Binary-Anhydride Esterification for Lignocellulose Nanofibril Dispersion
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Solution Overview
Problem
Current methods for preparing lignocellulose nanofibril (LCNF) face challenges in achieving high lignin content, uniform size distribution, and high mechanical properties under environmentally friendly and low-energy conditions, while also requiring complex processes for dispersing LCNF in polymer matrices.
Innovation Solution
A method involving esterification pretreatment with binary anhydrides at low temperatures (≤120°C) to graft carboxyl groups onto biomass fibers, followed by dissociation, which enhances repulsion forces and allows for the direct preparation of LCNF reinforced composite materials without complex solvent exchanges or mechanical blending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical dissociation methods (high-pressure homogenization, grinding, microfluidizer) are used to prepare LCNF, then nanofibril structure is achieved, but the process requires toxic chemical reagents and high energy consumption
Solution Approach 1:
The patent applies preliminary action by performing esterification pretreatment on the biomass raw material before mechanical dissociation. The binary anhydride grafts carboxyl groups onto the fiber surface in advance, which facilitates subsequent mechanical fibrillation and reduces the energy required for the dissociation process while maintaining nanofibril structure quality
2Productivity
If high temperature pretreatment (up to 165°C) is used to prepare LCNF, then fibrillation is enhanced, but lignin condensation and cellulose degradation occur, reducing raw material utilization
Solution Approach 1:
The patent applies parameter changes by modifying the pretreatment temperature parameter to be below 120°C, which is lower than conventional methods. This temperature change prevents lignin condensation and cellulose degradation while still achieving effective fibrillation when combined with the binary anhydride esterification treatment
3Strength
If LCNF is prepared with high lignin content to maintain hydrophobicity and mechanical properties, then dispersion in hydrophobic polymers is improved, but hydrophilic hydroxyl groups cause aggregation and poor dispersibility
Solution Approach 1:
The patent applies local quality by selectively modifying the surface properties of the LCNF through esterification with binary anhydride. The carboxyl groups are grafted onto the fiber surface locally, creating a hydrophobic surface layer that improves compatibility with hydrophobic polymer matrices while preserving the bulk lignin content and mechanical properties
Solution Approach 2:
The patent converts the harmful effect of abundant surface hydroxyl groups (which cause aggregation) into a benefit by reacting them with binary anhydride to form ester groups. This transforms the hydrophilic surface into a hydrophobic one, enabling better dispersion in hydrophobic polymers while retaining the lignin content for mechanical strength
4Stability of the object's composition
If complex solvent exchange or mechanical blending processes are used to disperse LCNF in polymer matrices, then thorough mixing is achieved, but process complexity and processing difficulty increase
Solution Approach 1:
The patent applies preliminary action by pre-modifying the LCNF surface with binary anhydride to create hydrophobic character. This preliminary surface treatment enables direct mixing with hydrophobic polymers without requiring subsequent solvent exchange or complex mechanical blending processes, simplifying the overall processing while achieving uniform dispersion
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 method produces LCNF with improved lignin content, surface charge, and mechanical properties, enabling efficient dispersion in polymer matrices and resulting in composite materials with enhanced mechanical properties, UV resistance, and barrier properties.
Implementation Method 1
dispersing a biomass raw material in a binary anhydride and about 0-5% water, performing an esterification pretreatment reaction at a temperature below 120° C. to obtain a pretreatment reaction product
Implementation Method 2
dispersing the neutral pretreatment reaction product in a medium and performing a dissociation treatment in nanofibrillation equipment to obtain a dispersion of lignocellulose nanofibril
Data Source
AI summary
The present invention relates to a method for preparing lignocellulose nanofibril and a lignocellulose nanofibril prepared by the method. The present invention also relates to a method for preparing a lignocellulose nanofibri reinforced composite material, and a lignocellulose nanofibri reinforced composite material prepared by the method.