Mechanical Properties Of Elastomers Research Articles

Network formation of low molecular weight ‘liquid’ polymers studied by gel permeation chromatography and stress-strain analysis according to Mooney-Rivlin

The rheological and mechanical properties of elastomers are defined by their different networks: The crosslink network and the filler network. The crosslink network is influenced by the polymer structure. The filler network – particularly in case of silica as filler – depends on the interaction between the filler particles and the polymer. Liquid polymers can affect these networks by their lower molecular weight and with certain types by their functional groups. The goal of the present work is to gain a better understanding of the network formation: 1. During the sulfur curing of pure liquid polybutadienes with different concentrations of sulfur and curatives, and 2. Through differently added liquid polymer-silica-masterbatches in sulfur cured silica/SSBR mixtures. For the first point, the pre-cured liquid polymer samples were analyzed by gel permeation chromatography. The results indicate an association between weight concentration and the polymer chain length. For the second point, stress-strain analysis according to Mooney-Rivlin provides information about the interaction of liquid polymers with silica and the main polymer when it is added differently throughout the masterbatch approach.

Synthesis and Study of Physical and Mechanical Properties of Urethane-Containing Elastomers Based on Epoxyurethane Oligomers with Controlled Crystallinity.

The influence of the molecular weight of oligoamine, oligoether, and the type of diisocyanate on the physical and mechanical properties of elastomers with urethane hydroxyl hard segments was studied. For this purpose, oligoetherdiamines with molecular weights ~1008 and ~1400 g mol−1 were synthesized by a three-stage method. Epoxyurethane oligomers were synthesized according to a two-step route with an oligodiisocyanate as an intermediate product. A series of 12 elastomers with controlled crystallinity were synthesized from these elastomers and amines. The deformation and strength properties of the elastomers were studied.

BLOCK COPOLYMERS WITH URETHANE HYDROXY HARD SEGMENTS BASED ON OLIGOETHERTETRAURETHANEDIEPOXIDE AND A BINARY HARDENER

The paper describes a method for controlling the physical and mechanical properties of elastomers with urethane hydroxyl rigid blocks. For this, an epoxyurethane oligomer was obtained on the basis of oligotetramethylene oxide diol, isophorone diisocyanate, and glycidol. Oligoetherdiamine was proposed as a hardener, that was synthesized for the first time from oligotetramethylene oxide diol with molecular weight of 1400 through the stage of bromination followed by amination. Molecular structure was determined by NMR and FTIR spectroscopy. On the basis of the synthesized amine and its mixtures with isophoronediamine, 5 new elastomers with different degrees of microphase separation and crystallinity were fabricated. Using differential scanning calorimetry, it was proved that the glass transition temperature of the obtained elastomers, regardless of the hardener type, is less than minus 70°C, which makes it possible to use these elastomers in the conditions of the Arctic and the Far North. It was shown that the degree of crystallinity and microphase separation of soft and hard segments in elastomers with urethane hydroxyl hard blocks can be used to control physical and mechanical characteristics of epoxyurethane elastomers.

Mussel-inspired self-healing PDMS/AgNPs conductive elastomer with tunable mechanical properties and efficient antibacterial performances for wearable sensor

The ability to accurately and stably monitor the electrical signals and present the information in time is very important for wearable strain sensors. At the same time, the mechanical properties of the sensor determine whether the product can be competent for more difficult tasks. However, it is still a challenge to develop strain sensors to overcome the contradiction between mechanical properties and repairability. Inspired by mussel, we prepared self-healing antibacterial organosilicon conductive elastomer with good mechanical properties . The mechanical properties of elastomers are controlled by hard and soft domains. The materials were further reinforced by adding AgNPs, and the elastomers containing 10 wt% nano fillers had classy tensile strength (2.4 MPa stress) and prominent stretchability (1762% strain). Due to multiple reversible interactions and dynamic disulfide bonds, the prepared elastomers had outstanding self-healing ability 91.2% at room temperature. The combination of the bactericidal effect of AgNPs and zinc ions with the bacteriostatic effect of hydrophobic surface endowed the conductive elastomer with efficient antibacterial performance. Furthermore, the developed elastomer can accurately monitor the bending motion of human joints. We believe that this kind of mussel-inspired self-healing conductive elastomer could provide inspiration for the design of strain sensors which can be used in the fields of medical equipment, movement monitoring and so on.

