Test 4 Chapter 14

What is pultrusion?

A process in which continuous fiber rovings are dipped into a resin bath and pulled through a shaping die where the impregnated resin cures. 5 steps: filament feeding, resin impregnation, pre-die forming, shaping and curing, pulling and cutting.

What is filament winding?

A process in which resin-impregnated continuous fibers are wrapped around a rotating mandrel that has the internal shape of the desired FRP product. The resin is subsequently cured and the mandrel removed.

Why are laminated FRP products made by the spray-up method not as strong as similar products made by hand lay-up?

The fiber content in spray-up is limited to about 35% as opposed to 65% for hand lay-up method. Hand lay-up method is a shaping method in which successive layers of resin and reinforcement are manually applied to an open mold to build the laminated FRP composite structure. Spray-up method mechanizes the process and reduces time for lay-up, having a liquid resin and chopped fibers sprayed onto an open mold to build successive FRP laminations.

What does vulcanization do to the rubber?

The treatment that accomplishes corss-linking of elastomer molecules, so that the rubber becomes stiffer and stronger but retains extensibility.

What are some of the additives that are combined with rubber during compounding?

Traditionally sulfur, carbon black, antioxidants, fatigue and ozone protective chemicals, coloring pigments, plasticizers and softening oils.

Name the four basic categories of processes used to shape rubber.

Extrusion, calendering, coating, molding and casting.

How are FRPs cut?

Fiber reinforced polymers are cut by cemented carbide cutting tools and high-speed steel saw blades. For advanced composites, diamonds cutting tools are used. Also water jet cutting.

How is a prepreg different from a molding compound?

Prepreg: another prefabricated form for FRP shaping operations which consists of fibers impregnated with partially cured thermosetting resins to facilitate shape processing. -Molding compound: designed for use in molding operations and must be capable of flowing. Most are thermosetting polymers.

What is reinforced reaction injection molding?

RIM: two reactive ingredients are mixed and immediately injected into a mold cavity where curing and solidification of the chemicals occur rapidly. For RRIM, includes reinforced fibers, typically glass, in the mixture and has added benefit of fiber reinforcement.