorimeter (MLC), and tensile tests. The thermal stability of PBT slightly enhanced with the use of BX, whereas the use of C and ZnB reduced the thermal stability. Improvement in LOI value, a reduction in peak heat release rate (pHRR), and total heat release (THR) values were observed with the use of all boron compounds. The improvement in UL-94V rating was observed only with the use C. The addition of all boron compounds deteriorates the tensile strength of the composites. In brief, the highest flame retardant performance with V0 rating (UL-94 V), 33.5% (LOI), and 48 Kw·m−2 (pHRR) was achieved with the use of C.

Morphologies, Compatibilization and Properties of Immiscible PLA-Based Blends with Engineering Polymers: An Overview of Recent Works.

Poly(L-Lactide) (PLA), a fully biobased aliphatic polyester, has attracted significant attention in the last decade due to its exceptional set of properties, such as high tensile modulus/strength, biocompatibility, (bio)degradability in various media, easy recyclability and good melt-state processability by the conventional processes of the plastic/textile industry. Blending PLA with other polymers represents one of the most cost-effective and efficient approaches to develop a next-generation of PLA-based materials with superior properties. In particular, intensive research has been carried out on PLA-based blends with engineering polymers such as polycarbonate (PC), poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT) and various polyamides (PA). This overview, consequently, aims to gather recent works over the last 10 years on these immiscible PLA-based blends processed by melt extrusion, such as twin screw compounding. Furthermore, for a better scientific understanding of various ultimate properties, processing by internal mixers has also been ventured. A specific emphasis on blend morphologies, compatibilization strategies and final (thermo)mechanical properties (tensile/impact strength, ductility and heat deflection temperature) for potential durable and high-performance applications, such as electronic parts (3C parts, electronic cases) to replace PC/ABS blends, has been made.

Discrimination and simultaneous quantification of poly(ethylene terephthalate) and poly(butylene terephthalate) microplastics in environmental samples via gas chromatography-tandem mass spectrometry.

A method has been developed to quantify PET and PBT microplastics (MPs) based on depolymerization and detection of depolymerization products by gas chromatography-tandem mass spectrometry (GC-MS/MS) without a complex separation process from environmental samples. Under the optimal depolymerization conditions, PET and PBT were efficiently convertedto ethylene glycol (78%) and 1,4-butanediol (87%), respectively. Subsequently, the linear curves were constructed between signal intensities of depolymerization products and polymer masses by GC-MS/MS, and the correlation coefficients of PET and PBT were 0.996 and 0.997, respectively. The spiking and recovery experiments of PET and PBT in the environmental samples showed that the recovery was stable in the range 89-100%, and the limit of detection was 4.95μg and 1.39μg of PET and PBT, respectively. The method has been proven to be capable of simultaneous identification and quantification of PBT and PET MPs in real environmental water samples without complex separation process, which provided a scheme for the determination of microplastics.

A Proteomic Approach to Determine Stem Cell Skeletal Differentiation Signature on Additive Manufactured Scaffolds

Understanding how porous biomaterials interact with cells at their surface and how they either promote or inhibit cellular processes has presented several challenges. Additive manufacturing enables the fabrication of scaffolds with distinct compositions and designs for different tissue engineering applications. To evaluate the in vitro performance of multiple printed materials, biochemical assays can be limiting in providing valuable insight and key information to select the best tissue destination. Omics technologies like proteomics are crucial for studying important cellular events and gathering valuable information about cellular processes and mechanisms. However, only few studies focus on proteomics to decipher cell–material interactions and cell differentiation on additive manufactured scaffolds. Here, scaffolds were fabricated using three polymers (polycaprolactone (PCL), poly(ethylene oxide)–poly(butylene terephthalate) (PEOT/PBT), and polylactic acid (PLA)) through additive manufacturing. Their chondrogenic and osteogenic potential were characterized and compared using human bone marrow‐derived mesenchymal stem cells (hBMSCs) through proteomics analysis. The 3D scaffolds were all hydrophilic and displayed Young's moduli close to those of bone or cartilage for PLA and PCL and PEOT/PBT, respectively. Biochemical assays indicated that PEOT/PBT and PLA scaffolds have a greater chondrogenic potential by higher glycosaminoglycan (GAG) and collagen deposition compared to PCL. PLA and PEOT/PBT showed to be more effective in promoting bone formation, as evidenced by higher calcium deposits detected by alizarin red staining, and higher alkaline phosphatase (ALP), especially for PLA in osteogenic medium. Proteomics data revealed the most distinct separation between conditions in chondrogenic medium, which had the highest protein identification rates. Pathway analysis showed that PCL did not induce any differentiation‐related pathways when compared to PEOT/PBT and PLA in any of the tested media conditions. Analysis of PEOT/PBT proteins showed pathways involved in chondrogenesis in all three media and pathways related to hypertrophic phenotype progression in chondrogenic medium. These data suggests that PEOT/PBT is a valuable candidate for cartilage and osteochondral applications, able to drive hBMSCs differentiation without the need of growth factors. PLA was also a valuable candidate for cartilage and bone applications by upregulating both chondrogenic and osteogenic‐related proteins in maintenance and chondrogenic media. In osteogenic and maintenance media, the upregulation of angiogenic proteins makes PLA a better candidate for bone application where vascularization is key.

