Part One: The Rotational Molding Industry

Other Plastic Materials, Composites and Additives

Other Plastic Materials, Composites and Additives

Although the practical choice of polymers for rotomolding is limited, a number of other thermoplastics and thermosets have been rotomolded, at least experimentally. In most of these special cases, markets have not grown large enough to justify the development of the specially compounded plastics that would be suitable for the rotational molding process. The following list of plastic materials are used occasionally for the rotational molding of highly specialized products:

1. LDPE
2. Acetal
3. Acrylic
4. Cellulosics
5. Epoxy
6. Fluoropolymer
7. Phenolic
8. Polybutylene
9. Other Grades of Nylon
10. Polyurethane
11. SAN
12. Silicone
13. Polyesters
14. EVA
15. EBA

The properties and appearance of materials may be modified with additives. Most rotomolding materials will incorporate an antioxidant package, which prevents degradation by heat during processing. Most rotomolding applications require outdoor weatherability, which will necessitate inclusion of UV stabilizers. Other common additives are flow lubricants and antistatic agents

Colorants, which are normally solid pigments, are very commonly used in rotomolding formulations, to enhance aesthetic appearance. The colorant can be dry blended into the powdered polymer, often by the rotomolder, or can be supplied as a finished product using hot melt compounding of pigment into base polymer, followed by subsequent grinding into a suitable powder.

Fillers, extenders and fibers can also be added. These are generally low-cost inorganic materials which increase bulk and thereby reduce the material cost. The physical properties of such extended materials will be significantly reduced, so they can only be used for non-critical applications.