Reactive Oligomers for Melt Processing High-Temperature Polyamideimides
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Solution Overview
Problem
High molecular weight all-aromatic polyamideimides (PAIs) face challenges in melt processing due to high sensitivity to temperature and shear rate, requiring extensive drying and thermal post-treatment, which limits their use in manufacturing complex parts and is time-consuming, especially for injection molding and additive manufacturing processes.
Innovation Solution
Development of reactive oligomers with unreacted functional groups capable of thermal chain extension and crosslinking, allowing for fully imidized polyamideimide oligomers that can be melt processed and thermally cured in a single step, eliminating the need for extensive drying and long thermal post-treatment, and enabling the production of complex parts with superior thermal and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high molecular weight PAI is used to achieve excellent high temperature strength and chemical resistance, then mechanical properties are improved, but melt processing becomes difficult due to high viscosity and sensitivity to temperature and shear rate
Solution Approach 1:
The patent segments the processing into two distinct stages: (1) melt processing of low molecular weight oligomers with unreacted functional groups, and (2) subsequent thermal curing to build molecular weight and crosslink. This segmentation allows each stage to be optimized independently, resolving the contradiction between processability and final strength.
Solution Approach 2:
The patent performs preliminary action by pre-synthesizing oligomers with controlled molecular weight and unreacted functional groups before processing. This preliminary preparation ensures low viscosity during extrusion/injection molding, while the unreacted groups are reserved for later crosslinking to achieve high strength, eliminating the need to process high molecular weight material directly.
2Ease of manufacture
If amic acid groups are present in the polymer backbone to provide flexibility and melt processability, then ease of processing is improved, but extensive drying and thermal post-treatment are required to remove water, increasing processing time
Solution Approach 1:
The patent performs preliminary imidization to convert amic acid groups to cyclic imide groups and removes water before processing. The oligomers are supplied in a pre-dried, fully imidized state with unreacted functional groups, eliminating the need for extensive drying during processing and reducing post-cure time to merely 1-24 hours for crosslinking rather than days for water removal.
Solution Approach 2:
The patent extracts water from the system before processing by using pre-dried oligomers with fully imidized groups. This removal of water (the harmful factor) before processing eliminates the need for extended thermal post-treatment to remove water generated during imidization, significantly reducing processing time while maintaining processability through the unreacted functional groups.
3Ease of manufacture
If injection molding grade PAI with lower molecular weight oligomers is used to improve melt processing, then ease of manufacture is improved, but large amounts of water must be removed from final parts, requiring time-consuming post-treatment
Solution Approach 1:
The patent extracts water from the system before processing by supplying pre-dried oligomers with fully imidized groups and unreacted functional groups. This eliminates water generation during processing, removing the need for time-consuming water removal from final parts while maintaining the melt processing advantages of low molecular weight oligomers.
Solution Approach 2:
The patent changes the chemical state of the oligomers by fully imidizing them before processing, converting them from amic acid-containing intermediates to fully imidized species with unreacted functional groups. This parameter change (chemical composition) eliminates water generation during curing while maintaining low viscosity for easy processing, resolving both the ease of manufacture and time loss contradictions.
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 reactive oligomers facilitate rapid thermal curing, reducing processing time to hours from days, improving mechanical properties, and enabling the production of parts with enhanced toughness, strength, and thermal resistance, suitable for various manufacturing processes including injection molding and additive manufacturing.
Implementation Method 1
functionalized with at least one unreacted functional group capable of thermal chain extension and crosslinking after formation of the reactive oligomer
Implementation Method 2
The reactive oligomer can be melt processed
Data Source
AI summary
A reactive oligomer has a backbone derived from at least one of polyamideimide, polyimide, polyetherimide, polyaryletherketone, polyethersulfone, polyphenylene sulfide, polyamide, polyester, polyarylate, polyesteramide, polycarbonate, polybenzoxazole or polybenzimidazole and functionalized with at least one unreacted functional group capable of thermal chain extension and crosslinking after formation of the reactive oligomer, wherein the reactive oligomer has an Mn of about 250 to about 10,000 g/mol, calculated using the Carothers equation. Compositions comprising the reactive oligomer have at least one other component that includes a second reactive oligomer, an oligomer lacking unreacted functional groups capable of thermal chain extension and crosslinking, a thermoplastic polymer, a thermoplastic polymer having the same backbone repeat units as the reactive oligomer, a filler, or an additive. A method of manufacture of an article comprises heating a composition comprising the reactive oligomer at a sufficient temperature and time to shape and crosslink the reactive oligomer, including additive manufacturing.