Polyolefin Waste Recycling via Oxidation Sorting
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Solution Overview
Problem
Current recycling processes for polyolefin waste do not effectively produce high-quality recycled products without mixing virgin polyolefin, as they fail to manage the degree of oxidation in source waste materials of different grades, leading to inferior material properties due to contamination and mixing of highly and less oxidized polyolefins.
Innovation Solution
A recycling process involving sorting polyolefin waste pieces by their degree of oxidation, followed by contaminant removal using water and organic solvents, and subsequent extrusion into desired forms, allowing for the production of polyolefin products with tunable oxidation levels and improved quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polyolefin waste of different oxidation grades is mixed and recycled together, then the recycling process is simpler and more efficient, but the quality of the recycled product deteriorates due to inconsistent material properties
Solution Approach 1:
The patent divides polyolefin waste into separate batches based on oxidation degree (measured by carbonyl index). Sorting equipment such as NIR spectrometers automatically categorize waste pieces into different streams (e.g., CI < 0.2, 0.2 ≤ CI < 0.4, CI ≥ 0.4), allowing each batch to be processed independently and recycled into products with consistent quality characteristics.
Solution Approach 2:
The patent uses the carbonyl index (CI) as a key parameter to differentiate waste batches. By measuring and controlling this oxidation parameter, the process transforms unsorted mixed waste into sorted batches with defined CI ranges, enabling quality control and consistent recycling outcomes without compromising overall recycling efficiency.
2Quantity of substance
If highly oxidized polyolefin is included in the recycled material, then more waste can be recycled, but the material strength decreases and brittleness increases
Solution Approach 1:
The patent establishes carbonyl index thresholds to determine which oxidized polyolefin can be recycled into which product grades. By controlling the CI parameter in each batch, highly oxidized material (CI ≥ 0.4) can be directed toward applications where higher strength is not critical, while preserving material strength in applications requiring lower CI values.
3Manufacturing precision
If virgin polyolefin is mixed with recycled material to decrease oxidation degree, then the overall quality improves, but the amount of virgin material required increases
Solution Approach 1:
The patent uses carbonyl index measurement to precisely control the oxidation level of recycled batches, reducing or eliminating the need to blend with virgin polyolefin. By maintaining defined CI ranges through sorting and selective processing, the patent achieves consistent quality in recycled products without requiring additional virgin material input.
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 process enables the production of high-quality recycled polyolefins by separating and processing polyolefin waste based on oxidation levels, preventing mixing of degraded and pristine materials, thus enhancing the material's strength and brittleness, and ensuring efficient contaminant removal.
Implementation Method 1
the sorting procedure comprises measuring the degree of oxidation of the polyolefin pieces by means of spectroscopic analysis, in particular infrared analysis (IR), such as near-infrared (NIR), mid-infrared (MIR), or far-infrared (FIR) analysis
Implementation Method 2
the removing comprises washing the pieces with water prior to washing the pieces with an organic solvent
Implementation Method 3
thereafter evaporating traces of the organic solvent and water from the washed polyolefin pieces
Implementation Method 4
thereafter extruding the cleaned and dried polyolefin pieces into a desired form
Data Source
Figure 1
AI summary
The invention relates to recycling process for the recycling of polyolefin waste, comprising providing the polyolefin waste as a plurality of polyolefin pieces; thereafter removing contaminants from the polyolefin pieces, wherein the removing comprises washing the pieces with water prior to washing the pieces with an organic solvent; thereafter evaporating traces of the organic solvent and water from the washed polyolefin pieces to yield dry polyolefin pieces; thereafter extruding the resulting cleaned and dried polyolefin pieces into a desired form; wherein the recycling process comprises a sorting procedure that is performed before or after the removing of contaminants, the sorting procedure comprising dividing the plurality of polyolefin pieces into at least two groups of polyolefin pieces, wherein the dividing occurs according to the degree of oxidation of the polyolefin pieces; at least one of the groups of polyolefin pieces undergoes the exruding into a desired form.