Elastomeric nanocomposite for recovery of worn-out basic parts of agricultural machinery

Due to the high specific surface area of nanoparticles, in comparison with micro-sized particles, a significant improvement in the consumer properties of polymer nanocomposites is achieved at relatively low concentrations of nanoscale fillers (up to 5%). Research and subsequent development of new polymer nanocomposites are of great scientific and practical interest, as they provide further development of promising high-performance technologies for restoring landing holes, increasing the post-repair life of basic parts and reliability and significantly reducing the cost of repairing agricultural machinery. The article describes the influence of metal nanoparticles on the thermophysical and mechanical properties of elastomers, presents the results of experimental studies of the deformation-strength and adhesive properties of a nanocomposite based on F-40 elastomer filled with nanoscale copper and aluminum particles as well as its optimal composition. Comparative data on the heat and heat resistance of the F - 40 elastomer and the nanocomposite based on it are presented.

Systematic Literature Review of the Effect of Layered Double Hydroxides on the Mechanical Properties of Rubber.

Layered double hydroxides (LDHs) have attracted interest as reinforcing fillers in elastomers due to their ease of synthesis and customisability. A systematic review was performed on the effect of LDHs on the mechanical properties of elastomers using the Scopus database. Of the 61 articles relevant to the search criteria, the majority were published on polyurethane (PU) and nitrile butadiene rubber (NBR). Mg-Al LDH was used in most of the studies and Zn-Al LDH was used second most common. LDH can act as a reinforcing filler, typically increasing tensile strength even at low concentrations, so it could be used as an alternative to traditional reinforcing fillers for elastomers. LDH can also be made a functional filler by selecting the right metals and interlayer anions. It was found that Mg-Al LDH and Zn-Al LDH can both participate in crosslinking reactions and can replace MgO and ZnO, respectively. Less Zn ions are required for crosslinking when LDH is used than when ZnO is used, making LDH more environmentally friendly. Organic modification is usually required to improve compatibility with the elastomer matrix, especially in non-polar elastomers. It enables exfoliation of the LDH and intercalation of polymer chains into the LDH interlayer to occur. Organic modifiers can also be used to functionalise the LDH. Stearic acid used in crosslinking systems can be replaced by stearate anions from stearate-modified LDH.

Energy dissipating poly(hydroxyurethane) elastomers – Synthesis, characterization and comparison with shear thickening fluid materials

In this article we report preparation and characterization of cross-linked non-isocyanate poly(hydroxyurethane) polymeric materials showing energy-dissipating properties. The materials were obtained by the ring-opening polyaddition reaction of hyperbranched multi(cyclic carbonate) (HBPG2) with various diamines. The hyperbranched multi(cyclic carbonate) was obtained in two step procedure including anionic polymerization of glycidol with trimethylolpropane (TMP) as a core yielding polyglycerol (HBPG1) and reaction of terminal vicinal hydroxyl groups of HBPG1 with dimethyl carbonate in the presence of potassium carbonate. HBPG1 and HBPG2 were characterized using various NMR techniques, FTIR and MALDI-ToF mass spectroscopy. Thermal and mechanical properties of elastomers, including dissipated energy capacity have been studied. Analysis of force absorbing efficiency test results showed that synthesized elastomers have the capability to dissipate about 60% of the energy. The energy dissipating properties of obtained poly(hydroxyurethane) elastomers were similar to those of shear thickening fluid materials that are currently used in human body protectors, in vibration damping devices or sound insulations. The article proves that it is possible to obtain advanced engineering materials using environmentally friendly materials.

Conductive stretchable shape memory elastomers combining with electrical stimulation for synergistic osteogenic differentiation

The natural extracellular matrix (ECM) possessed varying biomechanical properties which played important roles in the dynamic cellular microenvironment. However, for the conventional bone tissue engineering scaffolds, stretchability and shape memory property were normally absent. Thus, the behaviors of responsive changes required in dynamic physiological settings were unsatisfactory. Herein, a series of conductive polyurethane shape memory elastomers (PCL-IPDI-AT) were synthesized, which based on conductive amino capped aniline trimer (AT), isophorone diisocyanate (IPDI) and poly(ԑ-caprolactone) (PCL). The conductive elastomers possessed high elasticity and flexibility, especially, the breaking elongation of copolymer with 15% AT content was up to 570 ± 56%. The mechanical properties of elastomers could be adjusted by regulating the content of AT in copolymers. The conductive elastomers exhibited excellent shape fixity ratio and good shape recovery ability at 37 °C. The electrical conductivity of elastomers was measured via the standard van der Pauw four-probe method. They were all around 10−7 S/cm and similar to that in human physiological environments. On the one hand, excellent cytocompatibility was demonstrated by the viability and proliferation results of MC3T3-E1 pre-osteoblasts seeded on the elastomer. On the other hand, the elastomer could synergistically promote the osteogenic differentiation compared to PCL in terms of ALP activity, calcium deposition, and bone-related protein and gene expression levels as combined with electrical stimulation (ES). Specifically, the ALP activity for conductive elastomer under ES was notably improved by 1.4-fold compared to PCL at 7 days. Overall, the conductive elastomers displayed excellent stretchability, shape memory property, fatigue resistance and osteogenic bioactivity. They may be applied as bone substitutes for electrical-signal-sensitive bone tissue engineering.