Structure of Molecular Chains of Poly(trimethylene terephtalate) Studied by Low-Frequency Vibrational Spectroscopy and Quantum Chemical Calculations: In Comparison with That of Poly(ethylene terephthalate) and Poly(butylene terephthalate) from the Point of Parity of Methylene Chain Length

Structure of Molecular Chains of Poly(trimethylene terephtalate) Studied by Low-Frequency Vibrational Spectroscopy and Quantum Chemical Calculations: In Comparison with That of Poly(ethylene terephthalate) and Poly(butylene terephthalate) from the Point of Parity of Methylene Chain Length

Fluorinated graphite reinforced polytetrafluoroethylene/poly(butylene terephthalate) composites as friction materials for deep‐sea applications

AbstractThe application of polymer composites is one of the most effective methods for preventing lubrication failure in deep‐sea engineering. In this study, fluorinated graphite (FGr) microsheets were incorporated into polytetrafluoroethylene (PTFE) microparticle‐filled poly(butylene terephthalate) (PBT) composites. The tribological performance in the simulated deep‐sea environment at elevated seawater pressure equivalent to 3000 m ocean depth was investigated. The results showed that FGr enhances the flexural and compressive strengths, thermal stability, and seawater resistance of the PTFE/PBT composite. The wear rate was decreased to 96% at the critical FGr content of 4% by improving the transfer onto the metallic counterfaces, preventing direct contact and shear between friction couples. Moreover, the seawater pressure impedes composite transfer, leading to a 29% increase in the wear rate.

Porous Melt Blown Poly(butylene terephthalate) Fibers with High Ductility and High-Temperature Structural Stability.

In this study, porous poly(butylene terephthalate) (PBT) fibers were produced by melt blowing cocontinuous blends of PBT and polystyrene (PS) and selectively extracting the interconnected PS domains. Small amounts of hydroxyl terminated PS additives that can undergo transesterification with the ester units in PBT were added to stabilize the cocontinuous structure during melt processing. The resulting fibers are highly ductile and display fine porous structural features, which persist at temperatures over 150 °C. Single fiber tensile testing and electron microscopy are presented to demonstrate the role of rapid quenching and drawing of the melt blowing process in defining the fiber properties. The templated highly aligned pore structure, which is not easily produced in solvent-based fiber spinning methods, leads to remarkable mechanical properties of the porous fibers and overcomes the notoriously poor tensile properties common to other cellular materials like foams.

Comprehensive characterizations of organoclay types based on their integration to poly (butylene terephthalate) nanocomposites

Comprehensive characterizations of organoclay types based on their integration to poly (butylene terephthalate) nanocomposites

Aggregation and Interfacial Adhesion of Nano-Sb2O3 Particles in Poly(Butylene Terephthalate) Composites: Effect of Surface Structure of the Nanoparticles

To study the effect of different surface structures on the aggregation level and interfacial adhesion, nano-Sb2O3 particles were treated with cetyltrimethylammonium bromide (CTAB), silane coupling agent KH550 and their compounds (CTAB + KH550). The surface properties and morphologies of the nano-Sb2O3 particles were characterized by Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The aggregation level and interfacial adhesion of nano-Sb2O3 particles within PBT matrix were characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), and quantitatively evaluated by some semi-empirical parameters including aggregates size (Dagg ), real filling degree (Vre ), interfacial adhesion ( B ) and aggregated interfacial adhesion (Bagg ) from the tensile strength and the Young’s modulus measurements. The results showed that the highest interfacial adhesion and lowest aggregation level were obtained for the CTAB + KH550 modified nano-Sb2O3/PBT composites followed by the KH550 modified, CTAB modified and bare nano-Sb2O3/PBT composites, respectively.

