Devulcanizing Thermoset Elastomer Scrap via High Shear Mixer and Extruder
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Solution Overview
Problem
Current devulcanization processes for waste cross-linked rubber are batch-operated and require additional post-processing in a roll mill, limiting efficiency and material reuse.
Innovation Solution
A combination of a batch-operated high shear mixer for initial devulcanization followed by a continuously-operated multi-screw cooled extruder for further mechanical shearing, eliminating the need for a separate roll mill and producing reusable pellets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If batch-operated high shear mixing is used for devulcanization, then chemical reactions are induced to partly devulcanize the material, but additional post-processing in a roll mill is still required
Solution Approach 1:
The patent combines the high shear mixing devulcanization process with a multi-screw extruder into a single integrated system. The extruder performs both devulcanization and extrusion in one continuous operation, eliminating the need for separate roll mill processing and reducing overall process complexity despite using multiple pieces of equipment.
Solution Approach 2:
The multi-screw extruder is designed to perform multiple functions: it continues the devulcanization process initiated by the high shear mixer, extrudes the processed material, and produces final pellets ready for revulcanization. This multi-functional approach eliminates the need for dedicated roll mill equipment.
2Productivity
If batch operation is used for devulcanization, then material can be processed, but productivity is limited compared to continuous processing
Solution Approach 1:
The patent transitions from batch operation to continuous operation by using a multi-screw extruder that processes material continuously. The extruder maintains continuous devulcanization and extrusion operations, eliminating idle time between batches and significantly improving productivity and material processing rate.
3Reliability
If high shear mixing is used to un-crosslink thermoset elastomers, then approximately 60% of original physical properties are recovered, but some cross-linking remains requiring further processing
Solution Approach 1:
The high shear mixer performs preliminary devulcanization to break down cross-links and produce a partly processed material with improved physical properties. This preliminary action prepares the material for the extruder, which completes the devulcanization process and produces final pellets ready for revulcanization, eliminating the need for separate roll mill processing.
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 integrated system efficiently recycles thermoset elastomeric scrap into revulcanizable pellets, enhancing material recovery and streamlining the process for producing useful rubber products.
Implementation Method 1
This mechanical process has been demonstrated to have the ability to un-crosslink thermoset elastomers using shear energy such that approximately 60% of the original physical properties of the materials are recovered
Implementation Method 2
a continuously-operated multi-screw cooled extruder for receiving the partly devulcanized material from the high shear mixer and further devulcanizing the material by mechanical shearing action
Data Source
AI summary
An apparatus for processing thermoset cross-linked elastomeric scrap material has a batch-operated high shear mixer for inducing chemical reactions to partly devulcanize the material in a first devulcanizing stage. A continuously-operated multi-screw cooled extruder receives the partly devulcanized material from the high shear mixer and further devulcanizes the material by a mechanical shearing action in a second stage to produce an extruded product for revulcanization.