Aligned CNT Composite Interfaces for Interlaminar Strength

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Solution Overview

Problem

Existing methods for processing carbon nanotubes in composite materials face challenges such as the formation of structures with large diameters and insufficient length, poor alignment of CNT axes, and agglomeration, leading to disordered arrangements and low volume fractions, which hinder the achievement of enhanced mechanical, thermal, and electrical properties.

Innovation Solution

A method involving the growth of substantially aligned nanostructures on a substrate, followed by their uniform dispersion and binding to form an interface between composite layers, enhancing mechanical, thermal, and electrical properties through improved alignment and interlaminar interactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional CNT synthesis methods are used, then CNTs can be produced, but the structures have large diameter and insufficient length resulting in poor alignment

Engineering Contradiction:
Improvealignment of CNT axesVSAvoidstructure quality
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-aligning carbon nanotubes on a substrate before embedding them in the matrix material. The nanotubes are grown or deposited in a controlled manner on a substrate surface with desired orientation, then this pre-aligned structure is transferred or embedded into the final composite. This preliminary alignment step ensures that the nanotubes maintain their oriented arrangement throughout the composite fabrication process, solving the alignment problem that plagues conventional synthesis methods.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention segments the composite fabrication process into distinct steps: (1) growing/depositing aligned nanotubes on a substrate, (2) preparing the matrix material, (3) embedding the substrate with aligned nanotubes into the matrix, and (4) curing or solidifying the composite. This segmentation allows each step to be optimized independently, particularly the alignment step, without compromising the other steps in the process.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If CNTs are dispersed in secondary materials, then composite materials can be formed, but CNT agglomeration hinders uniform wetting and dispersion

Engineering Contradiction:
Improveuniform dispersion of CNTsVSAvoiddispersion process
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by pre-dispersing carbon nanotubes uniformly on a substrate surface before embedding the substrate in the matrix material. This preliminary dispersion step ensures that nanotubes are evenly distributed and prevented from agglomerating during subsequent composite fabrication steps. The substrate acts as a temporary carrier that maintains uniform nanotube spacing, eliminating the need for difficult dispersion steps that typically cause agglomeration.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The substrate serves as an intermediary carrier that facilitates uniform nanotube distribution. The nanotubes are first grown or deposited on the substrate in a controlled, uniform manner. This substrate-nanotube assembly then acts as a pre-formed unit that is embedded into the matrix material. The substrate intermediary prevents direct interaction between nanotubes and matrix during mixing, thereby preventing agglomeration and ensuring uniform wetting.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If alignment of CNTs in secondary materials is attempted, then directional properties can be achieved, but alignment is difficult to achieve particularly in systems with large advanced fibers and matrix materials

Engineering Contradiction:
Improvealignment of nanotubes in compositeVSAvoidalignment process
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-aligning carbon nanotubes on a substrate before embedding them in the composite system containing large fibers and matrix material. This preliminary alignment creates a template structure where nanotubes are already oriented in the desired direction. When this substrate-nanotube assembly is embedded into the composite, the nanotube alignment is preserved, providing directional properties without requiring complex alignment processes during composite fabrication.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention segments the alignment function into a separate preliminary step on the substrate, independent of the composite fabrication process. The substrate is prepared with aligned nanotubes in advance, then this pre-aligned assembly is introduced as a unit into the composite system. This segmentation isolates the alignment complexity to the substrate preparation step, simplifying the overall composite manufacturing process while achieving the desired directional nanotube arrangement.

Inventive Principle:
Principle #1Segmentation

4Ease of manufacture

If disordered arrangements of CNTs are used, then processing is simpler, but mechanical strength and other properties are not enhanced

Engineering Contradiction:
Improveprocessing simplicityVSAvoidmechanical properties
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent applies preliminary action by pre-aligning carbon nanotubes on a substrate before composite fabrication, achieving both enhanced mechanical properties and processing simplicity. The pre-aligned nanotube structure on the substrate provides the mechanical reinforcement benefits of ordered arrangements while requiring minimal processing steps during composite manufacturing. This eliminates the need for complex alignment procedures during composite fabrication that would otherwise be needed to achieve property enhancement.

Inventive Principle:
Principle #10Preliminary action

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 method results in composite materials with increased mechanical strength, toughness, and thermal conductivity, as well as tailored anisotropic properties, by ensuring uniform alignment and dispersion of nanostructures within the matrix, thereby overcoming the limitations of existing CNT processing techniques.

Implementation Method 1

exposing the substrate to a set of conditions selected to cause catalytic formation of carbon nanotubes on the surface

Methodology Applied
Scientific EffectCatalytic formation: Catalysis

Implementation Method 2

the use of a carbon nanotube forest for increasing interlaminar strength and toughness between stacked fabrics in a composite material

Methodology Applied
Scientific EffectMechanical reinforcement:

Implementation Method 3

arranging a set of substantially aligned nanostructures on or in the joining surface of at least one of the first and second substrates

Methodology Applied
Scientific EffectPhysical transfer:

Data Source

PatentEP2441729B1Method of forming a composite article
Publication Date: 2017.04.05 MASSACHUSETTS INST OF TECH
  • EP2441729B1 patent drawingFigure 1A
  • EP2441729B1 patent drawingFigure 1B~1C
  • EP2441729B1 patent drawingFigure 2

AI summary

The present invention provides a method of forming a composite article, comprising: providing a substrate with a surface comprising a set of substantially aligned nanostructures on or in the surface, wherein the long axes of the nanostructures are substantially aligned in an orientation that is substantially non-parallel to the surface; and treating the substrate with a mechanical tool to change the orientation of the nanostructures such that the long axes of the nanostructures are substantially aligned in an orientation that is parallel to the surface.