Non‐isothermal crystallization kinetic of recycled PET and its blends with PBT modified with epoxy‐based multifunctional chain extender

AbstractA fundamental understanding of crystallization behavior is essential for the processing of both virgin and recycled polymers. This research delves into the crystallization characteristics and non‐isothermal crystallization kinetics of recycled polyethylene terephthalate (rPET) and its blends with poly butylene terephthalate (PBT), which have been modified using epoxy‐based multifunctional chain extenders (CE). The preparation of rPET/PBT blends involved a twin‐screw extruder, with varying weight ratios and different CE concentrations. Differential scanning calorimetry was employed to perform crystallization analysis on the samples. The results underscore the profound impact of blend composition on the thermal characteristics of the system, with CE exerting only a marginal influence. The glass transition temperatures (Tg) of the two polymers were measured at 49 and 79°C. During blending, the Tg values demonstrated variations relative to the proportions but did not adhere to the Fox equation. Furthermore, PBT was found to enhance the crystallization tendencies of rPET, resulting in an increase in relative crystallinity from 11% to 36%. Notably, the crystallization rate of PBT at 0.40 min−1 exceeded that of rPET at 0.36 min−1. PBT minimally affected the crystallization rate constant of rPET‐dominant blends, while rPET significantly reduced the crystallization rate in PBT‐dominant blends.

Contribution of silane modification of halloysite nanotube to its poly (butylene terephthalate)-based nanocomposites: structural, mechanical and thermal properties

Polybutylene terephthalate (PBT) nanocomposites were melt-blended with two types of Turkish halloysite nanotubes (HN). Naturally occurring HN samples were used to produce PBT-based composites at the HN compositions of 1%, 3%, 5%, and 10%. Findings of neat and silane-coated HN-containing composite samples were compared to investigate the interfacial adhesion between polymer matrix and reinforcement material. According to test results, a 1% amount of HN was found to be the most suitable option in the case of mechanical and thermal properties of composites. Additionally, silane-modified grade displayed highly indicative improvements compared to pristine HN clay due to better interfacial adhesion of halloysite nanotubes to the PBT matrix was accomplished. Property enhancements achieved for composite samples containing low contents of HN were confirmed by morphological examinations. As a result, the PBT/ 1% HN-S composite sample was bookmarked as the most suitable option to fabricate HN-reinforced PBT-based nanocomposites in terms of mechanical, thermo-mechanical, morphological, thermal, and physical performances based on the findings in this study. Silane-modified halloysite grades exhibited better results, and they were found to be more suitable in the case of applications of PBT.Graphical abstract

Scaffolds with a Tunable Nonlinear Elastic Region Using a Corrugated Design

Elastin is the main component of arteries and is responsible for their high‐elastic high‐strain capacity. The biomechanics of biological tissues typically display a stress–strain curve characterized by a sigmoidal shape that has an initial region with low stress and high strain. Studies aimed at mimicking such biomechanical behavior focus on improving the synthesis of elastin or replicating elastin behavior, which proves to be a continuous challenge. Alternatively, scaffolds' architecture can potentially mimic the sigmoidal stress–strain curve of tissues. Hence, the aim of this study was to replicate the stress–strain curve of a carotid artery using a tailorable corrugated design. Results showed that the corrugated design unfolded during extension without generating significant stress and displayed a sigmoidal stress–strain curve that could be controlled depending on the corrugation features. Editing the amount of fibers resulted in a different Young's modulus, while the amplitude of the fibers and the amount of repeating units influenced the initial nonlinear region of the stress–strain curve. Scaffolds made of poly(ε‐caprolactone) (PCL) and poly(ethylene oxide terephthalate)/poly(butylene terephthalate (PEOT/PBT) were compared to determine the applicability of the design principles to different biodegradable polymers that normally do not have the same biomechanical behavior of soft tissues like arteries. The optimized designs had a similar stress–strain curve within the physiological range as porcine arteries. The corrugated design can serve as a biomimicry approach for vascular grafts or an alternative to vascular stents.

Effect of post-polymerization on the crystallization and melting behavior of poly(butylene terephthalate)

In this paper, the chemical and physical structures of poly (butylene terephthalate) (PBT) after different thermal treatments, in the range of 180–260 °C and up to 10 h, were systematically investigated. Nuclear magnetic resonance and Fourier transform infrared spectroscopy results showed that the chemical structure of PBT did not change significantly after treatment. The thermal stability of the heat-treated samples, reflected by the decomposition temperature shown in thermogravimetric analysis, was the same as that of the untreated samples. During the treatment, the molecular weight increased, while the polydispersity remained essentially constant (∼2). The highest increase in molecular weight was observed when the samples were subjected to heat treatment near the melting point temperature (220 °C). Importantly, the crystallization temperature of the samples changed with heat treatment temperatures and times, while the melting point remained essentially constant.

