Thermoplastic Polyurethane Elastomers Research Articles

Regulating the structure of thermoplastic polyurethane elastomers with a diol chain extender to strength performance

AbstractThe structural defects of thermoplastic polyurethane elastomer (TPU) caused by the uneven distribution of hard segments limiting their potential application in special industrial fields such as aerospace or defense equipment. Optimizing the TPUs' structure is a useful method to adjustable uneven distribution of hard segments and enhance the performance of TPUs. In this work, a chain extender (BMB) embedded in carbamate‐derive units was successfully synthesized by 4,4′‐diphenylmethane diisocyanate (MDI) and 1,4‐butanediol (BDO). Using BMB and as chain extender, a modified BMB‐TPU was prepared, and its properties were systematically evaluated. Compared with conventional thermoplastic polyurethane elastomer (BDO‐TPU), BMB‐TPU had a regular structure with uniform hard segments, narrower molecular weight distribution and stronger intra/inter‐chain hydrogen bonding interactions, and thus better microphase separation. The BMB‐TPU exhibited an excellent tensile strength of 35 MPa, 46% higher than 24 MPa for the control BDO‐TPU. Moreover, the heat resistance of BMB‐TPU was also reinforced compared to BDO‐TPU, with an increase of 7.2°C for the degradation temperature of 5% loss and 9.6°C for the viscous flow transition temperature. We believe our paradigm can provide a feasible guide for designing high‐performance TPUs.

A highly sensitive and wide-range pressure sensor based on orientated and strengthened TPU nanofiber membranes fabricated by a conjugated electrospinning technology

Flexible capacitive pressure sensors as one of the crucial sensing components have aroused widespread concern because of their vital role in development of wearable artificial devices, healthcare biomonitoring and human-machine interface. However, there has been a considerable challenge to successfully fabricate them with a tradeoff between high sensitivity and wide sensing range by low-cost and convenient manufacturing methods. Herein, the orientated thermoplastic polyurethane elastomer rubber nanofiber membranes (TPU-O NMs) were prepared via conjugated electrospinning to build a dielectric layer for the flexible capacitive wide-range pressure sensors with high sensitivity. In addition, polyaniline (PANI) was in situ polymerized on the TPU-O NMs as flexible electrodes to maintain the conductive pathway, flexibility, and breathability of the sensors. The TPU@PANI NMs form a bamboo-raft-like microstructure between the aligned fibers under pressure, resulting in a significant increase in sensitivity and working range. Furthermore, the conductive TPU@PANI NMs can be stretched to 1600% without fracture. The assembled sensor has a high sensitivity of 31.73 kPa−1 and a fast response/recovery time of 96 ms. Meantime, it also exhibits a minimum detection limit of 1 Pa, an excellent stability of 10,000 cycles, and a good linearity in a broad working age (1 Pa∼122.5 kPa). Finally, the capacitive pressure sensor was successfully applied for full-range detection of human motions, such as finger bending, joint bending, and even boxing movements. Hence this highly sensitive and wide-range pressure sensor can be a promising candidate for healthcare monitoring, motion recognition, and wearable circuitry in artificial intelligence.

The Influence of Diisocyanate Structure on Thermal Stability of Thermoplastic Polyurethane Elastomers Based on Diphenylmethane-Derivative Chain Extender with Sulfur Atoms.

The work is a continuation of the research on thermoplastic polyurethane (TPU) elastomers containing sulfur atoms which are incorporated into the polyurethane chain using aliphatic-aromatic chain extenders. These materials show some improved properties in relation to conventional ones, e.g., adhesion to metals, bacterial resistance and refractive index. The present study deals with the detailed characteristics of the process of thermal decomposition of TPU elastomers obtained from 2,2'-[methylenebis(1,4-phenylenemethylenethio)]diethanol, 1,1'-methanediylbis(4-isocyanatobenzene) (MDI) or 1,6-diisocyanatohexane (HDI) and poly(oxytetramethylene) diol of Mn = 2000 g/mol by thermogravimetric analysis coupled on-line with Fourier transform infrared spectroscopy. The analysis was performed under inert and oxidative conditions. All TPU elastomers were found to have a relatively good thermal stability, with those based on aromatic diisocyanate being at an advantage. In helium, they are stable up to 280-282 °C (from HDI) and 299-301 °C (from MDI), whereas in synthetic air up to 252-265 °C (from HDI) and 261-272 °C (from MDI), as measured by the temperature of 1% mass loss. Depending on the content of the hard segments and the tested atmosphere, the TPU elastomers decompose from one to four stages. From the analysis of the volatile decomposition products, it follows that the decomposition of both types of hard segments was accompanied by the evolution of carbonyl sulfide, carbon dioxide, water, sulfide dioxide, alcohols and aromatic compounds. For the hard segment derived from HDI, isocyanates, amines, and unsaturated compounds were also identified, while for the MDI-derived one, aldehydes were discovered. In turn, the polyether soft segment decomposed mainly into aliphatic ethers, aldehydes, and carbon monoxide.

