Foamed Shoe Material r-PET EVA Compatibilizer Extrusion
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Solution Overview
Problem
The challenge lies in effectively combining recycled polyethylene terephthalate (r-PET) with ethylene vinyl acetate (EVA) due to differences in molecular structure and physical properties, which hinders the production of homogeneous blends for foamed shoe materials, and also affects the processing performance and quality of recycled PET products.
Innovation Solution
A method involving the use of a compatibilizer to form a polymer alloy by mixing r-PET and EVA, followed by extrusion with controlled temperature and shear rate using a twin-screw extruder, resulting in composite material masterbatches with improved compatibility, which are then used to produce foamed shoe materials, thereby reusing recycled PET and reducing carbon emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If recycled PET and EVA are directly mixed, then the processing is simple, but the blend is not homogeneous due to differences in molecular structure and physical properties
Solution Approach 1:
The patent introduces a compatibilizer as an intermediary substance to facilitate the mixing of recycled PET and EVA. The compatibilizer has molecular structures that are compatible with both PET and EVA, acting as a bridge to reduce interfacial tension and improve dispersion. This mediator enables homogeneous blending without requiring complex processing equipment or extreme conditions.
2Object-affected harmful factors
If recycled PET is used, then the environmental benefit and reduction of petrochemical demand are achieved, but the melt viscosity and thermal stability decrease affecting processing performance
Solution Approach 1:
The patent modifies the processing parameters specifically for recycled PET blends. The extrusion temperature is optimized to balance melt viscosity reduction with thermal stability maintenance. The screw speed and residence time are adjusted to ensure adequate mixing without excessive degradation. These parameter changes enable successful processing of recycled PET while maintaining product quality.
Solution Approach 2:
The patent creates a composite material system combining recycled PET, EVA, and compatibilizer. This composite formulation leverages the complementary properties of each component: recycled PET provides structural integrity and sustainability, EVA contributes flexibility and ease of processing, and the compatibilizer ensures uniform distribution. The composite material achieves both environmental benefits and reliable processing performance.
3Stability of the object's composition
If the temperature is increased during extrusion to improve mixing, then the homogeneity improves, but the thermal degradation of recycled PET increases
Solution Approach 1:
The compatibilizer serves as a thermal protective intermediary during the extrusion process. It forms a protective interface around recycled PET particles, reducing direct exposure to high temperatures and preventing excessive thermal degradation. This allows the process to achieve adequate homogeneity while minimizing harmful thermal effects on the recycled PET.
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 enables the production of foamed shoe materials with enhanced compatibility between r-PET and EVA, promoting the reuse of recycled PET, reducing carbon emissions, and minimizing the demand for fresh PET materials and petrochemical raw materials.
Implementation Method 1
heating the polymer alloy from temperature of 160° C. to 245° C.
Implementation Method 2
cooling it down to less than 240° C.
Implementation Method 3
an average shear rate of 100/sec to 300/sec
Data Source
AI summary
A method for making foamed shoe materials includes mixing r-PET and EVA with a compatibilizer for melt modification, a new polymer alloy is formed. The polymer alloy is then extruded into strips with an screw extruder under a temperature of 160° C. to 245° C. and an average shear rate of 100/sec to 300/sec, and at an extrusion rate of 100 kg/hr to 250 kg/hr. Simultaneously, the temperature of the screw in the extrusion process is controlled to rise from 160° C. to 245° C., then decrease to less than 240° C., so as to produce composite material masterbatches with good compatibility between recycled PET and EVA, which are used to produce foamed shoe materials, thus achieving the purpose of reusing recycled PET, reducing carbon emissions, and protecting the environment. Furthermore, it reduces the demand for fresh PET materials, thereby reducing the demand for petrochemical raw materials.