More in

Bradford team gives pipes super strength

Engineers at Bradford University have developed a technique claimed to give ordinary plastic pipes ‘super strength’.

A cross section showing a die-drawn pipe
A cross section showing a die-drawn pipe - University of Bradford

The die-drawing process turns ordinary plastic into a lighter, stronger material. The process is now being commercialised by Saudia-Arabian company SABIC.

According to the team, the new pipes outperform standard plastic plumbing pipes in pressure tests, are much cheaper to transport and last longer, and will therefore be more sustainable.

SABIC aims to capture 20 per cent of the market with the new ‘biaxially oriented’ polyethylene and polypropylene pressure pipes.

Dr Fin Caton-Rose, who runs the research laboratory in the university’s Polymer IRC, said: “Biaxially oriented pipes are lighter and much stronger than traditional polyolefin pipes. They are cheaper to make, cheaper to transport and they last longer which means they are better for the environment.”

Biaxially oriented pipes are created using ordinary plastic that has been drawn through a die, or in this case, through a die and over a mandrel - this process changes the properties of the plastic at the molecular level, making them far stronger and more durable than traditional plastic pipes.

Dr Caton-Rose explained: “Most people will be familiar with the plastic yokes that were widely used to keep cans together on supermarket shelves. If you were to pull those apart with your hands, you will notice part of the plastic turns white. This indicates you have changed the properties of that part of the plastic. If you were to then try to pull that apart, you will find you cannot, because it is now much stiffer.

MORE IN MATERIALS

“Pulling plastic through a die has a similar effect, in that it forces the molecules in the plastic to realign, so they are all facing the same direction, which makes it much stronger. In our biaxial pipes, we use a combination of a die and a mandrel to give us a balanced molecular alignment down the length of the pipe and through its thickness.”

Dr Ajay Taraiya from SABIC said that the collaboration is crucial in terms of the research the Bradford team can conduct to accelerate solutions for commercial products.

“We selected the University of Bradford based on our needs and their expertise. Scientists there have a wealth of knowledge in the solid-phase deformation of polymers," said Taraiya.

Over the last few years, SABIC and Bradford University have been involved in a successful collaboration to develop the process of biaxial stretching of polyolefin pipes. This has involved linking the material design to the structure and has led to the development of high performance pressure pipes. 

These results are being applied to the development of a commercial scale pilot line by Tecnomatic in Italy and Aquatherm in Germany, both in collaboration with SABIC.

Professor Phil Coates, who invented the die-drawing process, said: “This is an exemplary collaboration between a major global company with its significant research and development, plus commercial capabilities and a world-class polymer research laboratory. It is genuinely a win-win collaboration and serves as an example of how the kind of research universities do can have a direct impact on helping industry innovate.”