Thermoplastic Elastomer Material Research Articles

Thermoplastic Elastomers Derived from Menthide and Tulipalin A

Renewable ABA triblock copolymers were prepared by sequential polymerization of the plant-based monomers menthide and α-methylene-γ-butyrolactone (MBL or tulipalin A). Ring-opening transesterification polymerization of menthide using diethylene glycol as an initiator gave α,ω-dihydroxy poly(menthide) (HO-PM-OH), which was converted to α,ω-dibromo end-functionalized poly(menthide) (Br-PM-Br) by esterification with excess 2-bromoisobutyryl bromide. The resulting 100 kg mol(-1) Br-PM-Br macroinitiator was used for the atom transfer radical polymerization of MBL. Four poly(α-methylene-γ-butyrolactone)-b-poly(menthide)-b-poly(α-methylene-γ-butyrolactone) (PMBL-PM-PMBL) triblock copolymers were prepared containing 6-20 wt % PMBL, as determined by NMR spectroscopy. Small-angle X-ray scattering, differential scanning calorimetry, and atomic force microscopy experiments supported microphase separation in the four samples. The mechanical behavior of the triblocks was investigated by tensile and elastic recovery experiments. The tensile properties at both ambient and elevated temperature show that these materials are useful candidates for high-performance and renewable thermoplastic elastomer materials.

Superhydrophobic elastomer surfaces with nanostructured micronails

New approaches to the fabrication of microstructures of special shape were developed for polymers. Unusual superhydrophobic surface structures were achieved with the use of flexible polymers and hierarchical molds. Flexible polyurethane−acrylate coatings were patterned with microstructures with use of microstructured aluminum mold in a controlled UV-curing process. Electron microscope images of the UV-cured coatings on polymethylmethacrylate (PMMA) substrates revealed micropillars that were significantly higher than the corresponding depressions of the mold (even 47 vs. 35 μm). The elongation was achieved by detaching the mold from the flexible, partially cured acrylate surface and then further curing the separated microstructure. The modified acrylate surface is superhydrophobic with a water contact angle of 156° and sliding angle of < 10°. Acrylic thermoplastic elastomers (TPE) were patterned with micro−nanostructured aluminum oxide molds through injection molding. The hierarchical surface of the elastomer showed elongated micropillars (57 μm) with nail-head tops covered with nanograss. Comparison with a reference microstructure of the same material (35 μm) indicated that the nanopores of the micro−nanomold assisted the formation of the nail-shaped micropillars. The elasticity of the TPE materials evidently plays a role in the elongation because similar elongation has not been found in hierarchically structured thermoplastic surfaces. The hierarchical micronail structure supports a high water contact angle (164°), representing an increase of 88° relative to the smooth TPE surface. The sliding angle was close to zero degrees, indicating the Cassie–Baxter state.

Thermal resistance and dynamic damping properties of poly (styrene–butadiene–styrene)/thermoplastic polyurethane composites elastomer material

We present the preparation of novel thermoplastic composites elastomer material based on poly (styrene–butadiene–styrene) (SBS), ester-type polyurethane (TPU-EX) and ether-type polyurethane (TPU-ER) materials via melt blending. A series of studies were conducted on the relationship between their morphology, thermal resistance, mechanical properties, and dynamic damping properties, given different compositions. An important feature of the SBS/TPU composites elastomer materials of all compositions is their uniform transparency, because the particles are very small with a narrow size distribution and the refractive indices of SBS and TPU are coincide. Additionally, the thermal resistance, dynamic damping properties and mechanical properties of SBS before and after thermal aging are improved as the amount of added TPU is increased, suggesting that blending SBS with TPU is consistent with the compound rule. In addition, the SBS/TPU composites elastomer materials have better dynamic damping properties at high frequency.

Characterization of the Fracture and Fatigue Behavior of Thermoplastic Elastomer Materials

Thermoplastic elastomers are a relatively new group of engineering materials and are increasingly used in various technical applications (i.e., seals, gaskets, damping elements, and membranes) where the fatigue resistance plays an important role. The fracture behavior of elastomers is often characterized using the tearing energy concept, T. However, hardly any data are available for these types of materials. Hence, an unfilled and a filled thermoplastic polyurethane (TPU) type were investigated under cyclic loading conditions. The pure shear specimen configuration was used in the experimental part of this study. Crack growth kinetics curves were determined and the cycle number and the tests frequency dependence of these curves investigated. While a stable crack growth process was observed at 2 Hz the crack growth became unstable above specific test amplitude at 10 Hz.

