Cross-Linked Polyethylene Balloon Film for Strength Consistency
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Solution Overview
Problem
Current polyethylene films used in stratospheric balloons suffer from inconsistency in strength and characteristics, leading to unexpected failures such as viscoplastic tearing and stress concentration, which reduces the reliability and lifespan of the balloons.
Innovation Solution
A method involving extruding a polyethylene mixture, orienting polymer chains, and cross-linking the film using electron beams, followed by water quenching and heat sealing to form a balloon envelope, enhancing the film's strength and optical clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyethylene films are used for balloon envelopes, then manufacturing is simple and cost-effective, but the films exhibit inconsistency in strength and characteristics leading to unexpected failures
Solution Approach 1:
The patent applies parameter changes by controlling the cooling rate during film manufacturing to achieve a crystalline structure with 70-90% crystallinity. This specific parameter control transforms the polymer structure to eliminate stress areas and achieve consistent strength characteristics, resolving the reliability issue while maintaining a manageable manufacturing process
Solution Approach 2:
The patent creates a composite structure within the polyethylene film by forming a specific crystalline arrangement where polymer chains are organized in a regular pattern. This internal composite structure provides uniform strength distribution and eliminates the inconsistent characteristics of conventional films
2Weight of moving object
If polyethylene films are used for stratospheric balloons, then the material is lightweight, but the films suffer from stress concentration and viscoplastic tearing reducing lifespan
Solution Approach 1:
By changing the crystallinity parameter to 70-90% through controlled cooling, the film achieves a structure that resists stress concentration and viscoplastic tearing. This parameter optimization maintains the lightweight property while dramatically improving durability and lifespan in stratospheric conditions
Solution Approach 2:
The patent achieves local quality by creating a uniformly crystalline structure throughout the film that eliminates weak spots and stress concentration areas. This local structural optimization prevents tearing and extends the operational lifespan while keeping the overall film weight low
3Ease of manufacture
If conventional polyethylene films are used, then manufacturing is straightforward, but the films exhibit stress areas that are inherently weak and prone to tearing
Solution Approach 1:
The patent modifies the manufacturing parameter of cooling rate to achieve 70-90% crystallinity, which transforms the film structure to eliminate stress areas. This parameter change maintains manufacturing simplicity while achieving uniform strength distribution throughout the film, preventing weak spots and tearing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The improved film exhibits a higher strength-to-weight ratio, increased tensile strain, and improved optical clarity, resulting in a more reliable and durable balloon envelope with enhanced performance in stratospheric conditions.
Implementation Method 1
passing the oriented film through an electron beam and thereby crosslinking the polymer chains to provide a cross-linked film
Implementation Method 2
cooling the bubble using a water quenching process in order to increase optical clarity of the oriented film
Data Source
AI summary
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.