Boron nitride for modification of rubber based on isoprene elastomer

The work studies vulcanization characteristics of elastomers based on isoprene rubber filled with carbon black N330 and boron nitride (BN). The influence of the boron nitride (BN) concentration on technological, dynamic, physical and mechanical properties of elastomers has been researched. The application of boron nitride for producing rubber with good properties has been considered. With a gradual increase of the inert filler BN concentration up to 35%, a decrease in the curing rate by 33% and polymer cross-link density by 26% is observed. Moreover, the start time of vulcanization increases by almost 300%, the optimal curing time by 200%.

The effect of the compositional curing activator formation on the properties of elastomers

The properties of rubber compounds and vulcanizates made using a compositional curing activator with a low content of zinc oxide were studied in this work. Technological modes of obtaining new curing activator activators in the form of an alloy of zinc oxide with a mixture of fatty acids have been developed. To give a convenient outlet shape, finely dispersed fillers of various types were introduced into the experimental products: silicon dioxide, carbon black, microcellulose, bentonite, shungite. The physicochemical properties of compositional curing activator were studied and it was established that, according to the values of acid and iodine numbers, the experimental products satisfy the regulatory requirements for stearic acid. A comparative analysis of the properties of elastomers of experimental products with widely used as curing activator activators of zinc oxide and stearic acid is carried out. It was found that the use of experimental products improves the processability of the compositions due to their better dispersion in an elastomeric medium. The ratios of the compositional curing activator components are determined, which ensure the optimal complex of vulcanization and physical and mechanical properties of elastomers made on their basis. The effectiveness of the action of composite vulcanization activator in the manufacture of elastomeric products is shown - a reduction in the mixing cycle of experimental compositions by an average of 10% is noted compared to the standard rubber compound. The analysis of the research results confirmed the improvement of technological and vulcanization properties of rubber compounds, resistance to scorching. It is shown that the use of compositional curing activators provides the required level of physical and mechanical properties of rubbers even with a decrease in the content of zinc oxide in the experimental product to 20 wt%, and also improves the dispersion of the components of the rubber compound, having a positive effect on the technological and vulcanization properties of rubber compounds.

Preparation and characterization of polybutadiene curing system by click chemistry

ABSTRACTPolybutadiene curing systems from propargyl-terminal polybutadiene (PTPB), triazide acetate propane (TAP) and terminal azido polyethylene glycol (APEG) were prepared via the 1,3-dipolar cycloaddition reaction between azido and propargyl groups. By systematically tuning the ratio between TAP and APEG from 0.5 to 6.0, a series of elastomers were prepared and characterized. It was found that at a ratio TAP:APEG of 2.0, the tensile strength of the elastomer is 1.35 MPa, and the elongation at break is as high as 243%. The elongation at break was increased by 835% without the reduction of tensile strength compared to the ones with only TAP as curing agent. In addition, increasing the molecular weight of APEG from 200 g mol−1 to 1000 g mol−1 can improve the mechanical properties of elastomer, and the optimal comprehensive mechanical properties and preparation process were achieved with APEG600.

Contributions of network topological structures to the mechanical properties of PDMS elastomers

Silicone elastomers (poly dimethyl siloxane, PDMS) are widely used in the fabrication of MEMS devices and in mechanobiological studies. Mechanical properties of the elastomers may be varied by changing the crosslinking density and physical entanglements in the networks. Other factors like dangling chains and uncrosslinked sol fractions also influence the network mechanics. We investigated the role of crosslinks, entanglements and sol fraction in the mechanical properties of PDMS prepared with different ratios of base to crosslinker. Results from compression tests show greater elastic modulus for the highly crosslinked networks. We removed uncrosslinked sol, altered the entanglement density with xylene extraction, and used data from mechanical tests to assess predictions from the Frenkel-Flory-Rehner model. These studies show that the polymer-solvent interaction parameter, χ, varied linearly with the equilibrium volume fraction. Dynamic mechanical analyses of extracted PDMS samples showed that crosslinking density, solvent presence, and sol fraction affect their overall viscoelasticity properties. We also compared experimental data with scaling laws and demonstrate that trapped entanglements in the networks contribute to the mechanical properties of PDMS. Finally, we show from these studies that swelling behaviors of PDMS in xylene follow affine deformation.

