Page 310 - Carrahers_Polymer_Chemistry,_Eighth_Edition

Composites and Fillers 273

FIGURE 8.7 Composite formed from the reinforcing material being present as disk-like rounded rectangu-
lar particles.

FIGURE 8.8 General forms for discontinuous-phase materials, from left, are continuous or long fi bers, short
fibers, whiskers, and particulates.

Space-age or advanced composites were front stage in the early 1960s with the development
of high-modulus whiskers and filaments. Whiskers were easily made but at that time the science

and engineering for the development of good composites had not been established. Counter, high-

modulus fibers from boron were successfully impregnated into epoxy forming high-strength and
modulus composites.
Often there is a borrowing of terms between metal-intense materials science and polymer-in-
tense materials science where there is really little relationship between the two topics. This is not
the case with metal-matrix composites (MMCs). While the materials are often different, there are a
number of similarities. For polymer-intense composites, the matrix materials are organic polymers.
For MMCs the matrix materials are typically a metal or less likely an alloy. Popular metals include
aluminum, copper, copper-alloys, magnesium, titanium, and so-called superalloys.
In polymer-matrix composites, the noncontinuous phase or reinforcement material is a fi ber

such as glass, carbon fibers (graphite), aromatic nylons, and a number of inorganic fi bers includ-
ing WC, TiC, ZrO , and Al O . For the MMCs, the discontinuous phase generally exists as fi bers,
3
2
2
wires, whiskers, and particulates (Figure 8.8). A few of the discontinuous-phase materials overlap
with the listing given for polymer-intense composites, including WC, TiC, Al O , and graphite,
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3

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