Pultrusion process continuous fiber reinforcement

Pultrusion is a modern technique used for producing continuous fiber-reinforced profile in which the orientation of the fiber is kept constant during cure. Although this process is utilized for both thermoplastic and thermoset resins, it is mainly suitable for thermosetting resins like polyester, epoxy and phenolic resin systems. Jute, available in continuous forms such as mat, roving, tapes, yarn, etc., is impregnated with... 

T Asai, T Ohara, T Tanaka, S Hashizume. Method of Manufacturing Continuous Fiber-Reinforced Thermoplastic Prepregs. U.S. Patent 5529652, June 25, 1996. J-M Charrier, PJ Bates, D Guillon, G Zanella. The Effect of Pin Shape on Spreading Roving Filaments for a Thermoplastic Pultrusion Process. 45th Annual Conference, Composites Institute, SPI, Washington DC, 1990, 18-A, pp 1-4. 

The surface treatment chemistry of glass fiber is normally tailored to match the product function. Reinforcement size chemistries must be compatible with a multitude of processes and with the composite material end-use performance criteria. Processes such as injection molding require chopped fibers with compatibility for thermoplastic compounds. Filament winding and pultrusion require continuous fibers with utihty in thermoset and thermoplastic compovmds. Typically three basic components cue used with glass size chemistries a film former, lubricant, and coupling agent. Readers are directed to the patent literature or [1] and [2] for more specific details. 

Extrusion. The process of extrusion is closely related to pultrusion. In extrusion, the plastic material is pushed through a die under pressure rather than drawn through with continuous fiber-reinforcement materials. Random-oriented fiber-reinforcement materials can be used in the extrusion process if they are blended with the molten plastic before entering the die. Extrusion can be used only to produce structures that have a constant cross-sectional profile along their entire length, as determined by the die profile. Quite complex cross-sectional designs can be produced in this way, but they are essentially only two-dimensional. 

C Koppernses, S Nolet, JP Fanned. Method and Apparatus for Wetting Fiber Reinforcements with Matrix Materials in the Pultrusion Process Using Continuous In-Line Degassing. U.S. Patent No. 5073413, Dec. 17, 1991. 

The impregnated tows can be used for many applications which are generally subdivided into those where the fiber reinforcement is continuous (e.g. filament winding or pultrusion) and those where the tow is cut and the unidirectionally reinforced peUets (discontinuous long fiber reinforced thermoplastics) are then further processed into parts (e.g. in extrusion or injection molding). 

Similar to the described combination of pultrusion and extrusion is the so-called pull-extrusion process, which is illustrated in Fig. 8.15. It enables the production of products which are reinforced with both continuous and discontinuous fibers in one profile. A thermoplastic polymer is molten in an extrusion unit. In a first step, the extrudate is combined with a continuous fiber strand. In the second step the remaining polymer is added with... 

Since pultrusion is an automatic and continuous process for fabricating fiber reinforced plastics, a proper pulling velocity will optimize production rate and mechanical properties. 

Pultrusion is a continuous process whereby reinforcing fibers are first pulled through a resin bath, then into a shaping and forming guide system and finally into a die where the product is generally heated and cured to its final dimensions. 

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