Rotational molding polycarbonate

Focusing collectors are usually cast acrylic Fresnel lenses, or mirrors of aluminized polyester film in frames of aluminum. These reflectors are either enclosed in a bubble of poly(vinyl fluoride) film, or under polycarbonate glazing, which may be covered with a fluorocarbon film to reduce the reflectivity. The absorbers for active systems are copper or aluminum since the temperatures are too high (325—370°C) for plastics. The frames, however, can be molded ABS, high density polyethylene or polyurethane, either solid or structural foam. Polybutylene or chlorinated PVC can be used for piping hot water, and tanks can be made of either reinforced polyester or blow- or rotational-molded, high density polyethylene (12—15). 

This technique, termed rotational molding (e.g. Engel Process), can be used with thermoplastic materials such as polyethylene, polypropylene, nylon, polycarbonate and polyurethane. The powdered plastic is placed in a mold and heated externally in an oven chamber to about 220-400°C, whilst it is rotated around both vertical and horizontal axes. As the powder melts, it adheres to the inner mold surface, building up an even layer over the surface of the mold. The mold, whilst still rotating, is withdrawn from the heated chamber and moved into a cooling chamber and the component removed after solidification [85]. 

The copolymers are used for waterproofdjreathable outerwear air-conditioning hose underhood wire covering automotive bellows flexible keypads decorative watch faces rotationally molded basket-, soccer-, and volley balls and athletic footwear soles. They are insert-molded over metal cores for nonslip handle covers (for video cameras) and coinjected with polycarbonate core for radio/TV control knobs. ... 

Fatty acid esters are commonly used as intemal/extemal release agents. PVC is the most typical application, but they work well also on acrylic and polycarbonate. They do not reduce clarity. Fatty acid esters and amides do not usually interfere with the secondary finishing operations, and some have high temperature stability, making them well suited for rotational mold resins and engineering plastics. Fatty acid... 

Most common thermoplastics, such as polyethylene, polyvinyl chloride, nylon, polycarbonate, acetate butyrate, and polypropylene, are suitable for the rotational molding process. In recent years, some thermosetting formulations have been found successful. 

Materials. Rotational molding is restricted to the use of thermoplastics that are specially formulated to woric well with the process. The normal materials of choice are primarily olefins (polyethylene or polypropylene), although PVC, polycarbonate and nylons are also used. 

Many polymers can be purchased as finely divided powders. These include polyethylene, polycarbonate, nylon, and rigid or lightly plasticized polyvinyl chloride. Highly plasticized polyvinyl chloride comes in a plastisol form. After the material is charged into the mold it is clamped shut prior to heating and rotation. 

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