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258 Carraher’s Polymer Chemistry

Einstein–Guth–Gold (EGG) equation (8.3), have been used to predict changes in modulus when
spherical fillers are added.

2
M = M (1 + 2.5c − 14.1c ) (8.3)
o
Since carbon black and amorphous silica tend to form clusters of spheres (grasping effect), an

additional modification of the Einstein equation was made to account for the nonspherical shape
or aspect ratio (L/D). This factor (f) is equal to the ratio of the length (L) to the diameter (D) of the
nonspherical particles (f = L/D).
η = η (1 + 0.67 fc + 1.62 f c ) (8.4)
2 2
o

Both natural and synthetic fillers are used. Examples of such fillers are given in Table 8.1.

TABLE 8.1
Types of Fillers for Polymers
I. Organic materials
A. Cellulosic Products B. Silicates
1. Wood products 1. Minerals
a. Kraft paper a. Asbestos
b. Chips b. Karolinite (China clay)
c. Course fl our c. Mica
d. Ground fl our d. Talc
2. Comminuted cellulose products e. Wollastonite
a. Chopped paper 2. Synthetic products
b. Diced resin board a. Calcium silicate
c. Crepe paper b. Aluminum silicate
d. Pulp preforms C. Glass
3. Fibers 1. Glass fl akes
a. α-cellulose 2. Solid and hollow glass spheres
b. Pulp preforms 3. Milled glass fi bers

c. Cotton flock 4. Fibrous glass
d. Textile byproducts a. Filament
e. Jute b. Rovings and woven rovings
f. Rayon c. Yarn
g. Sisal d. Mat
B. Lignin-type products-processed lignin e. Fabric
C. Synthetic fi bers D. Metals
1. Polyamides (nylons) E. Boron fi bers
2. Polyesters F. Metallic oxides
3. Polyacrylonitrile 1. Ground material
D. Carbon a. Zinc oxide
1. Carbon black b. Alumina
a. Channel black c. Magnesia
b. Furnace black d. Titania

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