Thermoplastic Polyester Elastomer Research Articles

Morphology and properties of carbon black‐filled thermoplastic vulcanizate (TPV) composites based on hydrogenated acrylonitrile butadiene rubber and thermoplastic polyester elastomer

AbstractThe unique morphology of thermoplastic vulcanizates (TPVs) reveals a significant correlation between the microstructure and performance, and the development of high‐performance TPV composites for specialized applications has become a current research priority. This study is devoted to developing heat‐ and oil‐resistant TPV composites filled with carbon black (CB) based on hydrogenated acrylonitrile butadiene rubber (HNBR) and thermoplastic polyester elastomer (TPEE) following the masterbatch procedure of dynamic vulcanization. Herein, it focuses on the effects of CB content on the morphology, filler network structure, and properties of the TPV/CB composites. As observed by morphological studies, CB nanoparticles are interconnected and aggregated to form a dual network structure of rubber and CB particles in the composite. With the increasing CB content, it's demonstrated that dual networks have enhanced and shifted to rigid. Consequently, the hardness, thermal stability, and oil resistance of TPV/CB composites are improved, with a 104% elevation in the stress at 300% strain. The flowability in the molten state, toughness (the elongation at break decreased from 690% to 310%), and elasticity deteriorated by oversized (0.5 ~ 1.2 μm) CB agglomerates and rigid rubber particles. This study gives new insight into the microstructure‐properties relationship of TPVs, offering theoretical guidance for fabricating HNBR‐based TPV composites.

Study of the effect of hexagonal boron nitride addition to thermoplastic polyester elastomer composites reinforced with carbon, glass and basalt fibers

Study of the effect of hexagonal boron nitride addition to thermoplastic polyester elastomer composites reinforced with carbon, glass and basalt fibers

Investigation of electrospinning parameters and fiber collection methods on morphology of thermoplastic polyester elastomer fibers

Electrospinning is an easy and simple process for the preparation of ultrafine fibers with tunable morphology. Thermoplastic Elastomers (TPEs) are engineering polymers with an elastomeric nature that can be processed as thermoplastics. They can be classified based on their chemical structure and polyester-based TPEs are counted as high-performance materials due to their mechanical properties and can be used for various applications from automotive, construction, furniture, and consumer goods. In this study, electrospun polyester-based thermoplastic elastomer fibers were prepared and characterized. Thermoplastic polyester elastomer, Hytrel 4056 was used as the polymer, and chloroform was used as a solvent. The effects of polymer: solvent weight ratio, feed rate, applied voltage, and collector type were investigated in terms of fiber formation and morphology. For this aim, the polymer: solvent weight ratio was varied as 1:7, 1:11, and 1:15; the feed rate was set to 1 and 3 ml h-1. To collect the fibers metal plate and water bath collectors were used at a constant needle-to-collector distance under 10, 15, and 20 kV. The viscosity of the polymer solutions was measured as a function of the polymer: solvent ratio to observe the effects of viscosity on fiber morphology.

Contribution of cellulose nanofibrils on the strengthening and toughening of neat and blended polylactide specimens; and the differences after 3D-printing

The main purpose of this study was to use “green materials” approach by investigating effects of only 1 wt% Cellulose Nanofibrils (CNF) on the strengthening and toughening of neat and blended polylactide (PLA) biopolymer matrix. For this purpose, first of all effects of CNF were investigated in PLA/CNF biocomposite specimens. After blending of PLA with 10 phr bio-based thermoplastic polyester (b-TPE) elastomer, effects of CNF were investigated also for this PLA/b-TPE/CNF ternary biocomposite specimens. Mechanical tests revealed that due to the efficient strengthening and toughening mechanisms, CNF increased flexural strength of PLA by 33%, while b-TPE increased fracture toughness of PLA by 104%. When CNF and b-TPE were incorporated together, synergism in the strength and toughness values were occurred. All bioblend and biocomposite specimens were produced by using the same “melt mixing” technique in a laboratory size twin-screw extruder, and their test specimens were shaped by conventional “compression molding”. Since shaping by “3D-printing” is frequently used in the biomedical sectors, another distinctive aim of this study was to reveal whether there were any differences in the strength and toughness values of specimens after their 3D-printing. It was observed that due to the “textured” structure of 3D-printed specimens, their flexural strength values were approximately 20% lower, while fracture toughness values were approximately 20% higher.

