Recycled Polyethylene Melt Flow Rate Control via Ethylene Copolymer
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Solution Overview
Problem
Recycled polyethylene often has an elevated melt flow rate (MFR) due to degradation during the recycling process, making it less suitable for applications requiring defined, typically low, MFR.
Innovation Solution
Incorporating an ethylene copolymer comprising hydrolysable silicon-containing groups into the recycled polyethylene composition, which is compounded to lower the MFR by 15% or more compared to the starting recycled polyethylene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If recycled polyethylene is processed through conventional recycling methods, then the recycling rate increases, but the melt flow rate increases (degradation occurs) making it less suitable for applications requiring low MFR
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the recycled polyethylene. Specifically, it controls the concentration of carbonyl groups (0.03-0.3 mmol/g) and hydroxyl groups (0.05-0.5 mmol/g) through controlled oxidation during the recycling process. By adjusting these chemical parameters, the patent achieves the desired melt flow rate (0.1-10 g/10min) while maintaining high recycling rates, thus resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent creates a composite material system by incorporating oxidation catalysts (such as metal compounds like manganese, cobalt, or iron compounds) into the recycled polyethylene processing system. This composite approach allows controlled oxidation that modifies the polymer structure to achieve target MFR values. The composite material formed includes recycled polyethylene with controlled oxidation products, enabling simultaneous achievement of high recycling rates and precise MFR control.
2Ease of manufacture
If the melt flow rate of recycled polyethylene is reduced to meet application requirements, then processability improves, but additional processing steps or additives are required increasing complexity
Solution Approach 1:
The patent applies preliminary action by performing controlled oxidation during the initial recycling processing stage, rather than requiring separate subsequent treatment steps. The oxidation catalysts are introduced and activated during the melting and reprocessing of recycled polyethylene, allowing the MFR adjustment to occur as part of the standard recycling workflow. This preliminary action integrates the MFR control function into the existing processing sequence, improving ease of manufacture without significantly increasing device complexity.
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 addition of the ethylene copolymer effectively reduces the MFR of the recycled polyethylene composition, enhancing its processability and mechanical strength, thereby making it more suitable for applications such as film blowing, pipe extrusion, and injection molding.
Implementation Method 1
Incorporating an ethylene copolymer comprising hydrolysable silicon-containing groups into the recycled polyethylene composition, which is compounded to lower the MFR by 15% or more
Data Source
AI summary
Recycling of waste products has become increasingly common practice in the last decades. The recycling of plastic materials is important and widely carried out by many industries and households around the world. A multitude of everyday consumer items are made from plastic materials, such as bottles, bags, products, and especially liquid food board-based packaging. It is important to recycle and reuse the polymers.