Process for improving creep and stress relaxation of fiber reinforced polymer composites
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Carbon fiber reinforced polymer composites used in deployable space structures face dimensional instability due to creep and stress relaxation, particularly from the viscoelastic behavior of polymers, leading to performance degradation and potential mission failure.
Innovation Solution
Enhancing the interfacial strength between carbon fibers and the polymer matrix by siliconizing the carbon fiber fabric and applying a polymeric sizing material, such as bismaleimide or epoxy resin, to create a composite material with improved creep and stress relaxation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional carbon fiber reinforced polymer composites are used, then the structure achieves light weight and high specific strength, but dimensional instability occurs due to creep and stress relaxation from polymer viscoelasticity
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the carbon fiber and polymer matrix. The silane forms a chemical bridge that couples the inorganic carbon fiber surface with the organic polymer matrix, creating a transition layer that improves interfacial bonding and reduces stress transfer inefficiency, thereby minimizing creep and stress relaxation while maintaining the composite's high strength properties
Solution Approach 2:
The invention creates a multi-component composite system consisting of carbon fiber, silane coupling agent, and polymer matrix. This hierarchical composite structure addresses the fundamental incompatibility between rigid carbon fibers and viscoelastic polymers by introducing the silane intermediate, resulting in a composite material that simultaneously achieves high strength and dimensional stability
2Ease of manufacture
If thermoplastic polymers are used as matrix, then ease of processing is improved, but creep and stress relaxation increase compared to thermosetting polymers
Solution Approach 1:
The silane coupling agent serves as a mediator that enhances the effectiveness of the polymer matrix by improving stress transfer at the fiber-matrix interface. This allows thermoplastic matrices to achieve creep resistance comparable to or exceeding thermosetting matrices, as the strengthened interface prevents interfacial slippage that would otherwise lead to creep deformation
Solution Approach 2:
The invention changes the interfacial parameters between fiber and matrix by introducing silane modification. This alters the stress transfer mechanism and interfacial bonding characteristics, enabling thermoplastic matrices to exhibit reduced creep and stress relaxation behavior while retaining their processing advantages
3Adaptability or versatility
If extended stowage time is allowed between assembly and deployment, then logistical flexibility is improved, but performance degradation occurs due to accumulated creep and stress relaxation
Solution Approach 1:
The silane coupling treatment performs a preliminary anti-action by pre-strengthening the fiber-matrix interface before the composite is subjected to stowage conditions. This preemptive reinforcement creates a robust interface that resists the cumulative effects of creep and stress relaxation during extended storage, ensuring that structural performance is maintained upon deployment regardless of stowage duration
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 modified composite materials exhibit reduced viscoelastic creep and stress relaxation, maintaining mechanical stability and durability even after extended storage periods, suitable for applications in space structures and other equipment.
Implementation Method 1
The silane coupling agent is hydrolyzed to form silanols
Implementation Method 2
The silanols then condense with hydroxyl groups on the carbon fiber surface to form siloxane bonds
Implementation Method 3
The creep and stress relaxation of materials originate from the viscoelastic behavior of materials including polymeric materials. Under stress, parts of molecular chains or entire chains rearrange and slide past each other
Implementation Method 4
Thermosetting polymers can be expected to show less creep and stress relaxation compared to thermoplastic polymers due to restriction of chain motions by crosslinking
Data Source
AI summary
Disclosed herein are composite materials comprising a siliconized carbon fiber fabric and polymeric sizing. In one embodiment, the polymeric sizing can be bismaleimide, an epoxy resin, or both. In another embodiment, the composite materials possess mechanical strength and durability and acceptable performance after extended periods of time in storage. In another embodiment, disclosed herein is a method for making the composite materials, the method including at least the steps of (a) siliconizing the carbon fiber fabric to produce a siliconized carbon fiber fabric; and (b) applying a polymeric sizing material to the siliconized carbon fiber fabric to create the composite material. In yet another embodiment, disclosed herein are composite materials formed by the disclosed process and articles comprising the composite materials including, but not limited to, camping equipment, military equipment, clothing, sporting equipment, aerospace equipment, wrinkle-free fabric, or any combination thereof.