Kinds Of Elastomers Research Articles

Effect of compressibility on the mechanics of hyperelastic membranes

Elastic membranes are usually studied assuming material incompressibility. However, in several applications they are made of compressible materials such as polymeric foams, hydrogels, and certain kinds of elastomers. Only a few works attempted to incorporate volume changes into membrane problems, but with significant limitations. The models proposed were designed for nearly incompressible materials and lacked a foundation in experimental data, leading to results of limited value. In this work, we investigate the effect of compressibility in membrane problems adopting a consistent model based on the real response of materials to large volume changes. We consider three benchmark problems of nonlinear elasticity: (i) inflation of a circular flat membrane; (ii) inflation of a thin-walled cylindrical tube; (iii) inflation of a thin-walled spherical balloon. Four types of materials divided by increasing degree of compressibility are studied. The results indicate that volumetric deformations have a significant impact on both the limit pressure and the deformed shape. The proposed solutions represent benchmarks for developing new applications of compressible membranes made of polymeric foams and hydrogels, playing an increasingly important role in engineering technologies.

A Novel Method of Improving the Mechanical Properties of Propellant Using Energetic Thermoplastic Elastomers with Bonding Groups.

The relatively poor mechanical properties of extruded modified double base (EMDB) propellants limit their range of applications. To overcome these drawbacks, a novel method was proposed to introduce glycidyl azide polymer-based energetic thermoplastic elastomers (GAP-ETPE) with bonding groups into the propellant adhesive. The influence of the molecular structure of three kinds of elastomers on the mechanical properties of the resultant propellant was analyzed. It was found that the mechanical properties of the propellant with 3% CBA-ETPE (a type of GAP-ETPE that features chain extensions using N-(2-Cyanoethyl) diethanolamine and 1,4-butanediol) were improved at both 50 °C and -40 °C compared to a control propellant without GAP-ETPE. The elongation and impact strength of the propellant at -40 °C were 7.49% and 6.58 MPa, respectively, while the impact strength and maximum tensile strength of the propellant at 50 °C reached 21.1 MPa and 1.19 MPa, respectively. In addition, all three types of GAP-ETPE improved the safety of EMDB propellants. The friction sensitivity of the propellant with 3% CBA-ETPE was found to be 0%, and its characteristic drop height H50 was found to be 39.0 cm; 126% higher than the traditional EMDB propellant. These results provide guidance for studies aiming to optimize the performance of EMDB propellants.

A Wax-Elastomer Superwetting Membrane with Controllable Permeability: Toward Separating a Crude Oil-in-Water Emulsion from an Oil Field.

Smart superwetting membranes with finely tunable properties have attracted increased attention recently. However, they mostly focus on controllable wettability rather than controllable permeability. Also, the oil/water separation performance is usually tested with laboratory-simulated samples, making it hard for the materials to meet practical applications. Herein, we fabricate thermally responsive superwetting membranes with wax, polystyrene-B-poly(ethylene-ran-butylene)-B-polys (SEBS, a kind of elastomer), and polydopamine (PDA) to realize emulsion separation with controllable permeability. Benefiting from the elasticity of SEBS and the fluidity difference of wax at different temperatures, the pore size of the membrane could be readily tuned, resulting in different permeability. The separation flux is 0 at ambient temperature (pore size 0.394 μm) and is over 100 L m-2 h-1 at a high temperature (pore size 0.477 μm). The membrane could realize the separation of simulated oil-in-water emulsions with efficiency above 99.4%. Furthermore, it successfully achieved crude oil-in-water emulsion separation from the oil field with oil residues of less than 300 mg L-1 in the temperature range of 60-80 °C, which is the actual working temperature adopted in industrial production. Such a polydopamine/wax-SEBS modified membrane with unprecedented controllable permeability can promote the development of the emulsion treatment field and provide a new direction for designing smart superwetting materials.

