Glass fibre modulus

As with poly(ethylene terephthalate) there is particular interest in glass-fibre-filled grades. As seen from Table 25.8, the glass has a profound effect on such properties as flexural modulus and impact strength whilst creep resistance is also markedly improved. 

Such is the anisotropy that flexural modulus may be four times as high in the flow direction as in the transverse directions. This difference may be reduced by incorporating fillers such as glass fibre or mica. 

A reinforced plastic sheet is to be made from a matrix with a tensile strength of 60 MN/m and continuous glass fibres with a modulus of 76 GN/m. If the resin ratio by volume is 70% and the modular ratio of the composite is 25, estimate the tensile strength and modulus of the composite. 

Figure 1 Illustration showing the increase in HDT at a fixed modulus by the addition of glass fibres to amorphous and semi-crystalline polymers.

Figure 3.35. Reinforced thermoplastics 100h creep modulus examples versus stress at 20°C. A figure of 4 after the acronym indicates 40% glass fibre, etc.

Finally, Figure 4.11(d) shows that glass fibre reinforcement is an efficient means to reach more suitable creep moduli. It should be noted that the modulus scale is four times that of the previous diagrams and that the load is ten times higher. 

Figure 4.61(b) displays the high creep moduli of glass fibre reinforced PA 12 for comparison with the neat PA 12 in Figure 4.61(a). It should be noted that the modulus scale is ten times that of Figure 4.61(a) and, moreover, with five to seven times heavier loads. 

Figure 4.61. (a) Neat PA 12 creep examples of creep modulus (GPa) versus time (h) under lOMPa (b) Glass fibre... 

The short-term modulus or tensile strength retention at 120°C as a percentage of the value at 20°C is roughly 30-50% for a few glass fibre reinforced grades. 

Figure 4.76 displays two examples of modulus retention versus temperature for a neat and a glass fibre reinforced polycarbonate the two curves are practically intermingled with an abrupt fall at roughly 140-145°C. 

As for the other thermoplastics, reinforcement with 30% glass fibres strongly enhances creep moduli, as seen in Figure 4.85(b), in which the modulus scale is more than three times that of Figure 4.85(a). 

Figure 4.127 shows the creep modulus of several grades of glass fibre reinforced LCPs in various conditions of sample geometry, loading and temperature. The two samples tested... 

Figure 6.8 plots the reinforcement ratios for short glass fibre reinforced polyamide (PA-GF) versus neat polyamide for six important characteristics calculated versus density and material cost. These characteristics are tensile strength, tensile and flexural modulus, impact strength, HDT A and B. 

As for glass fibres, reinforcement with continuous fibres leads to the highest performances. Compared to short glass fibres, short carbon fibres yield higher reinforcement ratios for the modulus and tensile strength but the impact strength decreases. 

Table 6.13 displays the strength and modulus of a 60% glass fibre reinforced resin for various fibre forms. The properties are roughly ... 

The (property/volume cost) ratios show that the self-reinforced polypropylene has a much higher impact resistance ratio than general-purpose GMTs and glass fibre reinforced thermoplastics but a slightly lower modulus ratio. 

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