Application of fractional time derivatives in modeling the finite deformation viscoelastic behavior of carbon-black filled NR and SBR

Mechanical behavior of elastomers includes nonlinear and time dependent phenomena such as creep and relaxation where due to low stiffness, these materials usually undergo large deformations. The classical approaches of viscoelasticity,i.e. differential constitutive models and hereditary integrals have been widely used to model the viscoelastic behavior of these materials even at finite deformations. However, from the viewpoint of computational analysis, the integral based methods are often time and memory consuming and the differential methods usually need a large number of material parameters whose identification is a real challenge. A potential solution is to introduce fractional order derivatives instead of regular differential operators in the standard spring-dashpot mechanical models which remarkably reduces the number of required material parameters. In the present paper, relaxation behavior of NR and SBR is investigated in finite strains. Due to the remarkable effects of filler particles and deformation rate on the mechanical properties of elastomers, compounds of each material with different amounts of filler content are investigated at two strain rates. A main interest is to examine efficiency of the fractional derivative models in modeling the finite deformation relaxation behavior of elastomers with different filler contents. The other goal is to investigate the effect of loading rate on the obtained model parameters. It is observed that, the fractional Maxwell chain is able to well fit the stress relaxation response of all compounds with only three parameters. Analyzing the obtained parameters and the experimental data, it is concluded that, order of the associated Maxwell element is not much affected with the filler content. Seemingly, it depends on the matrix material and more noticeably on the deformation rate. Moreover, as much as the deformation rate, the associated relaxation time is low. Decrease of the relaxation time with the deformation rate is more evident for compounds of SBR compared with NR compounds.

Effects of variation in temperature on the permanent deformation of elastic chains.

Aim: The Aim of the study is to check the effects of variation in temperature on the Permanent deformation of elastic chains. Objective: To investigate the effect of variation in temperature on the permanent deformation of elastic chains. Materials and method: Samples of elastic chains are taken and subjected to various temperature for 5 minutes 4 times a day .Samples are put under 5 groups;Group 1 was subjected to a temperature of 0°,Group 2 was subjected to a temperature of 20°,Group 3was subjected to a temperature of 40°,Group 4 was subjected to a temperature of 60°,Group 5 was subjected to a temperature of 80°.Background: In orthodontic treatment,elastomeric chains exhibit good elasticity they are used for retraction,space closure.The main advantage of these elastomeric chains are they are cost efficient,ease of application, patient and clinician comfort.Any alteration in the mechanical properties of elastomers affects the function of the chains.It s influenced by the change in temperature due to consumption of very cold to very hot food.Constant exposure to such varying temperatures may affect the elastomers and lead to deformation.

CO2 SOLUBILITY AND DIFFUSIVITY AND RAPID GAS DECOMPRESSION RESISTANCE OF ELASTOMERS CONTAINING CNT

ABSTRACTUnderstanding the structure–property relationship of elastomers is of critical importance in developing next-generation elastomers for high-pressure, high-temperature (HPHT) applications and in extending the application temperature and pressure range of existing oilfield products. Gas dissolution and diffusion in elastomers are essential to understanding the relationship among elastomer structures, rapid gas decompression (RGD) resistance, and sealing performance. Solubility and diffusivity (or diffusion efficiency) of carbon dioxide (CO2) in hydrogenated nitrile butadiene rubber (HNBR) and fluoroelastomers (FKM) comprising carbon nanotubes (CNT) were measured using a gravimetric method. The Rubotherm method was also used to estimate the solubility and swelling of HNBR in both subcritical liquid and supercritical CO2. It was demonstrated that CNT had a direct impact on CO2 solubility, diffusion, and mechanical properties of elastomers, hence improving the RGD resistance of the elastomers.

ASSESSMENT OF THE INFLUENCE OF RADIATION AND DEFORMATION ON THE ELASTOMER DETERIORATION BY USING FUZZY LOGIC

Elastomers belong to the group of polymer materials and they have an important role as technical material in the shipbuilding industry. The radiation crosslinking of elastomers shows significant advantages over chemical crosslinking. It can improve mechanical strength, resistance to chemicals and insulation properties of elastomers. An undesirable side reaction, which can occur during radiation, is the degradation process. This results in cracks breaking, chemical disintegration and reduction of mechanical properties of elastomers. In this paper fuzzy logic is used to estimate the influence of radiation and deformation on the behavior of elastomer samples. A Gaussian model is created according to both the experts' experience and the measuring data. The results of the model are calculated by using the Normalized Roth Mean Square Error (NRMSE) and the Roth Mean Square Error (RMSE). The so developed model gives new conceptions, which offer a possibility to improve the application of elastomer materials.

