Prepreg rolls

Helmet material preparation process (a) Prepreg roll, (b) Petal marking process, (c) Manual cutting, (d) Dome formation. 

Figure 1.4 CFRP waste a) out-of-date prepreg rolls b) manufacturing cut-offs c) yatch mould and d) end-of-life aircraft wings. Reproduced with permission from S. Pimenta and S.T. Pinho, Waste Management, 2011, 31, 378. 2011,...

Fibers or fabrics are impregnated with the low viscosity solution, and the solvent is removed at a relatively low temperature to provide tacky prepregs containing the three monomer reactants and 5—10% by weight of residual methanol. To prevent any reaction of the monomers, prepreg rolls protected with polyethylene films are stored at low temperature (-18 °C). 

The prepreg is prepared as the carbon paper from a roll is run at approximately 3 mmin-1 through a bath containing the resin solution. Then the impregnated paper is run through a pair of driven stainless steel nip rolls set at a gap of from 0.5 mm to remove excess resin solution and achieve the desired pick-up of 78-80% by weight of the resin solution. 

Uses Acrylic resin comonomer anaerobic adhesives and sealants printed circuit boards cosmetics artificial finger nails modifier for hard rubber rolls wire and cable coatings screen printing inks emulsion polymerization plastic modifier EB-curable coatings reactive diluent for hot-melt prepregs and adhesives... 

Properties M.w. 170.21 dens. 1.044 b.p. 52 C (0.4 mm) flash pt. 90 C ref. index 1.4580 Uses Acrylic resin comonomer anaerobic adhesives and sealants printed circuit boards cosmetics artificial finger nails modifier for hard rubber rolls wire and cable coatings screen printing inks emulsion polymerization plastic modifier EB-curable coatings reactive diluent for hot-melt prepregs and adhesives Manuf./Distrib. Aldrich http //www.sigma-aldrich.com, CPS Monomer-Polymer 8i Dajac Labs Polysciences... 

Paper roll phenolic resin prepreg /r i/75-l,4-Poly(isoprene), gutta percha (BS)... 

Layers of fibre pre-impregnated with resin (prepreg) are applied to a mould and rolled. A rubber bag is placed over the lay-up and the air is removed by means of a vacuum pump. Generally the mould is then placed in an autoclave, which applies further pressure and temperature to cure the resin, or simply in an oven. 

The mould is cleaned and a release agent or release film is applied. The backing film is removed from the prepreg surface and successive layers of prepreg are placed on the mould and rolled to conform to the mould surface. The layers are applied in a predetermined order and angle to achieve the laminate properties required. 

Dicy is soluble in 2-methoxyethanol, DMF and an acetone/H20 mix. In solventless systems, pulverized dicy is used, which is well dispersed into the resin system using either a ball or a 3-roll mill. If the dicy is in suspension in a prepreg system and the particle size is too great, it is possible that the carbon fiber reinforcement will filter the dicy out from the resin matrix, producing dicy starved areas, and result in a partial cure. Dicy can be dissolved prior to use by a technique called spiking, when the dicy/resin mix is held at 120°C for one hour. If lower temperatures are used, say 65°C, the dicy becomes encapsulated within the resin and subsequent heating at 120°C will not allow the dicy to diffuse into the resin, resulting in a product with a Tg some 50° C lower. 

This is a manual lay-up method, where prepreg tape is rolled onto a metal mandrel on a hot table. The mandrel can be truncated when required for fishing rod blanks, ski poles and aerials. When wrapping is complete, the lay-up is over-wrapped with shrink wrap tape, which contracts when heated and applies pressure to the assembly. The wrapped mandrels are suspended vertically in an oven for curing to ensure straightness of the component. 

A carbon fiber bicycle wheel rim is fabricated by Sun Rims saving 400 g over an A1 rim and with 30% less carbon than that achieved by competitors using carbon fiber braid. A core of foam is rolled into a circle to fit the mold rim periphery and a braid sleeve drawn over the core with the ends overlapped. Extra pieces of carbon fiber prepreg are positioned at high stress points, the reinforcement is impregnated with epoxy resin and the lay-up is then compression molded. The pressures are sufficient for the overlap joint to be uniformly incorporated into the rim thickness. 

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