Multimodal Polyethylene Composition Branching Distribution
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Solution Overview
Problem
Current polyethylene compositions are not versatile enough to be useful in multiple applications such as films, pipes, blow molding, and rotomolding due to limited branching distribution between low and high molecular weight fractions.
Innovation Solution
A multimodal polyethylene composition with a density range of 0.940 to 0.965 g/cm3, comprising a low molecular weight ethylene copolymer with a weight average molecular weight from 5,000 to 50,000 amu and a high molecular weight ethylene copolymer with a weight average molecular weight from 60,000 to 800,000 amu, where the high molecular weight fraction's weight fraction ranges from 0.3 to 0.7 and the branching index ratio of low to high molecular weight fractions ranges from 1.2 to 6.0.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single polyethylene composition is designed for one application, then performance in that specific application is optimized, but versatility across multiple applications is reduced
Solution Approach 1:
The patent achieves universality by formulating a multimodal polyethylene composition with a broad molecular weight distribution (5,000-800,000 amu) and controlled branching indices. The low molecular weight fraction provides flexibility and processability for film and rotomolding, while the high molecular weight fraction provides strength and rigidity for pipe applications. This multi-functional design allows a single composition to reliably perform across diverse applications including film, pipe, blow molding, and rotomolding.
Solution Approach 2:
The patent employs composite material principles by combining ethylene copolymers with different molecular weights and branching characteristics into a single multimodal composition. The low molecular weight ethylene copolymer (5,000-50,000 amu, branching index 2.5-4.5) and high molecular weight ethylene copolymer (60,000-800,000 amu, branching index 1.0-2.5) work synergistically to provide properties that neither component could achieve alone, enabling versatility across multiple applications.
Data Source
AI summary
Multimodal polyethylenes possessing a density from 0.940 to 0.965 g/cm3, and an I21 from 4 to 20 dg/min, and comprising a low molecular weight ethylene copolymer having a weight average molecular weight from 5,000 amu to 50,000 amu; and a high molecular weight ethylene copolymer having a weight average molecular weight from 60,000 amu to 800,000 amu, both components having a desirable balance of short chain branching making the multimodal polyethylene suitable for films, pipes, rotomolding applications and blow molding applications.