Extensional Flow Extender for Polymerization Molecular Weight Control
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Solution Overview
Problem
The synthesis of high molecular weight polymers is challenging due to reduced chain extension rates and increased branching side reactions under standard polymerization conditions, where polymer chains fold and entangle, reducing availability for further reactions and leading to lower molecular weight species.
Innovation Solution
The use of an extender to place components in an extensional flow regime during polymerization, enhancing mixing and degassing, which stretches polymer chains to prevent backbiting reactions and maintain chain length, thereby increasing molecular weight and controlling branching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard polymerization conditions are used, then polymer chains can be formed, but chain extension rate decreases and molecular weight is limited due to folding and entanglement
Solution Approach 1:
The patent applies extensional flow conditions as a physical parameter change to the polymerization system. By subjecting the polymerizing mixture to extensional flow (as opposed to conventional shear flow or stagnant conditions), the patent modifies the physical environment to prevent chain folding and entanglement, thereby maintaining high polymerization rates while achieving superior molecular weight control and narrower molecular weight distributions.
Solution Approach 2:
The patent replaces conventional mechanical mixing methods with extensional flow mechanics. Instead of using traditional stirrers or pumps that create shear flow and turbulence, the patent employs extensional flow conditions that gently stretch and align polymer chains, reducing entanglement and chain scission while maintaining reaction efficiency.
2Quantity of substance
If polymer chains are allowed to grow, then molecular weight increases, but chain entanglement increases and reduces availability of chain ends for further reactions
Solution Approach 1:
The patent changes the flow regime parameter from conventional shear flow to extensional flow. This parameter change fundamentally alters how polymer chains behave during growth: extensional flow stretches chains in an orderly manner, preventing the random coiling and entanglement that normally occurs, thereby maintaining chain end accessibility even as molecular weight increases.
3Ease of manufacture
If conventional mixing is used, then components are combined, but polymer chains fold and entangle, leading to branching side reactions
Solution Approach 1:
The patent substitutes conventional mechanical mixing with extensional flow conditions. This replacement eliminates the shear forces and turbulence that cause chain folding and entanglement during mixing, thereby preventing branching side reactions while still achieving thorough component combination and enhanced degassing.
4Quantity of substance
If high molecular weight polymers are synthesized, then polymer chains become longer, but chain scission increases due to entanglement and folding
Solution Approach 1:
The patent changes the physical condition parameter from conventional stagnant or shear flow to extensional flow. This parameter change creates a controlled environment where polymer chains are stretched and aligned, reducing the random collisions and entanglement-induced scission that normally occur during high molecular weight synthesis, thereby maintaining chain integrity.
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 increases polymerization rates and molecular weight, reduces chain scission, and achieves better reaction efficiency by maintaining chain length and structural integrity, allowing for polymers with defined molecular weight distributions and controllable branching.
Implementation Method 1
The use of an extender to place components in an extensional flow regime during polymerization, enhancing mixing and degassing, which stretches polymer chains to prevent backbiting reactions and maintain chain length
Implementation Method 2
The use of an extender to place components in an extensional flow regime during polymerization, enhancing mixing and degassing
Implementation Method 3
The use of an extender to place components in an extensional flow regime during polymerization, enhancing mixing and degassing
Data Source
AI summary
A method includes combining an aqueous fluid and an oleaginous fluid to prepare an invert emulsion comprising a polymerizable composition, degassing the invert emulsion under an extensional flow regime through an elongated passageway of an extender and thereby removing oxygen to produce a degassed invert emulsion. A flow rate of the invert emulsion and a diameter of the elongated passageway are sufficient to achieve a Reynolds number of 20,000 or greater. The method also includes transferring at least a portion of the degassed invert emulsion to the second extender at one or more time intervals and returning the portion of the degassed invert emulsion to the reactor, and isolating a polymer product from the degassed invert emulsion. A flow rate of the invert emulsion and a diameter of the elongated passageway are sufficient to achieve a Reynolds number of 20,000 or greater.