Here are some plastics that can be used for rotational molding:

• Low density polyethylene is popular due to low costs.
• High desity polyethelene is used due its higher rigidity.
• High impact polystyrene.
• Polypropylene.
• Cellulose acetate butyrate is used for its good weatherability and scratch resistance.

Some advantages and disadvantages to consider when using rotational molding:

• Hollow parts can be molded quite efficiently with this process yet internal ribbing is not possible.
• Wall thickness is constant making variations difficult to control. Thickness can range from 1/16 to .5 inches.
• Fine detailling and textures are easy to achieve. Very large and flat areas are quite difficult to mold.
• Part are relatively stress free given the lack of pressure in the process during the molding cycle.
• In general, the process is labour and material intensive, especially if multiple parts are molded in one cavity and have to be separared.

Some break through technological developments in recent years have increased rotational molding's accessibility and effectiveness. Here are some new ares of application:

• Urathane foam used to fill rotationally molded parts:
  For added stiffness and structural strenght, double walled rotational moldings are filled with polyurethane (PU) foam. For products such as boats, the foam in some instances provides permanent buoyancy.
  
  
• Structural foam molding:
  Large, thick-walled, lightweight parts can be rotationnally molded using a multistage process that produces foam moldings having a solid outer layer. Different materials can used for each layer; for instance, each layer could be a different color, the outer layer could be impact resistant polyolefin compound, or the inner layer could be a postconsumer resin.
  
  
• Powders based on postconsumer resins:
  Pressure from environmental groups is leading some rotational molders to use post consumer resin (PCR) into their products. Most commercially available PCRs are made from high-density polyethylene (HDPE) blow-molded containers, which results in resins having lower melt indexes than do typical rotormolding resins. For rotormolding, HDPE PCR is blended with virgin resin with content ranging from 10 to 25 percent.
  
  
• Molds that dio not require release agents and coatings:
  Coating a rotational mold with fluoropolymer can improve a part's surface gloss and smoothness and reduce manufacturing costs. The fluoropolymer coating allows the polyolefin melt to flow more uniformly, which can significantly reduce pin holes in the surface of molded parts. A fluropolymer-coated mold can sometimes eliminate the need for and expensise o frepeatedly spraying the mold with a release agent.
  
  
• Water-borne release agents and coatings:
  The U.S. Clean Air Act of 1993 forced many rotormolders to change from CFC and solvent borne release agents to more environmentally safe, water-borne release agents that provide comparable performance for both part removal and durability.
  
  
• Molded-in graphics:
  Embedding a graphic into the surface or a rotational molded part is a possible addition that won't peel off. No surface pretreatments are required, nor painting equipment.
  
  

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