Structure Of Rubber Research Articles

Effects of carbon nanotubes and graphene on the structure and properties of natural rubber

Natural rubber (NR) is an important strategic material for national defense industry. It is also used in the food industry and medicine. However, due to the unsaturated double bond, its aging resistance, mechanical properties and solvent resistance are very poor. In order to improve these properties, carbon nanotubes (CNTs) and reduced graphene oxide (rGO) were used, added at 1 : 1 ratio. TheNR/CNTs/rGO nanocomposites were obtained by mechanical mixing after adding 1, 2, 3 and 4 phr offiller. The influence of the filler content on the structure (TEM), vulcanization properties, abrasion and solvent resistance, mechanical properties, dynamic mechanical properties (DMA) and thermal properties (TGA) of nanocomposites was investigated. Increasing the content of CNTs/rGO increased the crosslinking density of the composites. TEM studies showed that CNTs and graphene sheets were evenly dispersed throughout the NR matrix. They also had good compatibility with the rubber matrix. The addition of CNTs and graphene increased the abrasion and solvent resistance as well as improved the mechanical properties. TGA analysis showed that the nanocomposites had excellent thermal stability. The best properties were obtained with the CNTs/rGO content of 2 phr.

Structure and Temperature Induced Crystallization of Natural Rubber with Different Milling Times

Crystallization, a characteristic property of natural rubber, has great effect on the storage and application in industrial. Based on different milling times, natural rubber samples were prepared. Moreover, structure of natural rubber with different milling times, i.e. molecular weight, group transform, cross-link density (entanglement), and rheology were analyzed by gel permeation chromatograph (GPC), Fourier transform infrared spectrum (FTIR), and rubber processing analyzer (RPA), respectively. Furthermore, temperature induced crystallization parameters were mounted on differential scanning calorimeter (DSC). The results demonstrated that temperature induced crystallization rate decreased with the increment of milling times, whereas the average molecular weight measured by GPC decreased with milling times increasing. However, the average cross-link molecular weight increased which was compatible to the temperature induced crystallization rate. It was concluded that temperature induced crystallization rate was related to the average cross-link molecular weight, but not average molecular weight.

Failure analysis on rubber sealing structure of mandrel hanger and improvement in extreme environments

In view of the failure of the sealing structure of mandrel hanger under high pressure and extreme temperature environment, according to the sealing structure characteristics and application requirements of conventional mandrel hanger, based on the principle of the minimum sealing pressure ratio of metal sealing surface and the constitutive model of rubber material, the advantages and disadvantages of three conventional sealing structures are analyzed and compared. Based on the heat conduction theory and the energy conservation equation of thermal coupling, the transient temperature field model of the hanger seal structure is established. The heat transfer analysis and thermo-mechanical coupling calculation of the new metal seal structure are carried out at extreme temperature. The results show that the contact pressure on the double U and single U sealing rings is greater than 140 MPa at extreme temperature, which meets the principle of minimum sealing pressure ratio. The temperature distribution law of the conventional rubber structure under the temperature and pressure load is analyzed, and the reason of early failure of rubber is found. The mandrel hanger of full metal sealing structure is used in the field. The mandrel hanger of full metal have been tested for more than 20 times of gas pressure. The pressure is stable and the sealing effect is good. The test results show that this new structure has the advantages of good seal performance.

The performance optimization of the stripper rubber for the rotating blowout preventer based on experiments and simulation

The rotating blowout preventer (RBOP) is an essential safety-ensuring equipment in underbalanced drilling. RBOP is vulnerable to fatigue failure resulted from being subject to a cyclic alternating load during pressure drilling. To enhance the lifespan of RBOP, this paper used a finite element simulation combined with experiments to realize a structural optimization of RBOP. The results showed that the optimal thickness of the iron frame for the stripper rubber is 34 mm, the optimal radius of the fillet is 12 mm, and the optimal inner diameters for the stripper rubber that seals 2–3/8″, 2–7/8″, 3–1/2″, 4″, 4–1/2″, and 5″ drill pipes are respectively 48 mm, 58 mm, 75 mm, 87 mm, 95 mm, and 100 mm. The optimized RBOP was examined in a test center and demonstrated a lifespan that was 2.18 times the national standard. When it was deployed in the drilling site, its lifespan was 2.8 times that before optimization. The improvement in the performance and lifespan of RBOP is very meaningful for ensuring security in the drilling site and lowering drilling cost for oil production. • Constitutive model of the rubber matrix is described. • A dynamic finite element model for stripper rubber is established. • The dynamic sealing process of stripper rubber is simulated. • The structure of the stripper rubber for failed parts was optimized. • The optimized stripper rubber was verified in the indoor and oilfield test.

