Cross-linked Foam Reprocessing via Particle Size Control
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Solution Overview
Problem
Recycling cross-linked polymeric materials, especially foamed cross-linked materials, is challenging due to their inability to melt again and the difficulties in separating them from thermoplastics, leading to costly and environmentally impactful chemical methods that can affect the final product with gas release and residual cross-linking agents.
Innovation Solution
A method of reprocessing cross-linked foams by processing them into a form with an average particle size less than or equal to the average cell size, allowing for melt processing, which can be done individually or bonded with thermoplastics, using techniques like shredding, grinding, and melt mixing with compatibilizers to minimize residual agents and gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cross-linked foam is processed using chemical methods to reduce cross links, then the material can be reused, but the process becomes expensive and environmentally harmful with gas release and residual cross-linking agents
Solution Approach 1:
The patent changes the physical state and size parameters of the cross-linked foam by processing it into small particles (average particle size less than or equal to average cell size). This physical transformation allows the material to be melt-processable without requiring chemical degradation, thus avoiding harmful chemical methods while enabling recycling
Solution Approach 2:
The patent replaces chemical methods (which use chemicals to break cross-links) with a mechanical/physical approach. By reducing the foam to fine particles through mechanical processing, the material can be directly melt-processed and reused without chemical treatment, eliminating environmental harm and residual agents
2Ease of manufacture
If cross-linked foam is separated from thermoplastics for recycling, then the material can be processed, but the process becomes time consuming and labor intensive
Solution Approach 1:
The patent segments the cross-linked foam into very fine particles (average particle size less than or equal to average cell size). This segmentation allows the material to be directly fed to melt processors without requiring separation from thermoplastics, as the fine particles can be uniformly mixed and processed together, dramatically reducing separation time and labor
3Ease of manufacture
If cross-linked foam is ground to fine particles for melt processing, then the material becomes melt-processable, but gas release from foam cells may negatively impact the final product
Solution Approach 1:
The patent optimizes the particle size parameter to be less than or equal to the average cell size of the foam. This specific size range allows the particles to be melt-processable while minimizing gas release issues. The fine particle size enables better gas evacuation during processing compared to larger particles, achieving a balance between processability and product quality
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 creation of melt-processable materials from cross-linked foams, reducing processing time and environmental impact, and allowing for tailored properties by controlling particle size and gas content, thus overcoming the limitations of existing recycling methods.
Implementation Method 1
A method of making a melt-processable material comprising: processing a cross-linked polymeric foam to form a processed cross-linked polymeric foam material wherein the processed cross-linked polymeric foam material has an average particle size suitable for feeding to a melt processor; feeding the processed cross-linked polymeric foam to the melt processor; and melt mixing a composition comprising a thermoplastic material and the processed cross-linked polymeric foam material in the melt processor
Data Source
AI summary
Disclosed herein is a method of making a melt-processable material comprises: processing a cross-linked polymeric foam to form a processed cross-linked polymeric foam material wherein the processed cross-linked polymeric foam material has an average particle size suitable for feeding to a melt processor, feeding the processed cross-linked polymeric foam material to the melt processor, and melt mixing a composition comprising the processed cross-linked polymeric foam material and a thermoplastic material wherein the processed cross-linked foam material has a domain size, under melt mixing conditions, less than or equal to the processing spaces of the melt processor.