Reactive Compatibilization of Recycled Polyethylenes and Scrap Rubber in Thermoplastic Elastomers: Chemical and Radiation-Chemical Approach

Abstract Reactive compatibilization of recycled low- or high-density polyethylenes (LDPE and HDPE, respectively) and ground tire rubber (GTR) via chemical interactions of pre-functionalized components in their blend interface has been carried out. Polyethylene component was functionalized with maleic anhydride (MAH); as well, the rubber component was modified via functionalization with MAH or acrylamide (AAm) using chemically or irradiation (γ-rays) induced grafting techniques. The grafting degree and molecular mass distribution of the functionalized polymers have been measured via FTIR and Size Exclusion Chromatography (SEC) analyses, respectively. Additional coupling agents such as p-phenylene diamine (PDA) and polyamide fiber were used for producing some thermoplastic elastomer (TPE). Thermoplastic elastomer materials based on synthesized reactive polyethylenes and GTR as well as ethylene-propylenediene monomer rubber (EPDM) were prepared by dynamic vulcanization of the rubber phase inside thermoplastic (polyethylene) matrix and their phase structure, and main properties have been studied using DSC, DMTA and mechanical testing. As a result, high performance thermoplastic elastomers based on functionalized polyethylene and ground rubber with improved mechanical properties have been developed.

Study on heat transfer of liquid cooling garment based on a novel thermal manikin

PurposeThe purpose of this paper is to explore the heat transfer and establish a heat transfer model of an extravehicular liquid cooling garment based on a thermal manikin covered with soft simulated skin.Design/methodology/approachThe thermal manikin applied in this study was a copper manikin, typical of which was its soft simulated skin – a newly thermoplastic elastomer material. Based on this novel thermal manikin, the heat transfer analysis of an extravehicular liquid cooling garment was performed. To satisfy the practical engineering application and simplify analysis, the hypotheses were proposed, and then the heat transfer model was established by heat transfer theory, in which the heat exchange equation of the liquid cooling garment with the thermal manikin and with the air layer, and the garment's total heat dissipating capacity were derived.FindingsThe verification experiments performed in a climatic chamber by a thermal manikin wearing a liquid cooling garment at different surface temperatures of the thermal manikin show that the modeling value fits well with the experimental value, and the heat transfer model of the liquid cooling garment has a high accuracy. Meanwhile, the relationship between the heat‐dissipating capacity of the liquid cooling garment and its design parameters – inlet temperature and liquid velocity – is suggested as being based on the heat transfer model.Originality/valueThe paper shows that it is an effective method to control the heat‐dissipating capacity of a liquid cooling garment by changing the inlet temperature to some degree, but not by changing the liquid velocity.

Dynamic properties of rubber vibration isolators and antivibration performance of ethylene–propylene–diene monomer/nylon 6 blend systems

AbstractThis article examines thermoplastic elastomers (TPEs) and thermoplastic vulcanizates (TPVs) as two types of elastomers from melt‐blended and dynamically vulcanized ethylene–propylene–diene monomer (EPDM) rubber materials and nylon 6 plastic materials. A series of investigations were conducted on the mechanical properties, morphology, dynamic mechanical properties, hysteresis behavior, and dynamic antivibration properties with different nylon 6 contents. The experimental results showed that the incompatibility between EPDM and nylon 6 led to the easy destruction of the TPV materials in two interfacial polymers upon the application of an external force. Thus, after a dynamic vulcanization process, the mechanical properties of the EPDM/nylon 6 blends were not as good as those of the TPE materials. In terms of morphology, nylon 6 plastics were uniformly distributed in the EPDM/nylon 6 blends during the EPDM rubber phase before vulcanization was performed. After the dynamic vulcanization, phase inversion was produced in which rubber microparticles were formed and dispersed in the nylon 6 plastic phase. The results of dynamic mechanical analysis, compression vibration hysteresis behavior, and dynamic property antivibration experiments showed that the blends provided better vibration isolation and antivibration performance after the amount of nylon 6 was increased and EPDM and nylon 6 were blended through dynamic vulcanization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008

Reactive Compatibilization of Polyethylene/Ground Tire Rubber Inhomogeneous Blends via Interactions of Pre‐Functionalized Polymers in Interface