3D hydrangea-like Ti3C2Tx MXene@FeNi layered double hydroxide derived to efficiently inhibit the fire hazard of thermoplastic polyurethane

The broader application of thermoplastic polyurethane elastomer (TPU) as encapsulation materials is severely restricted by their serious tensile strength and appreciable fire hazard. Hence, 3D hydrangea-like Ti3C2Tx MXene@FeNi layered double hydroxides (M@LDH) are prepared through in situ growth, and incorporated into the TPU. Excitedly, compared to neat TPU, upon adding 3 wt% M@LDH, the obtained M@LDH-3 was capable of achieving a 38.3% and 67.0% decrease in the peak heat release rate (pHRR) and total smoke release (TSR), respectively, exhibiting peerless flame-retardant effects under low addition. In addition, the elongation at break of TPU/M@LDH-3 increased to 637.28% and its tensile strength increased to 42.97 MPa, revealing excellent mechanical properties. The mechanisms for the fire safety and mechanical performance were both studied deeply, expecting this work to illuminate the approach of designing efficient nanomaterials and promote the development of advanced TPU in high-end fields.

Study and Characterization of Regenerated Hard Foam Prepared by Polyol Hydrolysis of Waste Polyurethane.

In this paper, four different kinds of diols were used for the alcoholysis of waste thermoplastic polyurethane elastomers. The recycled polyether polyols were used to prepare regenerated thermosetting polyurethane rigid foam through one-step foaming. We used four different kinds of alcoholysis agents, according to different proportions of the complex, and we combined them with an alkali metal catalyst (KOH) to trigger the catalytic cleavage of the carbamate bonds in the waste polyurethane elastomers. The effects of the different types and different chain lengths of the alcoholysis agents on the degradation of the waste polyurethane elastomers and the preparation of regenerated polyurethane rigid foam were studied. Based on the viscosity, GPC, FT-IR, foaming time and compression strength, water absorption, TG, apparent density, and thermal conductivity of the recycled polyurethane foam, eight groups of optimal components were selected and discussed. The results showed that the viscosity of the recovered biodegradable materials was between 485 and 1200 mPa·s. The hard foam of the regenerated polyurethane was prepared using biodegradable materials instead of commercially available polyether polyols, and its compressive strength was between 0.131 and 0.176 MPa. The water absorption rate ranged from 0.7265 to 1.9923%. The apparent density of the foam was between 0.0303 and 0.0403 kg/m3. The thermal conductivity ranged from 0.0151 to 0.0202 W/(m·K). A large number of experimental results showed that the degradation of the waste polyurethane elastomers by the alcoholysis agents was successful. The thermoplastic polyurethane elastomers can not only be reconstructed, but they can also be degraded by alcoholysis to produce regenerated polyurethane rigid foam.

Flexible Strain Sensor Enabled by Carbon Nanotubes‐Decorated Electrospun TPU Membrane for Human Motion Monitoring

AbstractHigh‐performance flexible strain sensors are gaining more and more attention with their bespoken detection range, excellent sensing performance, and good stability, which are highly desired in wearable electronics. Herein, a thermoplastic polyurethane elastomer (TPU) fibrous membrane is prepared as a flexible substrate by electrostatic spinning technology, then a coating of polydopamine is formed through fast synthesizing the dopamine on TPU fibrous membrane surface and loaded with carbon nanotubes (CNTs) to develop an extremely sensitive flexible strain sensor. The flexible sensor prepared by TPU fibrous membrane coated with polydopamine layer has an outstanding sensibility under the pulling force (Gauge Factor of 10 528.53 with 200% strain), rapid reaction time (188–221 ms), wide sensing range (up to 200%), good stability, and durability. The theoretical studies reveal the underlying cause for the high sensitivity and the inherent relationship between the amount of conducting routes and the length between adjacent conducting fillers in the sensor. The demonstration of the device shows a promising application to sense human motion at various locations of the body, with the accurate and stable electrical signal output generated at corresponding motion.

