Ductile Expanded Polyesters with Acrylic Elastomer Impact Resistance
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Solution Overview
Problem
Polyester materials, particularly aromatic polyethylene terephthalate, exhibit high mechanical strength but are brittle and have poor impact resistance and ductility, limiting their application in scenarios with periodic mechanical loading or thermoforming, as they tend to break easily under shock loading and have low shear elongation at break.
Innovation Solution
A polymer blend of polyesters with 2-20 wt% of a reactive or non-reactive acrylic elastomer, processed with a multifunctional compound and blowing agent, enhances melt strength and dispersion within the polyester matrix, improving ductility and impact resistance while maintaining mechanical strength and rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyester materials are used to achieve high mechanical strength, then compression strength and shear strength are improved, but impact resistance and ductility deteriorate
Solution Approach 1:
The patent applies composite materials by blending polyester with acrylic elastomers (2-20 wt%) to create a multi-phase material system. The acrylic elastomer domains act as impact modifiers within the polyester matrix, allowing the composite to simultaneously achieve high compression strength from the polyester and improved impact resistance from the elastomer phase, directly resolving the contradiction between strength and impact resistance
Solution Approach 2:
The patent changes the chemical composition parameter by introducing acrylic elastomers with specific functional groups that can react with polyester. This parameter change modifies the material's molecular structure and phase morphology, enabling the material to exhibit both the high strength of polyester and the ductility of elastomers, thereby improving impact resistance while maintaining compression strength
2Strength
If polyester materials are used to achieve high mechanical strength, then shear strength is improved, but shear elongation at break deteriorates
Solution Approach 1:
The polyester-acrylic elastomer composite utilizes the synergistic effect between the rigid polyester matrix (providing shear strength) and the flexible elastomer domains (providing elongation capacity). The elastomer phases can undergo significant deformation and energy dissipation, enabling shear elongation at break to exceed 15% while the polyester matrix maintains high shear strength through its crystalline structure
Solution Approach 2:
The patent applies local quality by creating distinct phases with different properties: the polyester matrix provides local regions of high strength and rigidity, while the dispersed acrylic elastomer domains provide local regions of high flexibility and elongation. This spatial differentiation of material properties allows the composite to exhibit both high shear strength and high shear elongation at break simultaneously
3Ease of operation
If acrylic elastomer blend is added to improve ductility, then shear elongation at break is improved, but melt strength deteriorates
Solution Approach 1:
The patent changes the chemical reactivity parameter by selecting acrylic elastomers containing functional groups (carboxyl, hydroxyl, or reactive sites) that can chemically interact with polyester. This chemical parameter change creates strong interfacial adhesion between phases, forming a network structure that enhances melt strength and elastic recovery even at low elastomer concentrations (2-20 wt%), thereby improving ductility without sacrificing melt strength
Solution Approach 2:
The acrylic elastomer acts as an intermediary that bridges the polyester matrix and the foaming agents. The reactive functional groups on the elastomer molecules form chemical bonds or strong interactions with polyester chains, creating a unified network structure that maintains melt strength. This intermediary role allows the elastomer to improve ductility while the chemical bonding preserves the overall structural integrity during processing
4Weight of moving object
If polyester is expanded to reduce density, then weight is reduced, but ductility and impact resistance deteriorate
Solution Approach 1:
The patent creates a composite foam structure where polyester-acrylic elastomer blend forms the matrix and foaming agents create dispersed gas cells. The acrylic elastomer domains within the foam matrix act as impact-absorbing phases that prevent crack propagation, maintaining high impact resistance even at reduced densities. The composite structure allows the foam to achieve low density while the elastomer phases provide toughness and ductility
Solution Approach 2:
The patent utilizes porous materials by incorporating foaming agents that create a cellular structure within the polyester-acrylic elastomer matrix. The porous foam structure reduces density and weight, while the acrylic elastomer phases distributed within the pores and cell walls maintain ductility and impact resistance. The combination of porous structure and elastomer reinforcement enables the material to be both lightweight and tough
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 blend significantly increases shear elongation at break and impact strength of expanded polyester materials, allowing for better thermoformability and fatigue behavior, with improved resistance to dynamic loading and thermal stability, enabling applications in sandwich structures and 3D articles without compromising mechanical strength.
Implementation Method 1
An addition of a non-reactive/reactive acrylic mixture serving as the blend partner improves the melt strength in an expanding process
Implementation Method 2
The blend significantly increases shear elongation at break and impact strength of expanded polyester materials
Implementation Method 3
processed with a multifunctional compound and blowing agent, enhances melt strength and dispersion within the polyester matrix, improving ductility and impact resistance
Data Source
AI summary
This invention relates to expanded polyester materials comprised of polyester/acrylic elastomer blend having an improved ductility and impact resistance, while the compression strength, shear strength/modulus of polyesters remain almost unchanged or unworsened. Addition of a non-reactive/reactive acrylic mixture serving as the blend partner improves the melt strength in an expanding process and leads to a better impact resistance of expanded aromatic polyester materials. All expanded polyester materials are produced with help of a reactive process.