Butylene Terephthalate Research Articles

Effect of addition of aluminum phosphinate as fire retardant in a PBT vitrimer

This work investigates the effect of flame-retardant additives on the thermo-mechanical and dynamic properties of poly(butylene terephthalate) (PBT) vitrimers. The vitrimers were synthesized and compounded in a single step by reactive extrusion from commercially available PBT, an epoxy resin, a zinc-based transesterification catalyst, and aluminum phosphinate (AlPi) as a conventional flame retardant additive. We demonstrated that the presence of AlPi in relatively large amount (20 wt.-%) is compatible with the formation of the vitrimer network and does even play the role of a transesterification (co)catalyst accelerating the exchange reactions and improving the processability of the vitrimer. UL-94 flammability tests also confirm the effective role of AlPi as flame retardant in vitrimer.

Accelerated nonisothermal crystallization and improved material properties of biobased poly(butylene 2,5-furandicarboxylate)/talc composites

Biobased poly(butylene 2,5-furandicarboxylate) (PBF) reflects the much poorer crystallizability than its petroleum-based counterpart poly(butylene terephthalate). By introducing talc platelets into PBF matrix to fabricate composites, the effects of low loadings’ layered filler upon nonisothermal melt crystallization and material properties of PBF/talc composites are investigated for the first time. Obviously accelerated crystallization of the composites relative to pure PBF is first evidenced by the simultaneous increase of crystallization temperature and decline of crystallization half-time, and further supported by both the crystallization rate coefficient and crystallization rate parameter. Nonisothermal crystallization kinetics are analyzed by both the Jeziorny model and Mo equations, and the intensifying effect of talc upon PBF's crystallization is attributed to the coupling of enlarging nucleation activity and lowering crystallization activation energy. Meanwhile, the incorporation of layered talc doesn't modify the crystal structure of PBF. Moreover, both the thermal and mechanical properties of PBF/talc composites are reinforced slightly.

Partially Bio‐Based Polyester Bead Foams via Extrusion Foaming of Poly(butylene terephthalate)/Poly(butylene furanoate) Blends

AbstractThe interest in bio‐based alternatives to classical polyesters such as poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) is steadily growing to achieve a more sustainable approach to polymer materials. In this study, PBT/poly(butylene furanoate) (PBF) blends are prepared, characterized and extrusion foamed. PBF as a bio‐based polyester offers two advantages. The ecological footprint of the material is reduced, and additionally, it can be used in Diels‐Alder reactions at the blend surface to support fusion of the foamed beads. The blending behavior of the polyesters is investigated using samples prepared in a microcompounder, particularly focused on the miscibility of the blends and transesterification reactions. The blends are thermodynamically immiscible but show a certain degree of transesterification according to nuclear magnetic resonance (NMR) spectroscopy. The morphology of blend beads produced by an extrusion foaming process is analyzed regarding their cell density, cell size distribution, and open‐cell content. It is shown that PBF has a positive effect on the bead foam morphology. The use of a bifunctional linker designed for chemical fusion of the bead surfaces allows to obtaining of molded parts, in contrast to beads containing pure PBT.

Modification of melt memory effect by addition of poly(butylene terephthalate) to thermoplastic polyester elastomer

The structure and properties of a thermoplastic polyester elastomer (TPEE) containing a small amount of poly(butylene terephthalate) (PBT) were investigated by focusing on the residual crystals in the molten state. When the pure TPEE was extruded at a slightly higher temperature than its melting point, the crystallization rate increased. This phenomenon has been called the melt memory effect and has been attributed to unmolten crystals that act as nuclei. The addition of PBT widened the temperature range of the melt memory effect, because PBT crystals were present at the higher temperatures. Moreover, the addition of PBT induced phase separation, leading to a decrease in the dissolution of hard segments in the soft matrix. As a result, the glass transition temperature of the soft matrix decreased. Furthermore, the modulus at room temperature increased with good rubber elasticity.

