Nucleated Polyethylene Haze Reduction via Solid State Stretching
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Solution Overview
Problem
Nucleated ethylene polymers are difficult to stretch using solid state stretching processes due to polyethylene's high initial crystal growth rate, limiting the ability to maintain stretchability, and previous attempts have focused on linear low density polyethylene with limited success for medium and high density polyethylenes.
Innovation Solution
Blending ethylene-based polymers with a nucleator, such as HPN-20E, to form modified polyethylene, which reduces haze and increases gloss and barrier properties, allowing for improved stretchability and processing characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polyethylene is nucleated to increase crystallization rate, then crystallization rate is improved, but stretchability is lost due to high initial crystal growth rate
Solution Approach 1:
The patent applies parameter changes by modifying the crystallization kinetics through specific nucleating agents and processing conditions. By controlling the nucleation density and crystal growth rate parameters, the invention achieves both rapid crystallization and maintained stretchability during solid-state stretching processes
Solution Approach 2:
The invention uses composite approaches by combining polyethylene with specific nucleating agents and modifiers. This creates a composite system where the nucleating agents provide controlled crystallization while the base polyethylene maintains its stretchability, resolving the contradiction between rapid crystallization and stretchability
2Productivity
If linear low density polyethylene is used with nucleators, then crystallization rate increases, but applicability to medium and high density polyethylenes is limited
Solution Approach 1:
The patent achieves universality by developing a nucleation system that works across multiple polyethylene density types (LLDPE, MDPE, HDPE). The selected nucleating agents and processing methods are applicable to various polyethylene formulations, making the solution multi-functional rather than limited to a single polymer type
3Illumination intensity
If haze is reduced in polymer articles, then optical clarity is improved, but other properties may be compromised
Solution Approach 1:
The patent applies parameter changes by optimizing crystallization conditions and nucleating agent concentrations to achieve reduced haze while maintaining mechanical properties. By controlling crystal size, distribution, and orientation parameters, the invention improves optical clarity without compromising overall material reliability
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 modified polyethylene exhibits a significant reduction in haze, increase in gloss, and decrease in water vapor transmission rate, while maintaining toughness and control over the coefficient of friction, demonstrating improved optical and processing properties compared to unmodified and similarly modified polyethylenes.
Implementation Method 1
nucleated ethylene polymers have been difficult to stretch with solid state stretching process due, at least in part, to polyethylene's high initial crystal growth rate
Implementation Method 2
blending the ethylene based polymer with a modifier to form modified polyethylene... the modifier is a nucleator
Data Source
AI summary
Polymer articles and processes of forming the same are described herein. The processes generally include providing an ethylene based polymer, blending the ethylene based polymer with a modifier to form modified polyethylene and forming the modified polyethylene into a polymer article, wherein the polymer article exhibits a haze that is at least about 10% less than a polymer article prepared with a similarly modified polyethylene.