Grade Selection for Rotational Moulding
Rotational moulding is a means of producing polyethylene articles of a size and shape that cannot be manufactured economically in any other way, and they are especially useful for poly tanks. For many years, low-density polyethylene (LDPE) powders were used for the rotational moulding process. However, more recently, linear low-density polyethylenes (LLDPEs) have taken a leading position in rotational moulding applications. As a result, Alkatuff LLDPE powders are eminently suitable for rotational moulding because of their superior crack resistance and impact performance.
The Alkatuff grade range is designed to provide optimum performance in moulding and durability. The grades provide a range in flow, balanced with excellent crack resistance. Alkatuff LL711UV is a premium tank grade providing high rigidity along with excellent processability. This material is known for its proven performance and broad processing window. For smaller mouldings where rigidity is of less importance, the higher flow Alkatuff LL705UV, again with excellent crack resistance may be suitable. Both Alkatuff LL711UV and LL705UV contain premium UV and antioxidant packages and meet the requirements of the tank standard AS/NZS 4766. Both are supported with technical data to enable Finite Element Analysis (FEA) of designs. For parts requiring higher flow and sharpness of detail, but allowing greater flexibility, the higher flow grade Alkatuff LL710UV may be considered.
Choosing a grade for rotational moulding is dependant on many things which this blog series will explore. The next post will look into the effects of melt flow index and density and how they will affect the end uses of the product.