Thermoplastic Elastomers Research Articles

Transformation of truck tire rubber waste into thermoplastic vulcanizates: influence of vulcanization systems and compatibilizers in copolyester blends

Transformation of truck tire rubber waste into thermoplastic vulcanizates: influence of vulcanization systems and compatibilizers in copolyester blends

Building Ultrastrong, Tough and Biodegradable Thermoplastic Elastomers from Multiblock Copolyesters Via a “Reserve‐Release” Crystallization Strategy

AbstractSimultaneously attaining high strength and toughness has been a significant challenge in designing thermoplastic elastomers, especially biodegradable ones. In this context, we present a class of biodegradable elastomers based on multiblock copolyesters that afford extraordinary strength, toughness, and low‐strain resilience despite expedient chemical synthesis and sample processing. With the incorporation of the semi‐crystalline soft block and the judicious selection of block periodicity, the thermoplastic materials feature low quiescent crystallinity (“reserve”) albeit with vast potential for strain‐induced crystallization (“release”), resulting in their significantly enhanced ultimate strength and energy‐dissipating capabilities. Moreover, a breadth of mechanical responses of the materials – from reinforced elastomers to shape‐memory materials to toughened thermoplastics – can be achieved by orthogonal variation of segment lengths and ratios. This work and the “reserve‐release” crystallization strategy herein highlight the double crystalline multiblock chain architecture as a potential avenue towards reconciling the strength‐toughness trade‐off in thermoplastic elastomers and can possibly be extended to other biodegradable building blocks to deliver functional materials with diverse mechanical performances.

Building Ultrastrong, Tough and Biodegradable Thermoplastic Elastomers from Multiblock Copolyesters Via a "Reserve-Release" Crystallization Strategy.

Simultaneously attaining high strength and toughness has been a significant challenge in designing thermoplastic elastomers, especially biodegradable ones. In this context, we present a class of biodegradable elastomers based on multiblock copolyesters that afford extraordinary strength, toughness, and low-strain resilience despite expedient chemical synthesis and sample processing. With the incorporation of the semi-crystalline soft block and the judicious selection of block periodicity, the thermoplastic materials feature low quiescent crystallinity ("reserve") albeit with vast potential for strain-induced crystallization ("release"), resulting in their significantly enhanced ultimate strength and energy-dissipating capabilities. Moreover, a breadth of mechanical responses of the materials - from reinforced elastomers to shape-memory materials to toughened thermoplastics - can be achieved by orthogonal variation of segment lengths and ratios. This work and the "reserve-release" crystallization strategy herein highlight the double crystalline multiblock chain architecture as a potential avenue towards reconciling the strength-toughness trade-off in thermoplastic elastomers and can possibly be extended to other biodegradable building blocks to deliver functional materials with diverse mechanical performances.

Diffusion of organic solvents in thermoplastic elastomers: infinite dilution experiments

Diffusion of organic solvents in thermoplastic elastomers: infinite dilution experiments

Effects of crosslinked rubber particles on rheological behaviors of ethylene-propylene-diene rubber/ polypropylene thermoplastic vulcanizates

A novel secondary vulcanization-dilution process was employed to prepare ethylene-propylene-diene rubber/polypropylene (EPDM/PP) thermoplastic vulcanizates (TPVs) with uniform size, controllable crosslinking density, and content of rubber particles to assess their significant impact on rheological behavior using Fourier-rheology, shedding light on the interplay between microstructural features and macroscopic material properties. Through the application of the time-concentration superposition principle, a broad reinforcement spectrum is established, enhancing the understanding of TPV structure-property relationships. Also studied is the Mullins effect of the TPVs at two different temperatures, contributing to a deeper understanding of their deformation mechanisms. The results offer valuable insights for the formulation and processing of TPVs, emphasizing the importance of tailored particle characteristics for optimizing material performance.