Investigation into the effects of foaming variables on the cellular structure and expansion ratio of foamed TPU using response surface methodology

Thermoplastic polyurethane elastomer (TPU) foams were prepared using the high-pressure autoclave with supercritical fluid carbon dioxide (SC-CO2). The effects of foaming variables (i.e. saturation temperature, saturation pressure, and depressurization rate) on cellular structure and expansion ratio were investigated. The model between expansion ratio and foaming variables was constructed using the Box-Behnken design (BBD) of response surface methodology (RSM), and analysis of variance (ANOVA) was conducted to evaluate the validity and significance of the model. Finally, the interactive effects of foaming variables on the expansion ratio were investigated, and the expansion ratios of maximum and center point from numerical model were verified by experiment. The result showed higher saturation pressure and depressurization rate resulted in the more uniform cellular structure and higher cell density, however the higher saturation temperature resulted in the bigger cell and nonuniform structure. The ranges of average cell diameter and cell density were 15.26–45.4 μm and 0.32 × 108 to 6.24 × 108 cells/cm3, respectively. The model obtained using BBD of RSM was valid to predict the expansion ratio in the design window. The saturation temperature was the most important factor influencing the expansion ratio. With the increase of saturation temperature, the expansion ratio always increases in the design window. The maximum expansion ratio from numerical optimization was 4.91, which was located at saturation temperature 190°C, saturation pressure 12.51 MPa, and depressurization rate 5 MPa/s, and the corresponding experiment value was 4.56. The error between them was 7.13%.

Sustainable Strategy for Algae Biomass Waste Management via Development of Novel Bio-Based Thermoplastic Polyurethane Elastomers Composites.

This work concerns the waste management method of algae biomass wastes (ABW). For this purpose, we prepared bio-based thermoplastic polyurethane elastomer (bio-TPU) composites. Algae biomass wastes are derived from algal oil extraction of Chlorella vulgaris and from biomass of Enteromorpha and Zostera marina. ABWs were used in the bio-TPUs composites as a filler in the quantity of 1, 5, 10, and 15 wt.%. The bio-based composites were prepared via the in situ method. Polymer matrix was synthesized from a bio-based polyester polyol, diisocyanate mixture (composed of partially bio-based and synthetic diisocyanates), and bio-based 1,3 propanediol. In this study, the chemical structure, morphology, thermal and mechanical properties of prepared composites were investigated. Based on the conducted research, it was determined that the type and the content of algae waste influence the properties of the bio-based polyurethane matrix. In general, the addition of algae biomass wastes led to obtain materials characterized by good mechanical properties and noticeable positive ecological impact by increasing the total amount of green components in prepared bio-TPU-based composites from 68.7% to 73.54%.

SO2-based thermoplastic polyurethane elastomer: synthesis, microstructure, and mechanical properties

A novel thermoplastic polyurethane elastomer is constructed from SO2-derived polysulfite. Systemic investigations, including the synthetic methodology, characterization, modification of structures, were conducted to obtain optimized polyurethane.

Synthesis and characterization of low surface energy thermoplastic polyurethane elastomers based on polydimethylsiloxane

Organosilicon modified polyurethane elastomers (Si-MTPUs) were synthesized in order to improve the anti-graffiti property of thermoplastic polyurethane elastomers (TPUs). Si-MTPUs were prepared from polydimethylsiloxane (PDMS) and polytetramethylene glycol (PTMG) as mixed soft segment, 1,4-butanediol (BDO) and imidazole salt ionic liquid N-glyceryl-N-methyl imidazolium chloride ([MIMl,g]Cl) used as chain extender, and 4,4'-dicyclohexylmethane diisocyanate (HMDI). The structure, thermal stability, mechanical properties and physical crosslinking density of Si-MTPUs were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA), mechanical test and low field nuclear magnetic resonance. Surface energy and water absorption were characterized by static contact angle test and water resistance test, and anti-graffiti and self-cleaning properties were characterized with water, milk, ink, lipstick, oily markers and spray paint. It was found that the mechanical properties of Si-MTPU-10 with the content of PDMS 10 wt% were optimized, with a maximum tensile strength of 32.3 MPa and elongation at break of 656%. Surface energy reached the minimum value of 23.1 mN m-1 with the best anti-graffiti performance, which no longer decreased with the increase of PDMS contents. This work provides novel idea and strategy for the preparation of low surface energy TPUs.

