Reinforced VDF Fluoropolymer Articles Without Full Crosslinking
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Solution Overview
Problem
The challenge lies in achieving good mechanical properties in fluoropolymer-based shaped articles without compromising their ease of processing, as lower melting points and viscosities, which facilitate easier handling, often result in lower mechanical strength and recyclability issues due to full cross-linking.
Innovation Solution
A method involving fluoropolymers with more than 30% recurring units derived from VDF, iodine-containing chain ends, and specific molecular weights, which are dissolved, precipitated, and then thermally treated below their melting point to enhance mechanical properties without full cross-linking, allowing for improved adhesion and recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If VDF based fluoropolymers with lower melting points and viscosities are selected for easier processing, then ease of manufacture is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent applies preliminary action by introducing iodine-containing chain ends during polymer synthesis before processing. These chain ends are prepared in advance to enable controlled thermal cross-linking later, allowing the polymer to be processed easily in its uncrosslinked state and then reinforced subsequently through thermal treatment.
Solution Approach 2:
The patent employs parameter changes by controlling the thermal treatment temperature to be below the melting point of the fluoropolymer. This specific temperature parameter change enables cross-linking activation without complete melting, thereby reinforcing the material while preserving its processability and avoiding full cross-linking that would eliminate thermoplasticity.
2Strength
If fully crosslinked polymers are used to enhance mechanical properties, then strength is improved, but ease of operation deteriorates due to loss of thermoplasticity
Solution Approach 1:
The patent applies partial action by performing incomplete cross-linking through thermal treatment below the melting point. This partial cross-linking provides sufficient mechanical reinforcement while leaving the polymer partially thermoplastic, enabling recycling and reprocessing. The cross-linking is deliberately kept partial rather than complete to maintain operational flexibility.
3Strength
If cross linkers or radical initiators are added to easy-to-process polymers, then mechanical properties are improved, but device complexity increases
Solution Approach 1:
The patent extracts the cross-linking function from separate additives (cross-linkers and radical initiators) and integrates it into the polymer chain structure itself through iodine-containing chain ends. This eliminates the need for additional chemical additives and simplifies the overall process by using only thermal treatment without requiring separate cross-linking agents.
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
This method effectively reinforces shaped articles with enhanced mechanical properties and improved adhesion, while maintaining the benefits of easy processing and recyclability, suitable for applications like electrodes and membranes.
Implementation Method 1
dissolving said fluoropolymer in a suitable solvent and forming a precursor solution
Implementation Method 2
precipitating said fluoropolymer as a solid from said precursor solution thereby obtaining a shaped article
Implementation Method 3
thermally treating said shaped article for at least 15 minutes at a temperature comprised between 100° C. and the lowest melting point Tm of said one or more fluoropolymers thereby obtaining said reinforced shaped article
Data Source
AI summary
The present invention pertains to a method for making a reinforced shaped article comprising the steps of: a) providing one or more fluoropolymers having a melting point Tm, said one or more fluoropolymers being characterized in that they: (i) comprise more than 30% by moles of recurring units derived from VDF, with respect to the total number of recurring units of the polymer; (ii) have iodine-containing chain ends —CH2I in an amount of 0.1 to 0.9 per chain; b) dissolving said fluoropolymer in a suitable solvent and forming a precursor solution c) precipitating said fluoropolymer as a solid from said precursor solution thereby obtaining a shaped article comprising said fluoropolymer e) thermally treating said shaped article for at least 15 minutes at a temperature comprised between 100° C. and the lowest melting point Tm of said one or more fluoropolymers thereby obtaining said reinforced shaped article.