Materials Guide
Material manufacturers are continually developing and improving grades suitable for rotational moulding. Imagenta, work closely with raw material manufacturers on the development of new grades. See our latest collaboration with ICO Polymers:
Imagenta will work with you in selecting the correct material for your specific application. The choice depends upon the design, function, performance and cost parameters but together we can arrive at a viable designed solution.
Some basic classification of routinely rotomoulded materials are laid out below for more detailed advice please contact Imagenta.
Ultra low density (ULDPE) - A material of very high flexibility used as an elastomer where very good impact resistance, stress cracking, low temperature performance, and chemical resistance are required.
Low Density (LDPE) - A material of relatively low rigidity and surface hardness with good impact properties stress cracking and low temperature performance.
Medium Density (MDPE) - Mouldings exhibit increased rigidity and hardness compared to low density whilst retaining reasonable impact, stress cracking and low temperature performance characteristics. Certain Linear (LLDPE) grades come under this category.
High Density (HDPE). - Mouldings which require higher rigidity and surface hardness can be produced economically with these grades.
Cross-Linked (xPE) - This material contains a chemical additive which substantially improves the physical and chemical performance of the material. Although the material carries a cost premium compared with ordinary polyethylene's, cross-linked PE can be cost effective in higher performance applications. However unlike other Polyethylene's it is not possible to recycle this material cost effectively at the moment.
Ethylene Vinyl Acetate (EVA) - EVA is moulded in the same manner as polyethylene's, but has greater flexibility, impact resistance and weathering properties. It is most commonly employed where the requirement for these properties exceeds that available from low density polyethylene or ultra low density polyethylene.
Plasticized Polyvinyl Chloride (PVC) - The raw material is available in a liquid form, (plastisol) or in the form of powder. PVC is available in a wide range of grades and when processed can vary in hardness from 40 to 100 Shore A. PVC has excellent weathering and ageing characteristics and is highly resistant to certain chemicals. Flexibility, impact and temperature performances differ according to grade. Because of their elastomeric qualities, the softer grades of PVC are commonly employed where rubber like qualities are required.
Nylon 11, 12, 6 - These materials offer full engineering material performance for rotational moulding applications. In the case of nylon 11 and 12 they are processed in the presence of air without degradation of the polymer, in the case of nylon 6 an inert atmosphere has to be used (normally nitrogen) which makes processing more complex, although the lower material cost of this grade is a compensation.
Polypropylene copolymer - A material which offers greater rigidity and higher temperature resistance than PE but lower impact resistance. Grades are currently being developed with improved impact resistance albeit at increased cost.
Polyester elastomer - Polyester elastomer offers higher temperature and chemical resistance than other elastomers available for rotational moulding. Its cost places this material among the engineering polymers.
Ethylene Butyl Acetate (EBA) - EBA is moulded in the same manner as polyethylene's but has greater flexibility, impact resistance, and weathering properties. It is most commonly employed where the requirement for these properties renders low density polyethylene or ultra low density polyethylene unsuitable. Processing is a little easier than it is for EVA.
The data given is intended as a reference guideline only, we strongly advise you discuss to your specific requirements with Imagenta taking into account cost and performance before selecting a specific material type.
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For more information or to discuss your requirements, call us on 01909 472 210 or email: enquiries@rototek.com