Pultrusion process standards

Like the pultrusion process, the selection of a suitable thermoplastic matrix material mainly depends on the desired mechanical properties and the desired long-term service temperature. The range of usable matrix materials starts with standard polymers such as polyethylene (PE) or polypropylene (PP) and ends with high performance polymers such as polyetherimide (PEI) or poyletheretherketone (PEEK). Recent developments have shown that the processing of reactive thermoplastic materials is possible as well (CBT). For some physical properties of common matrix materials see Table 8.2. °... 

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. 

A visual check on the finished product will not only be a measure of the quality but also a check on the production process. Defects such as pinholes and blisters in the resin should be checked against an agreed Standard and, where possible, adjustments made to the production process, such as the pull speed in pultrusion, to eliminate the problem subsequently. 

Owing to the capital investment, pultrusion is generally not a viable option if the quantity of profile is less than about 5000 m, but above this level it is an extremely efficient process. Some manufacturers keep stocks of standard sections, enabling relatively small quantities to be obtained at reasonable cost. 

In 1968, Morgan joined a team at Courtaulds to manufacture carbon fibers and subsequently set up and managed a control laboratory to monitor production. He later became involved with production aspects relating to carbon fiber prepreg and pultrusion. Morgan took on the additional role of chief quality inspector in 1976 and gained approval for the production processes to Defence Standard 05-24, the forerunner of BS 5750. In 1980, he was appointed to Courtauld s Carbon Fibres division board as director with technical responsibilities. 

Clariant has found that use of APP, such as Exolit AP422, and red phosphorus, Exolit RP65x family, in combination with ATH allows useful formulations to be prepared that meet these standards with relatively low loadings of fillers. These can be around 50-70 phr in place of the 150-250 phr for ATH alone. The low viscosity of the resin mixes allows processing by all the conventional methods, such as RTM, hand lay-up, pultrusion etc. 

Pultrusion Pultrusion is the continuous, automated closed-molding process that is cost effective for high volume production of constant cross sectional parts. Pultruded custom profiles include standard shapes such as channels, angles, beams, rods, bars, tubing and sheets. 

Pultrusion is one of the fastest growing processes within the industry for manufacturing composite products. The developments such as standards available to date, global market scenario, novel applications and future trends of the pultrusion industry are of interest to composite manufacturers and researchers. 

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