Crystallization and mechanical properties of basalt fiber-reinforced polypropylene composites with different elastomers

In this study, composites based on polypropylene (PP), basalt fiber (BF), polypropylene-graft-maleic anhydride (MAPP) and different elastomers were manufactured by extrusion compounding and injection molding. The main focus of this study was to comparatively investigate the effect of three kinds of elastomers (ethylene–propylene–diene monomer (EPDM), polyethylene–octene (POE) and ethylene–vinyl–acetate (EVA)) on non-isothermal crystallization and mechanical properties of the composites with various BF contents. The tensile test results showed that BF had a reinforcing effect on PP resin, and the addition of MAPP further improved the tensile properties by the enhancement of PP/BF interfacial bonding. Among the elastomers, EPDM was more effective in improving the tensile strength and tensile modulus, while POE significantly toughened the impact strength. Micrographs of scanning electron microscope on the impact fracture surfaces indicated a good dispersion by the addition of POE and EPDM, while some agglomerations were observed in the presence of EVA. The non-isothermal crystallization kinetics were investigated based on Avrami and Mo equations at six different cooling rates by using differential scanning calorimetry. Micrographic images of polarized optical microscopy showed that the spherulite size of PP reduced in the presence of EPDM and EVA.

Preparation and characterization of nano-scaled composites of elastomeric ter-polypropylene blended with iPP through in-situ polymerization strategy

The preparation method of nano-scaled polymeric materials was described in this work. Nano-scaled novel composites of elastomeric ter-polypropylene blended with isotactic polypropylene (iPP) were investigated. The composites were synthesized by zirconium complex/methylaluminoxane(MAO) catalyst system through in-situ polymerization. This novel materials consisted of different lengths of crystallizable iPP segments and rubbery amorphous blocks that polymerized by 1-octene, propylene and ethylene in varying proportions. The mechanical properties of the composites were desired that the iPP segments contributed to the strength and the rubbery amorphous blocks contributed to the flexibility. The result showed that the composites can be used as a kind of elastomer.

Stress Applied Patterns to the Influence of Stress Impedance Effect in Silicon/FeCuNbSiB Amorphous Powder Compound Film

We made use of compression-testing machine and LCR digital electric bridge to apply pressure stress and record the value of impedance which controlled by a computer throughout the whole testing process. Four stress loading methods were designed for testing, and a systematic research had been done with a scanning frequency at 1KHz for silicon/FeCuNbSiB amorphous powder compound films. It has been found that rubber matrix film is a kind of elastomer, which has some elastic deformation phenomenon such as elastic hysteresis and ratcheting. The radical reason of stress impedance (SI) effect is the internal relations between elastic deformation and impedance change. Deformation of elastic film will directly influenced the impedance, and the function of stress applied on the film will directly cause elastic deformation, thereby indirectly cause the change of impedance. Result shows, stress impedance effect is relevant to the recover process of elastic deformation. In the course of stress loading, the longer deformation recovered, the more indistinctively changed of impedance.

各種エラストマー真空シールO-ringにおける，ガス透過挙動の温度依存性

各種エラストマー真空シールO-ringにおける，ガス透過挙動の温度依存性

Effect of chain extender on the mechanical and thermal resistance properties of polyurethane liners for composite propellants

AbstractPolyurethane formulations utilized as liners for composite propellants were prepared by the reaction of toluene-2,4-diisocyanate (TDI) and isophorone diisocyanate (IPDI) with hydroxyl terminated polybutadiene (HTPB), while polymer chains were further extended with neopentyl glycol diol, NPG triol and two different triols (monoglyceryl ricinoleate, MRG and trimethylolpropane, TMP). Liners were formulated with micronized titanium dioxide mechanically dispersed in hydroxyl-terminated polybutadiene (HTPB). The molecular structures of liners were confirmed by FT-IR. Thermal properties indicated that the nature of chain extender (crosslinker) only slightly affected the temperatures for decomposition of liners. Two main thermal changes were found at 370∘C and another at around 440–500∘C, depending on the chain extender utilized. On the other side, mechanical properties varied within the range of 0,7-1,8 MPa, consistent with this kind of elastomers. Tensile strength at break was only significantly affected with TMP and MRG-chain extended liners at the lowest concentrations tested of 1,3 and 2% (w/w), respectively. However, the behaviour depended on whether TDI or IPDI isocyanate was utilized for curing. TMP 1,3% crosslinked liner cured with TDI had a tensile strength of 1,82MPa whileMRG-crosslinked liner cured with IPDI had a tensile strength of 1,56 MPa. It was observed that at the higher NCO/OH ratios essayed, tensile strength and hardness increased, improving mechanical properties. Our results confirmed that TMP and MRG triols together with NPG diols can be used to tailor mechanical and thermal properties of liners, considering their different hydroxyl functionalities and chain lengths.

