Thermoplastic polymers pultrusion

The ring opening polymerization of cyclic monomers that yield thermoplastic polymers of interest in composite processing is reviewed. In addition, the chemistry, kinetics, and rheology of the ring opening polymerization of caprolactam to nylon 6 are presented. Finally, the rheo-kinetics modelsfor polycaprolactam are applied to the composite process of reaction injection pultrusion. 

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... 

LFT-G are produced by means of pultrusion. In a variant of the pultrusion process, endless fibers are drawn through a thermoplastic melt then partially or completely impregnated, depending on the production process, by means of a mold. Fig. 35. In another variant, mixtures of glass filaments and polymer filaments are used for pultrusion, so-called hybrid fibers. 

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. 

The selection of a suitable thermoplastic matrix material mostly depends on the desired mechanical properties and the desired long-term service temperature. Depending on the application area, there are other decision criteria known from thermoset matrix materials, which can be of major interest, for example the chemical resistance or the water absorption properties. In contrast, thermoplastic composites are normally featured with an improved toughness compared to their thermoset competitors. Table 8.2 gives an overview on properties of different common polymers which are used for the pultrusion process. 

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. °... 

Evstatiev M, Angelov I and Friedrich K (2010) Structure and properties of microfibrillar-reinforced composites based on thermoplastic PET/LDPE blends after manufacturing by means of pultrusion, Polym Eng Sci 50 402-410. 

B. T. Astrom, R. B. Pipes (1993) A modeling approach to thermoplastic pultrusion 1 formulation of models, Polym. Compos. 14,173. 

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