Boosting fire safety and mechanical performance of thermoplastic polyurethane by the face-to-face two-dimensional phosphorene/MXene architecture

• A black phosphorus-MXene@polydopamine nanohybrid was synthesized. • The TPU/BP-MXene@PDA nanocomposite simultaneously showed reinforcing and toughening effects towards TPU. • The TPU/BP-MXene@PDA nanocomposite could be achieved excellent thermal stability, mechanical properties and flame retardancy. • A synergistic flame-retardant mechanism between black phosphorus and MXene in the TPU were discussed and clarified. Black phosphorus (BP), as one of the most promising fillers for flame retarding polymer, has been seriously limited in practical application, due to the agglomeration and poor structural stability challenges. Here, the BP was modified by MXene and polydopamine (PDA) via ultrasonication and dopamine modification strategy to improve the structural stability and dispersibility in the matrix. Then, the obtained (BP-MXene@PDA) nanohybrid was employed to promote the mechanical performance, thermal stability, and flame retardancy of thermoplastic polyurethane elastomer (TPU). The resultant TPU composite containing 2 wt.% of BP1-MXene2@PDA showed a 19.2% improvement in the tensile strength and a 13.8% increase in the elongation at break compared to those of the pure TPU. The thermogravimetric analysis suggested that BP-MXene@PDA clearly enhances the thermal stability of TPU composites. Furthermore, the introduction of the BP-MXene@PDA nanohybrids could considerably improve the flame retardancy of TPU composite, i.e., 64.2% and 27.3% decrease in peak heat release rate and total heat release, respectively. The flame-retardant mechanisms of TPU/BP-MXene@PDA in the gas phase and condensed phase were investigated systematically. This work provides a novel strategy to simultaneously enhance the fire safety and mechanical properties of TPU, thus expanding its industrial applications.

The preparation of phosphorus and nitrogen-containing structure towards the enhancement of flame retardancy for thermoplastic polyurethane elastomer

Thermoplastic polyurethane elastomer (TPU) is an easily flammable materials with serious droplets and smoke toxicity, which critically restrict its practical application. In order to improve the flame retardancy of TPU, the present work designed a halogen free flame retardant (AL-APP) containing phosphorus and nitrogen elements via the modification of ammonium polyphosphate (APP) with sodium alendronate (Al). It was found that the limiting oxygen index of TPU/AL-APP5 composites increased from 20.7 % to 26.5 % and got past the V-0 rating without any droplets in the UL-94 vertical measurement. Meanwhile, the peak heat release rate (PHRR) and total heat release (THR) of TPU/AL-APP5 system reduced from 1021 to 255 kW/m2 and 87.5–61.2 MJ/m2 in cone calorimeter (CC) measurement when comparing to that of purchased TPU. According the thermogravimetric-infrared and Raman spectroscopy results, the production of the inert gas and formation of continuous carbon layer of AL-APP mutually improved the fire safety of TPU composites. Furthermore, the elongation at break of TPU/AL-APP5 was significantly increased by 19.9 % than that of neat TPU, showing a better softness and elasticity than neat TPU. According the above results, it was concluded that this work advancing in the high flame-retarding efficient and good mechanical property for TPU composites via a simple method.

Soft Gripper with Electro-Thermally Driven Artificial Fingers Made of Tri-layer Polymers and a Dry Adhesive Surface.

Soft grippers have attracted great interest in the soft robotics research field. Due to their lack of deformability and control over compliance, it can be challenging for them to pick up objects that are too large or too small in size. In particular, compliant objects are vulnerable to the large grasping force. Therefore, it is crucial to be able to adjust the stiffness of the gripper materials. In this study, a soft gripper consisting of three artificial fingers is reported on. Each of the artificial fingers is made of a tri-layer polymer structure. An exterior layer, made of an ecoflex-graphene composite is embedded with electric wires as a heating source, by applying direct-current potential. The Joule heat not only allows for deformation of the exterior layer, but also transfers heat to the middle layer of the thermoplastic polyurethane (TPU) elastomer. As a result, the stiffness of the TPU layer can be adjusted using electro-thermal heating. Meanwhile, the third layer consists of a polydimethylsiloxane replica as a supporting layer with a gecko-inspired dry adhesive structure. By applying voltage through electric wires, the artificial fingers can bend and, thus, the soft gripper can hold the objects, with the help of the dry adhesive layer. Finally, objects like a shuttlecock, tennis ball and a glass beaker, can be picked up by the soft gripper. This research may provide an insight for the design and fabrication of soft robotic manipulators.