Influence of Treated Distillate Aromatic Extract (TDAE) Content and Addition Time on Rubber-Filler Interactions in Silica Filled SBR/BR Blends.

High compatibility and good rubber–filler interactions are required in order to obtain high quality products. Rubber–filler and filler–filler interactions can be influenced by various material factors, such as the presence of processing aids. Although different processing aids, especially the plasticizers, and their effects on compatibility have been investigated in the literature, their influence on rubber–filler interactions in highly active filler reinforced mixtures is not explicit and has not been investigated in depth. For this purpose, the influence of treated distillate aromatic extract (TDAE) oil content and its addition time on interactions between silica and rubber chains were investigated in this study. Rubber–filler and filler–filler interactions of uncured and cured silica-filled SBR/BR blends were characterized by using rubber layer L concept and dynamic mechanical analysis, whereas mechanical properties were studied by tensile test and Shore A hardness. Five parts per hundred rubber (phr) TDAE addition at 0, 1.5, and 3 min of mixing were characterized to investigate the influence of TDAE addition time on rubber–filler interactions. It was observed that addition time of TDAE can influence the development of bounded rubber structure and the interfacial interactions, especially at short time of mixing, less than 5 min. Oil addition with silica at 1.5 min of mixing resulted in fast rubber layer development and a small reduction in storage shear modulus of uncured blends. The influence of oil content on rubber–filler and filler–filler interactions were investigated for the binary blends without oil, with 5 and 20 phr TDAE content. The addition of 5 phr oil resulted in a slight increase in rubber layer and 0.05 MPa reduction in Payne effect of uncured blends. The storage tensile modulus of vulcanizates at small strains decreased from 13.97 to 8.28 MPa after oil addition. Twenty parts per hundred rubber (phr) oil addition to binary blends caused rubber layer L to decrease from 0.45 to 0.42. The storage tensile modulus of the vulcanizates and its reduction with higher amplitudes were incontrovertibly high among the vulcanizates with lower oil content, which were 13.57 and 4.49 MPa, respectively. When any consequential change in mechanical properties of styrene–butadiene rubber (SBR)/butadiene rubber (BR) blends could not be observed at different TDAE addition time, increasing amount of oil in blends enhanced elongation at break, and decreased Shore A hardness and tensile strength.

Swelling and Degradation Characteristics of Crumb Rubber Modified Asphalt during Processing

The existence of cross-linked structure in crumb rubber modified asphalt (CRMA) leads to the complexity of its system. According to the preparation test of CRMA under different processing technology, the influence of processing temperature and time on the properties and cross-linking structure of CRMA was analyzed. By analyzing the volume expansion rate of the rubber powder after swelling and the toluene insoluble content attenuation rate, the formation conditions of the macro-level cross-linked structure were determined, and the relationship model between the cross-linked structure and the rubber asphalt performance was established. The results show that the rubber particles can form a continuous phase structure after swelling. At this time, the expansion ratio of the swollen rubber powder was 1.76–2.14. Too high temperature (above 200°C) and too long time (above 60 min) caused serious degradation of rubber. The suitable processing technology was stirring at 180–190°C for 45–60 min.

MODIFICATION OF MIXTURES BASED ON ETHYLENEPROPYLENE RUBBER AND SILICON ACID FILLER

The aim of the work was to study the effect of bis-(triethoxysilylpropyl)-tetrasulfide (TESPT) mixed with carbon black N330 in a ratio of 1:1, as a technical product OFS 6945 on the structure and properties of rubber mixtures and rubbers based on ethylene propylene rubber of the brand Vistalon 2504N and silica filler (KKN) of the brand Rosil-175, taken at a dosage of 30 wt. h. per 100 wt.h. rubber. The content of TESPT was 0.035, 0.050 and 0.070 mmol / 100 g of rubber. A group of vulcanizing agents included sulphur, thiuram, captax, zinc oxide and technical stearin. Rubber mixtures were prepared on rollers Lb 320 160/160. Organosilane was injected into rubber at the same time as Rosil-175. The homogeneity of the filler distribution in the finished mixtures was evaluated based on the results of testing samples on the RPA-2000 vibrorheometer. Vulcanization characteristics were determined using an MDR-2000 device. The structure of mixtures and rubbers was studied by the method of equal swelling of samples in toluene. It is shown that with the increasing content of TESPT, the proportion of bound rubber in a three-component mixture of the rubber – filler – organosilane increases due to the formation of interfacial connections. The uniformity of distribution of silica fillers in rubber matrix also increases. Workability of the mixtures on roller equipment improves. The rate of cross-linking in the core period and the degree of cross-linking of macromolecules at the same time curing increase as well. As a result, the elastic-strength properties of rubbers determined in the static test mode are improved, the best complex of which is provided with an organosilane content of 0.050 mmol/100 g of rubber.

