Filler Precipitated silica

Schaefer, D. W. Chen, C., Structure Optimization in Colloidal Reinforcing Fillers Precipitated Silica. Rubber Chem. Technol. 2002, 75(5), 773-793. 

Moisture. The presence of water in a filler is not usually beneficial. Most fillers added to adhesives have a moisture content lower than 1 wt%. Only precipitated silicas and sepiolite contain about 5-10 wt% moisture. For some applications, fillers must be completely dried to exhibit adequate performance. Moisture absorbed on the surface of fillers impacts the rate and extent of curing of rubber base adhesives. 

Although natural quartz, cristobalite and opal are used as fillers, only synthetic products (fumed and precipitated silicas) find use as fillers in rubber base adhesives. 

Fillers. They are generally added to reinforce NBR adhesives. However, fillers can be added to promote tack, to increase the storage life, to improve heat resistance or to reduce cost. The most common fillers are carbon blacks. Precipitated silica can be used in applications where black colour is not acceptable, but excessive amounts tend to reduce adhesion. Titanium dioxide can be used to impart whiteness, improves tack and extend storage life. 

Various additives and fillers may be employed. Calcium carbonate, talc, carbon black, titanium dioxide, and wollastonite are commonly used as fillers. Plasticizers are often utilized also. Plasticizers may reduce viscosity and may help adhesion to certain substrates. Thixotropes such as fumed silica, structured clays, precipitated silica, PVC powder, etc. can be added. Adhesion promoters, such as silane coupling agents, may also be used in the formulation [69]. 

This chapter reports the results of studies on the physical, dynamic mechanical, and rheological behavior of zinc oxide neutralized m-EPDM, particularly in the presence of stearic acid and zinc stearate, with special reference to the effects of precipitated silica filler. 

Zinc salt of maleated EPDM rubber in the presence of stearic acid and zinc stearate behaves as a thermoplastic elastomer, which can be reinforced by the incorporation of precipitated silica filler. It is believed that besides the dispersive type of forces operative in the interaction between the backbone chains and the filler particles, the ionic domains in the polymer interact strongly with the polar sites on the filler surface through formation of hydrogen bonded structures. 

Filler Carbon black Natural amorphous silica, precipitated silica, nonblack nanofiller Solvent Organic solvent Aqua-based solvent... 

Journal of Applied Polymer Science 83, No.2, 10th Jan.2002, p.357-66 MORPHOLOGY AND PHYSICAL PROPERTIES OF CLOSED CELL MICROCELLULAR ETHYLENE-OCTENE COPOLYMER EFFECT OF PRECIPITATED SILICA FILLER AND BLOWING AGENT Nayak N C Tripathy D K Indian Institute of Technology... 

Precipitated silica is used to produce molecular sieves, as an anti-caking agent, and as filler for paper and rubber. Hydrophobic silica is a defoaming agent. 

Nonblack fillers such as the precipitated silicas can reduce both rate and state of cure. The mechanism appears to be one of a competitive reaction between rubber and filler for the zinc oxide activator. Use of materials such as diethylene glycol or triethanolamine prevents this competition thereby maintaining the desired cure characteristics. Neutral fillers such as calcium carbonate (whiting) and clays have little or no effect on the cure properties. 

Figure 16.23. Proton image of the polymer in a crosslinked silicone polymeric block that contains in situ precipitated silica filler.

Particulate filled EPDM mbber can be produced via conventional mixing procedures as described in [141]. Pure precipitated silica (Ultrasil VN3) and silica modified with a commerically available organosilane (Si 69), as well as carbon black (N 550) are employed as fillers.7 Unvulcanized samples for AFM observation are prepared by cutting small pieces of the compounds using a scalpel knife [(cryo)... 

Methods of filler pretreatment silane treated talc increases modulus and reduces compression set maleated or sulfonated EPDM interacts with zinc oxide esterification of precipitated silica with methanol, propanol, and hexadecanol modification of precipitated silica with methacrylic and vinyl silane calcium carbonate was modified with monoallyl and monodecyl maleate ... 

Typical fillers firmed silica, calcium carbonate, carbon black, silver, glass beads, metal powders, precipitated silica, aluminum oxide, montmorillonite. mica, zinc oxide... 

For many decades carbon black has enjoyed a practical monopoly as a filler in the tire industry. It retains this position today, the tire industiy consumes 70% of carbon black production. A major breakthrough for non-black fillers came in the early 1970s when a winter tire containing silica in its treading compound was introduced. This resulted in numerous problems with rubber compound processing. The tire compound had different flow and molding characteristics. The development initiated friendly competition (friendly because the major producers of carbon black are also major manufacturers of precipitated silica) which continues to bring improvements to tire performance. 

Fine powders being composed of particle aggregates such as precipitated silicas or white carbon are made by the decomposition of sodium silicate by sulfuric acid in an aqueous phase at high temperature. This material has microporosity as well as macroporosity due to a rapid growth and aggregation of primary particles as will be discussed later. These are used as rubber filler, paper sizing and etc. 

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