11 Following total carbonation, a suspension of CaCO3 results. A cake comprising 40
- 60 solid matter depending on particle diameter is then obtained by filtration. This filter cake is then dried and subsequently deagglomerated in grinders. Ultrafine
PCC grades are reacted with fatty acids prior to filtration i.e. when still in the suspension stage Freeman, et al., 2002.
The fineness of the grain, as well as the crystal form aragonite, calcite, is controlled by
temperature, concentration of reactants and time.
Depending on the chemical composition of the milk of lime used and on the purifying stages during production, both technical as well as foodstuff and
pharmaceutical grades can be produced Freeman, et al., 2002.
Figure 2.2: Manufacturing Process for Nano Precipitated Calcium Carbonate
2.5 Filler
Fillers are particles added to material plastics, Composite material, Concrete to lower the consumption of more expensive binder material or to better some
properties of the mixtured material. Worldwide more than 50 million tons of fillers with a total sum of ca. 25 billion Euro for different application areas, such as paper,
plastics, rubber, paints and adhesives, are consumed annually. As such, fillers,
12 produced by more than 700 companies, rank among the worlds major raw materials
and are contained in a variety of goods for daily consumer needs http:en.wikipedia.orgwikiFiller_materials – online on – 28 August 2010
Formerly, fillers were used predominantly to cheapen end products. Today, it has been proven that fillers are also able to enhance technical properties of the products.
As a result, a number of optimized types of fillers, nano-fillers or surface treated goods have been developed. Among the 20 most important fillers, Calcium carbonate
holds the largest market volume and is mainly used in the paper industry and increasingly in the plastics sector. While formerly ground calcium carbonate was
used, today precipitated calcium carbonate which is manufactured with the natural mineral is increasingly applied to enhance technical properties of the end product.
2.6 Acrylonitrile-Butadiene Rubber NBR
Nitrile Rubber NBR is commonly considered the workhorse of the industrial and automotive rubber products industries. NBR is actually a complex family of
unsaturated copolymers of acrylonitrile and butadiene. By selecting an elastomer with the appropriate acrylonitrile content in balance with other properties, the rubber
compounder can use NBR in a wide variety of application areas requiring oil, fuel, and chemical resistance. In the automotive area, NBR is used in fuel and oil handling
hose, seals and grommets, and water handling applications. With a temperature range of –40C to +125C, NBR materials can withstand all but the most severe automotive
applications. On the industrial side NBR finds uses in roll covers, hydraulic hoses, conveyor belting, graphic arts, oil field packers, and seals for all kinds of plumbing
and appliance applications. Worldwide consumption of NBR is expected to reach 368,000 metric tons annually by the year 2005.
Like most unsaturated thermoset elastomers, NBR requires formulating with added ingredients, and further processing to make useful articles. Additional ingredients
typically include reinforcement fillers, plasticizers, protectants, and vulcanization packages. Processing includes mixing, pre-forming to required shape, and