Optimize Design of Run-Flat Tires by Simulation and Experimental Research.

In this study, the two key factors affecting the thermal performance of the insert rubber and stress distribution on the tire sidewall were analyzed extensively through various performance tests and simulations to promote the development of run-flat tires. Four compounds and two structures of insert rubber were designed to investigate the effects of heat accumulation and stress distribution on durability testing at zero pressure. It was concluded that the rigidity and tensile strength of the compound were negatively correlated with temperature. The deformation was a key factor that affects energy loss, which could not be judged solely by the loss factor. The stress distribution, however, should be considered in order to avoid early damage of the tire caused by stress concentration. On the whole, the careful balance of mechanical strength, energy loss, and structural rigidity was the key to the optimal development of run-flat tires. More importantly, the successful implementation of the simulations in the study provided important and useful guidance for run-flat tire development.

Constitutive model of disordered grid interpenetrating structure of flexible microporous metal rubber

In this study, the disordered grid interpenetrating structure (DGIS) of wire turns in flexible microporous metal rubber (FMP-MR) for vibration and noise reduction is investigated, and an effective constitutive model is developed to dynamically capture the nonlinear mechanical behavior of FMP-MR. In this model, a micro spring element with adaptive deformation (MSEAD) model with random spatial distribution is employed, based on the phenomena of irregular overlapping and interlacing of material turns. The spatial distribution of micro springs and the evolution of the contact area morphology in FMP-MR are taken into consideration and introduced as key variables in model development. The concept of combined probability distribution (CPD) of micro spring pairs between wire turns in FMP-MR is proposed to characterize the random combination mode of material turns. Eventually, based on the micro-patterns of wire turns in FMP-MR, a constitutive model including macroscopic parameters, such as shape, density, wire diameter, helix pitch, and wire elastic modulus, and microstructure parameters, such as spatial distribution of wire turns, contact shape, and friction coefficient is developed for the first time. By analyzing and discussing the fitting degree of quasi-static compression experimental results and the model constitutive curves, the validity of the proposed constitutive model is quantitatively confirmed by residual analysis. According to the results, the FMP-MR constitutive model based on DGIS can effectively reflect the nonlinear mechanical behavior and complex micro-contact friction phenomena of the material.

Fabrication of Silicone Rubber-Based Biochip for Disinfection Under Deep-UV Light by ArF Excimer Laser-Induced Photodissociation

A silicone rubber-based biochip for disinfection under deep-UV light exposure was successfully fabricated by an ArF excimer laser. To fabricate the biochip, periodic micro-swelling structure of silicone rubber was photochemically formed by the ArF excimer laser-induced photodissociation of Si–O bonds of silicone rubber. It was found that the growth rate of the micro-swelling structure could be controlled by varying the laser pulse repetition rate; a slow growth of roughly 100 ms and longer per laser pulse was recognized. In addition, no change of each the micro-swelling height formed at various laser pulse repetition rates was also found in the range of 300–18,000 of laser pulse number. Using such the wide processing window, moreover, the periodic micro-swelling structure could be modified into photoluminescent property by long irradiation of ArF excimer laser, while maintaining the micro-swelling height. Blue photoluminescence from the modified micro-swelling structure was observed under a deep-UV light exposure. Thus, each the periodic micro-swelling structure with various desired heights could be bonded to a flat plate of fused silica glass to have equal gaps. A small amount of solution could be confined in the equal gap to disinfect virus/bacteria in the solution under deep-UV light for analytical application.

