Comprehensive Polymer Processing & Rheology Notes

Manual placement of reinforcement (e.g., fiberglass mats, fabrics) into an open mold.
Resin is applied and impregnated using rollers or brushes to ensure complete wet-out of the fibers.
A gel coat can be applied to the mold surface first to create a smooth, durable exterior finish.
Characterized by low tooling costs and is suitable for producing large, complex parts.
Requires significant manual skill and can lead to high volatile organic compound (VOC) emissions.
Prepreg Lay-Up: Uses pre-impregnated materials (prepregs) that are stored cold to prevent premature curing.
Offers better control over fiber-to-resin ratio and part quality, and reduces VOC emissions compared to wet lay-up.

A process where chopped roving (fiberglass strands) and catalyzed resin are simultaneously sprayed onto an open mold surface.
The chopping action occurs directly at the spray gun nozzle.
Generally quicker than hand lay-up but results in shorter fiber lengths and typically a more resin-rich laminate.
Requires careful control of styrene emissions due to atomization of the resin.

Involves continuously winding resin-impregnated fibers (filaments) over a rotating mandrel.
The fibers are delivered under controlled tension and at precise angles to achieve specific mechanical properties.
Primarily used for producing hollow, rotational parts such as pressure vessels, pipes, and rocket motor casings.
Critical process parameters include fiber tension, winding angle, and resin viscosity, which influence interlaminar void content and structural integrity.

A continuous manufacturing process for composite materials with a constant cross-sectional profile.
Reinforcing fibers (rovings, mats, or woven fabrics) are pulled through a resin bath, where they are impregnated with a thermoset resin.
The wetted fibers then pass through a heated die, which cures the resin and forms the final part geometry.
Known for producing parts with a very high glass fiber percentage, leading to high strength and stiffness.
Commonly used for manufacturing structural profiles like beams, ladder rails, and window frames.
Limited to producing parts with a constant cross-section along their length.