Enhancing strength and toughness simultaneously: Diblock-grafted cellulose nanofiber one-component nanocomposites

To overcome the drawbacks of homopolymer-grafted CNF one-component nanocomposites, a range of diblock-grafted cellulose nanofiber (CNF), CNF-g-(polybutyl acrylate-b-polymethyl methacrylate)s were synthesized through reversible-deactivation radical polymerization (RDRP) methods. The chemical structures and ratios between the two blocks were confirmed, with surface-grafted CNF observed as submicron particles. Both thermal and thermodynamic analysis revealed two glass transition temperatures (Tg) in the diblock-grafted CNF, and phase-separated morphology was observed in the nanocomposites. The densely grafted CNF displayed island structures, while sparsely grafted samples transitioned into continuous structure. Thermodynamic analysis showed that the diblock-grafted CNF nanocomposites maintained mechanical properties at high temperatures. These nanocomposites demonstrated robust strength and toughnes, with tensile strength reaching as high as 43.7 ± 1.6 MPa and elongation at break of 70.3 ± 16.2 %. Moreover, while densely grafted CNF exhibited higher modulus and strength, whereas sparsely grafted CNF displayed behavior more reminiscent of thermoplastic elastomers, indicated by lower modulus and higher elongation.

Predicting tensile and fracture parameters in polypropylene-based nanocomposites using machine learning with sensitivity analysis and feature impact evaluation

This study examines the efficacy of decision tree and AdaBoost algorithms in predicting mechanical and fracture parameters of polypropylene nanocomposites toughened with ethylene-based and propylene-based thermoplastic elastomers and reinforced with fumed silica and halloysite nanotube nanoparticles. The essential work of the fracture approach was utilized to study the fracture parameters, including elastic and plastic works of the blended polymer nanocomposites. The data were divided into 80 % for training and 20 % for testing. AdaBoost consistently achieved superior performance compared to the decision tree model in all variables throughout both the training and testing stages. During the testing phase, the AdaBoost model obtained R2 values of 0.90 for Young's modulus, 0.93 for elongation at break, 0.87 for tensile strength, 0.86 for plastic work, and 0.60 for elastic work. Also, the mean absolute percentage error for the AdaBoost model during the test phase was 3.10 % for Young's modulus, 3.25 % for tensile strength, 10.34 % for elastic work, 13.55 % for plastic work, and 24.78 % for elongation at break. Furthermore, a sensitivity analysis examining the effects of various features such as TPO type, nanoparticles, and nanoparticle type on mechanical properties reveals that TPO has the most significant overall influence. The results also include an analysis of the impact of the key features on each mechanical property based on the sensitivity analysis.

Enhanced Recyclability of Thermoplastic Elastomer Toughened Polyamide 6 via Tri- and Multi-epoxy-Terminated POSS Hybrid Additives

Enhanced Recyclability of Thermoplastic Elastomer Toughened Polyamide 6 via Tri- and Multi-epoxy-Terminated POSS Hybrid Additives

Mechanical recycling of polyamide 6 and polypropylene for automotive applications

AbstractThis study investigates the mechanical recycling of polyamide 6 (PA6) from discarded fishing nets and polypropylene (PP) from automotive battery scraps and household waste for automotive applications. The mechanical properties of both materials were evaluated through tensile, impact, and thermal testing, revealing that recycled PA6 (r‐PA6) and recycled PP (r‐PP) can achieve mechanical performance similar to virgin materials. Recycled PA6 was reinforced with 30% glass fiber (GF), significantly enhancing its tensile strength from 70 to 170 MPa, comparable with virgin PA6's (76 MPa). Furthermore, the tensile modulus of r‐PA6 increased from 7720 to 8500 MPa. Recycled PP was compounded with thermoplastic elastomers (TPE) and fillers, such as calcium carbonate (CaCO₃) and talc, improving its impact strength from 5 to 18 KJ/m2 and improving thermal stability, with a heat deflection temperature (HDT) reaching 95°C. The optimized formulations for r‐PP, particularly from automotive battery scrap, achieved a melt flow index (MFI) of 12–16 g/10 min, preventing molding defects. This study highlights the importance of controlled thermal treatments, appropriate additive use, and accurate processing conditions in producing high‐quality recycled polymer compounds.Highlights Recycled PA6 reinforced with 30% GF achieves a tensile strength of 170 MPa. Thermal treatment increases the tensile modulus of r‐PA6 to 8500 MPa, similar to virgin PA6. Incorporating TPE improves the impact strength of r‐PP to 18 KJ/m2. Calcium carbonate and talc enhance the thermal stability of r‐PP to 95°C. The melt flow index of r‐PP optimized to 12–16 g/10 min for better moldability.