КОНФИГУРАЦИОННО-ИЗОМЕРНЫЙ СОСТАВ КАУЧУКОВ: ОПРЕДЕЛЕНИЕ МЕТОДОМ СПЕКТРОСКОПИИ ЯМР 1H И 13C

Nuclear magnetic resonance (NMR) spectroscopy is a convenient method for studying the structure and isomeric composition of diene rubbers. A simple and reproducible method is proposed for determining the content of both rubber and impurity compounds, which does not require additional sample preparation. Formulas for calculating the composition of industrial products and determining the initial substances are given, the applicability of the analysis method is confirmed. In the process of work, rubbers of various brands were analyzed, their configuration-isomeric composition was established. It was found that the integration ranges given in the literature earlier and the methods for processing 1H NMR spectra differ, the signals of the groups often overlap in the spectrum, which increases the calculation error. It is shown that the structure of the industrial products under study is established most accurately by carbon proton resonance spectroscopy, and the calculation based on the PMR spectra allows confirming the data obtained with sufficient accuracy.

Analysis of Hierarchical Structure of Rubber using Small Angle X-ray Scattering

Analysis of Hierarchical Structure of Rubber using Small Angle X-ray Scattering

Investigation of Physical and Mechanical Properties of Rubbers Reinforced by Carbon Nanostructured Components

The work presents investigation results of physical and mechanical properties of rubber mixtures based on SKI-3 and SKS-30-ARKM-15 rubbers reinforced with hybrid filler carbon black/carbon nanotubes (CB/CNT). Elasticity, hardness and strength were measured according to standard procedures presented in GOST. The content of the carbon nanotubes in rubber mixtures was 0,5 wt. %. parts per 100 wt. parts of rubber. According to experiments, it was found that the introduction of CB/CNT masterbatches into the structure of both investigated rubbers reduces their elasticity and increases Shore A hardness. During uniaxial tension of the tested rubbers, it was found that the presence of the nanostructured CB/CNT filler in the rubber structure leads to an increase in the nominal strength for SKI-3-based rubber by 19,6 %, and on SKS-30-ARKM-15 by 22,5 %. Therefore, the use of CB/CNT nanostructures as a rubber filler is a promising method of improving rubber performance characteristics.

Regulation effects of trans-1, 4-poly (isoprene-co-butadiene) copolymer on the processability, aggregation structure and properties of chloroprene rubber

Chloroprene rubber (CR) with excellent performances including flame retardancy and weather resistance, also suffers limitations like poor processability and unsatisfied fatigue resistance. Herein, a facile and effective method is proposed to modify CR by introducing trans-1,4-poly (butadiene-co-isoprene) copolymer (TBIR) as reactive component. The influences of TBIR component on rheological behaviors, crystalline behaviors, phase morphology and properties of CR/TBIR blends are studied. With increasing TBIR amount in CR/TBIR blends, the viscosity decreases, while the initial vulcanization induction time and the stress relaxation rate increase significantly, indicating improved fluidity, plasticity and processing safety of the CR/TBIR blends. A microphase separation morphology with TBIR domain in several-hundred nanometers and trans-1,4-polyisoprene (TPI) lamellar fibrils penetrating both TBIR and CR domains is observed in the un-vulcanized CR/TBIR blends. The CR/TBIR (90/10) blend with satisfied properties is recommended for potential applications in conveyor belt, vibration damper, etc.

Effect of diesel and microwave on the properties of crumb rubber and its modified binders

Some novel methods are introduced to improve thermal storage stability and pavement performance of crumb rubber modified binder. In this paper, the objective was to investigate the effects of compound activation on the molecular structure and physical properties of crumb rubber, as well as rheological properties and thermal storage stability of crumb rubber modified binders. Two activation methods, with and without diesel pre-swelling, and six microwave radiation intensities were designed in this study. Fourier transform infrared spectroscopy (FTIR) test, swelling equilibrium test and dynamic mechanical thermal analyzer (DMA) test were performed to evaluate the characteristic functional groups and physical properties of crumb rubbers before and after activation. Additionally, rheological properties test at various service temperatures and thermal storage stability test were carried out on the crumb rubber modified binders. The results show that certain microwave radiation intensity would break the C-S and C=S bonds and reduces the cross-linking density of crumb rubber. Activation mode was the main factor affecting high temperature stability, fatigue life and low temperature relaxation property rather than microwave radiation intensity compared with control one. In addition, thermal storage stabilities of activated crumb rubber modified binders were better than control one. The more radiation intensity, the improvement effect of thermal storage stability is. Synthesizes each kind of property, diesel pre-swelling and microwave radiation intensity of 1.2 kJ/g was a preferable combination in this study.

