CNT Thermoplastic Film Resistivity Reduction via Current Alignment

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Solution Overview

Problem

Commercially available carbon nanotube-filled thermoplastic films have high electrical resistivity, making them unsuitable for aerospace heating applications such as anti-icing and de-icing, where lower resistivity is required.

Innovation Solution

Applying electric current through the thermoplastic film to heat it to an elevated temperature below its melting point, causing the carbon nanotubes to align and reduce resistivity, thereby enhancing conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electric current is passed through the thermoplastic film to heat it to an elevated temperature, then the carbon nanotubes align and electrical resistivity reduces, but energy is consumed and the film temperature increases

Engineering Contradiction:

Improveelectrical conductivityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by controlling the temperature of the thermoplastic film to a specific elevated range (below melting point) where CNT alignment occurs. By adjusting temperature as a critical parameter, the method achieves optimal electrical conductivity without excessive energy consumption, resolving the contradiction between improving conductivity and minimizing energy use.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses preliminary action by pre-heating the thermoplastic film to align the carbon nanotubes before the film is put into service. This one-time alignment process during manufacturing or installation eliminates the need for continuous energy input to maintain alignment, thereby improving conductivity while minimizing ongoing energy consumption.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If electric current is passed through the thermoplastic film to align carbon nanotubes, then resistivity reduces, but the film must be heated to elevated temperature

Engineering Contradiction:

Improveelectrical conductivityVSAvoidfilm temperature

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The patent carefully controls the temperature parameter to be elevated but specifically below the melting point of the thermoplastic film. This parameter optimization allows CNT alignment to occur while preventing film degradation or melting, thus achieving improved conductivity without excessive temperature increase.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs periodic or pulsed electric current application to heat and align the carbon nanotubes, rather than continuous heating. This periodic action achieves the necessary temperature elevation for alignment while allowing cooling periods, thereby reducing the average temperature and preventing overheating or melting of the film.

Inventive Principle:

Principle #19Periodic action

3Reliability

If carbon nanotubes are distributed randomly in the thermoplastic film, then the film structure is simple, but electrical resistivity is high

Engineering Contradiction:

Improveelectrical conductivityVSAvoidCNT alignment process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical alignment methods with an electric field-based alignment mechanism. By passing electric current through the film, carbon nanotubes align along the current path due to electrostatic forces, eliminating the need for complex mechanical alignment equipment while achieving low resistivity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the temperature parameter to an elevated state (below melting point) to facilitate CNT alignment. This parameter change enables the nanotubes to move and reorient themselves along the electric field lines, achieving low resistivity without complex mechanical intervention while maintaining structural simplicity.

Inventive Principle:

Principle #35Parameter changes

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 effectively reduces the resistivity of the thermoplastic film to levels suitable for aerospace applications, allowing it to replace metal heating elements without adding mass or using chemical processes, achieving conductivities comparable to stainless steel.

Implementation Method 1

passing electric current through the thermoplastic film containing carbon nanotubes to heat the thermoplastic film to an elevated temperature

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

align carbon nanotubes within the thermoplastic film

Methodology Applied

Scientific EffectThermal alignment:

Data Source

PatentEP3332952B1Reducing CNT resistivity by aligning CNT particles in films

Publication Date: 2022.01.26 GOODRICH CORP

Figure 1~2

AI summary

A method for reducing the resistivity of a thermoplastic film (10) containing carbon nanotubes (14) includes connecting an electric power supply to the thermoplastic film (10) containing carbon nanotubes (14) and passing electric current through the thermoplastic film containing carbon nanotubes to heat the thermoplastic film (10) to an elevated temperature and align carbon nanotubes (14) within the thermoplastic film. The thermoplastic film is solid at room temperature.