Structured Thermoplastic Interleaves for Out-of-Autoclave Composite Curing
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Solution Overview
Problem
Composite materials with thermosetting resins and glass or carbon-fibre reinforcement suffer from poor impact resistance and delamination issues, particularly when cured outside of an autoclave, which limits their structural applications due to inadequate mechanical properties.
Innovation Solution
Incorporating a non-fibrous membrane or film made of soluble thermoplastic polymeric material within the interleaf zones of composite laminates, which provides toughness and allows for curing at lower pressures without compromising mechanical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermosetting resin composite materials are cured outside of an autoclave, then manufacturing cost and complexity are reduced, but mechanical properties and reliability are insufficient
Solution Approach 1:
A polyethersulfone film is introduced as an intermediary layer between fiber plies during laminate curing. This film acts as a mediator that enables out-of-autoclave curing processes to achieve mechanical properties comparable to autoclave-cured laminates, thereby resolving the contradiction between manufacturing accessibility and mechanical reliability
Solution Approach 2:
The invention creates a hybrid composite system combining thermosetting resin, fiber reinforcement, and thermoplastic polyethersulfone film. This multi-material composite structure leverages the complementary properties of each material to achieve both ease of manufacture and high mechanical reliability simultaneously
2Strength
If traditional particulate tougheners are used, then toughness is improved, but the material exhibits drawbacks that limit structural application
Solution Approach 1:
The invention changes the physical state and distribution parameters of the toughening agent from particulate form to continuous film form. This parameter change eliminates the drawbacks of particulate tougheners while maintaining their toughness-enhancing function, making the material suitable for structural applications
Solution Approach 2:
The invention replaces traditional particulate tougheners with thin polyethersulfone films that are interleaved between fiber plies. These flexible films provide superior toughness improvement while eliminating the limitations of particulate systems, enabling reliable structural applications
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 use of structured thermoplastic polymer layers in interleaf zones enhances the toughness of composite laminates, enabling successful curing at atmospheric pressure, thus meeting the mechanical specifications required for structural applications, including aerospace, without the drawbacks of traditional particulate tougheners.
Implementation Method 1
The polymeric material is at least partially soluble in a monomer and insoluble in a polymer derived from the monomer
Implementation Method 2
enables successful curing at atmospheric pressure
Implementation Method 3
at least partially soluble in a monomer and insoluble in a polymer derived from the monomer
Data Source
AI summary
One or more layers of structured thermoplastic polymer are located within the interleaf zones of a preform or prepreg. The structured thermoplastic polymer is a film or membrane formed by: a) dissolving polyethersulfone or polyetherimide in a solvent to form a polymer dope; b) dispersing a curing agent for an epoxy resin in the polymer dope to form a curative-enriched polymer dope; c) casting the curative-enriched polymer dope onto a surface to form a dope layer; and d) removing the solvent from the dope layer to form a layer of structured thermoplastic polymer.