Surface Modification of PP and PBT Nonwoven Membranes for Enhanced Efficiency in Photocatalytic MB Dye Removal and Antibacterial Activity.

In this study, we developed highly efficient nonwoven membranes by modifying the surface of polypropylene (PP) and poly(butylene terephthalate) (PBT) through photo-grafting polymerization. The nonwoven membrane surfaces of PP and PBT were grafted with poly(ethylene glycol) diacrylate (PEGDA) in the presence of benzophenone (BP) and metal salt. We immobilized tertiary amine groups as BP synergists on commercial nonwoven membranes to improve PP and PBT surfaces. In situ Ag, Au, and Au/Ag nanoparticle formation enhances the nonwoven membrane surface. SEM, FTIR, and EDX were used to analyze the surface. We evaluated modified nonwoven membranes for photocatalytic activity by degrading methylene blue (MB) under LED and sunlight. Additionally, we also tested modified membranes for antibacterial activity against E. coli. The results indicated that the modified membranes exhibited superior efficiency in removing MB from water. The PBT showed the highest efficiency in dye removal, and bimetallic nanoparticles were more effective than monometallic. Modified membranes exposed to sunlight had higher efficiency than those exposed to LED light, with the PBT/Au/Ag membrane showing the highest dye removal at 97% within 90 min. The modified membranes showed reuse potential, with dye removal efficiency decreasing from 97% in the first cycle to 85% in the fifth cycle.

Reprocessible nanohybrid shish-kebab superstructures of poly (lactic acid) crystallites evolving in quiescent melt: Soft epitaxy nucleation in correlation with mechanics

Poly (butylene terephthalate) (PBT) nanofibrils (NFs) were developed in-situ by implementing a rheologically tuned melt spinning process on poly (lactic acid) (PLA)/PBT blends. In the absence of any flow fields, melt crystallization of fabricated PLA/PBT in-situ nanofibrillar composites (NFCs) resulted in orthogonal patterning of PLA nanodomain crystallites around single or double PBT NFs. Geometric confinement (soft epitaxy) was the nucleation mechanism of PLA chains at the interface of isotropic distributed PBT NFs followed by the formation of reprocessible 2D nanohybrid shish-kebab (NHSK) superstructures. By increasing the PBT NFs content and their bundling, a fan-shaped transcrystalline structure was formed due to seeding or epitaxial nucleation on the bundle of PBT NFs owning a less curved interface. The nucleation and growth mechanism of crystallites structures which were influenced by temperature and PBT NF content have been discussed thermodynamically and kinetically by parallel investigations on microscopic observations and X-ray diffraction analysis. The evolution of different crystalline structures in quiescent melt in the forms of spherulites, NHSK, or fan-shaped transcrystallinity induces a local orientation in the isotropic NFCs. Mechanical propertie improvements of NFCs were compared in amorphous and crystalline states with tailored NHSK superstructures.

Role of monomer sequence in the crystallization and rheology of PBAT

Poly(butylene adipate-ran-terephthalate) (PBAT) is a typical biodegradable aliphatic−aromatic polyester. It has been widely used as compost bags, packaging films, and agricultural mulching films because of its complete biodegradability, good processability and mechanical properties, and low water vapor permeability. In this work, we showed that a small difference in the monomer ratio of the BT (butylene terephthalate) and BA (butylene adipate) units of PBAT would lead to significant differences in the continuous sequential block distributions as determined by the high-resolution NMR tests and the first-order Markovian model. As a result, macroscopic properties, such as crystallization behaviors, phase separation behaviors, and rheology, are greatly affected. A PBAT sample with a higher BA content and, consequently, a longer continuous BA block sequence has a lower crystallization temperature, a weaker concentration fluctuation at elevated temperatures, and a stronger strain hardening in melt elongation.