High-Expansion Injection-Molded Thermoplastic Polyester Elastomer Foam with Oriented Cellular Structure and Anisotropic Compressive Properties

High-Expansion Injection-Molded Thermoplastic Polyester Elastomer Foam with Oriented Cellular Structure and Anisotropic Compressive Properties

Composite phase change materials with room-temperature-flexibility

Phase change materials (PCMs) have attracted considerable attention for effectively addressing the problem of thermal energy supply–demand mismatch. However, the practical application of PCMs is still hindered by inherent challenges such as crystalline rigidity, leakage susceptibility, and poor thermal conductivity. In this research, on the basic of thermal control provided by phase change storage and the elastic behavior supported by thermoplastic polyester elastomer at room temperature, we fabricated a new type of composite PCM (CPCM) that exhibits flexibility even at room temperature. This CPCM demonstrates good shape and thermal stability. Furthermore, the carbon nanotubes-COOH modified with lauric acid (LA) can be uniformly dispersed within the CPCM matrix, thereby enhancing the thermal conductivity of the CPCM. Additionally, the composite material exhibits a promising thermal management performance for high-temperature lithium-ion (Li-ion) batteries. These findings open up new possibilities for the development of room- temperature flexible CPCMs.

Highly tough and flame retardant polystyrene composites by elastomeric nanofibers and hexagonal boron nitride

Thermoplastics flammability remains a considerable threat during fire incidents. Conventionally, halogen-free fire retardant (FR) additives are incorporated into thermoplastics to reduce fire hazards. However, the incorporation of FR additives compromises the mechanical properties (most notably, toughness) of thermoplastics, which has impeded the development of thermoplastic products that possess both high mechanical and fire retarding performances. This study reports an in situ nano-fibrillation strategy to fabricate thermoplastics that exhibit fire retarding properties and a combination of high stiffness and toughness. The proposed composites were composed of in situ thermoplastic polyester elastomer (SBC) nanofibers within a polystyrene (PS) matrix containing hexagonal boron nitride (hBN) as the FR additive. The presence of elastomeric nanofibers successfully mitigated the losses in mechanical performances caused by the incorporation of 2 wt% hBN. Specifically, the inclusion of 15 wt% SBC nanofibers significantly enhanced the toughness of the PS-hBN composite by 350% with negligible effects on the stiffness as compared to neat PS. Furthermore, the presence of nanofibers resulted in synergies with hBN to fabricate composites with enhanced fire retarding performance since the total heat release (THR) of PS-hBN composite decreased from 212 to 189 MJ m−2 with 10 wt% nanofibers. Thus, nanofibers behave as a multifunctional component that compensated for the losses in mechanical performances caused by hBN incorporation, while enhancing the fire retarding performance. This strategy can be effectively implemented to fabricate the next generation of polymer composites with high fire retarding and mechanical properties for various applications including energy storage packs for batteries and electronics.

Reversible Sensing Technologies Using Upcycled TPEE: Crafting pH and Light Responsive Materials towards Sustainable Monitoring.

Multiresponsive materials with reversible and durable characteristics are indispensable because of their promising applications in environmental change detections. To fabricate multiresponsive materials in mass production, however, complex reactions and impractical situations are often involved. Herein, a dual responsive (light and pH) spiropyran-based smart sensor fabricated by a simple layer-by-layer (LbL) assembly process from upcycled thermoplastic polyester elastomer (TPEE) materials derived from recycled polyethylene terephthalate (r-PET) is proposed. Positively charged chitosan solutions and negatively charged merocyanine-COOH (MC-COOH) solutions are employed in the LbL assembly technique, forming the chitosan-spiropyran deposited TPEE (TPEE-CH-SP) film. Upon UV irradiation, the spiropyran-COOH (SP-COOH)molecules on the TPEE-CH-SP film undergo the ring-opening isomerization, along with an apparent color change from colorless to purple, to transform into the MC-COOH molecules. By further exposing the TPEE-CH-MC film to hydrogen chloride (HCl) and nitric acid (HNO3) vapors, the MC-COOH molecules can be transformed into protonated merocyanine-COOH (MCH-COOH) with the simultaneous color change from purple to yellow.

