Decomposing Cross-Linked Polymers Using Alkyl Carbonate
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Solution Overview
Problem
Current methods for decomposing cross-linked polymers, such as those used in electric wire and cable waste, face challenges due to the toxicity of nitrogen dioxide and inefficiency in recycling polymers without silane bonds, making it difficult to recycle thermosetting and cross-linked polymers effectively.
Innovation Solution
A method using alkyl carbonate, specifically dimethyl carbonate or diethyl carbonate, at high temperatures (250° C or more, to decompose cross-linked polymers, including those with organic peroxide or radiation cross-linking, efficiently breaking down the cross-linked structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nitrogen dioxide is used to decompose cross-linked polyethylene in supercritical carbon dioxide, then decomposition can be achieved, but toxicity to human body and environmental harm increase
Solution Approach 1:
The patent extracts and removes nitrogen dioxide from the decomposition system, replacing it with alternative methods (enzymatic decomposition, mechanical recycling, or other non-toxic chemical agents) that maintain decomposition efficiency while eliminating the harmful toxic effects on human respiratory system and environment
Solution Approach 2:
The patent introduces an intermediary substance or method that can facilitate the decomposition of cross-linked polyethylene without the harmful effects of nitrogen dioxide. This intermediary could be an enzyme, a catalyst, or a different chemical agent that achieves the same decomposition goal through a safer mechanism
2Adaptability or versatility
If high-temperature alcohol is used to disconnect siloxane bonds in silane cross-linked polymer, then thermal plasticization is achieved, but the method is not effective for cross-linked polymers without siloxane bonds
Solution Approach 1:
The patent develops a universal decomposition method that can handle multiple types of cross-linked polymers (both silane cross-linked with siloxane bonds and non-silane cross-linked polymers) using a single approach or system, rather than requiring different methods for different polymer types. This could involve using enzymes with broad substrate specificity, mechanical recycling processes, or non-specific chemical degradation methods
Solution Approach 2:
The patent changes the decomposition parameters (temperature, pressure, chemical environment, enzyme type) to optimize the decomposition process for different polymer types. By adjusting these parameters, the system can effectively decompose both silane cross-linked polymers and other cross-linked polymers without sacrificing efficiency
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 allows for rapid decomposition of cross-linked polyethylenes, reducing the gel fraction to less than 50%, indicating effective breakdown of the polymer structure, and is safer than using nitrogen dioxide, with results showing significant decomposition even in short reaction times.
Implementation Method 1
decomposing an organic compound by alkyl carbonate at 250° C. or more
Data Source
AI summary
A method of decomposing an organic compound includes decomposing an organic compound by alkyl carbonate at 250° C. or more. The organic compound includes a cross-linked polymer. The cross-linked polymer includes a polymer cross-linked by organic peroxide cross-linking, radiation cross-linking, or silane cross-linking The alkyl carbonate includes dimethyl carbonate or diethyl carbonate.