Carbon Nanofiber Interlayer for Composite Delamination
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Solution Overview
Problem
Carbon fiber laminate reinforced polymer composites are susceptible to delamination along interlaminar planes, leading to reduced load carrying capacity and durability, and existing methods to improve delamination resistance often compromise in-plane mechanical properties.
Innovation Solution
Incorporating semi-aligned continuous carbon nanofibers derived from polyacrylonitrile (PAN) based electrospun nanofibers as a sheet between carbon fiber laminates in epoxy resin composites, using a process involving electrospinning, stabilization, and carbonization, to enhance interlaminar shear strength and bending strength without increasing bulk density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional carbon fiber laminates are used to improve in-plane mechanical properties, then strength and stiffness are enhanced, but delamination resistance along interlaminar planes deteriorates
Solution Approach 1:
The patent introduces carbon nanofibers oriented in the through-thickness (Z-direction) dimension to address delamination resistance, while maintaining carbon fiber fabric for in-plane strength. This multi-directional reinforcement approach resolves the contradiction by operating in different spatial dimensions - the nanofibers provide interlaminar connectivity without compromising the in-plane mechanical properties provided by the fiber fabric.
Solution Approach 2:
The patent creates a hybrid composite material system combining carbon fiber fabric (for in-plane properties) with carbon nanofiber reinforcement (for interlaminar properties). This composite approach allows simultaneous achievement of high in-plane strength and improved delamination resistance, as each component material contributes its specialized function within the unified composite structure.
2Strength
If carbon fiber content is increased to improve mechanical properties, then strength and stiffness increase, but composite density increases
Solution Approach 1:
The patent changes the reinforcement parameter from solely macro-scale carbon fiber fabric to a hybrid system incorporating nano-scale carbon nanofibers. This parameter change in reinforcement scale and morphology allows improved mechanical properties with lower overall fiber content, as the nanofibers provide high surface area and interlaminar connectivity that enhance strength without proportionally increasing density.
Solution Approach 2:
The patent applies different reinforcement strategies to different regions and functions: carbon fiber fabric provides in-plane strength where needed, while carbon nanofibers provide interlaminar reinforcement and toughness. This local quality differentiation allows optimization of mechanical properties without uniform increases in density throughout the entire composite.
3Reliability
If existing methods are used to improve delamination resistance, then interlaminar strength increases, but in-plane mechanical properties are compromised
Solution Approach 1:
The patent segments the reinforcement function between two distinct components: carbon fiber fabric handles in-plane loading, while carbon nanofibers handle interlaminar stress and delamination resistance. This functional segmentation allows each component to optimize its performance without interfering with the other, preventing compromise of in-plane properties while improving delamination resistance.
Solution Approach 2:
The carbon nanofibers act as an intermediary element between the carbon fiber fabric layers, providing bridging and load transfer across the interlaminar interfaces. This intermediary reinforcement mechanism improves delamination resistance without requiring changes to the primary carbon fiber fabric structure that would compromise in-plane strength.
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 hybrid composites exhibit significantly improved bending strength, interlaminar shear strength, and modulus, with bending strength increasing by 175% and interlaminar shear strength by 190% compared to composites without carbon nanofibers, while maintaining a reduced carbon fiber content, thus addressing the delamination issue without compromising other mechanical properties.
Implementation Method 1
electrospinning 8-12 wt % Polyacrylonitrile (PAN) in an organic solvent at applied voltage 15-20 KV and drum collector speed 2000-3000 rpm for 10-20 hrs
Implementation Method 2
carbonization of stabilized PAN nanofiber sheets at 800-1000° C. to get continuous carbon nanofiber sheets
Data Source
AI summary
The present disclosure relates to the development of high performance light weight carbon fiber fabric-electrospun carbon nanofibers hybrid polymer composites and a process thereof. In this process continuous carbon nanofiber sheets of diameter in the range of few hundred nanometers are developed from electrospun PAN nanofibers and sandwich between the carbon fiber fabric epoxy resin prepregs to develop hybrid polymer composites by compression molding technique with low content of carbon fibers.