Rubber blends viscoelasticity

Chlorinated polyethylene-natural rubber blends Viscoelastic changes and thermal degradation — 134... 

Darestani Farahani et al. used RPA to study viscoelastic parameters of natural rubber/reclaimed rubber blends. Viscoelastic behavior of compounds was studied in strain sweep mode at 100 °C, strain range 1-1,200 % and frequency 10 cpm (cycle per minute). They found that torque (S) increases in higher shear strains. 

Extruded films of PP/rubber blends [89] showed that the CO2 concentration is higher in the rubber domains than in the PP matrix. In addition, as expected, the rubber domains were the only place where the porous phase can develop according to different CO2 solubility and viscoelastic behavior of both phases. Nanostructured PP/TPS blends were foamed with a saturation stage performed at 20 MPa and 25°C during 1 h, followed by a pressure release at a rate of 1 MPa/s and a foaming stage at 120°C. In this study the 80-PP/20-HSIS blend presented the best results, with pore sizes of approximately 200-400nm but low porosities below 25% (Fig. 9.19). Another remarkable output from this study is the perfect relationship found between the sizes of the rubber domains of the precursor and the pores of the foam as well as between the shape and orientation of the nanostructure of the precursor and the porous structure of the foam. 

The mechanical and viscoelastic behaviours of natural rubber based blends and interpenetrating polymer networks (IPNs) are fimctions of their structures or morphologies. These properties of blended materials are generally not constant and depend on the chemical nature and type of the polymer blends, and also enviromnental faetors involved with any measurements. Preparations of natural rubber blends and IPNs are well known as effeetive modifieation methods used to improve the original meehanieal and viscoelastie properties of one or both of the eomponents, or to obtain new natural rubber blended materials that exhibit widely variable properties. The most common consideration for their mechanical properties include strength, duetility, hardness, impact resistance and fracture toughness, each of which can be deformed by tension, compression, shear, flexure, torsion and impaet methods, or a eombination of two or more methods. Moreover, the viseoelastieity theory is a way to predict the behaviours of deformation of natural rubber blends and IPNs. The time and... 

Viscoelasticity is one of the important mechanical properties of blended materials. Viscoelastic behaviour is the intermediate character between liquid and solid states that combines the viscous and elastic responses under mechanical stress. When a force is applied to blended materials, they can flow in the same as being liquids. The natural rubber blended materials do not stretch, but they will only gradually return to their original shapes when the force is released. This property depends on temperature, pressure, time, chemical composition, molecular weight, distribution, branching, crystallinity, and the composite of blending conditions and systems. ... 

The viscoelasticity can be categorized as either linear or nonlinear, but only the linear viscoelasticity can be described theoretically with uncomplicated mathematics. The fundamental viscoelastic parameters of a linear viscoelastic system do not depend on the magnitude of the stress or strain. Therefore, the linear viscoelastic regime is always used for studying the mechanical properties of viscoelastic blended materials. One of the accepted techniques for investigating the viscoelastic behaviours of natural rubber blended materials is the... 

Mechanical and Viscoelastic Properties of Natural Rubber Blends and IPNs... 

Natural rubber based-blends and IPNs have been developed to improve the physical and chemical properties of conventional natural rubber for applications in many industrial products. They can provide different materials that express various improved properties by blending with several types of polymer such as thermoplastics, thermosets, synthetic rubbers, and biopolymers, and may also adding some compatibilizers. However, the level of these blends also directly affects their mechanical and viscoelastic properties. The mechanical properties of these polymer blended materials can be determined by several mechanical instruments such as tensile machine and Shore durometer. In addition, the viscoelastic properties can mostly be determined by some thermal analyser such as dynamic mechanical thermal analysis and dynamic mechanical analysis to provide the glass transition temperature values of polymer blends. For most of these natural rubber blends and IPNs, increasing the level of polymer and compatibilizer blends resulted in an increase of the mechanical properties until reached an optimum level, and then their values decreased. On the other hand, the viscoelastic behaviours mainly depended on the intermolecular forces of each material blend that can be used to investigate the miscibility of them. Therefore, the natural rubber blends and IPNs with different components should be specifically investigated in their mechanical and viscoelastic properties to obtain the optimum blended materials for use in several applications. 

More systematic study of resin-rubber blends was reported by Class and Chu. i i ) It revealed the relationship between the structure, concentration, and molecular weight of the resin and their effect on the viscoelastic properties of the rubber-resin composition. These authors also attempted to correlate the viscoelastic properties of the adhesives and its PSA... 

Non-linear Viscoelastic Behaviour of Rubber-Rubber Blend Composites and Nanocomposites Effect of Spherical, Layered and Tubular Fillers... 

Abstract This chapter deals with the non-linear viscoelastic behaviour of rubber-rubber blend composites and nanocomposites with fillers of different particle size. The dynamic viscoelastic behaviour of the composites has been discussed with reference to the filler geometry, distribution, size and loading. The filler characteristics such as particle size, geometry, specific surface area and the surface structural features are found to be the key parameters influencing the Payne effect. Non-Unear decrease of storage modulus with increasing strain has been observed for the unfilled vulcanizates. The addition of spherical or near-spherical filler particles always increase the level of both the linear and the non-linear viscoelastic properties. However, the addition of high-aspect-ratio, fiber-like fillers increase the elasticity as well as the viscosity. 

Non-linear Viscoelastic Behaviour of RubbCT-Rubber Blend Cranposites and. 

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