One-step electrodeposition to fabricate robust superhydrophobic silver/graphene coatings with excellent stability

A facile method was proposed to prepare stretchable silver-based composite coatings with excellent conductivity and stability for flexible electronics. Silver coating was firstly deposited on thermoplastic polyurethane (TPU) elastomer rubber surface via two-component spraying technique, then the superhydrophobic surface was obtained by one-step electrodeposition of cerium compounds (CeM) and graphene nanosheets (GNS) to produce Ag/CeM/GNS composite coatings. The obtained Ag/CeM/GNS composite coatings maintained high conductivity after experiencing bending cycles and stretching cycles. Furthermore, the as-prepared Ag/CeM/GNS composite coatings showed excellent self-cleaning and anti-fouling properties, and the corrosion resistance has improved significantly compared to the original Ag coating. In addition, the Ag/CeM/GNS composite coatings could drive the circuit normally in the states of tensile, bending and twisting deformation, showing excellent mechanical stability and applicability. As a result, it is believed that the prepared Ag/CeM/GNS composite coatings with excellent conductivity and stability have promising applications for flexible electronics in harsh conditions.

Synthesis and properties of biobased non-isocyanate aliphatic thermoplastic polyurethane elastomers with butanediurethane hard segments

A simple non-isocyanate route is established to synthesize biobased aliphatic thermoplastic polyurethane elastomers (TPEUs) with excellent mechanical properties. Melt transurethane co-polycondensation of bis(hydroxyethyl) butanediurethane (BHBDU) with different polycaprolactone-diols (PCDLs) was conducted at 170°C under a reduced pressure of 3 mmHg, and a series of TPEUs were prepared. The TPEUs were characterized by gel permeation chromatography, FT-IR, 1H-NMR, wide angle X-ray scattering, DSC, TGA, dynamic mechanical analysis, atomic force microscopy, and tensile test. TPUEs exhibited Mn above 25,000 g/mol, Tg of −36 to 1°C, Tm up to 105°C, maximal tensile strength of 38 MPa with a strain at break of 926%, and resilience of 80%–90%. BHBDU and PCDLs may be synthesized from bioresources. Biobased aliphatic TPU elastomers with excellent tensile strength and resilience were prepared successfully through a non-isocyanate route.

Isocyanate-free, thermoplastic polyhydroxyurethane elastomers designed for cold temperatures: Influence of PDMS soft-segment chain length and hard-segment content

Polydimethylsiloxane (PDMS)-based, segmented polyhydroxyurethanes (PHUs) was synthesized from Bisphenol A (BPA) dicarbonate and diamine-terminated PDMS. Two PDMS samples were employed with 875 g/mol and 2500 g/mol number-average molecular weight (Mn) values. Due to the inherent hydrophobic nature of PDMS, the PDMS-based PHUs exhibit excellent surface hydrophobicity with a water contact angle >100°. Because of the strong thermodynamic incompatibility of PDMS with BPA-based hard segments, hard-segment content and soft-segment Mn are critical in ensuring macroscopic homogeneity and effective nanophase separation leading to thermoplastic elastomer (TPE) character extending from room temperature to temperatures as low as −100 °C. Nanophase separation was confirmed via small-angle X-ray scattering and dynamic mechanical analysis. With 20–25 wt% hard-segment content, the TPEs derived from 2500 g/mol PDMS exhibit quasi-rubbery plateau regions with tensile storage modulus in the range of 1–10 MPa and the absence of a yield point in tensile tests with strain at break values that can exceed 1000%. With 40–50 wt% hard-segment content, the TPEs derived from 875 g/mol PDMS exhibit quasi-rubbery plateau regions with tensile storage modulus in the range of 100–1000 MPa but yield points in tensile tests at 25–40% strain. This work presents a pathway to achieving hydrophobic, non-isocyanate thermoplastic polyurethane elastomers with highly tunable rubbery moduli that extend to extraordinarily low temperatures.

