PVC Upcycling to Elastomers via Controlled Dehydrochlorination

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Solution Overview

Problem

The challenge lies in effectively upcycling polyvinyl chloride (PVC) waste into valuable polymers and oligomers due to its propensity for uncontrolled dehydrochlorination, leading to spontaneous crosslinking and degradation, which limits its recycling potential and results in inferior products.

Innovation Solution

A method involving controlled partial dehydrochlorination of PVC using organic solvents and bases, followed by hydrofunctionalization and further dehydrochlorination steps, to produce tailored polymers with adjustable chlorinated and unsaturated segments, enabling the creation of reusable and recyclable elastomers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If PVC undergoes dehydrochlorination to create useful elastomers, then the value of the recycled product is improved, but uncontrolled spontaneous crosslinking and degradation occur

Engineering Contradiction:

Improvecontrolled partial dehydrochlorinationVSAvoidspontaneous crosslinking and degradation

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by first dissolving PVC in an organic solvent to create a homogeneous solution before adding the base catalyst. This preliminary dissolution step ensures uniform distribution of PVC chains and prevents localized uncontrolled reactions that would lead to spontaneous crosslinking and degradation during the subsequent dehydrochlorination process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs parameter changes by carefully controlling the concentration of the base catalyst, the ratio of organic solvent to PVC, and the reaction temperature. These parameter adjustments enable precise control over the dehydrochlorination process, achieving the desired level of unsaturation while preventing uncontrolled crosslinking and degradation reactions.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If mechanical recycling of PVC is performed, then the recycling process is simplified, but the product quality deteriorates due to downcycling

Engineering Contradiction:

Improvemechanical recycling processVSAvoidproduct quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical recycling system with a chemical recycling approach. Instead of physically reprocessing PVC through melting and reforming (mechanical recycling), the invention uses chemical dehydrochlorination reactions to transform PVC into elastomers with restored and enhanced properties, thereby eliminating the downcycling effect while maintaining process simplicity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent applies parameter changes by controlling the degree of dehydrochlorination through adjustment of base catalyst concentration and reaction conditions. This enables tailoring of the elastomer properties to match or exceed virgin material performance, overcoming the quality deterioration inherent in mechanical recycling.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If PVC is landfilled or incinerated, then disposal is simplified, but harmful chlorine-containing compounds are released

Engineering Contradiction:

Improvewaste disposal processVSAvoidchlorine-containing compounds

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful propensity of PVC to undergo dehydrochlorination (which releases HCl and forms aromatic degradation products during uncontrolled decomposition) into a beneficial process. By controlling the dehydrochlorination reaction under optimized conditions, the invention transforms what would be harmful decomposition into a valuable synthesis pathway for creating elastomers, thereby eliminating harmful emissions while simplifying waste disposal.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This approach allows for the production of high-value elastomers with tunable properties, overcoming the limitations of uncontrolled dehydrochlorination and enabling the recycling of PVC waste into reusable and thermally reversible materials.

Implementation Method 1

Partial dehydrochlorination of PVC can be used as a means of altering PVC properties, but if performed under uncontrolled conditions, spontaneous crosslinking and/or complete degradation can occur

Methodology Applied

Scientific EffectDehydrochlorination: Chemical Bonding

Implementation Method 2

contacting the PVC with a first organic solvent to form a PVC extract comprising dissolved PVC and the first organic solvent

Methodology Applied

Scientific EffectSolvation: Solvation

Implementation Method 3

the partially dehydrochlorinated PVC are partially hydrofunctionalized by contacting the partially dehydrochlorinated PVC with a hydrofunctionalization catalyst and a hydrofunctionalizing agent

Methodology Applied

Scientific EffectHydrofunctionalization: Chemical Bonding

Data Source

PatentUS20240084053A1Methods for converting PVC to elastomers

Publication Date: 2024.03.14 UNIVERSITY OF ALABAMA

AI summary

Disclosed are methods for upcycling polyvinyl chloride (PVC) that involve the dissolving of PVC in an organic solvent; and contacting the PVC with a base, thereby providing a partially dehydrochlorinated PVC. Polymers made by the disclosed, and articles therefore, are also disclosed.