Ethylene Polymer Biodiesel Resistance Stabilization
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Solution Overview
Problem
High molecular mass polyethylene used in plastic fuel tanks is susceptible to thermo-oxidative degradation when exposed to biodiesel fuels, particularly at elevated temperatures and in the presence of oxygen, leading to embrittlement and reduced long-term service properties, with existing stabilization methods failing to provide adequate resistance.
Innovation Solution
The use of a combination of sterically hindered amine compounds, such as Chimassorb 944 and Tinuvin 770, added in specific amounts to ethylene homo- or copolymer compositions to enhance resistance against thermo-oxidative degradation, maintaining a high Oxidative Induction Time (OIT) value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high molecular mass polyethylene is used to produce plastic fuel tanks, then the mechanical strength and durability are improved, but the resistance against thermooxidative degradation in the presence of biodiesel and oxygen deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the concentrations and types of stabilizers (sterically hindered amines and N-hydroxy- or N-oxylderivatives) in the polyethylene composition. By adjusting stabilizer levels and selecting specific chemical compounds, the patent achieves improved thermooxidative resistance while maintaining the mechanical properties of high molecular mass polyethylene.
Solution Approach 2:
The patent creates a composite material system by combining polyethylene with multiple stabilizing agents (sterically hindered amines and N-hydroxy- or N-oxylderivatives). This composite approach provides synergistic protection against thermooxidative degradation, where the combination of stabilizers offers superior performance compared to single stabilizer systems.
2Reliability
If interior coating is applied to overcome biodiesel aggressiveness, then the resistance against chemical attack is improved, but the manufacturing complexity and costs increase
Solution Approach 1:
The patent extracts the protection function from a separate interior coating layer and integrates it directly into the polyethylene material itself through stabilization additives. This eliminates the need for additional coating layers and their associated manufacturing complexity while maintaining chemical resistance.
Solution Approach 2:
The stabilized polyethylene performs multiple functions simultaneously: it provides the structural mechanical strength of polyethylene while also offering chemical resistance to biodiesel and oxygen through the incorporated stabilizers. This multi-functionality eliminates the need for separate protective layers.
3Reliability
If co-extruded 6-layer tanks with central barrier layer are used, then the resistance against biodiesel penetration is improved, but the manufacturing costs increase significantly
Solution Approach 1:
The patent extracts the barrier function from a complex multi-layer co-extruded structure and achieves it through chemical stabilization of a simpler polyethylene material. By using stabilizers that provide resistance to biodiesel penetration, the patent eliminates or simplifies the need for multiple barrier layers.
Solution Approach 2:
The patent changes the chemical parameters of polyethylene through stabilization, transforming it from a material susceptible to biodiesel degradation to one with enhanced resistance. This parameter change allows the use of simpler, less expensive single-layer or fewer-layer constructions while maintaining the required barrier performance.
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 combination of stabilizers significantly improves the resistance of ethylene homo- or copolymer compositions against thermo-oxidative degradation, as demonstrated by increased OIT values and maintained intrinsic viscosity even after prolonged storage at elevated temperatures in contact with biodiesel fuels.
Implementation Method 1
stabilized by a combination of at least two sterically hindered amine compounds or N-hydroxy- or N-oxylderivatives thereof
Implementation Method 2
resistance against thermooxidative degradation occurring in the presence of liquid fuels comprising biodiesel in combination with oxygen
Data Source
AI summary
An ethylene homo- or copolymer composition is stabilized by suitable stabilizers conferring improved resistance against thermo-oxidative degradation, which occurs in the presence of liquid fuels comprising biodiesel, such as vegetable oil esters, in combination with oxygen. The stabilizers comprise a combination of at least two sterically hindered amine compounds or N-hydroxy- or N-oxylderivatives thereof in an amount of from 100 to 10 000 ppm. Such ethylene homo- or copolymer composition is highly suitable for articles of plastic and components for the transport and storage of liquid fuels comprising biodiesel, such as vegetable oil esters, preferably for plastic fuel tanks for automotive vehicles.