Silica compounds rubber mixing with

Rubber Mixing with Emphasis on Silica Compounds.804... 

This chapter deals with recent developments of rubber mixing and calendering. Rubber extm-sion is discussed elsewhere in this book. Although it dominates mbber mixing in the last ten years, the mixing of silica-filled tread compounds is only slightly discussed in this chapter, since another chapter in this book totally covers the mixing of silica compounds. 

The usage of this fiber can be found in construction and automobile industries. For instance, rubbers are rarely used in their unmodified form with respect to their applications. They are often mixed with fillers to improve their process ability, mechanical strength, and to reduce cost. Carbon black and silica are well-known filler that highly is commercialized. Rice husk ash in rubber compounding has drags intense interest because of its low cost, environmental preservation benefit, and an increased emphasis on the use of renewable resources (Arayapranee et al. 2005). Numerous trials have been done by the researchers which use Rice Husk as a filler for polymeric materials. Sae-oui et al. (2002) investigated the effects of filler loading on the properties of RHA-filled natural rubber (NR) materials compared with those of commercial fillers. 

The silica fillers used are given in Table 9.3. All the compounds contained 50 phr of a filler by weight. The compounds were prepared with a Haake Buchler Rheocord 750 laboratory mixer at 50 rpm and a machine temperature of 100 °C. The fresh rubber was charged and masticated for one minute. After that silica was added over a period of about 2.5 minutes. An additional 6.5 minutes was required to complete the mixing. No coupling agent was required. 

FIGURE 35.13 Typical fingerprint of a masterbatch mixing process of a solution-based styrene-butadiene rubber (S-SBR)/Silica/TESPT tread compound on a GK 320E (Harburg Freudenberger) with PES5 rotors. 

Mechanical Mixing of PFAP(II) Compounds. PFAP(II) O-ring seal formulations were mixed in a Brabender internal mixer equipped with a mixer head of 85-mL volume and cam-type blades. The mix order was as follows (1) PFAP(II), (2) silica (Quso WR82, silane-treated surface) (3) magnesium oxide and (4) bis(8-oxyquinolate)zinc(II). This compound then was placed on a small two-roll rubber mill (2 in. X 6 in.) and dicumyl peroxide was mixed in at 57°C. 

The usual commercial practice is to mix the rubber on a mill with the diamine derivative, together with filler (such as carbon black or silica) and a metal oxide. The compounded stock is then given a short press cure (typically, 0.5 hours at 150°C) and a long oven cure (typically, 24 hours at 200°C). 

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