3D POROUS COMPOSITE SCAFFOLDS WITH HIGH CALCIUM PHOSPHATE CONTENT AND ADDITION OF INORGANIC IONS FOR BONE REGENERATION APPLICATIONS

Critical-sized bone defects remain challenging in the clinical setting. Autologous bone grafting remains preferred by clinicians. However, the use of autologous tissue is associated with donor-site morbidity and limited accessibility to the graft tissue. Advances in the development of synthetic bone substitutes focus on improving their osteoinductive properties. Whereas osteoinductivity has been demonstrated with ceramics, it is still a challenge in case of polymeric composites. One of the approaches to improve the regenerative properties of biomaterials, without changing their synthetic character, is the addition of inorganic ions with known osteogenic and angiogenic properties. We have previously reported that the use of a bioactive composite with high ceramic content composed of poly(ethyleneoxide terephthalate)/poly(butylene terephthalate) (1000PEOT70PBT30, PolyActive, PA) and 50% beta-tricalcium phosphate (β-TCP) with the addition of zinc in a form of a coating of the TCP particles can enhance the osteogenic differentiation of human mesenchymal stromal cells (hMSCs) (3). To further support the regenerative properties of these scaffolds, inorganic ions with known angiogenic properties, copper or cobalt, were added to the coating solution.β-TCP particles were immersed in a zinc and copper or zinc and cobalt solution with a concentration of 15 or 45 mM. 3D porous scaffolds composed of 1000PEOT70PBT30 and pure or coated β-TCP were additively manufactured by 3D fibre deposition. The osteogenic and angiogenic properties of the fabricated scaffolds were tested in vitro through culture with hMSCs and human umbilical vein endothelial cells, respectively. The materials were further evaluated through ectopic implantation in an in vivo mini-pig model. The early expression of relevant osteogenic gene markers (collagen-1, osteocalcin) of hMSCs was upregulated in the presence of lower concentration of inorganic ions. Further analysis will focus on the evaluation of ectopic bone formation and vascularisation of these scaffolds after implantation in a mini-pig ectopic intramuscular model.

Effect of Reprocessing on the Crystallization of Different Polyesters

The changes in crystallization characteristics of four polyesters were investigated during multiple processing. Two of these were petroleum-based materials: poly (ethylene terephthalate) (PET) and poly (butylene terephthalate) (PBT), and two were bio-based materials: poly (lactic acid) (PLA) and poly (butylene succinate) (PBS). We found that during non-isothermal crystallization the different type of polyesters shown different behaviour: the PET and PLA materials were more sensitive to the cooling rate than the PBT and PBS. Interestingly, at low cooling rates, the number of reprocessing steps had no significant effect on the crystallinity of PBT and PBS, but reduced it for PET, but increased it for PBT.

Miscibility and crystallization behavior of Poly(butylene terephthalate)/Poly(ethylene terephthalate-co-1,4-cyclohexylene dimethylene terephthalate) blends

The miscibility and crystallization behavior of a series of polymer blends containing different content of poly(butylene terephthalate) (PBT) and poly(ethylene terephthalate-co-1,4-cyclohexylene dimethylene terephthalate) (P(ET/CT)) have been studied. It is confirmed through DSC, SAXS and SEM that PBT is miscible with P(ET/CT) with different CT content. When the mole content of CT is 37 %, P(ET/CT) (abbreviated as P(ET/CT37 %)) is fully amorphous. But, as the mole ratio of CT is 66 %, P(ET/CT) (abbreviated as P(ET/CT66 %)) possesses crystallizability. Compared to the extremely fast crystallization of PBT, the crystallizability of P(ET/CT66 %) is so weak that non-isothermal crystallization (at a cooling rate of 10 °C/min) can hardly occur. Upon blending, however, it is interesting to find that the P(ET/CT66 %) could be involved in the crystallization of the blends within the entire composition range. In the DSC cooling curves, a double-peak crystallization could be observed, in which the Tc1 is attributed to the crystallization of PBT and the Tc2 to that of P(ET/CT66 %). Further, the two glass transition temperatures of the blends after crystallization confirm the occurrence of crystallization-induced phase separation at higher P(ET/CT) content. Therefore, the excluded P(ET/CT66 %) local domain or aggregation is regarded as the prerequisite of the P(ET/CT66 %) crystallization, and the previously formed PBT crystals act as its nucleating agent.