Twin-Screw Nanocellulose Dewatering to Prevent Agglomeration
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Solution Overview
Problem
The challenge of maintaining nanoscale dimensions and preventing irreversible agglomeration of nanocellulose particles during drying is significant, especially in non-aqueous-based systems, which impedes the effective incorporation of nanocellulose in polymer composites and increases transportation costs.
Innovation Solution
A nanocellulose-slurry dewatering system utilizing a twin-screw extruder or mixer, combined with a dispersion/drying agent, to intimately mix and remove water while preventing agglomeration, followed by milling to generate a nanocellulose-dispersion concentrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nanocellulose is dried to remove water for non-aqueous applications, then transportation costs are reduced and application versatility is improved, but nanocellulose particles irreversibly bond and agglomerate, losing nanoscale properties
Solution Approach 1:
A dispersion agent is introduced as an intermediary substance during the drying process. This agent coats the nanocellulose particles, preventing direct contact and irreversible bonding between them. The dispersion agent acts as a mediator that allows water removal while maintaining particle separation, thus preventing agglomeration and preserving nanoscale properties in the dried product
Solution Approach 2:
The drying process parameters are carefully controlled and modified, including temperature profiles, drying rate, and atmospheric conditions. By changing these parameters, the process removes water while maintaining conditions that prevent particle fusion. The controlled parameter changes ensure that nanocellulose particles dry without irreversibly bonding, preserving their nanoscale dimensions
2Quantity of substance
If conventional drying methods are used to remove water from nanocellulose, then water content is reduced, but the process is difficult to scale-up and becomes uneconomical for commercial production
Solution Approach 1:
The invention replaces conventional mechanical drying systems (such as freeze-drying equipment or high-temperature ovens) with a spray drying system. This substitution uses atomization and rapid evaporation in a fluidized bed, which is a more scalable and economically viable approach for commercial production. The spray drying technology allows continuous processing and easier scale-up compared to traditional methods
Solution Approach 2:
The drying process utilizes controlled phase transitions of water (from liquid to vapor) through spray atomization and rapid evaporation. This phase change approach enables efficient water removal in a continuous process that is scalable to commercial production. The phase transition occurs rapidly in the spray drying chamber, allowing economical water removal without requiring expensive specialized equipment
3Stability of the object's composition
If nanocellulose is processed as aqueous suspension, then nanoscale properties are maintained, but transportation costs increase and applications with water limitations are restricted
Solution Approach 1:
A dispersion agent serves as an intermediary that enables the transition from aqueous to dry form while preserving nanoscale properties. The agent coats particles during drying, preventing agglomeration, and allows the dried nanocellulose to be redispersed later. This intermediary approach removes the need for water in storage and transportation while maintaining the ability to achieve nanoscale dispersion when needed for applications
4Stability of the object's composition
If extreme measures are taken to prevent nanocellulose agglomeration during drying, then nanoscale properties are preserved, but the methods are difficult to scale-up and uneconomical
Solution Approach 1:
The invention replaces complex extreme measures (such as freeze-drying, supercritical drying, or extensive chemical modification) with a simpler spray drying system. This substitution uses straightforward atomization and evaporation mechanics, reducing device complexity while achieving the same goal of preventing agglomeration. The spray drying process is mechanically simple, easily scalable, and economical compared to extreme measures
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 system effectively produces a dewatered and dispersed nanocellulose concentrate, enabling its incorporation in a wide range of applications, including plastics, elastomers, adhesives, and non-polymer matrices, while reducing transportation costs and maintaining nanoscale properties.
Implementation Method 1
A nanocellulose-slurry dewatering system utilizing a twin-screw extruder or mixer, combined with a dispersion/drying agent, to intimately mix and remove water
Data Source
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AI summary
The present invention allows the production of nanocellulose in dry form, enabling incorporation into a wide variety of end-use applications. Some variations provide a nanocellulose-slurry dewatering system comprising: a nanocellulose slurry feed sub-system; a pre-concentration unit (e.g., a centrifuge) to remove at least a portion of the water from the nanocellulose slurry; an inlet for a dispersion/drying agent; a twin-screw extruder in flow communication with the nanocellulose slurry feed sub-system, wherein the twin-screw extruder intimately mixes the nanocellulose slurry and the dispersion/drying agent, wherein the twin-screw extruder shears the nanocellulose slurry, and wherein the twin-screw extruder is configured with one or more extruder vents to remove water from the nanocellulose slurry; and an extruder outlet for recovering a nanocellulose-dispersion concentrate. A milling device may be employed to generate a fine powder of the nanocellulose-dispersion concentrate. Methods of making and using the dewatered or dried nanocellulose are also described.