Page 340 - Handbook of Plastics Technologies

PLASTICS ADDITIVES

5.20 CHAPTER 5

FIGURE 5.7 Effect of fillers on heat deflection temperature of crystalline polymers.

TABLE 5.18 Effect of Fillers on Heat Deflection Temperature
Polymer Unfilled HDT, °C Glass fiber, % Filled HDT, °C

Acetal 110 10 160
Nylon 6 60 14 205
Nylon 66 71 13 243
PBT 67 10 200
PET 70 15 210

5.2.1.13 Opacity. Opacity results from the fact that inorganic fillers and fibers are
denser than organic polymers, so the speed of light is slower, so their refractive index is
higher, so light waves are scattered and dispersed as they pass through the interface. Fill-
ers are often used to produce opacity. Conversely, to seek transparency in filled and rein-
forced polymers, one must either match the refractive indices of the two phases or reduce
the particle size below the wavelength of visible light; both of these approaches are very
difficult.

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