Other Inorganic Whiskers

In addition to the aforementioned whiskers, there are many others whiskers, such as graphite (C) whiskers, barium titanate (BaTiOj) whiskers, titanium boride (TiB2) whiskers, titanium oxide (Ti02) whiskers, Si02-Mg0-Ca0 (SMC) whiskers, and so forth. Table 3.12 shows the chemical and physical properties of different whiskers. 

The average diameter, length, and L/D ratio of barium titanate whiskers produced by Otsuks, Co. Ltd. of Japan are 0.3 iim, 3 jim, and about 10, respectively. These whiskers can be used in piezoelectric composites because of their piezoelectricity when the crystal size is greater than 0.27 

Whisker Types Color Shape Density (glcm ) Diameter (pm) Length (pm) 

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Table 3.12 Physical and Chemical Properties of Other Inorganic Whiskers...

Like other inorganic whiskers, calcium carbonate whiskers have high polarity, and therefore surface modification is required for filling polymer materials. The common surface... 

Carbon fibres Potassium titanate Silicon carbide whiskers Other inorganic crystalline fibres... 

Inorganic whiskers as single crystal fibers have become a remarkable new type of filling material because of its high-intensity, heat-resistant, anti-friction, anti-corrosion, and fire-resistant properties and other special features. 

Although the price of inorganic whiskers is lower than in the past, it is still higher than that of other inorganic mineral packing. The price of relatively cheap calcium sulfate whiskers and calcium carbonate whiskers is hundreds of US dollars per tonne, but the price of calcium carbonate is tens of US dollars per tonne. Thus it can be seen that high cost hampers the... 

Three major breakthroughs in process technology have recently been made. These processes facilitate the growth from a liquid phase. They inciude the formation of (1) InP, InAs and GaAs whiskers [18] from other organic soivents by a soiution-iiquid-soiid phase transformation, (2) short carbon fibers from liquid pitch melts by centrifuging [19], and (3) silver nanowires by a novel self-assembly process [71]. Micro- and nanopillars (or micro-and nanocolumns) are a new class of short inorganic fibers. They are... 

Sustainability of the materials becomes one of the prime concerns in the research development in industries and academic institutions. The search for nonpetroleum-based fillers has accelerated the research into bio-nanofillers from biomass. In some cases, bio-based nanocomposites show unique advantages over traditional inorganic nanoparticles. Commonly used bio-nanofillers in NR are whiskers of cellulose, chitosan, nanocrystals of starch etc. The studies on these fillers are aimed at competitive production cost and equivalent properties as compared to other petroleum-based fillers. In addition, biocompatibility and biodegradability of the bio-based fillers are hoped to be retained after dispersion in the NR matrix. 

The nanocomposites based on cellulose can be made in two ways (a) the disintegrated microfibrils/nanoscale whiskers can be used for reinforcing polymers and (b) cellulose or cellulose derivatives can be reinforced by other nanoscale particles. In nanoscience and nanotechnology, cellulose and its derivatives are used as templates and surfactants for synthesizing inorganic nanoparticles for many industrial and biomedical applications. 

Man-made fibers ean be amorphous, polycrystalline, or ciystalline. The amorphous fibers inelude the man-made vitreous fibers typified by the insulation wools, which form the bulk of man-made inorganic fibers. Polycrystalline fibers include continuous carbon fibers used in composite material and specialty fibers such as Saffil. Crystalline man-made fibers include ceramic whiskers, such as silicon carbide and silicon nitride, which are used in reinforce metals and other composite materials. 

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