Zinc Oxide Polyethylene Pipe Composition for Chlorinated Water

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Solution Overview

Problem

Polymer compositions used in applications exposed to chlorinated water experience significant reduction in service lifetime due to degradation, necessitating improved resistance to chlorinated water exposure.

Innovation Solution

Incorporation of zinc oxide (ZnO) as an additive in polymer compositions to prevent or retard degradation when exposed to chlorinated water, forming chlorinated water-stabilized polymer compositions (CWS-PC), which can be produced using various polymerization methods and formed into pipes with enhanced structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If conventional polymer compositions are used in applications exposed to chlorinated water, then the articles can be manufactured with standard materials and processes, but the service lifetime is significantly reduced due to degradation

Engineering Contradiction:
Improveservice lifetimeVSAvoidresistance to degradation
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent applies preliminary action by incorporating zinc oxide additive into the polymer composition before the degradation process begins. The zinc oxide is pre-mixed with the polyethylene resin and other additives during the compounding stage, creating a stabilized polymer composition that is resistant to chlorinated water degradation from the outset. This prevents degradation before it can occur during service

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses zinc oxide as an intermediary substance that mediates between the polymer matrix and the harmful chlorinated water environment. The zinc oxide particles are distributed throughout the polyethylene resin, acting as a protective barrier that intercepts and neutralizes the degradation effects of chlorine, thereby protecting the polymer structure

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If zinc oxide additive is incorporated to improve resistance to chlorinated water, then service lifetime and structural integrity are significantly increased, but the manufacturing process becomes more complex

Engineering Contradiction:
Improveresistance to degradationVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the zinc oxide additive with the existing polymer composition formulation by incorporating it during the standard extrusion and compounding process. The zinc oxide is mixed with the polyethylene resin and conventional additives in a single compounding step, integrating the protective function into the existing manufacturing workflow without requiring separate processing stages

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent modifies the chemical composition parameter of the polymer by adding zinc oxide at specific concentrations (typically 0.1-5% by weight). This parameter change enhances the degradation resistance while maintaining compatibility with standard manufacturing processes, as the additive can be incorporated using conventional mixing and extrusion equipment

Inventive Principle:
Principle #35Parameter changes

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 use of ZnO in CWS-PC significantly increases the time-to-failure and structural integrity of pipes exposed to chlorinated water, offering improved resistance to chlorine-induced brittle oxidative failure by reducing degradation, with a time-to-failure increase of at least 25% compared to similar pipes lacking the additive.

Implementation Method 1

The polymer composition comprises an additive to prevent, reduce, or retard degradation of the polymer resulting from exposure to chlorinated water

Methodology Applied
Scientific EffectOxidation resistance: Oxidation

Data Source

PatentEP2753659B1Polyethylene additive compositions and articles made from same
Publication Date: 2021.10.27 CHEVRON PHILLIPS CHEMICAL COMPANY LP
  • EP2753659B1 patent drawingFigure 1
  • EP2753659B1 patent drawingFigure 2
  • EP2753659B1 patent drawingFigure 3

AI summary

A method comprising forming a polymeric composition by adding zinc oxide to a polymer wherein a pipe formed from the polymeric composition displays a time to failure as determined in accordance with ASTM F2263-07(E1) that is increased by greater than about 25% when compared to an otherwise similar pipe formed from a polymeric composition lacking zinc oxide. A pipe comprising polyethylene and greater than about 0.5 wt.% zinc oxide having a time to failure as determined in accordance with ASTM F2263-07(E1) that is at least about 25% greater than an otherwise similar pipe prepared in the absence of zinc oxide. A method comprising forming a composition comprising a polymer and zinc oxide into an article, and testing the structural integrity of the article when exposed to chlorinated water wherein the zinc oxide is present in an amount of from about 500 ppm to about 10000 ppm.