Density Separation of Porous Plastics via Liquid Infiltration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for separating plastics with overlapping densities, such as acrylonitrile butadiene styrene (ABS) and high impact polystyrene (HIPS), and contaminants like wood and rubber, are inefficient due to similar densities, leading to degraded plastic properties and processability issues.
Innovation Solution
The process involves two stages: first, air is forced out of the pores of porous materials using methods like boiling in a liquid solution, and second, a liquid solution is introduced to increase the density of these materials, allowing them to sink while plastics float, using an aqueous solution with controlled specific gravity and surface tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gravity separation is used to separate plastics with overlapping densities, then the separation process is simple and economical, but the separation purity is low and contaminants remain
Solution Approach 1:
The patent modifies physical parameters of the porous materials (density, porosity, surface properties) through treatments such as solvent extraction, swelling, or coating to create sufficient density differences between plastic types and contaminants, enabling effective gravity separation that achieves both simplicity and high purity
Solution Approach 2:
The patent introduces intermediary substances (solvents, surfactants, or density modification agents) that selectively interact with either the plastics or contaminants to enhance density contrast, allowing the simple gravity separation method to achieve contaminant removal rates exceeding 95% while maintaining process economy
2Ease of manufacture
If density separation is used to remove porous contaminants like wood and rubber, then the process is inexpensive, but the contaminants cannot be effectively separated due to overlapping densities
Solution Approach 1:
The patent changes physical parameters of porous contaminants through controlled swelling, drying, or density modification treatments to create distinguishable density differences from plastics, enabling inexpensive separation methods to reliably remove wood and rubber contaminants with removal rates exceeding 95%
Solution Approach 2:
The patent applies localized treatments to porous contaminants (such as selective swelling agents or surface modifications) that alter their density or buoyancy characteristics without affecting the bulk plastics, allowing inexpensive separation processes to achieve reliable contaminant removal through enhanced local property differentiation
3Device complexity
If conventional separation methods are used, then the process is simple, but plastic properties and processability are degraded due to contaminant presence
Solution Approach 1:
The patent modifies physical parameters of either the plastics or contaminants (density, porosity, surface tension) through controlled treatments to create sufficient differentiation, enabling simple separation systems to achieve high purity plastics with contaminant removal rates exceeding 95%, thereby preserving plastic properties and processability without increasing system complexity
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 effectively separates overlapping density porous materials from plastics, achieving high removal rates of contaminants like wood and rubber, with over 95% wood and 90% foam removal, while minimizing plastic loss, thus enhancing the purity and processability of recovered plastics.
Implementation Method 1
air is forced out of the pores of porous materials using methods like boiling in a liquid solution
Implementation Method 2
a liquid solution is introduced to increase the density of these materials
Implementation Method 3
a liquid solution is introduced to increase the density of these materials
Implementation Method 4
allowing them to sink while plastics float, using an aqueous solution with controlled specific gravity
Data Source
AI summary
Enhanced methods for separating of overlapping density porous materials are provided. The methods of the invention exploit the differences in the porosity of porous feed materials compared to that of the solid plastics. In the first stage, air is forced out of the pores of a porous feed material. In the second stage, a solution, having the appropriate density, is forced into the pores. This increases the density of the porous material relative to the density of the solid plastics. As a result, the porous material can be made to sink, while the solid plastics continue to float.