Inexpensive filler

Economic Benefits. The traditional costs of a product include raw materials, processing, overhead, and so forth. Designers and engineers considering potential composite appHcations cannot compare material costs only. Polymer composites, except for inexpensive fillers and small amounts of additives, consist mostly of resin and reinforcement, whose materials costs are usually higher than traditional materials. 

Kaohn is a common inexpensive filler used primarily as an extender in adhesive and sealant formulations. The cost of the adhesive is reduced because the kaohn addition increases the product s volume. Depending on the grade, kaohn can also... 

Microcellular fillers such as glass microballoons have been around for some time and are commonly used in syntactic foam. However, they are expensive raw materials. Sibrico Corporation, of Hodgkins, IL, has recently introduced a new, relatively inexpensive filler called Sil-Cell. This is a microsized, multiwall hollow glass filler. Sil-Cells range in size... 

Values of the thermal conductivity, k, have been determined in the present work with a thermal conductivity probe (24). It has long been known that sulfur has a low thermal conductivity although the values are even lower in such materials as PVC and expanded polystyrene. Sulfur-bonded composites made with inexpensive fillers such as soil and sand have thermal conductivities which are below those of typical portland cement concrete but with values higher than those of sulfur itself. The values for the composites are, however, still low as may be seen by comparison with the values for conductors such as steel and copper (Table II). 

Fly ash may become more extensively used as a inexpensive filler. It is not used in large quantities at the present time. Research studies" show that materials can be improved when fly ash is used as a filler. The major hurdle is health and safety since fly ash contains crystalline silica and is, consequently, considered a hazardous material. 

The performance expected from a sealant and the polymer used in its production determine the type of fillers used. From the point of view of performance, sealants can be divided into these having plastic behavior and these with elastomeric behavior. Sealants which have plastic behavior are low-cost and low-performance products which are being gradually eliminated from the market. These sealants use inexpensive fillers to lower cost and regulate non-sag properties. Typical fillers used in these products are calcium carbonate and some fibrous materials which are used as replacement for asbestos which was very popular in the past. This combination of fibrous and spherical particles provided a useful tool to the sealant formula-tor to regulate non-sag properties which are very important in sealants. Fibers have also been used to reinforce these products because the properties of polymers were poor. 

Sodium sulfate is often found in laundry detergent powders based on sodium linear alkylbenzenesulfonate. Aside from acting as an inexpensive filler, suggest other reasons for its presence and possible useful functions. 

In many countries, the largest market segment for the sale of limestone is as an aggregate in the construction and building industry. The major uses are in concrete and roadstone (both bound and unbound). Other applications include sand for mortar, rip rap, armourstone for sea defence works, land fill, filter media, pebble dash and roofing gravel. Finely divided limestone is used as an inexpensive filler for asphalt concrete. 

There is somewhat of a contradiction of discussing fillers and fibers in the same chapter. Fibers and many fillers can increase properties in very specific, desired ways yet the most common inexpensive fillers, such as calcium carbonate, are mostly used to displace the resin needed in a product to keep resin costs low (literally "filling out" or extending the volume of a product). In the first decade of the twenty-first century, when double-digit percentage increases in resin prices have been common, perhaps this use of fillers has become even more important. 

Inexpensive fillers are economically useful as "extenders" that displace more expensive resin needed in a resin system, without adversely affecting most properties. Indeed, processors often depend on increasing their use of such fillers during times of high polymer prices. 

Short fibers of cotton, wood, glass, etc., used as inexpensive filler. 

Recent studies showed that graphite nanoplatelets (GNP) or graphene could be used as a viable and inexpensive filler substitute for (3NTs (Fukushima and Drzal 2003). Typical values of the electrical percolation thresholds, which have been reported in the literature for graphene-based nanocomposites for selected polymer matrices, are presented in Table 13.3. The influence of graphene loading on the conductivity of one of the composites presented in Table 13.3 is shown in Fig. 13.2b. One can see that the electrical percolation thresholds achieved with graphene-based nanocomposites are often compared with those reported for CNT/polymer composites. 

Other systems were also selected, considering mechanical properties, processability, and cost of additives. In particular, CaCOs is an inexpensive filler, PE-g-MA and OCT/CH are also relatively inexpensive, and give some improvement of the mechanical properties. EPDM is quite expensive but it contributes to a remarkable enhancement of elongation at break and impact strength. 

One of the fascinations of working in the field of particulate-filled polymer composites is the wide variety of materials used as fillers, from relatively simple chalks and limestones to complex rare-earth magnetic powders. Even apparently, mundane, relatively inexpensive, fillers can vary in subtle, but important, ways according to their precise origin and method of manufacture, thus adding their interest to the scientific and technological mind. 

Limiting oxygen index (LOI) is the parameter most frequently used to characterize the improvements in fire retardancy. " " " " " Table 12.2 gives a summary of data obtained for various fillers. The data in Table 12.2 show that even the addition of very common and inexpensive fillers such as calcium carbonate or talc increases the LOI value. From the data presented, Sb203 and Mg(OH)2 are the most efficient in increasing LOI. 

As an example, calcium carbonate powder is an inexpensive filler with a high degree of whiteness that is widely applied to the processing of polyolefin products. The content of calcium carbonate powder is as high as 80% in the mas-terbatch. Filling with calcium carbonate dramatically reduces the cost of the product, but too much filling will lead to... 

Calcium carbonate comes from natural sources such as bone, limestone, shells, or it can be made synthehcally. It can be pure enough to take as medicine (anhacid), or it can be ground up rock with many impurities (also used as anhacid). It may be the most widely used filler. (A similar claim can be made for carbon black or carbon in ah its many forms.) Calcium carbonate is widely used in PVC as an acid acceptor, in polypropylene as a filler, and in many thermosets and thermoplashcs as an inexpensive filler. 

Clay is another common material of wide ranging properties. Like all fillers, just because one grade or type does not perform satisfactorily does not mean that all grades will fail. Some time with your vendor s technical department can pay off here in finding inexpensive filler with unique value to your application. Clay is becoming important in some nanocomposites because it can be exfoliated into nanothin platelets. 

Fly ash is another product toat comes from an increasing awareness of our environment. Some applications have been found in polymers for fly ash and in time there will be more. Modem technology is involving public relations and environmental issues more and more. Whenever these issues can be turned into commercial benefit for your company or organization that should be the direction of research when the cost can be justified. Quality products must never be sacrificed, however. Slag is also being processed into filler form for plastics. Inexpensive fillers like slag, fly ash, etc. must be carefully evaluated for toxicity. 

Calcium carbonate is another inexpensive filler used in rubber compounding as an economic diluent. 

---