Polyvinylidene Chloride Recycling via Polar Aprotic Solvent Extraction
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Solution Overview
Problem
Polyvinylidene chloride containing composite materials are difficult to recycle due to low thermal degradation temperature and contamination issues during mechanical separation, leading to unusable polyolefin and polyvinylidene chloride streams.
Innovation Solution
Subjecting the composite material to a polar aprotic solvent to dissolve polyvinylidene chloride, separating the undissolved polyolefin, and precipitating the pure polyvinylidene chloride, achieving high purity and reducing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical recycling and sink float separation are used to separate polyolefin and polyvinylidene chloride, then separation of resin streams is achieved, but contamination between streams occurs (polyolefin stream contains polyvinylidene chloride and vice versa)
Solution Approach 1:
The patent extracts polyvinylidene chloride from the composite material using a polar aprotic solvent, separating it from the polyolefin matrix. This extraction process achieves complete removal of polyvinylidene chloride from the polyolefin stream, eliminating the contamination issue that plagues mechanical separation methods.
Solution Approach 2:
The patent introduces a polar aprotic solvent as an intermediary substance to facilitate separation. The solvent selectively dissolves polyvinylidene chloride while leaving polyolefin intact, enabling clean separation without the cross-contamination that occurs in direct mechanical separation processes.
2Ease of manufacture
If polyvinylidene chloride is present in polyolefin stream during recycling, then mechanical separation is simplified, but thermal degradation occurs causing black carbon formation and browning
Solution Approach 1:
The patent applies preliminary action by removing polyvinylidene chloride from the composite material before the recycling process. The polar aprotic solvent treatment occurs prior to any thermal processing, preventing thermal degradation and black carbon formation during subsequent recycling operations.
Solution Approach 2:
The patent converts the harmful presence of polyvinylidene chloride in polyolefin streams into a beneficial separation opportunity. By using the selective solubility of polyvinylidene chloride in polar aprotic solvents, the process transforms what was previously a contamination problem into an effective separation mechanism.
3Ease of manufacture
If polyolefin is present in polyvinylidene chloride stream, then composite material recycling is simplified, but barrier properties of polyvinylidene chloride are degraded
Solution Approach 1:
The patent extracts polyolefin from the composite material using the polar aprotic solvent, which selectively dissolves polyvinylidene chloride while leaving polyolefin behind. This extraction ensures the polyvinylidene chloride stream remains free of polyolefin contaminants, preserving its barrier properties.
Solution Approach 2:
The polar aprotic solvent acts as an intermediary that enables selective separation. It facilitates the removal of polyolefin from the polyvinylidene chloride stream through differential solubility, ensuring the integrity of the polyvinylidene chloride's barrier properties.
4Productivity
If composite materials are subjected to normal shredding and grinding, then material is reduced to smaller pieces, but resin layers do not separate adequately
Solution Approach 1:
The patent replaces mechanical separation methods (shredding and grinding) with a chemical separation approach using polar aprotic solvents. This substitution enables effective separation of resin layers that mechanical methods cannot achieve, while maintaining productive processing rates.
Solution Approach 2:
The patent changes the separation parameter from mechanical (physical size reduction) to chemical (solubility-based). By using polar aprotic solvents, the process achieves effective resin separation based on differential solubility, overcoming the limitations of mechanical methods.
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
Enables the recycling of composite materials into pure polyolefin and polyvinylidene chloride streams, improving the recyclability and reusability of both materials by minimizing thermal degradation and contamination.
Implementation Method 1
The composite material is subjected to a polar aprotic solvent to dissolve the polyvinylidene chloride from the composite material into the solution of the polar aprotic solvent
Implementation Method 2
The polyvinylidene chloride can be precipitated out of the solution. The precipitated polyvinylidene chloride being substantially pure polyvinylidene chloride
Data Source
AI summary
A method of recycling a composite material of polyolefin and polyvinylidene chloride. The composite material is subjected to a polar aprotic solvent to dissolve the polyvinylidene chloride from the composite material into the solution of the polar aprotic solvent. The undissolved composite material from the solution can be collected and rinsed. The collected undissolved composite material being substantially free from polyvinylidene chloride. The polyvinylidene chloride can be precipitated out of the solution. The precipitated polyvinylidene chloride being substantially pure polyvinylidene chloride.