Thermoplastic Elastomers Research Articles

New Thermoplastic Elastomers based on Ethylene‐Butadiene‐Rubber (EBR) by Switching from Anionic to Coordinative Chain Transfer Polymerization

Olefin triblock copolymers based on glassy polystyrene (PS), ethylene butadiene rubber (EBR) and highly crystalline polyethylene (PE) segments were prepared for the first time using a switch strategy from anionic polymerization to coordinative chain transfer (co)polymerization (CCT(co)P). PS chains obtained by anionic polymerization were transmetalated with mesitylmagnesium bromide (BrMgMes) to act as macromolecular chain transfer agents (macro‐CTA, PS‐MgMes) in the CCTcoP of ethylene and butadiene using {Me2Si(C13H8)2Nd(BH4)2Li(THF)}2 complex (1). Further chain extension by CCTP using pure ethylene in the monomer feed afforded well‐defined PS‐b‐EBR‐b‐PE triblock copolymers. The structural, rheological and mechanical properties of these materials demonstrate excellent balance between properties and easy processability at moderate temperatures (> 150 °C). We demonstrate that such triblock copolymers behave effectively as low‐viscosity PS‐b‐EBR diblock copolymers above the melting point of PE domains and high performance thermoplastic elastomers (TPEs) upon crystallization of PE segments.

Synergistic Multimodal Energy Dissipation Enhances Certified Efficiency of Flexible Organic Photovoltaics beyond 19.

All-polymer organic solar cells (OSCs) have shown unparalleled application potential in the field of flexible wearable electronics in recent years due to the excellent mechanical and photovoltaic properties. However, the small molecule acceptors after polymerization in still retain some mechanical and aggregation properties of the small molecule, falling short of the ductility requirements for flexible devices. Here, based on the multimodal energy dissipation theory, the mechanical and photovoltaic properties of flexible devices are co-enhanced by adding the thermoplastic elastomer material (polyurethane, PU) to the PM6:PBQx-TF:PY-IT-based active layer films. The construction of multi-fiber network structure and the decrease of films' residual stresses contribute to the enhancement of carrier transport properties and the decrease of defect state density. Eventually, the PCE (power conversion efficiency) of 19.40% is achieved on the flexible devices with an effective area of 0.102 cm2, and the third-party certified PCE reaches 19.07%, which is the highest PCE for flexible OSCs currently available. To further validate the potential of this strategy for large-area module applications, the 25-cm2-based flexible and super-flexible modules are prepared with the PCEs of 15.48% and 14.61%, respectively, and demonstration applications are implemented.

High strength, high sensitivity, hydrophobic and conductive vegetable oil-based composites for human motion detection

The vulnerability of infants and young children due to their fragile bodies and inability to effectively express physical discomfort has raised widespread of concern in the society. As it continues to be difficult to develop sensors with superior mechanical qualities and response sensitivity for use in health monitoring and recognition. Here, a polymer known as, Polyurethane Thermoplastic Elastomer, enhanced by crosslinking which is prepared from Isophorone Diisocyanate (IPDI), soybean oil polyol ED, and polycaprolactone triol (PCT-L) also referred to as PTIED, was prepared based on previously prepared soybean oil polyol ED and polycaprolactone triol (PCT-L) as soft segments, with IPDI as hard segments. This was followed by the preparation of the PTIED-CNT sensor by using PTIED as a matrix and hydroxyl carbon nanotubes (CNT) as a conductive filler. The mechanical properties of the obtained PTIED-CNT sensor have been enhanced, with a tensile strength of approximately 5 MPa. The sensitivity GF of the PTIED-CNT7 % can reach up to 805.67 and remains stable after 4500 seconds of continuous operation at 10 % strain. Moreover, the device can support high stability in a simulated sweat environment and exhibit antibacterial and hydrophobic, which could be used to check for small movements, such as those of the face and throat, and could also recognize sound. Therefore, its potential applications in respiratory monitoring of infants as well as other health monitoring applications are expected.