Grafting waste rubber powder and its application in asphalt

Herein, rubber asphalt was modified to improve its comprehensive performance and the mechanism of its modification was investigated. Unmodified rubber powder was first treated with hydrogen peroxide, and then, grafted with prepolymer. The mechanism of modification of rubber powder and its effect on the structure and properties of rubber powder/asphalts were tested and characterized. Fourier transform infrared spectroscopy analysis proved that prepolymer was successfully grafted onto the surface of rubber particles. X-ray photoelectron spectrometer test revealed that graft modified rubber powder possessed high oxygen content along with the presence of nitrogen. These results indicated that rubber powder was successfully modified. The graft modified rubber powder was then applied to prepare rubber asphalt, significantly improving the low-temperature resistance to cracking and the stability performance, while it reduced high-temperature construction viscosity of rubber asphalt. The modification of rubber powder enhanced the dispersion of rubber powder in asphalt. The graft modified rubber powder/asphalt exhibited the highest weight fraction of restricted molecular layers, demonstrating the enhanced interfacial interaction between the graft modified rubber powder and asphalt matrix, which could be attributed to the simultaneous effect of physical entanglement and chemical bonding effect.

The Impact of Nano CaCO3 Modified in situ with Methacrylic Acid on the Structure and Properties of Natural Rubber

The Impact of Nano CaCO3 Modified in situ with Methacrylic Acid on the Structure and Properties of Natural Rubber

Adhesion enhancement between aluminum and butyl rubber by (3-mercaptopropyl) trimethoxy silane for vibration damping plate

A silane coupling agent for an aluminum-based vibrational damping plate with a butyl rubber damper, which shows excellent viscoelasticity and thermal stability, was studied to enhance the adhesion strength between aluminum and butyl rubber. Considering the chemical structure of the butyl rubber, we introduced (3-mercaptopropyl) trimethoxysilane (MPTMS) as the silane coupling agent because it has a thiol functional group that can bind to the carbon chain of butyl rubber via thiol-ene reaction under heating. Based on the results of various surface analyses and the T-peel strength test, the MPTMS treatment condition was optimized, and a 180% enhancement of peel strength was obtained. Finally, a central supporting vibration test was conducted to prove the damping performance of aluminum damping plated with MPTMS. As a result, a 7-fold enhancement in the damping loss factor was seen in the damping with MPTMS compared to without.

Effect of mineral oil on flashover voltage of HTV silicone rubber under AC corona ageing: from the view of trap level distribution

The flashover voltage of high temperature vulcanised (HTV) silicone rubber will be decreased after corona ageing, and it further decreases under the effect of mineral oil. The mechanisms for the phenomena can be explained by considering the role of trap level distribution. In this study, the corona ageing of silicone rubber was conducted and the flashover voltage was tested. The isothermal surface potential decay was tested to explore the internal relationship between trap distribution and flashover voltage. Besides, the surface microtopography and chemical structure of silicone rubber were gained by scanning electron microscopy and Fourier infrared spectroscopy to explain the change of trap distribution. The test results show that the flashover voltage of HTV silicone rubber decreases with AC corona ageing time, the reduction of flashover voltage for an oil-impregnated sample is more serious. The density of shallow electron traps increases at first and then decreases, while the density of shallow hole traps increases with ageing time. The density of deep traps decreases after corona ageing. These trap level distribution characteristics are beneficial to promote the development of flashover, leading to lower flashover voltage. The effect of mineral oil can be regarded as an accelerated ageing effect.

The Relationship between Pendant Phosphate Groups and Mechanical Properties of Polyisoprene Rubber

It is still a great challenge to mimic the structure and function of natural rubber by introducing polar components into synthetic polyisoprene. In order to explore the function of phosphate groups on the mechanical properties of polyisoprene rubber, a terminally functionalized compound (PIP-P) containing phosphate groups was synthesized and further vulcanized to prepare the model compound V-PIP-P. Through analyzing the test results, it was found that these phosphate groups formed polar aggregates in non-polar polyisoprene rubber matrix, serving as an additional dynamic cross-linking sites, which increases the cross-linking density and improves mechanical properties. The influence of the phosphate groups on the strain-induced crystallization (SIC) was further investigated via synchrotron wide-angle X-ray diffraction (WAXD) experiment. These phosphate group aggregates not only reduced the onset strain of SIC, but also slowed down the molecular chain mobility, which hinder the crystal lateral growth. The above results help us to gain a deeper understanding for the function of phosphate groups in the formation of “naturally occurring network” and guide the molecular design of next generation polyisoprene rubber.