Multilayer Composite Fuel Line Copolyamide Polyester
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Solution Overview
Problem
Current multilayer composites used in automotive applications, such as fuel lines, face challenges with heat distortion temperature, impact resistance, and elongation at break, particularly at high temperatures, due to the limitations of aliphatic polyamides and partly aromatic polyamides.
Innovation Solution
A multilayer composite comprising a first layer of a moulding compound with a partly aromatic copolyamide and an olefinic copolymer impact modifier, combined with a second layer of thermoplastic polyester, optimized to achieve high heat distortion temperature, impact resistance, and elongation at break, with specific molecular weight ratios and components to enhance mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crystalline partly aromatic polyamides with Tm ≥ 220°C are used to achieve high heat distortion temperature, then heat resistance is improved, but impact resistance and elongation at break deteriorate
Solution Approach 1:
The invention changes the chemical composition parameters of the polyamide by incorporating specific monomer units (hexamethylenediamine with terephthalic acid and linear aliphatic dicarboxylic acids with 8-19 carbon atoms) in controlled molar ratios, achieving a balance between crystallinity for heat resistance and molecular flexibility for impact resistance
Solution Approach 2:
The invention creates a composite moulding compound by combining the specially formulated partly aromatic copolyamide with impact modifiers (ethylene-propylene-diene rubber or butadiene-styrene rubber) and compatibilizers, achieving synergistic effects that simultaneously improve heat distortion temperature and impact resistance
2Temperature
If crystalline partly aromatic polyamides with Tm ≥ 220°C are used to achieve high heat distortion temperature, then heat resistance is improved, but elongation at break deteriorates
Solution Approach 1:
The invention adjusts the molar composition parameters to include 41-90 mol% of hexamethylenediamine and terephthalic acid units combined with 59-10 mol% of hexamethylenediamine and linear aliphatic dicarboxylic acid units, creating a molecular structure that maintains crystallinity for heat resistance while incorporating flexible aliphatic segments that enable elongation at break >100%
Solution Approach 2:
The invention introduces local flexible segments (aliphatic dicarboxylic acid units with 8-19 carbon atoms) within the aromatic polyamide chain, creating regions of different mechanical properties that allow the material to maintain overall crystallinity while having localized flexible zones that enable high elongation
3Strength
If aliphatic polyamides are used to achieve high elongation at break, then elongation and impact resistance are improved, but heat distortion temperature and barrier effect deteriorate
Solution Approach 1:
The invention creates a composite structure at the molecular level by combining aromatic polyamide segments (for heat resistance) with aliphatic polyamide segments (for flexibility and impact resistance), achieving a material that simultaneously exhibits high heat distortion temperature and excellent mechanical properties
Solution Approach 2:
The invention segments the polyamide chain into distinct aromatic and aliphatic units that maintain their individual properties while contributing to the overall material performance, with aromatic units providing thermal stability and aliphatic units providing mechanical flexibility
Data Source
AI summary
A multilayer composite containing the following layers: I. a first layer (layer I) of a molding compound containing at least 40 wt. % of the following components: 1) 60 to 99 parts by wt. of a copolyamide based on hexamethylenediamine, terephthalic acid and an aliphatic dicarboxylic acid having 8 to 19 carbon atoms and 2) 40 to 1 parts by wt. of an olefinic copolymer as impact modifier, wherein the parts by wt. of 1) and 2) sum to 100; and II. a second layer (layer II) of a molding compound containing at least 60 wt. % of thermoplastic polyester, has a high heat distortion temperature, a very good impact resistance, a high elongation at break and good layer adhesion.