High-performance prepregs

Mat and continuous glass fibre reinforcements theoretically all the thermoplastics are usable in these forms, but up to now developments have concentrated on polypropylenes (PP), polyamides (PA) and thermoplastic polyesters (PET) fibre-reinforced PEEK, polyetherimide (PEI) and polyphenylene sulfide (PPS) are used for high-performance applications. They are presented in a range of forms from stampable sheets to pellets, prepregs, ribbons, impregnated or coated continuous fibre rods. More rarely (as in the case of PA 12, for example), the thermoplastic is provided in liquid form. 

Diaminodiphenyl sulfone (DDS) cured tetraglycidyl-4,4 -diaminodiphenylmethane (TGDDM) epoxies are the mpst common composite matrices utilized in high performance fibrous composites prepared from prepregs. The structures of the unreacted TGDDM epoxide and DDS monomers are illustrated in Fig. 3. The TGDDM epoxide monomer is a liquid at 23 °C, whereas the DDS monomer is a crystalline... 

One of the most often used production procedures for fabricating a high-performance structural laminate is the Autoclave/Vacuum Degassing (AC/VD) laminating process. In this process, individual prepreg plies are laid up in a prescribed orientation to form a laminate. The laminate is laid against a smooth tool surface and covered with successive layers of glass bleeder fabric, Mylar or Teflon sheets, and finally a vacuum... 

A model has been developed for the prediction of the lay-up consolidation process during the lamination of prepreg lay-ups for the manufacture of printed circuit boards. This model can be used advantageously in prepreg material screening and in the optimization of lamination schedules for high-performance structural composites. 

Whereas other high performance fibers have exhibited annual growth rates of 15 - 25% per year in the period 1987 to 1992, boron fibers have not yet achieved major economic importance. The worldwide production decreased from 40 t in 1987 to ca. 20 t in 1996. The price of 1 kg boron prepreg has increased from 1300 DM/kg in 1979 to 3200 DM in 1995. The worldwide capacity is estimated to be less than 50 t/a. 

The use of these sensors is not restricted to high-performance composites, but can be extended to on-line monitoring of resin-transfer moulding (McIUiagger et al, 2000) and glass-polyester prepreg composite cure (Kim and Lee, 2002). 

The isothermal cure kinetics of a glass fiber-epoxy resin prepreg is investigated using high performance liquid chromatography (HPLC) and differential scanning calorimetry (DSC). The... 

While prepreg processing provides high performance composites, it is expensive. Costs include ... 

This process offers a method of producing more predictable laminated structures, for high performance applications. Prepreg tapes are mainly made of the higher performance materials, such as epoxy/carbon or PEEK/carbon. This system can also be used in filament winding. 

Prepreg and bag molding Used to obtain special high performance RP products requiring special fiber patterns and/or high fiber volume content such as 65%. These prepregs can be cut to the required shape and fitted in a mold. 

The primary function of the face sheets is to provide the required bending and in-plane shear stiffness, and to carry the axial, bending, and in-plane shear loading (Chapter 8 BEAMS). In high-performance structures, facings most commonly chosen are BPs (usually prepreg), URPs, aluminum, titanium, or stainless steel. 

In a majority of cases, the thermoset/thermoset blends are actually formulated by the fabricator or the end user during the fabrication and processing of such materials as composite prepregs, printed circuit boards, laminates, and adhesives. The formulations and compositions are often kept proprietary and are designed to meet their own individual requirements. The following are some commercially important high-performance thermoset/thermoset blend examples ... 

The family of PKs, also called polyaryletherketones (PAEKs), consists of polyetheretherketone (PEEK), polyetheretherketone-ketone (PEEKK), polyetherketone (PEK), and polyetherketone-etherketone-ketone (PEKEKK). They share similar molecular structures based upon repeating ether and ketone groups in various ratios. Cost of the resins is high but, in RPs with high-performance fibers, there are many appfications in the aerospace and defense industries, electrical and atomic installations, and industrial and electronics products. Compoimds for injection molding are available, but the major area of apphcation is with thermoplastic prepreg materials, using mats, fabrics and/or continuous fiber. 

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