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Chapter 1 Introduction to Pultrusion

Pultex® standard structural profiles are used in many highly-corrosive applications.

Creative Pultrusions, Inc. is The World’s Most Innovative Leader in the Fiber Reinforced PolymerComposites Industry. Established in 1973, the company operates in two manufacturing locations: AlumBank, Pennsylvania (Corporate Headquarters) and Roswell, New Mexico; Technology Center: PultrusionDynamics Division, Oakwood Village, Ohio; Creative Pultrusions International Ltd., United Kingdom;and a complementary Worldwide Distribution Network. Pultex® is the registered trademark of CreativePultrusions, Inc. (CP) for products made by the pultrusion process. Pultex® profiles are Pultruded FiberReinforced Polymer (FRP) components, manufactured from a wide variety of high performancethermosetting resins and reinforcements, classifying pultrusion as a structural engineering material. As aresult, Pultex® profiles have been used extensively in many industries for construction, corrosion-resistant, electrical/electronic, transportation, consumer and water/wastewater applications.

Within the last two decades, the pultrusion process has been used by the design engineer as having thecapability of manufacturing products that solve many modern problems. As a result, high-strength, light-weight and maintenance-free products and structures have been designed and built.

The New and Improved Pultex® Pultrusion Global Design Manual is developed to aid the design engineerin understanding the pultrusion process and how various elements of the process and design affect theperformance and cost of the final product.

The information provided is the result of many years of participation with industries worldwide.Applications vary from the development of new high-performance springs and bumpers for theautomotive industry to corrosion-resistant structural I-beams, channels and angles for the chemicalprocessing industry.

With The New and Improved Pultex® Pultrusion Global Design Manual, you, the design engineer, willshare in the knowledge and experience to assist in the design of your future pultrusion requirements.

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Pultex® Pultrusion Process

An integrated building system is lightweight, easy to erect and maintenance-free.

Fiberglass platform systems are idealin highly corrosive areas.

Bridges are easily installed in hard-to-access areas.

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Pultex® Pultrusion Process (cont’d)

Pultrusion is a continuous molding process using fiber reinforcement in polyester or other thermosettingresin matrices.

Pre-selected reinforcement materials, such as fiberglass roving, mat or cloth, are drawn through a resinbath in which all material is thoroughly impregnated with a liquid thermosetting resin.

The wet-out fiber is formed to the desired geometric shape and pulled into a heated steel die. Once insidethe die, the resin cure is initiated by controlling precise elevated temperatures. The laminate solidifies inthe exact cavity shape of the die, as it is continuously pulled by the pultrusion machine.

Process Advantages

The process provides maximum flexibility in the design of pultruded FRP profiles. Currently, profiles upto 1.83 m wide and 0.53 m high are possible. Since the process is continuous, length variations are limitedto shipping capabilities.

Specific strength characteristics can be designed into the composite, optimizing laminate performance fora particular application by strategic placement of high performance reinforcements. Color is uniformthroughout the cross section of the profile, eliminating the need for many painting requirements.

Processing capabilities include the production of both simple and complex profiles, eliminating the needfor much post-production assembly of components. Pultex® profiles can result in more satisfactoryperformance of your finished products and structures.

Raw Materials Used in the Pultrusion Process

ResinSelected high performance polyester resins are combined with suitable fillers, catalysts, UVinhibitors and pigments to formulate the resinous matrix, binding the fibers together and providingthe structural corrosion resistance and other properties required. Although the vast majority ofapplications can be serviced by the variety of polyester resins available, certain application

Each resin mix is formulated carefully to suitapplication requirements.

Roving and mat are of major importance indetermining physical properties.

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requirements of higher strength or corrosion resistance can be satisfied with the selection of vinylester.

RovingFiberglass roving provides the high longitudinal strength of pultruded products. The amount andlocation of these reinforcements can be determined in the design stage and can alter the subsequentphysical properties of the finished product. Roving also provides the tensile strength needed to pullthe other reinforcements through the die; therefore, it is a necessary ingredient in the profile design.

MatContinuous strand mat provides the most economical method of obtaining a high degree oftransverse physical properties. The mats are layered with roving; this process forms the basiccomposition found in most pultruded products. The ratio of mat to roving determines therelationship of transverse to longitudinal physical properties.

VeilSince pultrusion is a low-pressure process, fiberglass reinforcements normally appear close to thesurface of the product. These can affect the appearance, corrosion resistance or handling of theproducts. Surface veils can be added to the laminate construction to displace the reinforcementfrom the surface adding a resin-rich finish to the profile. The two most commonly used veils areA-glass and polyester .

Pultex® Resin Systems

Resin mixtures, glass content and their combination can be altered to achieve special properties in aprofile due to the versatility of the pultrusion process. The specific resin formula may be adjusted foreach profile due to processing requirements.

Table 1-1 Available Resin Systems

Pultex®

Resin Series CharacteristicsTypical

Applications1500Polyesters

Good chemical resistance combined with highmechanical and electrical properties.

Standard Structurals used in moderately corrosive environmentsCrossing gate armsDunnage barsLadders

1525Fire RetardantPolyesters

A flame spread rating of 25 or less when testedper ASTM E-84 plus the attributes of 1500Series profiles. UL 94 VO rating also availableon request.

Fire retardant standard structurals

1600Vinyl esters

Excellent corrosion resistance, as well as,improved physical properties and elevatedservice temperature capabilities.

High performance standard structurals

1625Fire RetardantVinyl esters

Same as Series 1600 plus the added bonus of a25 or less rating per ASTM E84 and lowsmoke generation.

High performance standard structurals for severely corrosive environments

2020Low Profile ModifiedPolyester Resin System

Profiles requiring optimum surface finish Transportation

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Table 1-1 Available Resin Systems (cont’d)Pultex®

Resin Series CharacteristicsTypical

Applications3535Modified Polyester

Halogen free, low flame and smoke. Mass TransitElectrical

Reference The Pultex® Product Availability List for stocked items.Other special resin systems are available; please contact the Engineering Department of CreativePultrusions, Inc.

Woven and Stitched Fabric

When the mix of required physical properties is not satisfied by conventional mat rovingconstruction, selected fabrics can be used to meet the end use requirements. Varieties of theseproducts can be used by themselves or in conjunction with the standard mat roving construction toobtain the necessary results. The fiberglass fabrics are available in balanced, high longitudinal, hightransverse or ± 45° multi-ply construction. Since these materials are more costly, the compositesusing these reinforcements are more expensive than standard construction pultrusion.

Other Reinforcing Material

Carbon and aramid fibers are also used in the pultrusion process in roving, woven fabric forms, orin combination with fiberglass. These high modulus fibers add considerable stiffness to thecomposite. Care must be taken when designing profiles with carbon and aramid fiber materialssince they are more costly. The composite should be designed for optimum performance.

Surfacing veils enhance the finishedprofile and increase corrosion

resistance.

Woven/stitched goods increase transverseproperties of pultruded profiles.