Synthesis of novel thermoplastic polyester elastomers with biobased amorphous polyester as the soft segment

The development of sustainable polymers from biobased blocks is urgently desirable. In this work, a class of novel biobased thermoplastic polyester elastomers, namely poly(butylene terephthalate)-poly(1,4-butylene/2,3-butylene succinate) (PBT-PBBS) copolyesters, were designed and synthesized via melt oligomer polycondensation of common PBT oligomer and biobased PBBS oligomer. The obtained PBT-PBBS copolyesters exhibited desired block structure and contained a hard phase of crystallized PBT and a soft phase of amorphous PBBS. Their mechanical properties could be tailored by tuning the polycondensation time or the molar ratio of PBT to PBBS. Specifically, the tensile strength and the elongation at break of these copolyesters could be flexibly adjusted in the range of 6–13 MPa and 240–650%, respectively. Therefore, they are expected to be widely used in the fields of elastomers, hot-melt adhesives, and toughening modifiers.

Effect of Physical Composition, Molecular Weight of the Polymer, and Processing Condition on Control of Phase Morphology and Physical Properties for Polycarbonate-Poly(Butylene Terephthalate) Blends

Effect of Physical Composition, Molecular Weight of the Polymer, and Processing Condition on Control of Phase Morphology and Physical Properties for Polycarbonate-Poly(Butylene Terephthalate) Blends

Fabricating super tough polylactic acid based composites by interfacial compatibilization of imidazolium polyurethane modified carbon nanotubes

The interfacial compatibilization and dispersion of carbon nanotubes (CNTs) in incompatible poly(lactic acid)/poly(butylene terephthalate adipate) (PLA/PBAT) composites are key points for evaluating the performance of the composites. To address this, a novel compatibilizer, sulfonate imidazolium polyurethane (IPU) containing PLA and poly(1,4-butylene adipate) segments modified CNTs, employed in conjunction with multi-component epoxy chain extender (ADR) to toughen synergistically PLA/PBAT composites. The thermal stability, rheological behavior, morphology, and mechanical properties of PLA/PBAT composites were performed by TGA, DSC, dynamic rheometer, SEM, tensile, and notched Izod impact measure. Moreover, the elongation at break and notched Izod impact strength of PLA5/PBAT5/4C/0.4I composites achieved 341 % and 61.8 kJ/m2 respectively, whose tensile strength was 33.7 MPa. The interfacial compatibilization and adhesion were enhanced because of the interface reaction catalyzed by IPU and the refined co-continuous phase structure. The CNTs non-covalently modified by IPU that bridged at the PBAT phase and interface transferred the stress into the matrix, prevented the development of microcracks, and absorbed impact fracture energy in the form of pull-out of the matrix, inducing shear yielding and plastic deformation. This new type of compatibilizer with modified CNTs is of great significance for realizing the high performance of PLA/PBAT composites.

Application of cutinase in the degradation of biodegradable polyester poly(butylene adipate-co-terephthalate)

With the environmental pollution caused by waste plastics becoming increasingly serious, biodegradable polyester has become the focus of public attention. Poly(butylene adipate-co-terephthalate) (PBAT) is a biodegradable polyester formed by the copolymerization of aliphatic and aromatic groups, which has excellent performance of both. The degradation of PBAT under natural conditions requires strict environmental conditions and long degradation cycle. To address these shortcomings, this study explored the application of cutinase in PBAT degradation and the impact of butylene terephthalate (BT) content on the biodegradability of PBAT, so as to improve the degradation rate of PBAT. Five Polyester degrading enzymes from different sources were selected to degrade PBAT to pick out the most efficient enzyme. Subsequently, the degradation rate of PBAT materials with different BT content were determined and compared. The results showed that cutinase ICCG was the best enzyme for PBAT biodegradation, and the higher the BT content, the lower the degradation rate of PBAT. Furthermore, the optimum temperature, buffer type, pH, the ratio of enzyme to substrate (E/S) and substrate concentration in the degradation system were determined to be 75 ℃, Tris HCl, 9.0, 0.4% and 1.0% respectively. These findings may facilitate the application of cutinase in PBAT degradation.

