Effect of filler concentration

FIGURE 9.7 Effect of filler concentration on compressive strength of DGEBA cured with 8 pph of DETA.24... 

This leads us to the conclusion that a percolation structure appears inappropriate for the modeling of filler networks in elastomers. Consequently, we will consider an alternative network structure in the next section that refers to a space-filling configuration of kinetically aggregated filler clusters. In particular, this model will be shown to be in agreement with experimental results concerning the effect of filler concentration on the storage modulus. 

Figure 8.49 shows the effect of filler concentration on fatigue resistance. The weight loss during the cycling stress experiment is caused by the reaction of ionic fragments with polymer chains. As a result of these reactions, volatile species are lost. In this experiment each sample was subjected to 60 cycles. 

Figure 9.13 shows the effect of filler concentration on torque. The smallest increase was due to magnesium carbonate and the largest due to the presence of glass fibers. The mechanical properties of filled composites are substantially improved by additions of magnesium carbonate, wollastonite and glass fiber. The most important improvement is in creep resistance (Figures 6.68 and 8.69). 

Heat conductivity of composite materials are severely and adversely affected by structural defects in the material. These defects are due to voids, uneven distribution of filler, agglomerates of some materials, unwetted particles, etc. Figure 15.18 shows the effect of filler concentration on thermal conductivity of polyethylene. Graphite, which is a heat conductive material, increases conductivity at a substantially lower concentration than does quartz. These data agree with the theoretical predictions of model. Figure 15.19 shows the effect of volume content and aspect ratio of carbon fiber on thermal conductivity. This figure should be compared with Figure 15.17 to see that, unlike electric conductivity which does depend on the aspect ratio of the carbon fiber, the thermal conductivity is only dependent on fiber concentration and increases as it increases. 

The filler effects on the chemoviscosity of thermosetting resins have not been studied extensively, but are vital to understanding the rheology of filled thermosets. For example, the effects of filler concentration on viscosity can be used in process control to monitor batch-to-batch variations or to provide essential information for research into alternative filler/resin batches. Ng and Manas-Zloczower (1993) examined an epoxy-resin system with silica filler and established that the elastic modulus of the resin can be expressed in terms of... 

Gahleitner et al. (1994) describe the rheology of talc-filled PP. They note the effects of filler concentration, particle size and dispersion on linear viscoelastic properties. 

Figure 6-9. Effect of filler concentration on the moduli of natural rubber samples (filler MX carbon black). The curve was calculated from equation (6-94). [After L. Mullins and N. R. Tobin, J. Appl. Polym. Sci., 9, 2993 (1965), by permission of John Wiley Sons, Inc.]...

Using the Kerner-Nielsen model for expressing the effect of filler concentration on Young s modulus (85) ... 

The effect of filler concentration on the complex viscosity and storage... 

Figure 8.6 Effect of filler concentration on the complex viscosity and storage modulus variation with frequency for alumina-filled low density polyethylene. (Reprinted from Ref. 44 with kind permission from Society of Plastics Engineers Inc., Connecticut, USA.)...

It is natural that tiie effect of filler concentration on steady-state... 

Lipatov IS, Nesterov AE. Effect of filler concentration on the phase separation poly(methyl methacrylate) mixtures. Polym Eng Sci 1992 32 1261-3. 

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