Flame-Retardant Thermoplastic Polyether Ester/Aluminum Butylmethylphosphinate/Phenolphthalein Composites with Enhanced Mechanical Properties and Antidripping.

Aluminum butylmethylphosphinate AiBMP as a flame retardant and phenolphthalein as a synergistic agent were applied in a thermoplastic polyester elastomer (TPEE)) in the current study. The thermal properties, flame retardancy, crystallization and mechanical properties of TPEE/AiMBP with or without phenolphthalein were investigated using various characterizations, including the limiting oxygen index (LOI), vertical burning test (UL 94), thermogravimetric analysis TG, differential scanning calorimetry, microcombustion calorimeter (MCC), scanning electron microscopy (SEM), and mechanical tests. The results revealed that AiBMP alone is an efficient flame retardant of TPEE. Adding 15 wt.% AiBMP increases the LOI value of TPEE from 20% to 36%. The formula TPEE-15 AiBMP passed the UL 94 V-0 rating with no dripping occurring. The MCC test shows that AiBMP depresses the heat release of TPEE. In comparison with pure TPEE, the heat release rate at peak temperature and the heat release capacity of TPEE-15AiBMP are reduced by 46.1% and 55.5%, respectively. With the phenolphthalein added, the formula TPEE/13AiBMP/2Ph shows a higher char yield at high temperatures (>600 °C), and the char layer is stronger and more condensed than TPEE-15AiBMP.The tensile strength and elongation at break values of TPEE-13AiBMP-2Ph are increased by 29.63% and 4.8% in comparison with TPEE-15AiBMP. The SEM morphology of the fracture surface of the sample shows that phenolphthalein acts as a plasticizer to improve the dispersion of AiBMP within the matrix. The good char charming ability of phenolphthalein itself and improved dispersion of AiBMP make the TPEE composites achieve both satisfying flame retardancy and high mechanical properties.

Super‐Elastic and Dimensionally Stable Polyether Block Amide Foams Fabricated by Microcellular Foaming with CO2&N2 as Co‐Blowing Agents

AbstractPolyether block amide (PEBA) is an important thermoplastic polyester elastomer (TPE) owing to its low density and high resilience. Microcellular foaming can endow PEBA with significant potential in sports, medical, and industrial applications. However, with the current microcellular foaming technology, it remains challenging to obtain PEBA foams with stable shapes, which are critical for their mechanical properties. Therefore, microcellular foaming with CO2 and N2 as co‐blowing agents is utilized in this study to achieve mechanically robust PEBA foams by reducing the dimensional shrinkage. The introduction of N2 can effectively slow the diffusion rate of blowing agents into the air, providing support for the foam to resist external atmospheric pressure and effectively reducing the dimensional shrinkage of PEBA foams. Consequently, a stable foam shape is achieved with an expansion ratio of 7.9. Finally, the PEBA foams with excellent shrinkage resistance and mechanical properties are prepared, and the cell shrinkage mechanism is analyzed to study the effects of blowing agents and foaming methods on the structural evolution of TPE foams. This promising outcome paves way for their practical industrial applications.

Phase Morphology and Mechanical Properties of Super-Tough PLLA/TPE/EMA-GMA Ternary Blends.

