Polymer-Nanoparticle Interlayer for Composite Toughening

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Solution Overview

Problem

Conventional toughening veils in composite materials lack stiffness, strength, and the ability to maintain compression and shear strength at elevated temperatures, especially after exposure to moisture, which limits their impact resistance and fracture toughness.

Innovation Solution

A polymer-nanoparticle-enhanced interlayer is created by mixing monomers with derivatized nanoparticles, which are then melt-spun into thermoplastic fibers, incorporating the nanoparticles directly into the polymer backbone to form a veil with improved stiffness and processability, enhancing the composite material's toughness and property retention at elevated temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional toughening veils are used to enhance impact resistance, then toughness is improved, but stiffness and strength at elevated temperatures deteriorate

Engineering Contradiction:
Improveimpact resistanceVSAvoidstrength retention at elevated temperatures
Core Design Contradiction:
StrengthVSTemperature

Solution Approach 1:

The patent uses a composite material system combining thermoplastic polymer matrix with nanoparticle reinforcements (such as carbon nanotubes, graphene, or nanoclay) to create an interlayer that simultaneously provides toughness and high-temperature strength retention. The nanoparticle-polymer composite structure allows the material to maintain its mechanical properties at elevated temperatures while retaining the energy-absorbing characteristics needed for impact resistance.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the thermal and mechanical parameters of the toughening veil by selecting specific polymer compositions (polyester, polyamide, polyimide) and controlling processing conditions (melt spinning at specific temperatures, fiber diameter control) to achieve optimal balance between toughness and heat resistance. The interlayer is designed with specific glass transition temperature ranges and crystallinity levels to perform adequately across temperature extremes.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If conventional toughening veils are used to improve toughness, then energy absorption capability is enhanced, but compression and shear strength deteriorate

Engineering Contradiction:
ImprovetoughnessVSAvoidcompression and shear strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent employs a composite interlayer structure where thermoplastic fibers are combined with high-strength nanoparticle reinforcements. This composite construction allows the material to absorb impact energy through fiber deformation and nanoparticle-matrix interface mechanisms while simultaneously maintaining compression and shear strength through the rigid nanoparticle framework and cross-linked polymer matrix.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies different functional characteristics to different aspects of the interlayer structure: the thermoplastic matrix provides toughness and energy absorption through ductile deformation, while the nanoparticle reinforcements and cross-linked regions provide localized stiffness and strength maintenance under compression and shear loads. This spatial differentiation of mechanical properties allows simultaneous optimization of toughness and strength.

Inventive Principle:
Principle #3Local quality

3Strength

If nanoparticle content is increased to improve stiffness, then strength is enhanced, but manufacturing complexity increases

Engineering Contradiction:
ImprovestiffnessVSAvoidmanufacturing process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent incorporates nanoparticle reinforcement into the polymer matrix during the melt spinning process itself, rather than adding them as separate components later. The nanoparticles are pre-dispersed in the polymer melt at controlled concentrations (0.1-5 wt%), and the homogeneous mixture is then extruded and solidified into fibers. This preliminary incorporation eliminates subsequent assembly steps and ensures uniform distribution without requiring complex multi-stage manufacturing processes.

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 polymer-nanoparticle-enhanced interlayer significantly improves the composite material's stiffness, strength, and ability to retain compression and shear strength at elevated temperatures, while maintaining toughness, thus addressing the limitations of conventional veils.

Implementation Method 1

mixing at least one monomer with the derivatized nanoparticles

Methodology Applied
Scientific EffectMixing:

Implementation Method 2

melt spinning the polymer and derivatized nanoparticles to form the polymer-nanoparticle-enhanced interlayer

Methodology Applied
Scientific EffectMelt spinning:

Data Source

PatentEP2926987B1Nonwoven interlayers made using polymer-nanoparticle polymers
Publication Date: 2020.11.25 THE BOEING CO
  • EP2926987B1 patent drawingFigure 1
  • EP2926987B1 patent drawingFigure 2
  • EP2926987B1 patent drawingFigure 3A~3B

AI summary

A method of manufacturing a composite structure is provided. The method includes positioning a polymer-nanoparticle-enhanced interlayer adjacent to a first fiber layer. The polymer-nanoparticle-enhanced interlayer comprises at least one polymer and derivatized nanoparticles included in the molecular backbone of the at least one polymer, wherein the nanoparticles are derivatized to include functional groups. The method further includes positioning a second fiber layer adjacent to the polymer-nanoparticle-enhanced interlayer attached to the first fiber layer. The first fiber layer and the second fiber layer are infused with resin. The resin is cured to harden the composite structure.