Using tannin as a biological curing agent to design fully bio-based epoxidized natural rubber/polylactic thermoplastic vulcanizates with mechanical robustness and multi-stimuli-responsive shape memory properties

To effectively mitigate carbon emissions and promote sustainability in the polymer field, biological macromolecules have emerged as a prominent strategy for fabricating functional materials. Herein, tannin (TA) was used as a biological curing agent to design fully bio-based polylactic/epoxidized natural rubber thermoplastic vulcanizates (PLA/ENR TPVs) with mechanical robustness and multi-stimuli-responsive shape memory properties. A dual cross-linking network, comprising both covalent bonds and hydrogen bonds, was successfully constructed in the ENR phase. A special co-continuous morphology was concomitantly constructed in the TPVs, which promoted effective stress transfer between the PLA and ENR phases, endowing the TPVs with balanced stiffness-toughness and shape memory properties. Moreover, the photothermal effect of TA also made it respond to near-infrared light and sunlight, which achieved the non-contact multistage shape memory performance, revealing the significant potential of the TPVs in the field of actuators.

Excellent Compatibilization Effect of (ENR/PP-g-MA) as a Dual Reactive Compatibilizer on the Immiscible Thermoplastic Elastomer based on Nitrile Rubber and Polypropylene Blends: Insights from Experimental and Computational Studies

Excellent Compatibilization Effect of (ENR/PP-g-MA) as a Dual Reactive Compatibilizer on the Immiscible Thermoplastic Elastomer based on Nitrile Rubber and Polypropylene Blends: Insights from Experimental and Computational Studies

Self-Healing Thermoplastic Elastomers Enabled by Dynamic Ordered Microphase Crosslinking of Random Copolymers

Self-Healing Thermoplastic Elastomers Enabled by Dynamic Ordered Microphase Crosslinking of Random Copolymers

Property Prediction of Bio-Derived Block Copolymer Thermoplastic Elastomers Using Graph Kernel Methods.

Increasing the diversity of bio-based polymers is needed to address the combined problems of plastic pollution and greenhouse gas emissions. The magnitude of the problems necessitates rapid discovery of new materials; however, identification of appropriate chemistries maybe slow using current iterative methods. Machine learning (ML) methods could significantly expedite new material discovery and property identification. Here, PolyAGM, a ML algorithm using graph kernel methods, is introduced and used to predict the properties of block copolymers and identify the responsible structural 'motifs'. It applies a "fingerprinting" method to convert Graph representations of polymers into numerical vectors. The Graphs explicitly encode the entire copolymer of atoms and bonds such that the sequencing of chemical features and polymer chain length are included, alongside relevant stereochemical information. PolyAGM gives predictions for both thermal and mechanical properties that are in good agreement with experimental measurements. This work focuses on predicting the properties of bio-derived ABA-block polymer thermoplastic elastomers, but the general fingerprinting technique of PolyAGM should be relevant to other application fields.

TPV concentrate: Fabrication and performance

Thermoplastic vulcanizates (TPVs) have been widely studied and applied in recent years because of their excellent elasticity and re-processibility similar to those of thermoplastics. However, its dynamical vulcanization processing normally requires an expensive twin-screw extruder with a very high L/D ratio. In this paper, a kind of thermoplastic vulcanizate concentrate (TPVC) with very high rubber phase content and low hardness was prepared by using highly oil-extended ultra-high molecular weight ethylene propylene diene rubber (EPDM) dynamically cured by peroxide and a low melt index polypropylene (PP) and extra oil softener. Then a new kind of high purity TPV with a wide hardness range was fabricated by using this TPVC simply melt blended with various contents of PP. The mechanical and recycling properties, rheological responses, phase morphology, crystallization, thermal stability and UV radiation resistance were systematically studied. In addition, because TPVC is filled with a large amount of white oil, the process parameters can be controlled reasonably by studying the distribution coefficient of white oil in the two phases.

