Glass fiber-reinforced SPS/Nylon

To date, the practical formulations of SPS/nylon blends have consisted of SPS dispersed in a nylon matrix. There are 10, 20, and 30 weight percent glass fiber-reinforced SPS/nylon blend commercial products. 

Since nylon is the matrix phase, the glass fiber-reinforced SPS/nylon blends contain glass fibers that are surface treated to be compatible with nylon. 

The room temperature dry-as-molded (DAM) tensile stress-strain curves for 30% glass fiber-reinforced SPS/nylon blends versus 30% glass fiber-reinforced... 

Figure 163 Apparent shear viscosity versus apparent shear rate for 30% glass fiber-reinforced SPS/nylon, PBT, impact-modified (IM) SPS, and nylon at mid-range processing temperatures.

It is well known that nylon-based materials absorb water and that this affects properties and results in moisture growth. In this section, the amount of moisture absorbed and resultant moisture growth for glass fiber-reinforced SPS/ nylon blends is compared with glass fiber-reinforced nylon. 

The data for percent moisture absorption versus time of the 30% glass fiber-reinforced SPS/nylon grades versus 30% glass fiber-reinforced nylon after exposure to 90°C, 95% r.h., are shown in Figure 16.4, and the data for moisture growth of these materials are plotted in Figure 16.5. 

Figure 16.4 Moisture absorption of 30% glass fiber-reinforced SPS/nylon blends and 30% glass fiber-reinforced nylon exposed to 90°C and 95% r.h.

Glass fiber-reinforced SPS/nylon blends have shown a synergistic combination of two aspects of dimensional stability for some applications. The first is out-of-the-mold dimensional stability, or the ability to hold the dimensions of the mold during injection molding, and the second is creep resistance, or resistance to permanent deflection under load at elevated temperatures. These are illustrated briefly below. 

Figure 16.6 Skew of a wall of a divided tray, right after injection molding with glass fiber-reinforced SPS/nylon blends versus glass fiber-reinforced SPS and PBT.

Table 16.4 shows that glass fiber-reinforced SPS/nylon blends start to lose strength and elongation in the Class IV thermal stability test. In practice, the connectors exposed to this testing have maintained their functionality with no degradation in performance. 

The environmental stress crack resistance (ESCR) of glass fiber-reinforced SPS/nylon blends was characterized by exposing the surface of test bars with 0% and 1 % strains applied to drops of solvent and then observing the damage to the surface. In addition, 7-day and 30-day chemical inunersion resistance were evaluated. The results of this testing for glass fiber-reinforced SPS/nylon blends are shown in Table 16.7. 

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