AbstractSummary: Reactive compatibilization of recycled low‐ or high‐density polyethylenes (LDPE and HDPE, respectively) and ground tire rubber (GTR) via chemical interactions of pre‐functionalized components in their blend interface has been carried out. Polyethylene component was functionalized with maleic anhydride (MAH) as well as the rubber component was modified via functionalization with MAH or acrylamide (AAm) using chemically or irradiation (γ‐rays) induced grafting techniques. The grafting degree and molecular mass distribution of the functionalized polymers have been measured via FTIR and Size Exclusion Chromatography (SEC) analyses, respectively. Thermoplastic elastomer (TPE) materials based on synthesized reactive polyethylenes and GTR as well as ethylene‐propylene‐diene rubber, EPDM were prepared by dynamic vulcanization of the rubber phase inside thermoplastic (polyethylene) matrix and their phase structure, and main properties have been studied using DSC and mechanical testing. As a final result, the high performance TPE with improved mechanical properties have been developed.

Dynamically Vulcanized EPDM/PP (40/60) Blends

Dynamically vulcanized thermoplastic elastomer (TPE) blends were first described by Fisher. In the 1960s, the usage of TPE was low. However, the consumption of TPE is increasing today. Due to hard and soft polymer phases in its structure, TPE replaced a lot of materials. TPE materials are preferred today due to their good thermal properties, oxidation resistance, transparency, adhesion, compatibility with other polymers etc. As a result of the studies that were done in 1975, TPV—vulcanized thermoplastic elastomers were developed. In this study, TPV elastomers were produced by forming crosslinks with peroxide from different ratios, of EPDM and PP. Mixing was done with twin screw extruder. After that yield and tensile strength, the modulus of elasticity, % elongation, Izod impact strength, hardness, Melt Flow Index (MFI), Vicat Softening Point, Heat Deflection Temperature (HDT), and density of crosslinks were determined. Thermal transition temperatures and microstructure were determined with DSC and SEM, respectively.

DAMPING BEHAVIOR OF THE PHENOLIC BASED COMPOSITE FRICTION MATERIALS CONTAINING THERMOPLASTIC ELASTOMERS (TPES)

Attempts have been made for the first time to produce a friction material with thermal sensitive modulus by the inclusion of combined plastic/rubber properties of thermoplastic elastomers (TPE) as viscoelastic polymeric materials into the formulation for the purpose of increasing the damping behavior. In order to evaluate the viscoelastic parameters such as loss factor (tan δ) and elastic modulus (E') for the friction material, dynamic mechanical analyzer (DMA) was used. Styrene-butadiene-styrene (SBS), styrene-ethylene-butylene-styrene (SEBS) and nitrile rubber/polyvinyl chloride (NBR/PVC) blend systems were used as TPE materials. However, NBR/PVC and SEBS were found to be more effective in damping behavior. All the friction materials containing TPEs exhibited more damping behavior at a wide range of temperature compared with the reference sample.

Reduction of Noise from Disc Brake Systems Using Composite Friction Materials Containing Thermoplastic Elastomers (TPEs)

Attempts have been made for the first time to prepare a friction material with the characteristic of thermal sensitive modulus, by the inclusion of thermoplastic elastomers (TPE) as viscoelastic polymeric materials into the formulation in order to the increase the damping behavior of the cured friction material. Styrene–butadiene–styrene (SBS), styrene–ethylene–butylene–styrene (SEBS) and nitrile rubber/polyvinyl chloride (NBR/PVC) blend system were used as TPE materials. In order to evaluate the viscoelastic parameters such as loss factor (tan δ) and storage modulus (E′) for the friction material, dynamic mechanical analyzer (DMA) were used. Natural frequencies and mode shapes of friction material and brake disc were determined by modal analysis. However, NBR/PVC and SEBS were found to be much more effective in damping behavior. The results from this comparative study suggest that the damping characteristics of commercial friction materials can be strongly affected by the TPE ingredients. This investigation also confirmed that the specimens with high TPE content had low noise propensity.

Sound attenuation in composite friction materials containing thermoplastic elastomers

AbstractAttempts have been made for the first time to modify and improve the sound attenuation ability of a friction material by the inclusion of combined plastic/rubber properties of thermoplastic elastomers (TPE) as viscoelastic polymeric materials, into the formulation. To evaluate the attenuation coefficient (α) and also the real part wave number (k′) for the friction material, the viscoelastic parameters such as loss factor (tan δ) and elastic modulus (E′) were measured by the use of dynamic mechanical analyzer (DMA). Styrene‐butadiene‐styrene (SBS), styrene‐ethylene‐butylene‐styrene (SEBS) and nitrile rubber/polyvinyl chloride (NBR/PVC) blend system were used as TPE materials. However, SEBS and NBR/PVC were found to be much more effective in reducing the sound propagating speed as well as the sound level. All the friction materials containing TPEs exhibited more sound damping behavior at a wide range of temperature compared with the reference sample. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2187–2194, 2006

