Pultruded products

The applications of pultruded products range from sporting goods to electrical and construction. Figure 11.3 illustrates the application distribution in the United States, Japan, and Europe [2], Some applications in the respective categories of Figure 11.3 include ... 

Note that Da1 is our dimensionless mean residence time and Da" = n3. Da111 represents the ratio of the heat of reaction to the heat removed via convection. The ratio DaIV /Da111 = Ped/L = Gr represents the convection in the machine direction to the conduction through the thickness of the pultruded product. 

To produce pultruded products with consistent and high quality, it is important to tailor and control the pultrusion process. To achieve a uniform degree of cure in the cross-section of a product, control of the temperature profile inside the pultrusion die is an essential aspect. Also, to achieve consistent fibre wetting, controlled flow and pressure build-up must... 

Typical applications of pultruded products are extensive and serve many different industries ... 

A number of workers have published results on cfrp using the losipescu test [55], 4- point shear test [56], effect of specimen size [57], effect of strain rate [58], in-plane shear test [59], shear strength of pultruded product [60], rail shear test [61] and torsion test [62,63],... 

In relation to pultruded products, fiber blooming is the exposure of fibers at the surface of the product. Also, in pultrusion, undercure blooming is a dull, often whitish appearance on the surface of a pultruded product resulting from inadequate curing of the resin at the surface. 

Applications for pultruded products include ladders, electrical poleline hardware, electric motor wedges, fishing rods, archery bows, hammer and ax handles, I-beams, and T-beams. Pultrusion can also be used for on-site construction of architectural structures. 

If the resin is scratched on the mold surface, not only flie final finishing of the product surface will be lacking, but the removed resin may be absorbed in oflier surface areas of the pultruded product as well, or may even clog up flie mold itself. In this case, an intermittent pultrusion is required, in order to obtain consistent polymerization along the entire mold. If so, flie initial part of the drawing should be cured to prevent the resin from gelling outside the mold and around it... 

In civil engineering, the most common pultruded products are T- or C-shaped sheets and sections. 

Pultrusion. Another method by which thermoplastic fiber-reinforced polymers are produced is pultrusion. In pultrusion, an appropriately designed bundle of continuous fiber strands is drawn through a die along with a molten thermoplastic matrix material. The die serves to consolidate the material combination, and as the matrix material solidifies on exiting the die, a continuous fiber-reinforced structure is produced. Examples of pultruded products include fiberglass rods and reinforced water hoses. 

Sufficient distance (of about 3 m) between the die exit and the pulling device should be maintained to cool the hot pultruded product coming out of the die in the open atmosphere or in an air-cooling stream. This allows the pultrudate to develop adequate strength so as to withstand clamp and puller forces. 

It is clear from the above discussion that the resin injection process parameters have significant bearing on the quality of the pultruded product. 

Standards play an important role in the acceptance of new materials. The following standards are available regarding the manufacture, quality determination and quality assurance of pultruded products ... 

Capacity. The capacity of pultrusion equipment is steadily increasing and the future market for pultruded product may be in profiles much larger than anything possible with traditional materials such as aluminum or rolled steel sizes. The Goldsworthy Pulmaster is designed to produce profiles up to 90 cm wide and 60 cm high. 

The previously described properties of the resin types make thermosetting resins much more useful for civil engineering structural applications, and in fact they have been used in almost all commercially available FRP pultruded products. Table 9.2 presents the basic properties of the thermoset resins most commonly used in pultrusion polyester, vinylester, epoxy and phenolic. 

Examples of GFRP pultruded products for non-structural applications and secondary structures (a) insulated ladders (b) stairways with handrails (c) floor gratings (d) working platforms and walkways (e) building fagade panels (courtesy of Strongwell). 

ASTM (2010), ASTM D4385 Standard Practice for Classifying Visual Defects in Thermosetting Reinforced Plastic Pultruded Products, West Conshohocken, PA, American Society for Testing and Materials. 

Sumerak J E and Hartman P H (2000) Selective Intervall Pulshaping - Introducing variable cross-section geometry features to thermoset pultruded products, Proc Int SAMPE Symp/Exhib, May 21-25, DOI, Long Beach,... 

For pultruded products, The Design Manual of Engineered Composite Profiles by J.A. Quinn (Fibreforce, Runcorn) is invaluable. MMFG (Chatfield, Minnesota) have developed load/deflection tables for fibreglass profiles used for floor gratings. 

The fiber volrune content calculation of the pultruded product is obtained by a development similar to Eq. (10.32), that is, the total material volume normalizes the reinforcement volume for one pitch length and is adjusted with the fill ratio J p. The fill ratio is the ratio of the area of the braid (Eq. (10.32)) over the die exit area. Note that the angle 0 is the consolidated BY angle. 

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. 

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