Rubber blends tensile testing

Abis et al. [32] also obtained evidence on compression molded blends of sPS/ SEBS of the occurrence of a phase compatibility between the components arising from the solubility of the polystyrene end-block of SEBS with the amorphous phase of sPS. In fact, although immiscible, a very fine dispersion and adhesion of the rubber particles is observed on SEM. However, contrary to the previous case, no improvement in the mechanical properties of sPS measured by tensile tests is observed, probably owing to the poorer performances of thermo-compressed samples than injection molded samples [38,39]. 

Abstract The effects of the amount of rubber, the concentration of fibres and the state of the fibre/matrix interface upon the mechanical behaviour of short glass fibre-reinforced rubber-toughened nylon 6 ternary blends are described. First, tensile tests were carried out on different intermediate materials and then on the ternary blends to derive the stress-strain curves and document the damage mechanisms. Fracture toughness tests were implemented on compact tension specimens and the results were correlated to fractographic observations and acoustic emission analysis to assess the role of the different constituents. 

Dijkstra, K., Laak, J., and Caymans, R. J. 1994. Nylon-6/rubber blends 6. Notched tensile impact testing of nylon-6/(ethylene- propylene rubber) blends. Polymer 35 315-322. 

Mechanical properties are the parameters used to measure the forces able to deform the natural rubber blended materials such as elongation, compression, twist and breakage as a function of an applied load, time, temperature or other conditions by testing materials. Results of these tests depend on the size and shape of the specimens of the tested materials. Generally, the specimens are cut into a specific shape and their mechanical properties tested with an accurate load cell capacity and crosshead speed by a tensile machine such as an Instron testing machine or universal testing machine until they deform. ... 

The most important mechanical property of natural rubber blended materials is their tensile or stress-strain relationship as shown in Figure 20.1. Stress is the force applied to produce deformation of a unit area of a test specimen. The standard unit of this value presents in Pascals (Pa) or pounds per square inch (psi). Strain is the ratio of elongation or deformation to the gauge length of the test specimen per unit of the original length. It is expressed as a... 

LLDPE and amine-terminated butadiene nitrile liquid rubber (ATBN) with di-peroxy initiator into the rubber tire powder. The compounded blends were molded into test specimens. The data showed about 50% better tensile and impact strength after compatibilization [Duhaime and Baker, 1991]. 

Mondragon et al ° reported that unmodified and modified NR latex were used to prepare thermoplastic starch/NR/MMT nanoeomposites by twin-screw extrusion. After drying, the nanoeomposites were injection moulded to produce test specimens. SEM of fractured samples revealed that chemical modification of NR latex enhanced the interfacial adhesion between NR and thermoplastic starch (TPS), and improved their dispersion. X-ray diffraction (XRD) showed that the nanoeomposites exhibited partially intercalated/exfoKated structures. Surprisingly, transmission electron microscopy (TEM) showed that clay nanoparticles were preferentially intercalated into the rubber phase. Elastic modulus and tensile strength of TPS/NR blends were dramatically improved from 1.5 to 43 MPa and from 0.03 to 1.5 MPa, respectively, as a result of rubber modification. 

The low-speed mechanical properties of polymer blends have been frequently used to discriminate between different formulations or methods of preparation. These tests have been often described in the literature. Examples of the results can be found in the references listed in Table 10.9. Measurements of tensile stress-strain behavior of polymer blends are essential (Borders et al. 1946 Satake 1970 Holden et al. 1969 Charrier and Ranchouse 1971). The rubber-modified polymer absorbs considerably more energy thus higher extension to break can be achieved. By contrast, an addition of rigid resin to ductile polymer enhances the modulus and the heat deflection temperature. These effects are best determined measuring the stress-strain dependence. 

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