Pultrusion characteristics

Table 11.2 Characteristics of Theremoset Matrixes Commonly Used in Pultrusion [3]...

The characteristics of the three most common thermoset resin systems used in pultrusion are compiled in Table 11.2 [3]. It is noteworthy that unreinforced polyesters and vinylesters shrink 7-9% upon crosslinking, whereas epoxies shrink much less and tend to adhere to the die. These epoxy characteristics translate into processing difficulties, reduced processing speed, and inferior component surface finish. It is normal practice to use resin additives to improve processability, mechanical properties, electrical properties, shrinkage, environmental resistance, temperature tolerance, fire tolerance, color, cost, and volatile evaporation. It is normally the resin, or rather its reactivity, that determines the pulling speed. Typical pulling speeds for polyesters tend to be on the order of 10-20 mm/s, whereas speeds may exceed lOOmm/s under certain circumstances. Apart from the resins characterized in Table 11.2, several other thermosets, such as phenolics, acrylics, and polyurethanes, have been tried, as have several thermoplastics (as will be discussed in Sec. 11.2.6). 

Thermoset polymeric esters consisting of neopentyl glycol, propylene glycol, trimethylol propane, adipic acid, maleic anhydride, and 2-ethyl hexanol were prepared by McAlvin et al. (3) and were used in blends containing styrene monomer. The mixture was cured by pultrusion and had improved weatherabil-ity characteristics. 

VE polyurethane resins have mechanical properties similar or superior to those of conventional VE and epoxies. Characteristics include a heat distortion temperature of 120C (248F). Ultimate elongation of an unreinforced molding compound without fillers is 5.5% tensile strength is 80 MPa and flexural strength 150 MPa. The resins can be custom-formulated. Applications include customized automobile parts, recreational vehicles, outdoor equipment, tubs/showers and electrical parts. The resins are suitable for standard molding processes some were specifically developed for pultrusion, RIM, foam, adhesive, and polymer concrete applications. 

Epoxidised allyl soyate resin (a mixture of epoxidised fatty acid esters) copolymerised with the base Shell Epon epoxy resin is used as matrix for glass fibre reinforced composite, which is prepared using a Durapul 6000 Labstar Pultrusion machine. The lubricating quality of soybean oil-based resin significantly reduces the pulling force which improves the structural performance characteristics of the composites. Curing is carried out in an oven at 80°C for one hour, followed by heating to 177 C for 1.5 h. 

The tubes which were made by pultrusion (which guarantees good mechanical characteristics), were of good quality (external aspect, lack of defects, regular dimensions, etc) and this led to very good test results ... 

PPG Industries has introduced MatVantage - a continuous strand mat for pultrusion, offering unique laminate characteristics - and new low-catenary conventional rovings plus three new chopped strands for thermoplastics. Type 2016 roving is for direct-draw filament winding for oilfield composite pipe and... 

Yun and Lee (2004) investigated pultrusion of phenolic foam composites. The effect of process variables on the foaming characteristics of phenolic resin during pultrusion was studied experimentally with the consideration of variables such as the heating temperature, the pulling speed and the mass fraction of the blowing agent. 

The FRP rebars are generally manufactured by the pultrusion technique from thermosetting resins such as continuous carbon, glass or aramid fibres embedded in polyester, vinylester or epoxy matrix (Nanni, 1997 ACI, 1996 Pilakoutas, 2000 Bank, 2006). Their geometric cross-sections are typically round, square or rectangular and have smooth surfaces these must be modified to improve the bond characteristics between the concrete and the rebar. The improvements in bond characteristics are effected by forming ... 

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