Evaluation of wash colour strength of a printed garment with flexible filaments on 3D printers

The research aims to evaluate the solidity of the washing colour of a garment printed with flexible filaments on 3D printers. Three groups of factors have been selected: Anet A8 and M3D Crane Quad printer, temperature (49° and 71°C) and flexible filaments TPE (thermoplastic elastomer) and TPU (polyurethane thermoplastic), framed in the factorial design, type applied of 10 units per combination of factors in a total of 80 sampling units, using Girowah equipment according to the technical standard AATCC TM61-2020. The results show that the printer factors Anet A8 and M3D Crane Quad with the CIELab and CMC (2:1) discolouration system exceed 50% in both the tolerances of the value 1. About the temperature factor (49° and 71°C), which exhibits a discolouration of 1.06 in CIE94 and 1.36 in CMC, it is determined that the combination with better resistance to discolouration of solidity at washing (CIE94 - 49°C) compared to CMC (2:1) better establishes the visual and technical concordance of the solidity of colour. As regards flexible filament types: TPE and TPU, the results show us that the colour tolerance assessments (CIELab CIE94) and (CMC (2,1)) prove that the TPE filament has greater resistance to the discoloration of the 3D-printed garment at different temperatures. In conclusion, the solidity of colour washing in a printed garment with flexible filaments in a 3D printer causes discolouration by the minimum, be it the factors of printer type, filament, and temperature. There is a need for analysis with other values and it remains open to other research.

Superhydrophobic Magnetic-Driven Reactor for Microliter Droplet Reaction Interface Visualization.

The development of an efficient, convenient, and cost-effective droplet-driven reactor to observe the reaction microphenomenon is crucial for investigating the chemical reaction and synthesis mechanisms. Herein, an efficient and economical strategy by combining micro-extrusion compression molding (μ-ECM) and surface modification was proposed to fabricate a superhydrophobic magnetic-driven reactor (SMDR) for microliter droplet reaction interface visualization. The wall-like array microstructures with favorable geometric uniformity and the nano-SiO2 coating with uniform dispersion endow the SMDR with robust superhydrophobicity, featuring a contact angle of 159.5 ± 1.0° and a rolling angle of 5.1 ± 0.5°. Due to the uniform dispersion of Fe3O4 in thermoplastic elastomer (TPE), the SMDR possesses sensitive magnetic responsiveness, which can drive droplets to move rapidly, continuously, and losslessly on horizontal and inclined planes, even on a plane with an inclination angle of up to 15°. Interestingly, the SMDR was successfully used to visualize the interface formation and evolution of three simple mixing/reaction processes, which provides a convenient, efficient, and low-cost method for the study of the droplet mixing reaction process and interface visualization.

Supercritical carbon dioxide foamed thermoplastic polyester elastomer with poly(lactic acid) blending: shrinkage reduction and expansion ratio improvement

Supercritical carbon dioxide foamed thermoplastic polyester elastomer with poly(lactic acid) blending: shrinkage reduction and expansion ratio improvement

Modulation of shape memory properties of trans-polyisoprene by sulfur

Abstract In this paper, TPI/S composites were prepared by a simple physical melt blending method, and the composites were hot-pressed and molded using a vulcanization system. The effect of cross-linking on the vulcanization properties, mechanical properties, crystalline properties, and shape memory properties of trans-1-4 polyisoprene (TPI) was investigated by varying the amount of sulfur (S). It was shown that with the increase of sulfur dosage, both TPI scorch time and orthoclave time were shortened and the mechanical properties decreased; The melting peak area and melting temperature of the crystalline region of TPI decreased with the increase of sulfur content, and the cross-linking density increased while the crystallinity tended to decrease and the heat resistance deteriorated; In addition, with the increase of sulfur content, the shape return rate of TPI/S composites was increasing and the shape fixation rate was decreasing. When the TPI/S composites were used as shape memory materials, the sulfur dosage of 1 phr had the best shape memory performance, at which time the shape fixation rate of the composites reached 96.9% and the shape recovery rate reached 86.2%. When the sulfur content was elevated to 2 phr, the shape memory fixation rate was significantly decreased, indicating that the shape memory properties were severely compromised. This study reveals that the quantity of sulfur exerts a significant influence on the application of TPI/S composites. An appropriate amount of sulfur can facilitate the preparation of thermoplastic elastomers for utilization in shape memory materials. Nevertheless, an excessive amount of sulfur will substantially enhance the internal cross-linked structure of the composite and deteriorate the shape memory performance.