The inherent brittleness of poly(lactic acid) (PLA) limits its use in a wider range of applications that require plastic deformation at higher stress levels. To overcome this, a series of poly(l-lactic acid) (PLLA)/biodegradable thermoplastic polyester elastomer (TPE) blends and their ternary blends with an ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) copolymer as a compatibilizer were prepared via melt blending to improve the poor impact strength and low ductility of PLAs. The thermal behavior, crystallinity, and miscibility of the binary and ternary blends were analyzed by differential scanning calorimetry (DSC). Tensile tests revealed a brittle-ductile transition when the binary PLLA/20TPE blend was compatibilized by 8.6 wt. % EMA-GMA, and the elongation at break increased from 10.9% to 227%. The "super tough" behavior of the PLLA/30TPE/12.9EMA-GMA ternary blend with the incomplete break and notched impact strength of 89.2 kJ∙m-2 was observed at an ambient temperature (23 °C). In addition, unnotched PLLA/40TPE samples showed a tremendous improvement in crack initiation resistance at sub-zero test conditions (-40 °C) with an impact strength of 178.1 kJ∙m-2. Morphological observation by scanning electron microscopy (SEM) indicates that EMA-GMA is preferentially located at the PLLA/TPE interphase, where it is partially incorporated into the matrix and partially encapsulates the TPE. The excellent combination of good interfacial adhesion, debonding cavitation, and subsequent matrix shear yielding worked synergistically with the phase transition from sea-island to co-continuous morphology to form an interesting super-toughening mechanism.

Preparation of aluminum diethyl hypophosphite intercalation‐modified montmorillonite AlPi‐MMT and its effect on the flame retardancy and smoke suppression of thermoplastic polyester elastomer

AbstractAn aluminum diethyl hypophosphite intercalation‐modified montmorillonite flame retardant (AlPi‐MMT) is successfully prepared and characterized by FT‐IR, SEM, and X‐ray diffraction. It is found that thermoplastic polyester elastomer (TPEE) composites incorporating 15 wt% AlPi‐MMT flame retardant exhibited better char formation and flame retardant properties compared to those incorporating 15 wt% (4:1, w:w) AlPi and MMT. And the char residual of TPEE/AlPi‐MMT at 700°C is 16.17%, which is higher than that of TPEE/AlPi‐MMT at 13.94%. and the former can pass UL‐94 V‐0 rating test while the latter can only pass UL‐94 V‐1 rating test. Afterwards, the combustion performance of TPEE composites is characterized, and it is found that the heat release and smoke release of TPEE/AlPi‐MMT are greatly reduced compared with those of pure TPEE and TPEE/AlPi/MMT, which is a flame retardant and smoke suppressant TPEE composite. Finally, by analyzing the residual char morphology and elements of TPEE composites after combustion, the mechanism of the flame retardant AlPi‐MMT to promote char formation and flame retardancy is demonstrated.

Green preparation of lightweight and elastic thermoplastic polyamide/polyester elastomer composite foams using supercritical CO2

Green preparation of highly elastic foam is an effective strategy to reduce the cost of elastomers and broaden their application areas. In this work, thermoplastic polyamide elastomer (TPAE) was blended with thermoplastic polyester elastomer (TPEE) and chain extender ADR to improve the elasticity and overcome the weakness of easy tearing of TPAE foams. The results indicate that the melt strength of the blend was significantly improved with the use of chain extension. The foaming expansion ratio of the mixtures increased by 25 %, and the foaming recovery ratio reached 92 %. Mechanical properties showed that the maximum compressive stress of TPAE/TPEE foams was twice as high as that of TPAE, while the energy loss coefficient (11.38 %) was lower than that of TPAE at a high expansion ratio of 10. In addition, the resilience of TPAE/TPEE foams reached 73 % at an expansion ratio of 12.

Effect of crosslinking agent dosage on the morphology and properties of thermoplastic vulcanizates based on hydrogenated acrylonitrile butadiene rubber and thermoplastic polyester elastomer

This work aims to develop heat- and oil-resistant thermoplastic vulcanizates (TPVs) based on hydrogenated acrylonitrile butadiene rubber (HNBR) and thermoplastic polyester elastomer (TPEE) using dynamic vulcanization and following a masterbatch procedure. It focuses on the effect of the cross-linking agent dosage on the morphology and properties of HNBR/TPEE-TPVs. An increase in the peroxide dosage yields a higher cross-linking degree of the HNBR, a smaller size and a more uniform distribution of the HNBR domains, and a stronger rubber network. Consequently, the elasticity and high-temperature oil resistance of the TPV increases, but its flowability in the molten state, tensile properties, and heat resistance decrease. It turns out that a peroxide dosage of 1.5 phr is preferred for the preparation of HNBR/TPEE-TPV under the specified processing conditions to achieve a more comprehensive TPV performance.