Mutual influence of the morphology and growth kinetics in binary crystalline blends of poly(butylene terephthalate) and polyarylate

The spherulitic morphology and crystallization behaviors of binary crystalline blends of poly(butylene terephthalate) (PBT) and polyarylate (PAr), based on bisphenol A, (27:73 isophthalic:terephthalic acids), are investigated herein. PBT and PAr crystallize simultaneously or sequentially; various crystallization behaviors and morphologies are observed. In the PBT-rich blends, PAr does not crystallize; the PBT spherulites coarsen as the PAr concentration increases. Non-crystallizable PAr is trapped inside the spherulites. The PBT spherulitic growth rate decreases when PAr is added and remains constant thereafter. For the 50/50 blends, PBT and PAr crystallize simultaneously, and their spherulites co-exist separately. The spherulitic growth rate of PBT increases with time while PAr is crystallizing, but it remains constant if PAr crystallizes prior. At a crystallization temperature of 250 °C, only PAr crystallizes; the non-crystallizable PBT is expelled from the PAr spherulites because the crystallization rate of PAr is low. The spherulites of PAr do not fill the space in the final crystallization stage. The crystallization rate of the binary crystalline PBT/PAr blends was notably influenced by the prior crystallization of the other component, and was due to the change of the amorphous composition in addition to the constraints of the crystals on the chain mobility.

Functionalized Poly(ethylene-octene)/Linear Low-Density Polyethylene Prepared by Melt Free-radical Grafting Reaction and Its Potential in Toughening Poly(butylene terephthalate) Resins

Glycidyl methacrylate (GMA) and styrene (St) were used as the graft monomer and co-graft monomer, respectively, and grafted onto poly(ethylene-octene) (POE) and linear low-density polyethylene (LLDPE) to prepare a series of GMA-functionalized (POE/LLDPE)-g-(GMA-co-St) graft copolymers. The copolymers were then blended with poly(butylene terephthalate) (PBT) to produce PBT/(POE/LLDPE)-g-(GMA-co-St) blends. The effects of grafting factors and copolymer content on the mechanical properties, thermal properties, rheology, morphology, and deformation mechanism of the blends were studied in detail. The results showed that GMA and St were successfully grafted onto the molecular chains of POE and LLDPE. In the grafting reaction, the best grafting degree and comprehensive performance were achieved when the amounts of dicumyl peroxide and GMA were 0.3 and 5 wt %, respectively, the mass ratio of GMA to St was 1:2, and the screw rotation speed was 60 rpm. By introducing graft copolymers into the PBT matrix, the toughness and thermal stability of the blends were improved. At the same time, the crystallinity and fluidity decreased, and the blends possessed the best mechanical properties when the copolymer content was 20 wt %, with the elongation at break and notched impact strength increasing to 409.98% and 945.90 J/m, respectively. Scanning electron microscopy analysis showed that the copolymers were uniformly dispersed in the PBT matrix. The principal toughening mechanisms were the shear-yielding properties of the PBT matrix and cavitation of (POE/LLDPE)-g-(GMA-co-St) phases.

Investigation of the Reaction Kinetics of Poly(butylene terephthalate) and Epoxide Chain Extender

AbstractPolyesters, such as poly (butylene terephthalate) (PBT), owe a rather low melt strength, which is considered as not beneficial for foaming. To overcome this issue, a typical attempt is the incorporation of chemical modifications—so‐called chain extenders (CE)—in the reactive extrusion process. In this study, the reaction kinetic variables are investigated depending on the material and process parameters. For this purpose, different series of experiments are performed with varying PBT with different molecular weights and the commonly used CE, Joncryl ADR4468, on a micro compounder. The screw force is recorded and analyzed using an Avrami and an Arrhenius plot. First, the amount of CE is systematically varied. To study the course of the reaction in more detail, the reaction is stopped in a series of measurements (10, 30, 60, and 90 s after complete filling). Gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT‐IR), and Raman spectra are recorded. In the second series, the effect of processing temperatures between 250 and 270 °C is investigated, and finally, in the third series, the average molecular weight of PBT is varied. It could be shown that the activation energy seems to be dependent on the initial molecular weight; lower molecular weights result in lower activation energy.