Reactive compatibilization of zinc dimethacrylate on dynamically vulcanized thermoplastic polyurethane/silicone rubber blends

AbstractThermoplastic polyurethane (TPU)/silicone rubber (SR) thermoplastic vulcanizates (TPVs) are considering to be a promising material for smart wearable technologies due to its low temperature and high temperature resistance and biological affinity. However, the poor compatibility between TPU and SR phases limits its practical application. In this paper, TPU/SR TPVs were prepared through dynamic vulcanization and zinc dimethacrylate (ZDMA) was used to improve the interface between TPU and SR phases. FTIR results and theoretical calculation showed that complex reactions including the graft‐polymerization of ZDMA occurred onto the main chains of TPU and SR in the presence of peroxides to form a strong interface and improve the compatibility. Dynamic mechanical analysis implied the difference of glass transition temperature of the two phases reduced from 86.4 to 67.3°C with the addition of 5 wt% of ZDMA compared to original TPVs. Scanning electron microscope showed that with the addition of 5 wt% ZDMA, the crosslinked SR phase formed a network structure when TPU phase was etched with dimethyl sulfoxide. By adding 5 wt% of ZDMA, the torques during mixing, tensile strength, and tear stress of TPVs were improved by 150%, 273%, and 217% respectively, compared to the TPVs without ZDMA.Highlights The compatibility between TPU and SR was improved by adding ZDMA. The mechanism for ZDMA enhancing the interface of TPU/SR TPVs was discussed. The addition of ZDMA improves the mechanical properties of TPU/SR TPVs. An appropriate loading of ZDMA used for TPU/SR TPVs was discussed.

Proof-of-Concept Validation of Noninvasive Detection of Cortical Spreading Depolarization with High Resolution Direct Current-Electroencephalography.

Cortical spreading depolarization (SD) is increasingly recognized as a major contributor to secondary brain injury. Monitoring SDs could be used to institute and guide SD-based therapeutics if noninvasive detection methods were available. Our primary objective is to use a high density array of electrodes to compare scalp direct current (DC)-shifts to SDs detected by gold standard electrocorticography (ECoG) to establish proof-of-concept validation that scalp DC-potentials can potentially provide noninvasive SD detection. Our secondary objective is to assess usability and artifact tolerance. An 83×58 mm thermoplastic elastomer array with 29 embedded 6-mm diameter Ag/AgCl 1-mcm spaced electrodes, the CerebroPatch™ Proof-of-Concept Prototype, was adhesively placed on the forehead with an intervening electrode gel interface to record DC-electroencephalography in normal volunteers and severe acute brain injury patients in the neuro-intensive care unit some with and some without invasive subdural ECoG electrodes. The scalp and ECoG voltages were collected by a Moberg® Advanced ICU Amplifier. Artifacts were visually identified and usability issues were recorded. SD was scored on ECoG using standard criteria of DC shift with associated suppression of high frequency activity with propagation across the electrode. A six parameter Gaussian plus quadratic baseline model was used to produce time-course ECoG and scalp electrode channel plots and heat-map movies of scalp voltages. The similarity of the noninvasive scalp and invasive ECoG DC-shift time-courses was compared via the Gaussian fit parameters and confirmed if the Coefficient-of-Determination exceeded 0.80. Usability and artifact issues obscured most scalp Prototype device data except for 38 of the 140 ECoG-coded SDs over a period of 11 days in one sub-arachnoid hemorrhage patient. 26 of these DC-shifts were in readable, artifact free portions of scalp recordings and 24 had an acceptable, >0.80 Coefficient-of-Determination (0.98 [0.02], median [IQR]) between invasive ECoG and noninvasive Prototype device DC-shifts. These data suggest that these scalp DC-shifts (peak -457 ± 69 µV [mean ± StD], full-width-half maximum 70.9 ± 5.92 sec, area 18.7 ± 2.76 cm 2 ) depicted in the heat-map movies represent noninvasively detected SDs. These results suggest that noninvasive SD detection is possible using scalp DC-potential signals with a high spatial resolution EEG array. Efforts to limit artifact and improve usability in DC-EEG detection are needed in order to improve the reliability of this approach and enable multi-modal monitoring for secondary brain injury.