Reactive processing and evaluation of butadiene–styrene copolymer/polyaniline conductive blends

AbstractBlending is an important way to obtain materials based on intrinsically conductive polymers and conventional plastics and rubber materials. Much research has been carried out to determine the best performance of materials be used for electrostatic dissipation and electromagnetic interference shielding. Mechanical mixing, codissolution, and in situ polymerization have been used to prepare these materials. The method used depends on the host polymer and its thermal stability and acid attack resistance. Homogeneity and miscibility are properties that should be controlled during blend preparation. In this study, we prepared a conductive thermoplastic elastomer material based on butadiene–styrene copolymer (SBR) and polyaniline (PANI) doped with dodecylbenzene sulfonic acid (DBSA) and poly(styrene sulfonic acid) (PSS). PSS also acted as compatibilizer between PANI and SBR. PANI was doped by reactive processing with DBSA and PSS to produce the conductive complex PANI–DBSA–PSS. This complex was mixed with 90, 70, and 50% (w/w) SBR in a counterrotatory internal mixer. Conductivity tests, swelling studies, thermal analysis, and mechanical property and reflectivity testing were done, and the results show a strong dependence on PANI concentration and the ratio between PANI–DBSA and PSS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 681–685, 2006

Noise generation and propagation control in disc brake systems using composite friction materials composed of thermoplastic elastomers as viscoelastic materials

Attempts have been made for the first time to produce a thermal sensitive friction material by the inclusion of thermoplastic elastomers (TPE) with combined plastic and rubbery properties as viscoelastic polymeric materials into the composition of the friction material for the purpose of increasing damping behavior. To evaluate the viscoelastic parameters such as loss factor (tan δ) and elastic modulus (E′) of the friction material on the molecular scale, dynamic mechanical thermal analysis was performed on the samples. Natural frequencies and mode shapes of the friction material and brake disc were determined by modal analysis. Styrene–butadiene–styrene (SBS), styrene–ethylene–butylene–styrene (SEBS) and nitrile rubber/polyvinyl chloride (NBR/PVC) blend systems have been used as TPE materials. However, NBR/PVC and SEBS were found to be more effective in preventing the noise generation and reducing the amplitude of the brake vibrations. All the friction materials containing TPEs exhibited more damping characteristics within a wide range of temperature compared with the damping characteristics of the reference sample. POLYM. COMPOS. 27:461–469, 2006. © 2006 Society of Plastics Engineers.

DESIGN OF MINI-SCREW-EXTRUDING DEPOSITION HEAD FED BASED ON BULK MATERIAL IN GRANULATED FORM

Based on the development of rapid prototyping (RP) technology, a new extruding deposition head fed with bulk material in granulated form is presented through analyzing the characteristics of existent head systems in the fused deposition modeling(FDM) process. The difficulties of the head realization are the miniaturization of extruding screw and the steady feeding of the granules. Therefore, a feasible design method of small extruding screw is founded, and a novel feeding set is adopted. Through a series of experiments, the new extrusion head technology is proven feasible. With further improvement, the deposition head can be used to fabricate prototypes with thermoplastic elastomer or biomaterial material.

New fluorinated thermoplastic elastomers. III. Novel method of synthesis and characterization of alternating fluorinated polyimide/fluorinated polyhybridsiloxane block copolymers via polycondensation

AbstractThe synthesis of fluorinated polyimide/fluorinated polyhybridsiloxane (FPI–FPHSX) block copolymers was achieved through the polycondensation of α,ω‐dichlorosilane fluorinated polyimides and α,ω‐disilanol fluorinated polyhybridsiloxanes. Three FPI–FPHSX block copolymers with 41, 50, and 76 wt % polyimide were synthesized and characterized by the tuning of the number‐average molecular weight of the soft polyhybridsiloxane segments. The influence of the soft‐segment length on the behavior of the thermoplastic elastomer material was studied, including the surface tension and thermal properties. The thermomechanical properties of the FPI–FPHSX block copolymers were also examined. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2237–2247, 2005

