Cryogenic Polymer Separation for Multi-Component Recycling
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Solution Overview
Problem
Recycling of multi-polymer articles, such as shoes, is challenging due to the difficulty in separating and classifying multiple polymer components with similar properties, which hinders effective material recovery and reuse.
Innovation Solution
A method and system utilizing temperature-dependent fracture properties of polymers, where articles are chopped and cooled to a temperature below the glass transition temperature of one polymer component, allowing it to shatter while the other remains intact, enabling separation and classification of polymer components, including the use of cryogenic chambers and impact mills for pulverization and separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional separation methods are used for multi-polymer articles, then metallic, glass, and plastic materials can be separated, but multiple polymer components cannot be effectively separated and classified
Solution Approach 1:
The patent applies parameter changes by cooling the article to cryogenic temperatures (below the glass transition temperature of the first polymer) to alter the physical properties of the polymers. This temperature change causes the first polymer to become brittle and shatterable while the second polymer remains flexible, enabling effective separation that was not possible at ambient conditions.
Solution Approach 2:
The patent applies segmentation by dividing the multi-polymer article into separate polymer component streams through sequential impacting and separation steps. The process segments the first polymer from the second polymer, and further segments the second polymer from textile components, creating distinct recyclable streams for each material type.
2Ease of manufacture
If articles are chopped and impacted at ambient temperature, then material processing is simple, but polymer components cannot be effectively separated due to similar fracture properties
Solution Approach 1:
The patent changes the temperature parameter from ambient to cryogenic conditions to differentiate the fracture properties of the polymer components. This parameter change transforms the processing from a simple but ineffective ambient temperature impact to a controlled cryogenic process that achieves both separation precision and manufacturing feasibility.
3Measurement precision
If cryogenic cooling is applied to separate polymer components, then separation precision is improved, but energy consumption and process complexity increase
Solution Approach 1:
The patent utilizes phase transitions by cooling the polymers below their glass transition temperatures to induce a transition from a flexible rubbery state to a brittle glassy state. This phase transition enables the first polymer to shatter upon impact while the second polymer remains intact, achieving high separation precision through a fundamental physical transformation.
Solution Approach 2:
The patent applies preliminary action by cooling the article to cryogenic temperatures before applying impact forces. This preliminary cooling step prepares the material in advance to exhibit differential fracture properties, ensuring that when impacting occurs, the separation is effective and precise without requiring complex real-time control during the impact process.
4Measurement precision
If multiple impacting steps are performed to maximize polymer separation, then separation completeness is improved, but processing time increases
Solution Approach 1:
The patent applies periodic action through sequential impacting and separation cycles. The process performs a first impacting step to separate the first polymer, then a second impacting step on the remaining fraction to further purify the separation. This periodic repetition of impact-separate cycles achieves complete separation while managing processing time through efficient cycle design.
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 approach allows for the effective separation and recovery of polymer components, maximizing recyclability by exploiting the differing embrittlement properties of polymers, enabling the recycling of materials like rubber and foam in shoes, and potentially other apparel articles.
Implementation Method 1
cooling the chips below a first temperature... while below the first temperature, pulverizing the chips, such that a portion of the first polymer component is shattered
Implementation Method 2
The cryogenic chamber cools the article pieces below a first temperature
Implementation Method 3
While still below the first temperature, the article pieces are impacted such that a portion of the first polymer component is shattered into first polymer component pieces
Data Source
AI summary
A system and method for separating polymer components of a multi-component article, such as a shoe, is presented. The described system and method exploits the differences in embrittlement and glass transition temperature of different polymer components of the multi-component article by cryogenically freezing the prepared article and impacting the article such that one polymer component is pulverized without substantially fracturing the remaining portion of the article. The system and method further includes a re-looping capability to maximize separation and recovery of polymer components.