Effects of Carbon Black and the Presence of Static Mechanical Strain on the Swelling of Elastomers in Solvent.

The effect of carbon black on the mechanical properties of elastomers is of great interest, because the filler is one of principal ingredients for the manufacturing of rubber products. While fillers can be used to enhance the properties of elastomers, including stress-free swelling resistance in solvent, it is widely known that the introduction of fillers yields significant inelastic responses of elastomers under cyclic mechanical loading, such as stress-softening, hysteresis and permanent set. When a filled elastomer is under mechanical deformation, the filler acts as a strain amplifier in the rubber matrix. Since the matrix local strain has a profound effect on the material’s ability to absorb solvent, the study of the effect of carbon black content on the swelling characteristics of elastomeric components exposed to solvent in the presence of mechanical deformation is a prerequisite for durability analysis. The aim of this study is to investigate the effect of carbon black content on the swelling of elastomers in solvent in the presence of static mechanical strains: simple extension and simple torsion. Three different types of elastomers are considered: unfilled, filled with 33 phr (parts per hundred) and 66 phr of carbon black. The peculiar role of carbon black on the swelling characteristics of elastomers in solvent in the presence of mechanical strain is explored.

Effect of carbon black content on the swelling of elastomers in solvent in the presence of static mechanical loading

The effect of carbon black on the mechanical properties of elastomers is of great interest because filler is one of the necessity items for manufacturing of rubber products. While fillers can be used to enhance the properties of elastomers, it is known that filler yields to significant inelastic responses such as stress-softening, hysteresis and permanent set. Moreover, under tensile loading, the filler acts as a strain amplifier in the rubber matrix resulting in a higher local strain state in the matrix as compared to the applied macroscopic strain. The study of the effect of carbon black content on the swelling characteristics of elastomeric components undergoing mechanical loading and simultaneously exposed to aggressive solvent is a prerequisite for durability analysis. The present study investigates the effect of carbon black content on the swelling of elastomers in solvent in the absence and in the presence of static tensile loadings.

Mechanical characterization of bulk Sylgard 184 for microfluidics and microengineering

Polydimethylsiloxane (PDMS) elastomers are extensively used for soft lithographic replication of microstructures in microfluidic and micro-engineering applications. Elastomeric microstructures are commonly required to fulfil an explicit mechanical role and accordingly their mechanical properties can critically affect device performance. The mechanical properties of elastomers are known to vary with both curing and operational temperatures. However, even for the elastomer most commonly employed in microfluidic applications, Sylgard 184, only a very limited range of data exists regarding the variation in mechanical properties of bulk PDMS with curing temperature. We report an investigation of the variation in the mechanical properties of bulk Sylgard 184 with curing temperature, over the range 25 °C to 200 °C. PDMS samples for tensile and compressive testing were fabricated according to ASTM standards. Data obtained indicates variation in mechanical properties due to curing temperature for Young's modulus of 1.32–2.97 MPa, ultimate tensile strength of 3.51–7.65 MPa, compressive modulus of 117.8–186.9 MPa and ultimate compressive strength of 28.4–51.7 GPa in a range up to 40% strain and hardness of 44–54 ShA.

Redox and thiol–ene cross-linking of mercapto poly(ε-caprolactone) for the preparation of reversible degradable elastomeric materials

A novel thiol-functionalized PCL (PCL-HDT) was synthesized following a convenient two-step procedure. Taking advantage of the pendant thiol group, degradable elastomeric materials have been prepared from PCL-HDT by redox or thiol–ene reaction. Elastomers were characterized by HRMAS NMR spectroscopy to confirm the formation of disulfide or thioether cross-links. The thermal and mechanical properties of elastomers have been assessed by DSC, DMA and tensile tests. Disulfide containing elastomers (EMSS) and thioether containing elastomers (EMTE) exhibited improved mechanical properties with ultimate strains up to 220%. The stability of the mechanical properties at temperatures close to body temperature was confirmed by DMA with G′ ≈ 200 MPa and G′′ ≈ 15 MPa. Finally, the reversibility of the disulfide formation and breaking has been evaluated, and confirmed the potential of these degradable elastomers as biomaterials.