Method of making a phosphonated PBI fiber
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Commercially available sulfonated polybenzimidazole (PBI) fibers, while thermo-oxidatively stable, have limitations in applications due to their phosphoric acid content and environmental concerns, prompting the need for alternative phosphonated PBI fibers with enhanced stability and reduced phosphate content.
Innovation Solution
A method involving spinning untreated PBI resin into fibers and treating them with phosphoric acid to achieve a phosphonated PBI fiber with a phosphoric acid pick-up range of 1-25 wt%, resulting in fibers with improved thermo-oxidative stability and reduced phosphate content, characterized by a Limiting Oxygen Index (LOI) ≥50% and an onset thermal degradation temperature ≥555°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfonated PBI fibers are used to achieve thermo-oxidative stability, then LOI reaches around 41%, but phosphate content increases causing environmental concerns
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating phosphonated side chains with specific phosphoric acid pick-up ranges (1-25 wt%) instead of traditional sulfonated groups. This parameter change maintains thermo-oxidative stability while reducing harmful phosphate content through controlled acid pick-up during fiber processing
Solution Approach 2:
The patent creates a composite structure by combining PBI polymer matrix with phosphonated side chains containing phosphoric acid. This composite approach allows the material to achieve both thermo-oxidative stability from the PBI backbone and reduced harmful effects through the specific phosphonated structure with controlled acid content
2Reliability
If phosphoric acid pick-up is increased to enhance thermo-oxidative stability, then LOI increases to ≥50%, but thermal degradation resistance decreases
Solution Approach 1:
The patent optimizes the phosphoric acid pick-up parameter within a specific range (1-25 wt%) to balance two competing requirements. By controlling this parameter, the fiber achieves LOI ≥50% for thermo-oxidative stability while maintaining onset thermal degradation temperature ≥555°C, resolving the trade-off between these two properties
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 phosphonated PBI fibers exhibit superior thermo-oxidative stability and reduced phosphate content, expanding their application potential while maintaining or exceeding the stability of sulfonated PBI fibers, with specific embodiments showing LOI values up to 65.5% and thermal decomposition temperatures up to 592°C.
Implementation Method 1
treating the PBI fiber with phosphoric acid, and thereby obtaining a FBI fiber with 1-25 wt. % phosphoric acid APU
Implementation Method 2
PBI-p fiber may have a LOI of ≥60% at ≥1% or 4% APU phosphoric acid
Implementation Method 3
onset thermal degradation temperature ≥555° C. determined by Thermo-Gravimetric_analysis (TGA) in air at a 20° C./min heating rate
Implementation Method 4
The phosphonated PBI fibers exhibit superior thermo-oxidative stability and reduced phosphate content, expanding their application potential while maintaining or exceeding the stability of sulfonated PBI fibers
Data Source
AI summary
A method of making a phosphonated polybenzimidazole fiber comprises the steps of: spinning an untreated PBI resin into a PBI fiber; treating the PBI fiber with phosphoric acid, and thereby obtaining a PBI fiber with 1-25 wt. % phosphoric acid APU. A fiber is made with a polybenzimidazole (PBI) polymer with a phosphoric acid pick-up (APU) in the range of 1-25% (PBI-p fiber). The PBI-p fiber may have a LOI≥50% and/or an initial thermal decomposition temperature in air of ≥555° C.