While it might not look like it, the polyethylene in poly water tanks has a crystalline structure. This means that polyethylene is a solid material whose constituents are arranged in a highly ordered microscopic structure.
In our earlier blog, we discussed the process called ‘cooking’ by which poly tanks are manufactured.
Cooking involves placing the raw materials in a mould that is heated and rotated. The raw material melts, creating a slurry, and the rotation spreads the slurry evenly throughout the mould. Once the mould has cooled, it is opened to reveal the poly water tank.
The size and structure of crystals has a profound impact on the physical properties of polyethylene. The most important variable that affects crystal development is the rate of cooling of the slurry. Slow cooling results in larger crystals whereas fast cooling results in smaller crystals.
A controlled, stable and consistent cooling rate results in uniform crystal size and optimises the physical properties of the finished poly water tank.
If cooling is too fast, smaller grain sizes result in a harder but more brittle product.
This is important because sitting outside and exposed to the elements, poly tanks expand and contract due to temperature. In addition, the weight of water in the tank pushes outwards and downwards, and the pressure the water exerts changes with the water level in the tank.
A brittle product is less likely to accommodate continual expansion and contraction and, over time, may result in a crack and tank failure.
Rapid Plas are one of only a handful of tank manufacturers that has complete control over the end-to-end manufacturing process and has a deep understanding of the importance of controlled cooling on the properties and integrity of a poly rainwater tank.
A tank manufacturer that does not control all the production inputs is rolling the dice in terms of quality of output, and the consumer bears the risk of potential flaws or weaknesses in the finished product that might result in product failure.
If you want to explore your options and find the rainwater tank that is perfect for you, talk to our expert team to find out how we can help you. Call our team on 1800 816 299 or email sales@rapidplas.com.au with your enquiry.
