Vulcanized hardness type Shore

Figure 15.8 shows the evolution of the parameter of surface hardness type Shore A, depending on the concentration of nanoparticles for vulcanized NR and magnetic nanocomposites (NR/NZF). Dots represent the experimental data and the line represents the theoretical fit. Measurements were made using a typical laboratorial durometer in Shore A scale. The assay was performed in quintuplicate and measurement time equal to Is, in accordance with the international standard ISO 868 2003. The hardness type Shore A was determined from Equation (15.1) ... 

Figure 15.8 Hardness type Shore A for the magnetic nanocomposites based on vulcanized natural rubber (NR/NZF) depending on the nanoparticle concentration.

Substitute for Conventional Vulcanized Rubbers, For this application, the products are processed by techniques and equipment developed for conventional thermoplastics, ie, injection molding, extrusion, etc. The S—B—S and S—EB—S polymers are preferred (small amounts of S—EP—S are also used). To obtain a satisfactory balance of properties, they must be compounded with oils, fillers, or other polymers compounding reduces costs. Compounding ingredients and their effects on properties are given in Table 8. Oils with high aromatic content should be avoided because they plasticize the polystyrene domains. Polystyrene is often used as an ingredient in S—B—S-based compounds it makes the products harder and improves their processibility. In S—EB—S-based compounds, crystalline polyolefins such as polypropylene and polyethylene are preferred. Some work has been reported on blends of liquid polysiloxanes with S—EB—S block copolymers. The products are primarily intended for medical and pharmaceutical-type applications and hardnesses as low as 5 on the Shore A scale have been reported (53). 

Styrenic TPEs have strength properties equal to vulcanized rubber, but they do not require vulcanization. Properties are determined by polymer type and formulation. There is a wide latitude in compounding to meet a wide variety of application properties. According to application-driven formulations, Kratons are compounded with a hardness range from Shore A 28 to 95 (Shore A 95 is approximately equal to Shore D 40), sp gr from 0.90 to 1.18, tensile strengths from 150 to 5000 Ib/in (1.03 to 34.4 MPa), and flexibility down to 112°F (-80 C) (see Table 3.1).2... 

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