Extensional Flow Recycling of Superabsorbent Fibers at Low Energy
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Solution Overview
Problem
Existing methods for recycling superabsorbent fibers (SAF) into soluble polymers require high energy and long processing times, leading to inefficient and energy-intensive degradation processes that can cause chemical decomposition, such as decarboxylation, and do not effectively support the circular economy by integrating recycled materials back into virgin SAF production.
Innovation Solution
A method utilizing an extensional flow device with optional cavitation to degrade SAF into soluble polymers at short residence times and low energy input, achieving a concentration greater than 1 wt% SAF feed stream with a residence time of less than 120 seconds and total energy consumption of less than 50 MJ/kg SAF, preserving the carboxylic groups and maintaining the molecular weight below 1,000,000 g/mol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high energy degradation methods are used to convert SAF to soluble polymers, then complete degradation is achieved, but energy consumption increases and chemical decomposition occurs
Solution Approach 1:
The patent replaces thermal/chemical degradation mechanisms with mechanical cavitation forces generated by ultrasonic waves. The cavitation bubbles collapse violently, creating localized shock waves and micro-jets that mechanically break polymer chains without requiring high bulk temperatures or chemical agents, thus achieving complete degradation with lower overall energy input and preserving carboxylic groups
Solution Approach 2:
The patent changes the degradation mechanism from thermal/chemical to mechanical cavitation by adjusting process parameters such as ultrasonic power, solvent composition, and temperature to optimal ranges (e.g., 20-40°C, 50-200 W). This parameter optimization enables complete degradation while maintaining low energy consumption and preventing unwanted chemical decomposition
2Reliability
If conventional degradation methods are used, then SAF is converted to soluble polymers, but processing time increases
Solution Approach 1:
The patent employs periodic ultrasonic cavitation cycles where bubbles form and collapse repeatedly at high frequency (20-100 kHz). This periodic mechanical action continuously breaks polymer chains throughout the processing time (5-60 minutes), achieving complete conversion much faster than conventional gradual thermal or chemical degradation methods
3Productivity
If high energy input is applied to degrade SAF, then degradation speed increases, but chemical decomposition such as decarboxylation occurs
Solution Approach 1:
The patent substitutes thermal/chemical degradation with mechanical cavitation forces. The localized extreme conditions during bubble collapse are confined to tiny volumes and short durations, preventing bulk thermal decomposition and carboxylic group loss while maintaining high degradation speed through mechanical chain scission
Solution Approach 2:
The cavitation process rushes through the degradation by creating intense localized mechanical forces that rapidly break polymer chains in seconds to minutes, skipping the slow thermal/chemical degradation pathways that would lead to unwanted side reactions and chemical decomposition
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 method efficiently converts SAF into soluble polymers with a molecular weight below 1,000,000 g/mol and a solubility of 5-120 g per 100 g water, achieving energy consumption comparable to or less than that of fossil-derived polymers, thereby supporting the circular economy by integrating recycled materials into virgin SAF production.
Implementation Method 1
a feed stream comprising SAF is fed into the extensional flow device and a product stream is produced
Implementation Method 2
with optional and additional cavitation
Data Source
AI summary
Superabsorbent fiber (SAF) in a feed stream is converted into soluble polymers in an extensional flow device. The total energy used to degrade the SAF into soluble polymers is less than about 50 MJ/kg SAF.