Co Hybrids modified piperazine pyrophosphate towards efficient flame retardancy, smoke suppression, and high mechanical properties of styrenic thermoplastic elastomer

The highly flammable nature of thermoplastic elastomers (TPE) results in poor fire safety performance. The large addition of flame retardants leads to a significant decrease in mechanical properties. To solve above challenges, we design a multilayer core-shell flame retardant, piperazine pyrophosphate@ tannic acid@ Co amorphous hybrids (PAPP@TA@Co-2-MIM) and add it to TPE to enhance the fire safety and mechanical performance simultaneously. It was found that the addition of 32 wt% PAPP@TA@Co-2-MIM achieved a UL-94 V-0 rating of TPE composites, with a limiting oxygen index of 27 %. Compared to pure TPE, the peak heat release rate, total heat release, total smoke production, and peak CO release rate of TPE/PAPP@TA@Co-2-MIM were reduced by 79.8 %, 37.1 %, 42.9 %, and 82.5 %, respectively, effectively suppressing the release of heat, smoke, and toxic gases. Besides, the flame-retardant mechanism was also explained. In terms of mechanical performance, benefiting by the bridging effect of the core-shell structure, the tensile strength of TPE/PAPP@TA@Co-2-MIM increased by 52.7 %, compared to TPE/PAPP. This study designed a TPE composite material that showed good thermal stability, high fire safety performance and enhanced mechanical properties.

Enhancing the Biomimetic Mechanics of Bottlebrush Graft-Copolymers through Selective Solvent Annealing.

Self-assembled networks of bottlebrush copolymers are promising materials for biomedical applications due to a unique combination of ultra-softness and strain-adaptive stiffening, characteristic of soft biological tissues. Transitioning from ABA linear-brush-linear triblock copolymers to A-g-B bottlebrush graft copolymer architectures allows significant increasing the mechanical strength of thermoplastic elastomers. Using real-time synchrotron small-angle X-ray scattering, it is shown that annealing of A-g-B elastomers in a selective solvent for the linear A blocks allows for substantial network reconfiguration, resulting in an increase of both the A domain size and the distance between the domains. The corresponding increases in the aggregation number and extension of bottlebrush strands lead to a significant increase of the strain-stiffening parameter up to 0.7, approaching values characteristic of the brain and skin tissues. Network reconfiguration without disassembly is an efficient approach to adjusting the mechanical performance of tissue-mimetic materials to meet the needs of diverse biomedical applications.

Main-Chain Azobenzene Poly(ether ester) Multiblock Copolymers for Strong and Tough Light-Driven Actuators.

The stimulus-responsive polymeric materials have attracted great research interest, especially those remotely manipulated materials with potential applications in actuators and soft robotics. Here we report a photoresponsive main-chain actuator based on azobenzene poly(ether ester) multiblock copolymer (mBCP) thermoplastic elastomers, (PTAD-b-PTMO-b-PTAD)n, which were synthesized by a cascade polycondensation-coupling ring-opening polymerization method using poly(tetramethylene oxide) (PTMO) and azobenzene-containing cyclic oligoesters (COTADs) as monomers. The thermal, mechanical, and microphase separation behaviors of mBCPs could be flexibly tuned by altering the ratios of soft-to-hard segments and block number (n). The oriented azobenzene mBCP fibers were prepared by melt spinning, showing reversible photoresponsive properties with remarkably high strength (∼1000 MPa) and high elongation at break comparable to spider silks. Fast photoinduced bending and contraction were successfully achieved in these fibers with high work and power densities and energy conversion efficiency, enabling it to lift up about 250 times of its own weight. Moreover, it can take out materials inside the tube by UV-light control. These fibers could be applied in light-driven actuators or telecontrolled robot arms.