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.

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.

Recyclable Thermoplastic Elastomer from Furan Functionalized Hairy Nanoparticles with Polystyrene Core and Polydimethylsiloxane Hairs.

Polymers synthesized with end-of-life consideration allow for recovery and reprocessing. "Living-anionic polymerization (LAP)" and hydrosilylation reaction were utilized to synthesize hair-end furan functionalized hairy nanoparticles (HNPs) with a hard polystyrene (PS) core and soft polydimethylsiloxane (PDMS) hairs via a one-pot approach. The synthesis was carried out by first preparing the living core through crosslinking styrene with divinylbenzene using sec-butyl lithium, followed by the addition of the hexamethylcyclotrisiloxane (D3) monomer to the living core. The living polymer was terminated by dimethylchlorosilane to obtain the HNPs with Si-H functional end groups. The furan functionalization was carried out by the hydrosilylation reaction between the Si-H of the functionalized HNP and 2-vinyl furan. Additionally, furan functionalized polystyrene (PS) and polydimethylsiloxane (PDMS) were also synthesized by LAP. 1H NMR and ATR-IR spectra confirmed the successful synthesis of the target polymers. Differential scanning calorimetry showed two glass transition temperatures indicative of a polydimethylsiloxane soft phase and a polystyrene hard phase, suggesting that the HNPs are microphase separated. The furan functionalized HNPs form thermo-reversible networks upon crosslinking with bismaleimide (BMI) via a Diels-Alder coupling reaction. The kinetics of the forward Diels-Alder reaction between the functionalized polymer and BMI were studied at three different temperatures: 50 °C, 60 °C, and 70 °C by UV-Vis spectroscopy. The activation energy for the furan functionalized HNPs reaction with the bismaleimide was lower compared to the furan functionalized polystyrene and polydimethylsiloxane linear polymers. The crosslinked polymer network formed from the Diels-Alder forward reaction dissociates at around 140-154 °C, and the HNPs are recovered. The recovered HNPs can be re-crosslinked at 50 °C. The results suggest that furan functionalized HNPs are promising building blocks for preparing thermo-reversible elastomeric networks.

SEGREGATED ELECTRICALLY CONDUCTIVE NANOCOMPOSITES BASED ON THERMOPLASTIC ELASTOMERS AND GRAPHITE

The paper presents the results of a study of the electrical conductive characteristics and a complex of physical-mechanical properties of graphite-based nanocomposites, a wide range of polyolefins - low-density polyethylene, high-density polyethylene, isotactic polypropylene, random copolymer of polypropylene, block copolymer of propylene with ethylene, ethylene/hexene copolymer and ethylene/butene-1 copolymer. For the considered nanocomposites based on polyolefins, the optimal concentrations of graphite were determined, at which the maximum values of electrical conductivity are achieved, within the range of 10–2–10–3 (Ωm)–1. A detailed description of the mechanism of tunneling and electronic electrical conductivity in the nanocomposites under consideration is given. Thermoplastic elastomers (TPE) based on polyolefins and ethylene-propylene-diene rubber have been developed. In a wide concentration range, the regularities of changes in the electrical conductivity of nanocomposites based on thermoplastic elastomers and nanodispersed graphite have been determined. When studying the physical-mechanical properties of TPE nanocomposites, the tensile strength, yield strength, elongation at break, bending strength, Vicat softening temperature, melt flow rate, and Young's modulus were determined. The regularity of the change in the dependence "stress-strain" for TPE depending on the content of ethylene-propylene-diene rubber has been established. Using the methods of derivatography, X-ray phase and SEM analyses, and electron microscopy, studies were carried out to assess the structural features of nanocomposites of thermoplastic elastomers depending on the ratio of the mixture components used. For visual interpretation, a schematic representation of the processes occurring in the interfacial region of thermoplastic elastomers is given. The method of X-ray phase analysis shows the regularity of the change in the degree of crystallinity of thermoplastic elastomers depending on the content of rubber and graphite. The principal possibility of obtaining flexible electrically conductive materials with predetermined properties by controlling the ratio of components in the composition of thermoplastic elastomers is shown. For citation: Kakhramanov N.T., Allahverdiyeva Kh.V., Gahramanli Yu.N., Mustafayeva F.A., Sadikhov N.M., Martynova G.S., Valimatova N.I., Gurbanova R.V. Segregated electrically conductive nanocomposites based on thermoplastic elastomers and graphite. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 11. P. 122-137. DOI: 10.6060/ivkkt.20246711.7045.

