Multimodal Polyethylene Composition for Pipe Strength and Processability
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Solution Overview
Problem
Current polyethylene compositions for pipes face challenges in achieving a balance between high pressure resistance, impact strength, processability, and surface appearance, while existing solutions often compromise on one or more of these properties.
Innovation Solution
A multimodal ethylene copolymer comprising 55 to 80 wt% ethylene homopolymer component A and 20 to 45 wt% ethylene copolymer component B, with specific density, melt flow index, and viscosity ranges, allowing for high pressure resistance, impact strength, and processability, and producing products with good surface appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyethylene composition with high molecular weight is used to improve pressure resistance, then pressure resistance is improved, but processability deteriorates
Solution Approach 1:
The polyethylene composition is segmented into multiple components with different molecular weights (very high molecular weight component for pressure resistance, high molecular weight component for balance, and low molecular weight component for processability). This segmentation allows each component to contribute its specific properties to the final composition, resolving the contradiction between pressure resistance and processability.
Solution Approach 2:
The invention creates a composite polyethylene material by combining components with different molecular weight characteristics. The very high molecular weight polyethylene (VHMWPE) provides exceptional pressure resistance, while the low molecular weight polyethylene (LMWPE) ensures good processability. This composite approach allows simultaneous achievement of both contradictory properties.
2Strength
If a polyethylene composition with high molecular weight is used to improve impact strength, then impact strength is improved, but processability deteriorates
Solution Approach 1:
The polyethylene composition is segmented into multiple components with different molecular weights (very high molecular weight component for impact strength, high molecular weight component for balance, and low molecular weight component for processability). This segmentation allows each component to contribute its specific properties to the final composition, resolving the contradiction between impact strength and processability.
Solution Approach 2:
The invention creates a composite polyethylene material by combining components with different molecular weight characteristics. The very high molecular weight polyethylene (VHMWPE) provides exceptional impact strength, while the low molecular weight polyethylene (LMWPE) ensures good processability. This composite approach allows simultaneous achievement of both contradictory properties.
3Strength
If polyethylene with high pressure resistance is used, then pressure resistance is improved, but surface appearance deteriorates
Solution Approach 1:
The invention creates a composite polyethylene material by combining components with different molecular weight characteristics. The very high molecular weight polyethylene (VHMWPE) provides exceptional pressure resistance, while the low molecular weight polyethylene (LMWPE) ensures good processability. This composite approach allows simultaneous achievement of both contradictory properties.
Data Source
AI summary
The invention relates to an ethylene copolymer which comprises or consists of 55 to 80 wt% of an ethylene homopolymer component A and 20 to 45 wt% of an ethylene copolymer component B of ethylene and an olefin comonomer, wherein the component A has a melt flow index as measured according to ISO1133-1:2011 at 190 °C and 1.2 kg of 80 to 400 dg/min and a density of at least 968 kg/m3, and wherein the ethylene copolymer has a melt flow index as measured according to ISO1133-1:2011 at 190 °C and 5 kg of 0.05 to 0.3 dg/min, a density of 956 to 962 kg/m3, a comonomer content of 0.03 to 0.30 mol%, a viscosity value η0.05 at a temperature of 190 °C and a shear rate of 0.05 rad/s of 200 to 1000 kPa.s and a viscosity value η300 at a temperature of 190 °C and a shear rate of 300 rad/s of 700 to 1500 Pa.s.