New Fluorinated Thermoplastic Elastomers, 4

AbstractSummary: The synthesis of fluorinated polyimide‐polyhybridsiloxane block copolymers (FPI‐HPHSX) was performed by polycondensation of α,ω‐dichlorosilane fluorinated polyimides (SiCl‐FPI) and α,ω‐disilanol‐polyhybridsiloxanes (SiOH‐HPHSX). The α,ω‐disilanol polyhybridsiloxanes were synthesized by polyhydrosilylation between 1,7‐octadiene and hexamethyltrisiloxane (HMTS). The resulting siloxanes exhibit a glass transition temperature close to −98 °C. The α,ω‐dichlorosilane fluorinated polyimide was prepared by hydrosilylation of α,ω‐diallyl fluorinated polyimide and dimethylchlorosilane in the presence of Karstedt's catalyst. Then a series of four FPI‐HPHSX was synthesized by polycondensation and, with tuning of the number average molecular weight ($\overline M _{\rm n}$) of the soft polyhybridsiloxane and the hard polyimide groups, they were characterized. The influence of the segment lengths on the behavior (surface tension and thermal stability) of the thermoplastic elastomer (TPE) material was studied. The FPI‐HPHSX block copolymers' thermomechanical properties are also reported and discussed.General procedure for the synthesis of alternating block copolymers FPI‐HPHSX by polycondensation.magnified imageGeneral procedure for the synthesis of alternating block copolymers FPI‐HPHSX by polycondensation.

New fluorinated thermoplastic elastomers. II. Synthesis and characterization of perfectly alternating fluorinated polyimide–fluorinated polyhybridsiloxane block copolymers via polyhydrosilylation

AbstractThe synthesis of perfectly alternating fluorinated polyimide–fluorinated polyhybridsiloxane block copolymers (FPI‐FPHSX) was achieved through polyhydrosilylation of α,ω‐diallylfluorinated polyimides (AT‐FPI) and α,ω‐dihydrosilane fluorinated–polyhybridsiloxanes (HT‐FPHSX). A series of three FPI‐FPHSX containing 15, 38, and 56 wt % of polyimide was synthesized and characterized by tuning the number‐average molecular weight either of the hard polyimide segments or of the soft polyhybridsiloxane segments. The influence of the soft and hard segment lengths on the behavior of the thermoplastic elastomer material was studied (hardness, surface tension, thermal stability). The FPI‐FPHSX block copolymers thermomechanical properties are also reported. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 200–207, 2004

Thermoplastic Elastomer Monolayers Grafted to a Functionalized Silicon Surface

We fabricated a robust ultrathin film of a triblock copolymer, poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS), functionalized with 2% of maleic anhydride by melt/solution grafting to a chemically reactive silicon surface. We used epoxy-terminated self-assembling monolayers to functionalize silicon surface. The thickness of grafted block polymer, t, was varied from 1.35 to 9.1 nm to test the limits of stability of microphase-separated structures of the triblock copolymer tethered under confined conditions. Accordingly, the ratio t/d was changed from 0.05 to 0.33, where d is the interdomain spacing. The contact angle measurements demonstrated that the surface of the complete block copolymer films was totally occupied by poly[ethylene-co-butene] (PEB) chains. When the SEBS film thickness reached 8.4 nm, the film possessed the well-defined microphase structure of the typical thermoplastic elastomer material, where PS phase formed the microdomain network that reinforced the elastomeric matrix. The mic...

Structure-property relationships of lightly chemical crosslinked poly(vinyl chloride) thermoplastic elastomer

Chemical crosslinked poly(vinyl chloride) (C-PVC) was synthesized by vinyl chloride suspension polymerization in the presence of diallyl phthalate (DAP) and plasticized to prepare poly(vinyl chloride) (PVC) thermoplastic elastomer (TPE) materials. The chemical crosslinking and physical crosslinking structure in chemical crosslinked PVC-TPE were investigated. It showed that the gel fraction and the crosslinking density of gel increased as the feed concentration of DAP increased. C-PVC prepared by VC/DAP copolymerization was lightly crosslinked as compared with irradiation crosslinked PVC. Physical entanglements would greatly influence the crosslinking density of gel when the gel fraction was high. Chemical crosslinking had little influence on the recrystallization behavior of PVC. A structure model of chemical crosslinked PVC-TPE was proposed, in which chemical networks acted with physical networks cooperatively. It also showed that chemical crosslinking and physical crosslinking influenced the processability and mechanical properties of chemical crosslinked PVC-TPE cooperatively. Although the processability of PVC-TPE deteriorated with chemical crosslinking, the dimension stability and elasticity of PVC-TPE were improved as the permanent chemical networks were introduced. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 868–874, 2000