New Generation of Thermoplastic Elastomers from Narrowly Dispersed All-(Meth)acrylic ABA Triblock Copolymers Made by RAFT

New Generation of Thermoplastic Elastomers from Narrowly Dispersed All-(Meth)acrylic ABA Triblock Copolymers Made by RAFT

Evaluation of the layering adhesion between PLA and TPE materials

Abstract The additive manufacturing industry has witnessed rapid growth and has applications across various sectors such as aerospace, automotive, healthcare, and consumer goods. Both Thermoplastic Elastomer (TPE) and Polylactic Acid (PLA) hold significant relevance in these industries because of their unique properties and environmental sustainability, thus driving the demand for research aimed at improving their compatibility and performance in multi-material printing processes. This study delves into the interlayer adhesion aspects of multi-material filament fabrication, particularly focusing on the incorporation of TPE and PLA. TPEs offer elasticity and flexibility, while PLA provides rigidity and biodegradability, making them an intriguing combination for a wide range of applications. Experimental investigations of mechanical properties, specifically tensile, compression, and Charpy impact tests, are conducted to evaluate the interlayer adhesion between TPE and PLA. This study aims to contribute to the understanding of interlayer adhesion in multi-material filament fabrication, focusing on the integration of TPE and PLA. Through experimental analysis and exploration of industrial applications, we seek to shed light on the potential of these materials in additive manufacturing and outline future directions for research and development in this field.

Effects of Sulfuric Acid-Water Immersion on the Properties of Ethylene Propylene Diene Monomer, Thermoplastic Vulcanizates, and Eco-Friendly Thermoplastic Vulcanizates

Abstract This research investigates the impact of sulfuric acid-water solutions on the physico-chemical characteristics of ethylene propylene diene monomer rubber (EPDM), thermoplastic vulcanizates (TPV), and ECO TPV materials. We evaluated the deterioration of these materials by subjecting them to acidic environments and using methods such as differential scanning calorimetry (DSC), volume and weight measurements, hardness measures, and scanning electron microscopy (SEM). The samples were submerged in solutions of H2SO4 with concentrations of 1M, 0.1M, and 0.001M at a temperature of 90°C for a duration of 1000 h. The results indicated that EPDM had superior chemical and thermal stability, accompanied by negligible changes in weight and volume. The TPV exhibited moderate stability, however the ECO TPV showed severe deterioration, as seen by major increases in weight and volume, as well as notable changes in DSC profiles. Surface degradation and cracking, especially in ECO TPV samples, were observed using SEM investigation. The hardness results indicated little changes in hardness after exposure to the various chemical aging techniques. The results indicate that EPDM and TPV are better suited for use in acidic conditions, such as fuel-cell systems. However, ECO TPV may need extra stabilization in order to enhance its endurance.

Impact of Aging on Tensile Properties of EPDM, TPV, and eco-TPV: A Comparative Study Across Diverse Environments

Abstract This study examines the effects of aging on the tensile characteristics of Ethylene Propylene Diene Monomer (EPDM), Thermoplastic Vulcanizates (TPV), and Eco-friendly Thermoplastic Vulcanizates (Eco TPV) in different conditions. The samples underwent thermal aging at a temperature of 90°C and were immersed in sulfuric acid solutions with varying concentrations (1M, 0.1M, and 0.001M) for a duration of 1000 hours at the same temperature. The findings revealed that EPDM demonstrated the maximum tensile strength and a moderate level of elongation and breakage. Furthermore, it retained substantial mechanical integrity after undergoing aging, thereby establishing it as the most resilient material among those evaluated. The thermoplastic vulcanizate (TPV) exhibited intermediate tensile strength and elongation, but experienced significant deterioration when exposed to very acidic environments while Eco TPV had lower tensile strength but good chemical stability. The stress-strain behavior and compression set tests emphasized EPDM’s exceptional durability and ability to recover elastically. The pH measurements of the immersion solutions indicated an elevation caused by the release of alkaline chemicals from the rubber components, especially in the 1M solution.