Polyetherimide Carbon Fiber Composites for Aircraft Metal Replacement

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Solution Overview

Problem

Short carbon fiber reinforced thermoplastics face challenges in achieving high modulus, high strength, and high flow while meeting OSU heat release compliance, particularly requiring high carbon fiber loading that increases melt viscosity and complicates processing for aircraft interior applications.

Innovation Solution

The development of fiber reinforced thermoplastic composites with a continuous thermoplastic polymer phase comprising polyetherimide and polyetheretherketone, combined with high-modulus carbon fibers, which maintains a specific modulus of at least 25 and tensile strength of 226 MPa, and exhibits a heat release profile compliant with the OSU 65/65 standard, achieved by optimizing the composition and processing conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If high loading of carbon fibers is used to meet stiffness and strength requirements, then the modulus and strength of the composite are improved, but the melt viscosity increases significantly creating processing difficulties

Engineering Contradiction:

Improvetensile strengthVSAvoidprocessing difficulty

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the molecular weight parameter of the polyetherimide resin to at least 50,000 Daltons, which fundamentally alters the melt viscosity characteristics. This parameter change enables the composite to maintain high carbon fiber loading (35-60 wt%) while preserving processability, as the higher molecular weight resin provides better melt strength and viscosity control during processing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system combining polyetherimide with high molecular weight (≥50,000 Daltons) and polyetheretherketone in specific ratios (PEI: 40-60 wt%, PEEK: 10-40 wt%). This composite resin system works synergistically with carbon fibers to achieve both high strength and manageable melt viscosity, resolving the contradiction between reinforcement level and processability.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If high loading of carbon fibers is used to achieve high modulus, then the stiffness of the composite is improved, but the melt viscosity increases creating processing difficulties

Engineering Contradiction:

ImprovemodulusVSAvoidprocessing difficulty

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If thermoplastic composites are designed to meet OSU heat release compliance, then the flammability is improved, but the composition and processing become more complex

Engineering Contradiction:

Improveheat releaseVSAvoidcomposition complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent specifies precise compositional parameters: polyetherimide with molecular weight ≥50,000 Daltons, polyetheretherketone content of 10-40 wt% of the total composite, and carbon fiber loading of 35-60 wt%. By controlling these parameters, the composite automatically achieves OSU 65/65 compliance without requiring complex additional flame retardant systems or processing modifications.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP2859034B1High modulus high strength high flow OSU compliant polyetherimide-carbon fiber composites for metal replacement

Publication Date: 2018.04.18 SABIC GLOBAL TECHNOLOGIES BV

AI summary

Disclosed herein are fiber reinforced thermoplastic composite with desired physical properties, such as high modulus, high stiffness and high flow while maintaining the OSU heat release compliancy.