Shape Memory Epoxy Adhesive for Structural Cavity Reinforcement

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Solution Overview

Problem

State-of-the-art expandable adhesives used for reinforcing structural components face challenges in achieving high expansion rates while maintaining high mechanical performance, as increasing the amount of thermoplastic elastomer to enhance recovery rates often compromises the mechanical properties of the cured adhesive.

Innovation Solution

A composition comprising a curable epoxy resin adhesive with epoxy resin modified acrylonitrile-butadiene copolymer and thermoplastic elastomer, where the thermoplastic elastomer is present as a penetrating polymer network, providing high recovery rates based on a shape memory effect and high mechanical performance without the need for chemical or physical blowing agents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the amount of thermoplastic elastomer is increased to enhance recovery rates, then shape memory effect is improved, but mechanical properties of the cured adhesive deteriorate

Engineering Contradiction:

Improveshape memory effectVSAvoidmechanical properties

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies parameter changes by precisely controlling the thermoplastic elastomer content within 5-30 wt% of the total composition, and by selecting specific glass transition temperatures (Tg) for the curable structural adhesive (20-105°C) and melting temperatures (Tm) for the thermoplastic elastomer (60-200°C). This optimization ensures sufficient shape memory effect while preserving mechanical strength after curing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system combining curable structural adhesive with thermoplastic elastomer, where the two materials work synergistically. The curable adhesive provides structural strength and bonding, while the thermoplastic elastomer contributes shape memory effect through its ability to recover from deformed states when heated above its melting temperature.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If structural components use hollow design to reduce weight, then weight is reduced, but stability and strength deteriorate

Engineering Contradiction:

Improvevehicle weightVSAvoidstructural strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent applies local quality by selectively reinforcing only the critical cavity structures with the expandable adhesive composition, rather than solidifying the entire structure. This localized reinforcement approach maintains the overall hollow lightweight design while providing sufficient strength and stability where needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining the hollow structural component with the expandable adhesive reinforcement, creating a hybrid structure that leverages the weight advantages of hollow design while compensating for strength deficiencies through the adhesive composite material.

Inventive Principle:

Principle #40Composite materials

3Strength

If structural components are reinforced with local reinforcing elements, then strength is improved, but device complexity increases

Engineering Contradiction:

Improvestructural strengthVSAvoidreinforcement structure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into a single material system. The expandable adhesive composition simultaneously provides structural reinforcement, sealing of cavities, and shape memory capabilities, eliminating the need for separate reinforcing elements and simplifying the overall device structure.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent applies universality by designing the expandable adhesive composition to perform multiple functions: structural reinforcement, cavity sealing, and shape memory recovery. This multi-functional material replaces what would traditionally require multiple separate components, reducing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 composition achieves high shape recovery rates and mechanical performance comparable to high-strength reactive adhesives, effectively reinforcing structural components with improved stability and sealing properties.

Implementation Method 1

high recovery rates based on a shape memory effect

Methodology Applied

Scientific EffectShape memory effect: Shape Memory Polymer

Implementation Method 2

The composition can be brought from a dimensionally stable temporary shape to an expanded permanent shape, for example, by heating the composition above the glass transition temperature

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

cured by initiating the curing reaction of adhesive

Methodology Applied

Scientific EffectCuring reaction: Chemical Bonding

Data Source

PatentUS11591503B2Shape memory material with improved mechanical properties

Publication Date: 2023.02.28 SIKA TECH AG

AI summary

A composition includes an epoxy-based curable adhesive having at least one an epoxy resin modified acrylonitrile-butadiene copolymer and at least one thermoplastic elastomer. The at least one thermoplastic elastomer is present in the curable adhesive as a penetrating polymer network. Further, an expandable article is composed of the composition, a reinforcing element includes a support and an expandable article, a method for reinforces cavities of structural components, and the composition is used as a shape memory material.