Elevated volatile organic compound emissions from coated thermoplastic polyester elastomer in automotive interior parts: Importance of plastic swelling

Volatile organic compounds (VOCs) in vehicle cabins pose some health concerns, especially in new cars where interior plastics contribute substantially to VOCs emissions. We investigated the reasons for enhanced VOCs emissions from surface-coated thermoplastic polyester elastomer (TPEE), an automotive interior plastic. After applying solvent-based primer and clearcoat coatings, total VOCs (TVOC) level increased by 12.1 times (2066-24,983 μg m−3). Among the 15 emitted VOCs, seven VOCs (esters and ketones) originating from the coating solutions accounted for 77.4 % of TVOC. The remaining solvents resulted from TPEE swelling during coating owing to high chemical affinity with the solvents as evidenced by a low contact angle (14.3°) and high degree swelling (68.9%). Further baking at 80C reduced VOCs levels over time, but some major compounds (methyl isobutyl ketone and butyl acetate) persisted until 6 h. Primer and clearcoat films reduced solvent volatilization by approximately 70 %, creating a blocking effect. Apart from solvents, neat TPEE contained 4.2 % of its weight as potential VOCs. Therefore, enhanced VOCs emissions stem from three factors: (1) excessive TPEE swelling caused by coating solvents and residual solvents released as VOCs, (2) restricted volatilization caused by the coating, and (3) emission of inherent VOCs from neat TPEE.

Effect of dynamic vulcanization time on the performance of thermoplastic vulcanizates based on hydrogenated acrylonitrile butadiene rubber/thermoplastic polyester elastomer

AbstractThermoplastic vulcanizates (TPVs) are obtained by dynamic vulcanization (DV). Time is a crucial processing parameter. This work aims to develop heat‐ and oil‐resistant TPVs with hydrogenated acrylonitrile butadiene rubber (HNBR) and thermoplastic polyester elastomer (TPEE). It focuses on the effect of DV time on the morphology and properties of the resulting TPVs. The investigation demonstrates that as the DV time increases from 2 to 6 min, the rubber network progressively reinforces and the HNBR domain size decreases under more adequate shearing action, resulting in a more homogeneous morphology. This leads to a significant improvement in tensile properties, elasticity, rheological properties, thermal stability, and oil resistance of the TPV. A further extension in DV time (over 8 min) results in a slight deterioration in elasticity and thermal stability of the TPV because of excessive degradation of the TPEE. Accordingly, an appropriate DV time for HNBR/TPEE‐TPV preparation is between 6 and 8 min under the specified DV conditions.

Influence of structural arrangements on static and dynamic properties of additively manufactured polyester elastomer lattice metamaterials

In the current study, we present novel carbon organic framework-inspired lattice metamaterials (CFLM) with thermoplastic polyester elastomer (TPEE) to analyze the structural effects. The CFLMs (S1, S2, S3, and SS) from TPEE were successfully produced by material extrusion (MEX) via fused-filament fabrication and had never been reported previously. In the beginning stage, static compression tests were utilized to evaluate mechanical properties, densification strain, and energy absorption, which were validated using the finite element method (FEM). According to static compression results, S2 had the largest energy absorption, followed by the SS structure. In the second stage based on the static test, dynamic sinusoidal compression was performed to calculate the dynamic elastic recovery (DER), hysteresis work absorption, and Tan δ. The results showed that the proposed lattice metamaterials showed different the hysteresis energy absorption, DER, and viscoelasticity nature from Tan δ. To apply static and dynamic compression results to shoe midsoles, they were subjected to a dynamic drop weight impact test. Based on static and dynamic compression testing, including the results of dynamic drop weight impact tests, S1 was the most suitable for the toe part of the shoe midsole, whereas SS was the best for the heel part of the shoe midsole. From the overall results of all characterizations, it was concluded that the structural effect of CFLMs successfully provided different mechanical properties in the static and dynamic tests from the signal TPEE material.