Interfacial adhesion evaluation in (low‐density polyethylene)/elastomer blends

Low‐density polyethylene (LDPE) with different elastomers at a ratio of 50/50 wt% blends was prepared by using a co‐rotating twin‐screw extruder. Three kinds of elastomers were used: ground tire rubber (GTR), partially crosslinked butyl rubber (Kalar®), and styrene‐butadiene‐rubber block copolymer (SBS; Kraton®). For better characterization of interaction between polyethylene and elastomer, influence of the type of elastomer on the properties of compositions LDPE/elastomer was determined. In the studies, two types of partially crosslinked butyl rubber (differing over filler content and Mooney viscosity) and two types of SBS (differing over structure: linear/branched) were used. The influence of kind and type of elastomer on static mechanical properties (tensile strength, elongation at break, hardness), dynamic mechanical properties, thermal properties, and morphology of obtained compositions were characterized. LDPE/linear SBS copolymer blend had the best mechanical properties, as a result of better compatibility in comparison with other investigated blends. The reason for improved compatibility was an increase of mobility of chain segments in the amorphous phase of polyethylene associated with their partial plasticization by flexible polybutadiene blocks present in SBS copolymer. J. VINYL ADDIT. TECHNOL., 22:492–500, 2016. © 2015 Society of Plastics Engineers

Mechanical properties and nonisothermal crystallization of polyamide 6/carbon fiber composites toughened by maleated elastomers

Polyamide 6/carbon fiber (PA6/CF) composites toughened with maleated elastomers were prepared by melt blending using twin‐screw extruder followed by injection molding. Three kinds of maleated elastomers, maleic anhydride (MAH)‐grafted ethylene‐vinyl acetate copolymer (EVA‐g‐MAH), MAH‐grafted ethylene‐propylene‐diene terpolymer (EPDM‐g‐MAH), and MAH‐grafted hydrogenated styrene‐butadiene‐styrene (SEBS‐g‐MAH), were used to toughen the PA6/CF composites. The mechanical properties, morphology, nonisothermal crystallization, and subsequent melting behavior of PA6 hybrid composites were investigated. Mechanical tests indicated that incorporation of elastomers improved the impact properties of CF‐reinforced PA composites accompanied with loss of tensile strength and modulus. It was observed from scanning electron microscope photographs that modification with maleated elastomers improved the interfacial adhesion between the CFs and PA6 matrix. Nonisothermal crystallization behavior showed that three kinds of elastomers had negative effect on crystallization and retarded crystallization of PA6. Kissinger's analysis illustrated that addition of CF slightly increased the crystallization activation energy of PA6, whereas incorporation of elastomers reversed it compared with pure PA6. Furthermore, a slight decrease in crystallinity and melting peak of the composites after incorporation of elastomers was observed compared with pure PA6. Polarizing optical microscope results showed that the transcrystallinity phenomenon seemed to be also affected when the matrix was added by the elastomers. POLYM. COMPOS., 35:2170–2179, 2014. © 2014 Society of Plastics Engineers

Fatigue Life Estimation for an NBR Rubber and an Expanded Polyurethane

In this paper, we deal with the mechanical behavior of elastomeric materials subjected to high cyclic loading in cases of high strain. First, a methodology for material parameter identification is used for a constitutive visco-hyperelastic law with discontinuous damage, modeling the Mullins effect. Then a fatigue model characterized by a strain energy density-based criterion is proposed and implemented in the finite element code, Code-Aster [1]. Two kinds of elastomer are considered, an incompressible rubber and an expanded compressible polyurethane. Cyclic tensile tests were performed to identify material fatigue parameters. Finally, a numerical application using a finite element model is presented. This model is a plate perforated by a ∅6 mm hole for the first sample and a ∅10 mm hole for the second one. The results obtained from the finite element model are compared to experimental results.

EXPERIMENTAL CHARACTERIZATION AND MODELLING OF LARGE-STRAIN VISCOELASTIC BEHAVIOR OF A THERMOPLASTIC POLYURETHANE ELASTOMER

ABSTRACTThermoplastic polyurethane elastomers (TPUs) are a kind of elastomer that can be processed as thermoplastics. These elastomers exhibit a highly nonlinear behavior characterized by hyper-elastic deformability. Furthermore, the mechanical behavior of these elastomers is time-dependent, that is, they exhibit a viscoelastic behavior. We describe the material response of a TPU under moderate strains (ɛ < 1) by using an overlay visco-hyperelastic model assuming separation of time dependence from nonlinear stress–strain behavior. To achieve this goal, cyclic loading–unloading experimental tests are carried out for two homogeneous deformation states, uniaxial tension and pure shear, and the strain–stress data are then analyzed to fit a hyperelastic model. Conversely, a viscoelastic model is obtained from relaxation tests. Finally, the visco-hyperelastic model is implemented in a finite element calculation tool (ABAQUS), and the numerical results show a reasonable correlation with experimental data. As a result, a overlay visco-hyperelastic model depending on maximum strain is proposed.