Evaluation and mechanism of interaction effect between thermoplastic polyurethane elastomer modified asphalt and fillers

AbstractThermoplastic polyurethane (TPU) elastomer modified asphalt mastic is regarded as a two‐phase composite composed of TPU modified asphalt and filler according to the micro‐mechanics theory of composites, and its rheological properties are affected by various types of asphalt, mineral filler, and dosage. In this study, different kinds of fillers (limestone, granite, fly‐ash, coal gangue) and TPU modified asphalt (grade of base asphalt labeled as 90# and polyether‐based TPU modified asphalt with Ch = 40, r = 1.05 through a self‐determined laboratory process) were prepared into asphalt mastic. The dynamic shear rheology and bending beam rheology (BBR) were used to test and evaluate the high and low temperature rheological properties of TPU modified asphalt mastic with different kinds of fillers. The scanning electron microscopy, atomic force microscopy, Brunauer, Emmett, and Teller method, X‐ray diffraction, Fourier transform infrared spectroscopy, and other tests were used to analyze the interaction mechanism between fillers and TPU modified asphalt. The results indicated that the enhancement coefficients and of different fillers are obtained based on the |G*| and S master curve, and the optimum ratio range in TPU modified asphalt with different kinds of fillers are from 1.04 to 1.41. The interaction parameters Luis Ibrarra‐A (A‐values) and Palierne‐C (C‐values) were obviously better than K. Ziegel‐B (B‐values) and Complex shear modulus coefficient (‐values). The surface of coal gangue was rough and emerged micro‐void, the BET specific surface area reached 2.681 m2/g, which was the largest than the other fillers, and the interaction with TPU modified asphalt was the strongest due to the C‐value is 1.562. The chemical composition of coal gangue played an important role in the interaction with asphalt. Physical adsorption is the main mechanism between TPU modified asphalt and fillers. The absorption peak of the original TPU modified asphalt disappeared at 3343 cm−1, and more CaO and Al2O3 in coal gangue are helpful to improve the interaction ability with TPU modified asphalt. There is a significant correlation between the number and area ratio of “bee‐like structure” in TPU modified asphalt mastic and interaction coefficient C‐values.

Highly Stretchable Fatty Acid Chain-Dangled Thermoplastic Polyurethane Elastomers Enabled by H-Bonds and Molecular Chain Entanglements

Thermoplastic polyurethane (TPU) elastomers are widely used in daily products owing to their flexible structures and decent mechanical properties. Vegetable oils (VOs) are promising renewable resources for polymer synthesis with readily availability and abundant derivatives. However, most VO-based polyurethanes are usually thermosets with an unsatisfactory material performance because the C═C bonds are randomly located on triglyceride long chains. Herein, a biobased TPU elastomer was facilely synthesized from palm oil (PO) with desirable and tunable mechanical properties. PO-based diol was synthesized from PO via amidation with 2-(2-hydroxyethylamino)ethanol. The resulting PO diethanolamide (POEA), combined with biobased butane-1,4-diol, was further reacted with 1,6-diisocyanatohexane to prepare PO-based TPU elastomers. The elastomers containing abundant H-bonds from carbamates in the backbone and dangling fatty acid side chains exhibited a microphase separation structure, endowing the elastomers with superior stretchability (up to a strain of 831%), restorability, and self-healing ability. The morphological, melting, crystallization, and rheological behaviors of the elastomers were fully studied. The dynamic and reversible three-dimensional cross-linked network consisting of van der Waals forces and H-bonds was investigated to reveal the formation mechanism of the elastomers.

Encapsulations of Magnetorheological Fluids Within 3-D Printed Elastomeric Cellular Structures

In this study, magnetorheological fluid (MRF) was successfully encapsulated in a 3-D printed elastomeric cellular structure. To this end, an MRF, which was composed of (40% volume fraction) carbonyl iron particles (6– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~\mu \text{m}$ </tex-math></inline-formula> in diameter) suspended in silicone oil, was encapsulated in a thermoplastic polyurethane (TPU) elastomeric cellular structure. A 3-D printer was used to print a TPU elastomer with a rectangular cellular structure in the shape of a circular cylinder. The MRF was injected into the rectangular voids within the TPU cellular structure (hereinafter MRF-TPU elastomeric composite), and then sealed into the composite by 3-D printing a capping or sealing layer on top. The mechanical stiffness and damping properties of the MRF-TPU elastomeric composite with respect to external magnetic fields (0, 2, and 7 kG) and excitation frequencies (1, 5, and 10 Hz) were measured via uniaxial dynamic mechanical testing. Also, the effects of excitation and prestrain amplitude on the mechanical properties of the MRF-TPU elastomeric composite were investigated in these experiments. The complex stiffness and dissipated energy measured via dynamic mechanical testing were used as the performance index.

Facile Preparation of Novel Carbon Microspheres for Improvement in Flame Retardancy, Smoke Suppression and Toxicity Reduction of Thermoplastic Polyurethane Elastomer

Facile Preparation of Novel Carbon Microspheres for Improvement in Flame Retardancy, Smoke Suppression and Toxicity Reduction of Thermoplastic Polyurethane Elastomer