Perfluoropolymer Composites with Layered Silicates
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Solution Overview
Problem
Perfluoropolymers exhibit low dynamic physical properties and reduced elasticity at temperatures above their glass transition temperature, and they tend to drip and spread fire when exposed to heat due to low viscosity at high shear rates, compromising their flame resistance and processability.
Innovation Solution
Homogeneously dispersing nano-sized layered-silicates with swelling or cleaving properties in perfluoropolymers, achieved through mixing and agglomerating aqueous dispersions under specific conditions, to create composites with improved melt viscosity and storage elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If perfluoropolymers are used for their flame resistance and chemical properties, then chemical resistance and flame resistance are improved, but dynamic physical properties and storage elasticity are reduced at temperatures above glass transition temperature
Solution Approach 1:
The patent combines perfluoropolymer with layered silicate to create a composite material that maintains the base polymer's flame resistance and chemical properties while adding reinforcement from the silicate structure. The composite leverages both materials' strengths to overcome the elasticity deficiency at elevated temperatures.
Solution Approach 2:
The layered silicate is dispersed at the nanoscale within the perfluoropolymer matrix, creating localized regions of enhanced mechanical properties. This nanodispersion ensures that the reinforcement is distributed throughout the material without compromising the overall chemical resistance or flame safety characteristics.
2Ease of manufacture
If perfluoropolymers are processed in melt state, then processability is improved, but viscosity decreases at high shear rates causing dripping and fire spread
Solution Approach 1:
The layered silicate forms a network structure within the melt that provides viscosity enhancement at low shear rates, preventing dripping during fire exposure, while allowing adequate flow during normal processing operations.
Solution Approach 2:
The addition of layered silicate fundamentally changes the rheological parameters of the perfluoropolymer melt, creating a material with higher zero-shear viscosity that maintains structural integrity under fire conditions while remaining processable.
3Strength
If inorganic fine particles are melt-mixed in polymers to improve mechanical characteristics, then mechanical properties are improved, but particle re-agglomeration occurs reducing dispersion quality
Solution Approach 1:
The patent achieves uniform nanoscale distribution of layered silicate throughout the perfluoropolymer matrix, ensuring consistent mechanical reinforcement without the re-agglomeration problems that plague conventional composite processing.
Solution Approach 2:
Processing the composite in the dispersed state and utilizing controlled aggregation during subsequent steps maintains particle separation at the nanoscale while achieving the desired mechanical property enhancements.
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 resulting perfluoropolymer composites exhibit superior dynamic physical properties, including high zero shear rate viscosity and storage elasticity at elevated temperatures, preventing dripping and enhancing flame resistance without compromising chemical resistance or electrical properties.
Implementation Method 1
homogeneously dispersing layered-silicates in perfluoropolymers
Implementation Method 2
layered-silicate having properties of swelling or cleaving in dispersion media
Implementation Method 3
the storage elasticity at temperatures greater than the glass transition temperature of the perfluoropolymer is improved
Implementation Method 4
the layer thickness of said layered-silicate in said composite is less than about 100 nm
Data Source
AI summary
Perfluoropolymer composites are provided which are obtained by dispersing layered-silicates having properties of swelling or cleaving in dispersion media in perfluoropolymers and having the ratio of the viscosity, V0.1, at 0.1 rad/sec by a parallel plate mode of a dynamic rheometer to the viscosity, V1, measured at 1 rad/sec is 1.5 or greater, viscosity being measured at 340° C. A method for making the perfluoropolymer composites is provided, and molded articles therefrom. And additionally, perfluoropolymer composites, where layered-silicates having properties of swelling or cleaving in dispersion media are dispersed in perfluoropolymers, with the storage elasticity of 2 times or higher than that of fluoropolymers, at temperatures greater than the glass transition temperature of perfluoropolymers.