Diffusion of organic solvents in thermoplastic elastomers: infinite dilution experiments

Diffusion of organic solvents in thermoplastic elastomers: infinite dilution experiments

Interaction of preservatives with contact materials during filling and storage of parenteral liquid formulations

Silicone tubing is a frequently used material in pharmaceutical filling processes for parenteral formulations, as its characteristics like flexibility, chemical resistance and easy handling make it particularly suitable for these purposes. This study investigated the time-dependent interaction of phenol and m-cresol with silicone tubing and other broadly applied contact materials used during the filling and transport processes of parenteral formulations. Phenol losses could be observed after incubation in silicone tubing, depending on the inner diameter (ID). This has been demonstrated for process interruptions of up to 120 minutes. A loss of 40 % could be observed for a small ID of 3.2 mm which can be found close to filling needles, and up to 12 % for larger tubes with an ID of 9.5 mm commonly used for sterile filtration and transport processes. Analysis of tubes with varying ID revealed a linear relationship between the decrease of phenol and the surface-to-volume ratio. m-cresol showed an even more pronounced loss in silicone tubing. Fluorinated polymers and thermoplastic elastomers were also analyzed, and no loss of phenol and m-cresol was observed. Pumping tests revealed that shear forces in peristaltic pumps led to strong particle formation in selected tubing. A strong increase in particle concentration was observed in thermoplastic elastomers, particularly in PharMed® BPT tubing. In contrast, the C-Flex® tubing demonstrated minimal particle formation. Fluorinated polymers are not compatible with peristaltic pumps, which is why they were not analyzed regarding pumpability. Although silicone tubes are not impervious to preservatives such as phenol, they did not generate particles when pumped.

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.

Padding the seat of a wheelchair reduces ischial pressure and improves sitting comfort.

In this study, we aimed to examine whether a wheelchair cushion placed directly atop a sling seat or deflection of the sling seat compensated by a pad along with the placement of a wheelchair cushion changed sitting pressure. Additionally, we examined whether these additions changed sitting comfort. For twenty healthy adults who consented to participate, measurements were taken for three types of cushions, each with and without padding, under six conditions. The cushion types tested included air (cushion A), urethane foam (cushion U), and three-dimensional thermoplastic elastomer (cushion T). A pressure distribution measurement equipment was used for the measurements. Following the measurement, the comfort of the wheelchair cushion was measured. The ischial area pressure of the cushion A pad was significantly lower than that without the pad. Cushions U and T were for ischial area pressure with a pad, resulting in a decreasing trend in ischial area pressure with a pad compared to that without a pad; however, the difference was insignificant. For all cushions, sitting comfort was significantly better in all groups with padding than in those without. In conclusion, ischial pressure can be dispersed by placing a pad on the seat surface of a wheelchair cushion, and pads were suggested to improve sitting comfort for all cushions.