Development of a 2.5 µm Polyethylene Film for the High Altitude Balloon

We have developed ultra thin polyethylene film for the high altitude balloon which can float in the mesosphere. It is required that the development of thin and strong polyethylene films to reduce the weight of balloons themselves. But it was difficult to manufacture the ultra thin film under 2.8 µm in thickness by a conventional film manufacturing machine. In 2005, we developed a new machine and succeeded in manufacturing 2.5-µm-thick film. We measured its strain-stress properties at low temperature and confirmed that the film is suitable for balloons which float in the mesosphere.