Polyetherester Elastomer Temperature Stability via Aromatic Hard Segments
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Solution Overview
Problem
Thermoplastic polyetherester elastomers face limitations in both low and high temperature performance, experiencing embrittlement at low temperatures and loss of mechanical strength at elevated temperatures, particularly in automotive applications.
Innovation Solution
A polyetherester elastomer composition comprising 25 to 59 weight percent poly(trimethylene ether) ester soft segments and 41 to 75 weight percent tetramethylene ester hard segments, with specific molecular weight ranges and reaction methods to enhance temperature stability, including esterification and transesterification processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polyetherester elastomers are used in automotive applications with operating temperatures from -40°C to 150°C, then broad temperature range applicability is achieved, but performance degradation occurs at extreme temperatures (embrittlement at low temperatures and loss of mechanical strength at high temperatures)
Solution Approach 1:
The patent changes the chemical composition parameters of the elastomer by incorporating aromatic dicarboxylic acid units (2-20 mole percent of total dicarboxylic acid units) into the hard segments. This compositional parameter change modifies the polymer's thermal properties, enabling it to maintain mechanical strength at high temperatures (150°C) and resist embrittlement at low temperatures (-40°C), thus resolving the performance degradation issue across the broad temperature range
Solution Approach 2:
The patent creates a composite segment structure within the polyetherester elastomer by combining aromatic dicarboxylic acid units with aliphatic dicarboxylic acid units in the hard segments. The aromatic units provide thermal stability and strength at elevated temperatures, while the polyether soft segments maintain flexibility at low temperatures. This composite approach at the molecular level enables the material to withstand the full -40°C to 150°C operating range without performance loss
2Strength
If the elastomer contains aromatic dicarboxylic acid units in the hard segments, then high temperature mechanical strength is improved, but manufacturing complexity increases due to specific compositional requirements
Solution Approach 1:
The patent establishes specific quantitative parameters for the aromatic dicarboxylic acid content (2-20 mole percent of total dicarboxylic acid units) to optimize high temperature strength. By defining this precise parameter range, the patent balances the need for thermal strength with manufacturability, allowing standard polymerization processes to produce the desired composition without requiring overly complex manufacturing procedures
Data Source
AI summary
Polyetherester elastomers comprising about 25 to about 59 weight percent poly(trimethylene ether) ester soft segments and about 41 to about 75 weight percent hard segments, wherein the poly(trimethylene ether) ester soft segments are derived from poly(trimethylene ether) glycol having a number average molecular weight of about 600 to about 2500. Compositions thereof and articles made therefrom are disclosed.