Manufacturing of polyethylene thin films for high-altitude balloons
AssigneeAerostar International, LLC
InventorsKevin Roach, Jacques Gagne
Life of this patent
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Abstract
Aspects of the disclosure relate to manufacturing a balloon envelope for use in a stratospheric balloon system. For instance, a stream of polyethylene mixture is extruded through an extruder in order to orient molecules of polymer chains of polyethylene and to provide an oriented film. The oriented film is passed through an electron beam and thereby crosslinking the polymer chains to provide a cross-linked film. The cross-linked film is heat sealed to form the balloon envelope.
Claims16
A balloon envelope for use in a stratospheric balloon, the balloon envelope comprising:
- a plurality of gores included in the balloon envelope;
- a plurality of tendon arranged at a centerline of one or more of the plurality of gores;
- the balloon envelope including a cross-linked film comprising an extruded polyethylene mixture having oriented molecules and crosslinked polymer chains, wherein the balloon envelope is formed by a process of:
- heat bonding the cross-linked film to form the plurality of gores;
- and
- bonding each of the plurality of tendons to each of a respective one or more of the plurality of gores,
- wherein crystallinity of the balloon envelope is greater than 50% after the process, and,
- wherein TD tensile strain is less than 2 mm/mm for a tensile stress of 150 MPa at −60° C. with a 50 mm/min pull rate.
A balloon envelope for use in a stratospheric balloon, the balloon envelope comprising:
- a plurality of gores;
- and
- a plurality of tendons, each tendon of the plurality of tendons arranged at a respective one or more of the plurality of gores;
- wherein crystallinity of the balloon envelope is greater than 50%;
- and wherein a thickness of the balloon envelope less than 1.5 mil and a strength to weight ratio of the balloon envelope is greater than 1 MPa/(dt*g/cm3).
A method of manufacturing a balloon envelope for use in a stratospheric balloon, the method comprising:
- extruding a stream of polyethylene mixture through to orient molecules of polymer chains of polyethylene and provide an oriented film;
- crosslinking the polymer chains by passing the oriented film through an electron beam to produce an oriented cross-linked film;
- heat bonding the cross-linked film to form a plurality of gores,
- wherein crystallinity of the balloon envelope is greater than 50%, and
- wherein a thickness of the cross-linked film of the balloon envelope less than 1.5 mil and a strength to weight ratio of the balloon envelope is greater than 1 MPa/(dt*g/cm3).
Dependencies are inferred from the claim text.