Shore A hardness

Fig. 1. Relative efficiency of plasticizers where H represents Cg phthalate +, C q phthalate A, phthalate and , phthalate phr = parts per hundred mbber. Values for the trimeUitates fall in the shaded area. BSS 35 is equivalent to a Shore A hardness of 80, test method BS2782.

Cured sihcone LIM mbber can be fabricated with physical properties equivalent to heat-cured mbber (385). Shore A hardness can range from 30 to 70, depending on formulations. Typical physical properties include tensile strengths as high as 9.7 MPa (1400 psi), 500—775% elongation at break, and tear strength of >30 N/mm (180 Ib/in.). Compression sets of less than 10% can be achieved if the material is baked after processing. 

Similar blends have been made by cross-linking the E-plastomer with peroxides. This process suffers from an inherent degradation of the iPP by peroxide. In a representative formulation, a mixture of 60 parts of E-plastomer (octene commoner), 15 parts maleated (0.6%) iPP, 25 parts of EPDM, 10 parts of paraffinic plasticizer, 5 parts of dicumyl peroxide, and 1 part of stabilizer was treated at 170°C for 5 min to give a cross-linked blend with Shore A hardness 66, tensile strength 5.5 MPa, and elongation 190%. Similar blends have been made with the incorporation of a limited amount of a SEES polymer to act as a compatibilizer between the E-plastomer and the iPP. 

Figure 4.134 displays examples of swelling (%) versus Shore A hardness after immersion ofaTPV in ASTMoils. 

Figure 4.135. SBS SEBS compression set (%) after 22h at20°C versus Shore A hardness...

Fluorel" Brand 2141 Elastometer of Minnesota Mining and Mfg Co, St Paul, Minn 55119 is a fully saturated fluorinated polymer contg more chan 60% F by wt auu is non-flammable. Lt colored gum, sp gr 1.85, shore A hard-... 

Stars with 32% PSt, (PSt/15-h-PIB/34)g-C8, showed -26 MPa tensile stress. There was no appreciable difference in the tensile properties of unextracted and MEK extracted star blocks [see (PSt/15-h-PIB/34)g-C8 and (PSt/16-h-PIB/34)g-C8]. The modulus and Shore A hardness were slightly higher for the unextracted star, (PSt/16-h-PIB/34)g-C8, which maybe due to the presence of PSt contamination which acts as a rigid filler. A dramatic difference in the tensile behavior was observed when PSt content was increased. Stars with low PIB block molecular weight and high PSt content (46%), e.g., (PSt/21-h-PIB/25)g-C8, showed plasticlike behavior, i.e., it showed a high modulus, a yield point, and a short draw. Ex-... 

Rubber Shore A Hardness Specific gravity (25° C) Refractive index 20° C) Dielectric constant (1 kcxsec, 25° C) Tg, <°C) Melting Temp. °C Tensile strength (psi) % Elongation... 

Corrections to hardness readings to compensate for test piece thickness are not entirely satisfactory because the effect varies from rubber to rubber however, typical readings are shown in Figure 8.5. Bassi et al32 have derived relationships between thickness and Shore A hardness and demonstrated their agreement with experiment. 

The final product is generally an adhesive solution or an adhesive film. The film is widely used in the construction of commercial jetliners where a high degree of peel strength and good resistance to moisture is required. The cured hybrid generally has a Shore A hardness of 75 and an elongation of over 100 percent. 

Tear strength (kN/m) Shore A hardness Shore D hardness Compression set (%) Clash-Berg T10,0oo (°C)... 

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