Study on the Effect of TPR Simulated Skin on Water Cooling Garment

A novel TPR simulated skin was applied in the system of thermal manikin and water cooling garment, and the satisfying result in improving the heat dissipating efficiency of water cooling garment was achieved. Firstly, five kinds of elastomer were selected as candidate simulated skin. To evaluate the synthetic performance of these materials, a series of experiments characterizing material's mechanical and thermodynamic properties was performed, including stiffness test, heat property test, TGA test and so on. Then, fuzzy mathematic method was employed to perform synthetic evaluation, which showed that TPR had satisfying optimization performance and can be used as simulated skin. Finally, to verify the function of TPR simulated skin to increase water cooling garment's heat dissipating efficiency, comparative experiments were performed in climate chamber. Results show that TPR simulated skin can effectively improve water cooling garment's heat dissipating efficiency measured by thermal manikin.

Phosphoester cross-linked vegetable oil to construct a biodegradable and biocompatible elastomer

Biodegradable and biocompatible elastomer polymers have significant potential in biotechnology and bioengineering. In this paper, we designed, synthesized, and characterized a series of biodegradable and biocompatible elastomers based on phosphoester cross-linked vegetable oils (PVOs), which were prepared by simple cross-linking reactions between phosphorylated castor oil (PCO) and epoxidized vegetable oils (EVOs), epoxidized soybean oil (ESO) and epoxidized linseed oil (ELO), without any solvent or initiator, at 37 °C. The ratios between PCO and the EVOs, and the functionality of the EVOs, play a role in the properties of the elastomer polymers, such as their mechanical properties and degradation. Moreover, the elastomer polymers can be degraded completely on account of the fracture of the phosphoester and triglyceride. The elastic evaluation tests show that PVOs meet the demand for elastomers that can deform and return to their original dimensions even after 1000 repeats of the cyclic compression test. Cytotoxicity studies in vitro indicate that the elastomer polymers and their corresponding degradation products are compatible with the L929 cell line. And the implantation test for the elastomer polymers in animal skin shows that this kind of elastomer can be absorbed completely within 3 months, accompanying the restoration of the implantation sites to their normal architecture.

A Novel Elastomer Simulated Skin Applied in Measurement of Extravehicular Liquid Cooling Garment

A novel thermoplastic elastomer was applied in the measurement of extravehicular liquid cooling garment and the satisfying result in improving the heat dissipating capacity of liquid cooling garment was achieved. Firstly, five kinds of elastomer were selected, which were ethylene-vinyl acetate copolymer (EVA), high temperature vulcanized silicone rubber (HTV), medical used silicon rubber (MSR), natural rubber latex (NRL) and thermoplastic SBS complex (TPR). To evaluate the synthetic performance of these materials, a series of experiments characterizing material’s mechanical and thermodynamic properties was performed, including tensile and compression test, heat property test and so on. Meanwhile, fuzzy mathematic method was employed to get parameters’ weight distribution, and then fuzzy decision-making method was adopted to perform synthetic evaluation, which showed that TPR had satisfying optimization performance and can be used as simulated skin in thermal manikin. Finally, to verify the function of TPR simulated skin, comparative experiments were performed in climate chamber when thermal manikin covered with TPR simulated skin and did not cover with TPR simulated skin. Results show that TPR simulated skin can effectively improve the heat dissipating capacity of liquid cooling garment.

A Review of Constitutive Models for Rubber-Like Materials

Problem statement: This study reviewed the needs of different constitutive models for rubber like material undergone large elastic deformation. The constitutive models are widely used in Finite Element Analysis (FEA) packages for rubber components. Most of the starting point for modeling of various kinds of elastomer is a strain energy function. In order to define the hyperelastic material behavior, stress-strain response is required to determine material parameters in the strain energy potential and also proper selection of rubber elastic material model is the first attention. Conclusion: This review provided a sound basis decision to engineers and manufactures to choose the right model from several constitutive models based on strain energy potential for incompressible and isotropic materials.