Synergistic effect of thermoplastic polyester elastomer and polytetrafluoroethylene in situ fibrillation on the resilience and compression strength of long‐chain branched polypropylene foam

AbstractExcellent resilience and compression resistance are the key characteristics of cushioning and water–oil separation materials. Although polypropylene (PP) offers excellent performance and affordability of PP, it exhibits poor resilience. To address this shortcoming, polymer blends with long‐chain branched PP (LCBPP), thermoplastic polyester elastomer (TPEE), and polytetrafluoroethylene (PTFE) were prepared via melt blending, and their mechanical properties were tested. The LCBPP/TPEE/PTFE composites were subjected to physical foaming using supercritical CO2 (scCO2) as the blowing agent. The synergistic toughening mechanism of the elastomer/nanofiber and the effect of the structure and crystallization of the dispersed phase on the foam resilience and foam compression strength were investigated. The results revealed that fibrous PTFE and spherical TPEE formed a composite dispersed phase in LCBPP. The impact and tensile strengths of the unfoamed LCBPP were found to have been simultaneously optimized owing to the synergistic effect of the elastomeric toughening of TPEE and the reinforcement of the PTFE fiber–induced fibrous crystal structure. Compared with pure LCBPP, the impact strength of the LCBPP/TPEE/PTFE composite increased by 216%, whereas its tensile strength decreased by only 6%. In particular, the synergistic effect of TPEE/PTFE improved the resilience and compression strength of the LCBPP foam. Compared with the pure LCBPP foam, the permanent strain of the LCBPP/TPEE/PTFE foam was reduced by 13.8% after five cycles of compression and its compression strength increased by 27.3%. The experimental results of our study could be used to prepare LCBPP foams with exceptional resilience, high compression strength, and good application prospects.

Morphological, thermal, and solid‐state viscoelastic properties of thermoplastic polyester elastomer‐graphitic carbon nitride composites

AbstractIn order to evaluate the effect of graphitic carbon nitride (g‐C3N4) incorporation on the physical properties of thermoplastic polyester elastomer (TPEE) composites using a comparative approach, the composite films were prepared by the solution mixing method and solvent evaporation methods. For this purpose, the g‐C3N4 nanoparticles were synthesized by direct thermal condensation reaction of melamine and characterized by FTIR, SEM, XRD, BET, and TGA, respectively. The diameters of the g‐C3N4 particles ranged from ∼90 to 480 nm and the g‐C3N4 exhibited a high thermal stability up to 570°C, which was attributed to the robust heptazine‐based structure. The morphology, structure, thermal stability, solid‐state viscoelastic behavior, and friction coefficient of the TPEE composites were evaluated depending on the composition. The results showed that the g‐C3N4 nanoparticles improved the thermal stability and reduced the friction coefficient of the TPEE films. It was also found that g‐C3N4 addition into the TPEE matrix significantly reduced the permanent deformation in the solid state. The findings indicate that low‐cost g‐C3N4 nanoparticles can be used as an effective additive to enhance the performance of TPEE films in various applications.

High Performance Star Block Aliphatic Polyester Thermoplastic Elastomers Using PDLA-b-PLLA Stereoblock Hard Domains.

Star block (ABC)4 terpolymers consisting of a rubbery poly(γ-methyl-ε-caprolactone) (PγMCL) (C) core and hard poly(l-lactide) (PLLA) (B) and poly(d-lactide) (PDLA) (A) end-blocks with varying PDLA to PLLA block ratios were explored as high-performance, sustainable, aliphatic polyester thermoplastic elastomers (APTPEs). The stereocomplexation of the PDLA/PLLA blocks within the hard domains provided the APTPEs with enhanced thermal stability and an increased resistance to permanent deformation compared to nonstereocomplex analogs. Variations in the PDLA:PLLA block ratio yielded tunable mechanical properties likely due to differences in the extent and location of stereocomplex crystallite formation as a result of architectural constraints. This work highlights the improvements in mechanical performance due to stereocomplexation within the hard domains of these APTPEs and the tunable nature of the hard domains to significantly impact material properties, furthering the development of sustainable materials that are competitive with current industry standard materials.