Properties of Pultruded Composites

The process is difficult to control unless one knows how to handle the exothermic chemical reactions taking place inside a pultrusion die. The highest reaction temperature must be kept below of the polymer degradation temperature (18,34). To achieve a uniform degree of cure in the cross section of a pultruded product, the temperature profile in the pultrusion die is the most important condition. 

Tabie 5 shows the flexural properties of pultruded composites (78% w/w glass fiber -polyurethane) measured at various thicknesses (34). It can be observed that the flexural properties of composites increased with decreasing die thickness that means, the less the die thickness, the greater tlK degree of conversion of composites. 

MATERIAL Die Thickness (10-2 m) Flexural Strength (MPA) Flexural Modulus (MPa) 

Usually fillers are added to the matrix in order to reduce the cost of materials, reduce shrinkage and, sometimes, to improve the mechanical properties and siqterficial appearance (surfaces without fillers could become coarse and, hence, mechanical properties could decrease). 

The shrinkage ratio of composites decreases witli increasing filler content as can be seen in Table 7 (35). 

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Table 8.2 Mechanical properties of pultruded composites (CSLLPP guidelines)...

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