Vulcanized Rubber Materials Research Articles

Comparative analysis of nonlinear dynamic behaviors of hyperelastic curved structure modelled by different constitutive laws

This work focuses on conducting numerical studies and comparisons on the nonlinear dynamic behaviors of hyperelastic curved structures subjected to external dynamic loadings. A numerical model of the hyperelastic structure is developed using the nonlinear finite element method, which considers both the geometric nonlinearity resulting from large deformations and the material nonlinearity due to hyperelasticity. Four commonly used hyperelastic constitutive laws, namely the Mooney-Rivlin model, the neo-Hookean model, the Yeoh model, and the Ogden model, are employed to describe the nonlinear stress-strain relationship of the hyperelastic material. The convergence performance of the numerical model with respect to grid element and time step is thoroughly examined through several numerical examples. Subsequently, based on the developed numerical model, the nonlinear dynamic behaviors of the hyperelastic curved structures excited by uniform pressure loadings with single and dual frequencies are studied and compared using various constitutive laws. The material constants used in these constitutive laws are estimated based on the well-known Treloar's test data on vulcanized rubber material. Additionally, comprehensive parametric analyses are conducted on the nonlinear dynamic behaviors of the hyperelastic structure simulated by different constitutive laws. The deformation evolution process, resonance curves, time-frequency analysis, bifurcation diagrams, and phase portraits are employed to demonstrate the similarities and differences in the nonlinear dynamic behaviors (i.e., super- and sub-harmonic resonance, internal resonance, chaotic motion and bifurcations) of the hyperelastic structure modeled by different constitutive laws.

Design and fabrication of recyclable and reshape vitrified elastomer reinforced with renewable cellulose nanocrystal

Developing the recyclable elastomeric vitrimer with dynamic covalent bonds is a very promising strategy to alleviate the burden of traditional vulcanized rubber materials on the environment. In this work, we proposed to introduce epoxidized soybean oil (ESO) as a cross-linking agent into carboxyl nitrile butadiene rubber (XNBR)/TEMPO-oxidized cellulose nanocrystals (TO-CNC) composites, and successfully prepared ESO-cured XNBR/TO-CNC elastomeric vitrimer with dynamic β-hydroxyl ester bonds, which are formed between the epoxy group of ESO and the carboxyl group of XNBR or TO-CNC. The TEMPO oxidation of CNC is validated by a series of characterizations such as FTIR, conductometric titration, and element analysis. The formation of the β-hydroxyl esters is as well evidenced by the FTIR analysis and the curing curves. Interestingly, the TO-CNC exhibits good dispersion in the composite, and a remarkable mechanical reinforcement is observed for ESO-cured XNBR/TO-CNC elastomer, for instance, the tensile strength of the composite with 15 phr TO-CNC was 2.4 times greater than that of the unfilled sample. Moreover, this composite as well shows good reshaping capability and reprocessability. Generally, this work offers a novel approach to preparing green cross-linked elastomer/bio-based CNC composites that can potentially overcome the bottleneck of the non-recycling of traditional vulcanized rubber.

Research on Combustion Characteristics of Vulcanized Rubber Based on Fire Propagation Apparatus

Vulcanized rubber is widely used as a vibration damping material for high-speed train floors. This paper aims to study the combustion characteristics of vulcanized rubber materials under fire propagation apparatus at 20-50 kW/m2. The results show that the ignition time and the time to peak heat release rate of the vulcanized rubber decrease with the increase of the external heat flux, and the transformed ignition time (l/tign)n increases linearly with the external heat flux. The fire risk of vulcanized rubber and the possibility of flashover increase with the increase of external heat flux. In addition, higher external heat flux will accelerate the generation of smoke in the fire scene, threatening the lives of people on the train. These data and results can be used to evaluate the interior materials of high-speed trains.

Suitability of devulcanized crumb rubber for oil spills remediation

Oil spills are common issue in the oil and gas industry. According to OECD statistics a world production of crude oil is slowly increasing since 2010 [1]. Meanwhile, according to ITOPF, a number of spill incidents (greater than 7 tons) from tankers is decreasing [2]. Efficient recycling of vulcanized rubber materials is in up-to-date agenda of the European Union. Current paper discusses a suitability of devulcanized crumb rubber for oil spills remediation. The significance of the topic comprises an extensive application of crumb rubber and devulcanized crumb rubber for oil spillage remediation with further use of rubber-oil mass in road construction industry. In order to increase an efficiency of oil sorption an application of impact disintegrator for DCR-milling is suggested.

Vulcanization reaction of squalene and S8 powder studied by Sulfur K-edge NEXAFS under liquid phase

Vulcanized rubber materials are useful in our surroundings. However, detail structure and reaction are not revealed even in present. Since squalene molecule possesses some same properties compared with natural rubber, we have prepared the samples of vulcanized squalene at 140 °C for several hours. To understand the vulcanization reaction,sulfur K-edge NEXAFS measurements have been carried out for the vulcanized squalene under liquid phase with He-path system and fluorescence detection mode. Moreover, we have tried curve fitting analysis of NEXAFS spectra. The results indicate that the squalene has been vulcanized by the S8 molecule at 140 °C and the S8 molecule length is shortened from 8 to 5-6 after the vulcanization reaction.

Dynamic Compressive Properties of Vulcanized Rubber Material from a Split Hopkinson Pressure Bar Experiment in Rubber Manufacturing

In this paper, an attempt has been made to study the dynamic mechanic properties of vulcanized rubber material which is used for industrial structure. A split Hopkinson pressure bar (SHPB) is utilized to obtain uniaxial compression response of the vulcanized rubber material under different strain-rate and temperatures loading conditions. The stress-strain curves under different conditions are obtained, which can be used as a basis for the data analysis procedure. It is found that the dynamic compressive strength of vulcanized rubber improves with the increase of strain-rate. And it is also significantly higher at low temperature than that at normal temperature，which is opposite from stiffness. Vulcanized rubber exhibits excellent superelasticity at temperature of -40°C that is noted as well.

Radial Oscillation of Incompressible Rectangular Vulcanized Rubber Sealing Rings

The oscillation problem is examined for a rectangular sealing ring composed of a class of transversely isotropic incompressible vulcanized rubber materials about radial direction, where the sealing ring is subjected to a suddenly applied radial load at its inner surface. A nonlinear ordinary differential equation that describes the radial motion of the sealing ring is obtained. It is proved that if the applied load is lower than the critical load, the motion of the rubber ring with time will present a nonlinear periodic oscillation, while if it exceeds the critical load, the motion will increase infinitely with the increasing time and so the rubber ring will be destroyed ultimately.

Electroconducting composites based on polyaniline and monomer-swollen polychloroprene

Electroconductive polychloroprene (CR)–polyaniline (Pani) composites were prepared by swelling the vulcanized rubber material in aniline followed by immersing the specimen in an aqueous solution of HCl containing ammonium persulfate as the oxidant. The results obtained from surface and volume conductivity, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) analysis suggest that the Pani component is preferentially located in the surface layer. These composites display better electrical and mechanical performance than those obtained by mixing both polymer components in the bulk state. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2329–2334, 1999