Composite Panels Fluid Impermeability Aramid Micropulp Barrier

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Solution Overview

Problem

Honeycomb sandwich panels are prone to moisture ingression, which compromises their mechanical performance, especially in wet and moist environments, due to their high permeability.

Innovation Solution

A prepreg formulation incorporating a thermoset resin, specific curing agents, and fibrous micropulp is used to create a fluid impermeable barrier, reducing fluid permeation in composite structures by forming a moisture barrier prepreg that can be applied in various forms such as film, liquid, or paste, and integrated into the panel assembly to prevent moisture ingress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If honeycomb sandwich panels are used for high strength to weight ratio, then structural performance is improved, but fluid impermeability deteriorates due to moisture ingression into core cells

Engineering Contradiction:
Improvestrength to weight ratioVSAvoidfluid impermeability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

A thin film moisture barrier coating is applied to the honeycomb core surfaces and within cell openings. This flexible film forms a continuous barrier layer that prevents moisture from penetrating into the core cells while maintaining the core's structural integrity and lightweight characteristics.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The honeycomb sandwich panel is enhanced by combining the honeycomb core with a moisture barrier film and outer skin layers to create a composite structure. This multi-material composite provides both the high strength-to-weight ratio of the honeycomb and the fluid impermeability of the barrier film, resolving the contradiction between structural performance and moisture resistance.

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If conventional prepreg is used for composite panels, then manufacturing is simplified, but moisture barrier performance is insufficient

Engineering Contradiction:
Improveprepreg applicationVSAvoidmoisture barrier performance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The moisture barrier function is merged with the structural skin layers by incorporating moisture barrier film into the prepreg stacking sequence. The barrier film is bonded between the honeycomb core and outer skin prepreg layers, creating an integrated moisture barrier system that maintains ease of manufacture through standard prepreg bonding processes while significantly improving moisture barrier performance.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP2259917B1Composite panels having improved fluid impermeability
Publication Date: 2019.06.05 EI DU PONT DE NEMOURS & CO
  • EP2259917B1 patent drawingFigure 1A~1B
  • EP2259917B1 patent drawingFigure 2~3
  • EP2259917B1 patent drawingFigure 4~5

AI summary

A prepreg composite material that includes a fiber layer and a resin comprising a thermoset resin component, a curing agent and a fibrous micropulp. The micropulp component is an aramid fiber having a volume average length of from 0.01 to 100 micrometers. The prepreg is useful in composite panel construction for minimizing fluid permeation into the cured structure. This prepreg is particularly suitable for making honeycomb sandwich panels. Film adhesives, liquid and paste resins containing aramid fiber micropulp are also disclosed.