An investigation of the flow behaviour of rotationally moulded NYRIM

Nowadays the vast majority of rotational moulding companies world-wide use powdered plastic as their feedstock. In recent years however, there has been a growing interest in the use of reactive liquid systems due to the advantages they offer over powdered resins. Not only do such systems offer the easy flow behaviour of liquids but the moulding temperatures are much lower and there is no need to have a cooling cycle. However, the rotational moulding of low viscosity liquids is not well understood and there are many problems compared with powdered plastics. This paper describes the general behaviour of a reactive liquid system, NYRIM, inside a rotating, heated mould. The viscosity changes which occur during moulding are monitored and optimum conditions are identified to produce fault-free mouldings with a good wall thickness distribution.