Twin-Screw Extruder Screw Profiles for Polymer Degassing
Solution Overview
Problem
Existing methods for extrusion of polymer-containing media, such as rubber, face challenges in minimizing energy input to prevent overheating, which can lead to product damage and reduced mechanical properties due to crosslinking and decomposition, while also struggling with low devolatilization performance and residual volatile components.
Innovation Solution
A degassing device with a twin-screw extruder featuring screw elements with specific geometric profiles that minimize energy input and maximize devolatilization performance, including features like relative maxima in the cross-sectional profile and tangent angles, ensuring efficient volatile component removal with low polymer damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional screw elements with high energy input are used for extrusion, then volatile component removal is improved, but polymer damage occurs due to localized overheating and crosslinking
Solution Approach 1:
The screw element geometry is optimized with specific radial clearance distributions and profile characteristics (circular arc segments with defined radii) to create localized low-shear zones that prevent overheating while maintaining effective volatile component removal in other regions
Solution Approach 2:
The invention changes the geometric parameters of the screw element, specifically using circular arc profiles with radii R1, R2, R3 and defined clearance values (s1, s2, s3) to minimize energy input while maintaining extrusion functionality and devolatilization performance
2Object-affected harmful factors
If energy input is minimized to prevent overheating, then polymer quality is improved, but devolatilization performance decreases and residual volatile components increase
Solution Approach 1:
The screw element design incorporates dynamic flow patterns through its geometric profile, creating varying shear rates along the extrusion path that enable effective volatile removal without sustained high energy input that would cause overheating
Solution Approach 2:
The screw element uses circular arc profiles with specific radii (R1, R2, R3) to create curved flow paths that enhance mixing and volatile component release while distributing shear energy more evenly, preventing localized overheating
3Ease of manufacture
If standard screw profiles are used, then manufacturing simplicity is maintained, but flexibility in adjusting shear and extensional flows is limited
Solution Approach 1:
The screw element profile is segmented into multiple circular arc sections (with radii R1, R2, R3) that can be independently designed and manufactured, allowing flexible adjustment of shear and extensional flow characteristics while maintaining manufacturability through modular construction
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
The solution significantly increases throughput and devolatilization performance while minimizing energy input and polymer damage, achieving a high degree of volatile component removal with low residual content, effectively addressing the limitations of prior methods.
Implementation Method 1
a significant amount of energy is dissipated into the polymer-containing media being extruded, which can lead to localized overheating
Implementation Method 2
removing volatile components such as monomers, oligomers, and auxiliary and solvent components from polymer-containing media
Implementation Method 3
depressurized, in particular by a factor of 10 to 1000, especially to a pressure in the range from 100 to 1000 hPa, in particular from 100 to 500 hPa
Data Source
Figure 1
Figure 2a~2b
Figure 2c~2d
AI summary
The invention relates to a method for degassing polymer-containing media, such as in particular polymer melts, polymer solutions, and polymer dispersions, and to degassing devices for performing the aforementioned method.