Wetting behavior of modified vinylester resins on the surface of UHMWPE materials

A new testing method was used to observe on-line the dynamic wetting course of liquid resins on PE fabric. The measure procedures and data processing were introduced in detail. To aim at some applications of vinylester resins/polyethylene fiber composites, vinylester resins (VRs) were at first modified by three kinds of additives, including elastomer, liquid rubber and isocyanate-terminated prepolymer. Then the wetting behaviors of these modified resins on the surface polyethylene (PE) materials were observed. After they were modified by six kinds of elastomers, the infiltrate-steady-times of these resins on the surface of PE fabric all increased; only the contact angle of natural rubber-modified VR on the surface of PE film decreased. After VRs were toughened by three kinds of liquid rubbers, their wetting velocities all became slower and the contact angles on the surface of PE film all decreased. In addition, VRs were also modified by three kinds of isocyanate-terminated prepolymers, which were the products of different hydroxyl-terminated polymers reacted with methylene bisphenyl isocyanate and whose structures were characterized by means of GPC, DSC and FT-IR, respectively. The wetting state of these modified resins on the surface of PE materials suggested that the interfacial compatibility of modified VRs and PE fabric did not decrease at the same time when the other properties of vinylester resins changed.

Fabrication and Normal/Shear Stress Responses of Tactile Sensors of Polymer/Si Cantilevers Embedded in PDMS and Urethane Gel Elastomers

Cantilever-type tactile sensors of silicon-polymer beam structures were fabricated by surface micromachining and covering with elastomers. Two kinds of elastomers with different Young's modulus PDMS and urethane gel have been used to control deflection of the cantilevers and adjust the sensitivity cantilever-type tactile sensors. The resistance change of the sensor with PDMS has linear dependence on normal and shear stresses, but that of the sensor with urethane gel is nonliner to normal and shear stresses. However, the sensitivity of urethane gel type sensor is about 30 times larger than PDMS type sensor.

Degradation of elastomer by heat and/or radiation

This article studied various problems on the degradation of elastomers by heat and/or radiation. Three kinds of elastomers were irradiated and evaluated by the radiation resistant property using the measurement of tensile test. The fluorine containing elastomer, which has excellent heat resistant properties, was found to be less durable for irradiation than ethylene–propylene–diene (EPDM) elastomer. Ten kinds of different compounding formulas of EPDM were prepared to investigate whether the compounding for heat resistant has durability for irradiation. The thermal exposure was performed in an air oven. The duration of thermal exposure at 140 °C was 384 h. The irradiation condition was 5.0 kGy/h at 70 °C, and the total dose was 0.9 MGy. Elongation retained was taken for the evaluation of the stability. It was found that the formulas for improving the thermal stability did not bring radiation resistant of samples in the experiment. The rate constant of the increase in C O concentration by heat and radiation was measured and defined as k c( h) and k c( r), respectively. The rate constant of that under the combined addition of the heat and the radiation is expressed as k c( h + r). Eq. (1) was obtained by the experiment and it was found that there is a synergistic relationship between heat and radiation on the increase in C O concentration (1) k c ( h + r ) > k c ( h ) + k ( r ) . Similar relationship was observed on the rate of decrease in ultimate elongation of a certain EPDM.

Morphology and Properties of Poly(ethylene terephthalate)/Polycarbonate Alloy Toughened with Different Kinds of Elastomers

Recycled Poly (ethylene terephthalate) (PET) was blended with Polycarbonate (PC) together with elastomers. Three kinds of elastomer: POE (ethylene-octene copolymer), SEBS(styrene- ethylene/butylenes-styrene triblock copolymer) and SEBS-g-MA (maleic anhydride grafted SEBS) were selected. Scanning electron microscope (SEM) results showed the alloy blended with SEBS exhibiting smallest particle size distribution and it had better mechanical properties than the others, especially in broken-elongation and impact strength. The alloy blended with SEBS-MA didn’t reach high performance was due to the existence of small amount of active monomer: MDI (methylenediphenyl diisocyanate). The preferential reaction by SEBS-MA with MDI not only resisted the chain-extending progress induced by MDI but also resulted in coalescence of SEBS-MA. In addition, though SEBS was the best selection to this system, experimental results showed that the weight ratio of SEBS must also be limited in a certain degree. Over much contents of SEBS resulted in coalescence together affect compatibility between components.