Weighting agents calcium carbonate

U.S. Pat. No. 5,153,241 [66] discloses composites made of thermoplastic polymers such as low-density polyethylene, polypropylene or polystyrene (90-60%) and wood pulp or sawdust (10-40% by weight) grafted with a titanium coupling agent (isopropyltri[n-ethylaminoethylamino] titanate) in acetone, along with some inorganic fillers, such as calcium carbonate and Portland cement. 

U.S. Pat. No. 6,207,729 [69] describes a similar thermoplastic composition comprising shredded and sheared cellulosic materials (33-59% by weight) such as old newspapers, magazines, kenaf, kraftboard, and so on, HDPE (33-50%), calcium carbonate (11-17%), and a coupling agent (Eusabond lOOD, 2%). 

Solid Phases. The commonest weighting agent is barite, which, in its pure form, has a density of 4500 kg/m3. The American Petroleum Institute (API) specification (12) for the density of barite is that it must be at least 4200 kg/m3. Other API specifications are the soluble alkaline metal concentrations must not exceed 250 ppm and a maximum of only 3 wt% of the barite must have a particle size in excess of 75 pm with a maximum of 30 wt% having a particle size of less than 6 m. Other suspended weighting agents are calcium carbonate and iron oxide [hematite (12)], although iron oxide is not often used due to its abrasiveness. 

Calcium pyruvate 2,4-Dintrophenol weighting agent, drilling muds Barium carbonate weighting agent, fabrics Lead sulfate... 

They also found that pre-treating the calcium carbonate with phosphoric acid resulted in the formation of higher molecular weight physisorbed material and enhanced the coupling agent effect, as assessed in a vulcanised elastomer. 

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