Vitrification of the Entire Amorphous Phase during Crystallization of Poly(butylene terephthalate) near the Glass-Transition Temperature

Vitrification of the Entire Amorphous Phase during Crystallization of Poly(butylene terephthalate) near the Glass-Transition Temperature

The addition of zinc ions to polymer-ceramic composites accelerated osteogenic differentiation of human mesenchymal stromal cells

Critical-sized bone defects, caused by congenital disorders or trauma, are defects that will not heal spontaneously and require surgical intervention. Recent advances in biomaterial design for the treatment of such defects focus on improving their osteoinductive properties. Here, we propose 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 on the TCP particles. Due to its essential role in bone homeostasis, we hypothesised that the addition of zinc to the polymer-ceramic composite will further enhance its osteogenic properties. β-TCP particles were immersed in a zinc solution with a concentration of 15 or 45 mM. The addition of zinc did not alter the β-TCP composition or the release of calcium or phosphate ions. 3D porous 1000PEOT70PBT30 - β-TCP scaffolds were additively manufactured by “3D fibre deposition” and their ability to support the osteogenic differentiation was assessed by culturing clinically relevant human mesenchymal stromal cells (hMSCs) on the scaffolds for 3, 7, 14 and 28 days. The expression of osteogenic gene markers was increased in the presence of both zinc concentrations. Remarkably, upregulation of osteocalcin (OCN), a late osteogenic marker, was observed after three days of culture. Furthermore, enhanced extracellular matrix (ECM) production and mineralization was observed. These findings support the existing evidence on the osteogenic properties of zinc and further demonstrate that the incorporation of zinc into a polymer-ceramic composite could be a promising strategy in the field of regeneration of critical-sized bone defects.

Chitin nanofibrils modulate mechanical response in tympanic membrane replacements

The tympanic membrane (TM), is a thin tissue lying at the intersection of the outer and the middle ear. TM perforations caused by traumas and infections often result in a conductive hearing loss. Tissue engineering has emerged as a promising approach for reconstructing the damaged TM by replicating the native material characteristics. In this regard, chitin nanofibrils (CN), a polysaccharide-derived nanomaterial, is known to exhibit excellent biocompatibility, immunomodulation and antimicrobial activity, thereby imparting essential qualities for an optimal TM regeneration. This work investigates the application of CN as a nanofiller for poly(ethylene oxide terephthalate)/poly(butylene terephthalate) (PEOT/PBT) copolymer to manufacture clinically suitable TM scaffolds using electrospinning and fused deposition modelling. The inclusion of CN within the PEOT/PBT matrix showed a three-fold reduction in the corresponding electrospun fiber diameters and demonstrated a significant improvement in the mechanical properties required for TM repair. Furthermore, in vitro biodegradation assay highlighted a favorable influence of CN in accelerating the scaffold degradation over a period of one year. Finally, the oto- and cytocompatibility response of the nanocomposite substrates corroborated their biological relevance for the reconstruction of perforated eardrums.

