Recycled Polyolefin Compositions with Heterophasic Phase
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Solution Overview
Problem
The recycling of waste polyolefin materials is hindered by their heterogeneity and poor mechanical properties, which limits their value in applications such as sheets, laminates, and geomembranes, despite efforts to improve processability with fillers and compatibilizing agents.
Innovation Solution
The development of polyolefin compositions comprising 30-80% waste polyethylene or polypropylene mixed with 20-70% heterophasic polyolefin compositions, specifically formulated with propylene polymers and ethylene copolymers to enhance tensile properties without the need for fillers or coupling agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If waste polyolefin materials are used for recycling, then the quantity of recycled material increases, but the mechanical properties and processability deteriorate due to heterogeneity and degradation
Solution Approach 1:
The patent creates a composite material system by combining waste polyolefin (30-80 wt%) with a specifically designed heterophasic polyolefin composition (20-70 wt%). The heterophasic composition contains two distinct polyolefin phases with different properties: a crystalline phase providing structural integrity and a rubbery phase providing flexibility and impact resistance. This composite approach allows the recycling of heterogeneous waste materials while restoring mechanical properties through the synergistic interaction between the waste polyolefin and the heterophasic composition.
Solution Approach 2:
The patent changes the compositional parameters of the recycled material by incorporating a heterophasic polyolefin composition with controlled phase distribution. The heterophasic composition contains a crystalline polyolefin phase (30-70 wt% of the heterophasic composition) and a rubbery polyolefin phase (30-70 wt% of the heterophasic composition), with specific glass transition temperatures and melting points. By controlling these parameters, the patent restores processability and mechanical properties to the waste polyolefin without requiring fillers or coupling agents.
2Strength
If fillers and compatibilizing agents are added to improve mechanical properties, then the strength increases, but the complexity of the composition and processing increases
Solution Approach 1:
The patent employs a self-service approach where the heterophasic polyolefin composition inherently provides both the strengthening function and the compatibility function without requiring external fillers or coupling agents. The rubbery phase in the heterophasic composition acts as an internal compatibilizer that naturally interfaces with the waste polyolefin, while the crystalline phase provides structural strength. This eliminates the need for additional additives and simplifies the overall composition.
Solution Approach 2:
The patent achieves homogeneous mixing and compatibility between waste polyolefin and the heterophasic composition through the molecular-level dispersion of the rubbery phase. The rubbery polyolefin phase, with its lower crystallinity and different glass transition temperature, creates a compatible matrix that naturally blends with the waste polyolefin chains. This homogeneity is achieved without requiring coupling agents, as the phase compatibility is built into the molecular structure of the heterophasic composition.
3Productivity
If waste polyolefin materials are mechanically recycled, then the productivity increases, but the quality of the reworked material deteriorates due to degradation during processing
Solution Approach 1:
The patent applies preliminary action by pre-forming the heterophasic polyolefin composition with controlled phase morphology and properties before blending with the waste polyolefin. The heterophasic composition is prepared with a specific phase distribution, crystallinity, and molecular weight characteristics that are optimized in advance. This preliminary preparation ensures that when the waste polyolefin is mechanically recycled, the pre-engineered heterophasic composition can immediately provide the necessary mechanical properties and processability, compensating for any degradation that occurs during the recycling process.
Data Source
AI summary
Polyolefin compositions comprising, by weight: A) 30-80% of a polyolefin component containing not less than 80% of a waste material selected from polyethylene, polypropylene or their mixtures; B) 20-70% of a heterophasic polyolefin composition having flexural modulus equal to or lower than 600 MPa.