EVA-Polyacrylate Blend for Heat Aging Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ethylene vinyl acetate copolymers used in automotive applications under the hood face challenges with heat aging resistance, leading to degradation in physical properties such as extensibility and hardness due to oxidative embrittlement at high temperatures.
Innovation Solution
A blend composition of ethylene vinyl acetate copolymer, peroxide curable polyacrylate elastomer, and polyamide is developed, where polyamide particles are dispersed in the blend to enhance heat aging resistance, maintaining tensile strength, modulus, hardness, and elasticity when cured with a free radical generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ethylene vinyl acetate copolymer is used in automotive applications under the hood, then oil resistance and cost-effectiveness are achieved, but heat aging resistance deteriorates leading to oxidative embrittlement
Solution Approach 1:
The patent creates a composite material system consisting of ethylene vinyl acetate copolymer dispersed in a polyacrylate elastomer matrix. This composite structure combines the oil resistance and cost benefits of EVA with the superior heat aging resistance of polyacrylate, resolving the contradiction between material performance and thermal stability.
Solution Approach 2:
The patent modifies the chemical structure of the polyacrylate elastomer by incorporating specific functional groups (carboxyl, hydroxyl, or amine groups) that react with polyamide. This parameter change in the polymer chemistry enables enhanced crosslinking and improved heat aging resistance while maintaining processability.
2Reliability
If polyamide is added to ethylene vinyl acetate copolymer blend, then heat aging resistance is enhanced, but processing difficulty increases due to high melting temperature
Solution Approach 1:
The patent changes the processing temperature parameter to exceed the melting point of polyamide (above 220°C), transforming the polyamide from a solid obstacle to a melt-state material that can be uniformly dispersed. This parameter change enables easy processing while maintaining the heat aging benefits of polyamide.
Solution Approach 2:
The patent performs preliminary mixing of all components (polyacrylate elastomer, polyamide, and ethylene vinyl acetate copolymer) at elevated temperatures before curing. This preliminary action ensures uniform dispersion and compatibility establishment prior to the curing process, simplifying subsequent manufacturing steps.
3Reliability
If peroxide curable polyacrylate elastomer is used, then heat aging resistance and strength are improved, but cure response deteriorates due to chain scission
Solution Approach 1:
The patent changes the chemical composition parameters of the polyacrylate elastomer by incorporating 5-50 mol% ethylene units and specific functional groups. This compositional change reduces chain scission during peroxide curing while maintaining crosslinking efficiency, thereby improving both heat aging resistance and cure response.
Solution Approach 2:
The patent introduces local functional groups (carboxyl, hydroxyl, or amine groups) at specific positions within the polyacrylate elastomer chains. These localized functional groups provide reactive sites for crosslinking with polyamide, creating strong local bonds that enhance overall network strength and cure response without requiring complete chain integrity.
4Strength
If uncured ethylene vinyl acetate copolymer is added to polyamide, then toughness is improved, but processing temperature must exceed polyamide melting point
Solution Approach 1:
The patent merges multiple functions into a single processing step by simultaneously achieving polyamide melting, EVA copolymer dispersion, and blend homogenization at elevated temperatures. This combined approach processes all components together in one operation, making the high temperature requirement practical rather than prohibitive.
Data Source
AI summary
Heat resistant ethylene vinyl acetate copolymer compositions comprising a blend of ethylene vinyl acetate copolymer, peroxide curable polyacrylate elastomer, and polyamide are described. When crosslinked with a peroxide curative, the ethylene vinyl acetate copolymer compositions exhibit enhanced resistance to heat aging compared to conventional ethylene vinyl acetate elastomer compositions.