Depolymerization of Polyesters by Transesterification with Ethanol Using (Cyclopentadienyl)titanium Trichlorides

Exclusive chemical conversions of polyesters [poly(ethylene adipate) (PEA), poly(butylene adipate) (PBA), poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT)] to the corresponding monomers (diethyl adipate, diethyl terephthalate, ethylene glycol, 1,4-butane diol) by transesterification with ethanol using Cp’TiCl3 (Cp’ = Cp, Cp*) catalyst have been demonstrated. The present acid-base-free depolymerizations by Cp’TiCl3 exhibited completed conversions (>99%) of PET, PBT to afford diethyl terephthalate and ethylene glycol or 1,4-butane diol exclusively (selectivity >99%) without formation of any other by-products in the NMR spectra (150–170 °C, Ti 1.0, or 2.0 mol%). The resultant reaction mixture after the depolymerization of PBA with ethanol via the CpTiCl3 catalyst (1.0 mol%, 150 °C, 3 h), consisting of diethyl adipate and 1,4-butane diol, was heated at 150 °C in vacuo for 24 h to afford high molecular weight recycled PBA with unimodal molecular weight distribution (Mn = 11,800, Mw/Mn = 1.6), strongly demonstrating a possibility of one-pot (acid-base-free) closed-loop chemical recycling.

Poly(ethylene terephthalate), Poly(butylene terephthalate), and Polystyrene Oligomers: Occurrence and Analysis in Food Contact Materials and Food.

Polyesters (PES) and polystyrene (PS) are among the most used plastics in the production of food contact materials (FCM). The existence of compounds that could migrate from these materials into food requires a constant analytical control to ensure the safety of consumers due to consumption. It also implies a significant research challenge for their identification and quantification. One of the most important groups of known FCM migrants are the substances known as oligomers. PES and PS oligomers have long been suspected to possess some toxicological effects. The International Agency for Research on Cancer and the European Food Safety Authority alerted recently to the potential carcinogenicity of styrene, with its oligomers consequently being also in the spotlight. At the same time, PES cyclic oligomers are categorized as having Cramer III toxicity. Many recent works on the occurrence of poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), and PS oligomers in FCM and food have been published. The oligomeric chemical analysis requires the use of demanding analytical strategies to address their different physicochemical characteristics (melting points, octanol/water partition coefficients, and solubility properties). Chromatographic methods are normally preferred due to the intrinsic complexity of the target matrices, but the reduced amount of reliable analytical standards still hinders the widespread screening analysis of oligomers in food. This work presents the most relevant recent studies and analytical methodologies used in the analysis of PET, PBT, and PS oligomers in food and FCM, as well as current and future challenges.

The Relationship between Microstructure and Mechanical Properties of PBST Two-Component Crystalline Random Copolymers with Different BT Contents

The mechanical properties of two-component crystalline random copolymers are primarily based on their microstructure. At the same time, the influence of the composition on the crystallization behavior and crystal structure of these materials is also well known. Thus, in this study, a poly (butylene succinate-co-butylene terephthalate) random copolymer (PBST) with different molar ratios of butylene terephthalate (BT) was prepared. A systematic analysis of the crystallization behavior, crystal structure, and mechanical properties of PBST with different BT contents was carried out using WAXD, SAXS, and DSC analyses. The investigations showed that PBST-37.5 containing 37.5 mol% of BT content had the lowest strength and highest elasticity among the different compositions. This was because the two-component crystallization of poly (butylene terephthalate) (PBT) and poly (butylene succinate) (PBS) was greatly inhibited at the corresponding BT composition and the crystal growth was the least perfect, imparting poor strength to the PBT-37.5. Alternately, when the content of BT was 32.5 mol% in the PBST, the PBS segment could crystallize, and both PBT and PBS crystals were formed in the PBST-32.5. Thus, PBST-32.5 showed a higher material hardness than PBST-37.5. In contrast, when the BT content was greater than 37.5 mol% in the PBST, only PBT crystals existed in the PBST copolymer. Further, as the BT content increased, the crystal size of PBT gradually increased, which led to a closer packing of the crystal arrangement, increasing the crystallinity. This led to a gradual increase in the strength of the PBST material and a gradual decrease in its elasticity.