Cellulose Formate Filament Esterification Without Cellulose Degradation
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Solution Overview
Problem
Existing methods for chemically modifying cellulose to improve solubility and processing properties are hindered by strong acidity causing degradation, leading to low-strength renewable materials, and high molecular weight cellulose remains difficult to esterify homogeneously.
Innovation Solution
An esterification method using a mixture of formic acid, zinc chloride, and water at specific molar ratios, conducted at room temperature, followed by filamentation, coagulation, and drying to produce a cellulose formate filament material with high strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If concentrated formic acid solution (99 wt%) is used for esterification, then dissolution of cellulose is achieved, but the process takes more than 24 hours and cannot dissolve high molecular weight cellulose
Solution Approach 1:
The patent changes the chemical parameters of the esterification system by using formic acid combined with zinc chloride and water in specific molar ratios (2-4):1:(1-2), rather than pure concentrated formic acid. This parameter modification enables rapid esterification of high molecular weight cellulose within 1-12 hours while achieving complete dissolution and homogeneous substitution.
2Productivity
If temperature is increased or strong acid catalysts (sulfuric acid, hydrochloric acid, phosphoric acid) are added to accelerate esterification, then reaction speed increases, but cellulose degradation occurs and homogeneous esterification of high molecular weight cellulose cannot be achieved
Solution Approach 1:
The patent replaces traditional strong acid catalysts with a zinc chloride-based system combined with formic acid and water. This chemical parameter change enables rapid esterification at room temperature without causing cellulose degradation, achieving both high productivity and preservation of cellulose strength.
Solution Approach 2:
Zinc chloride acts as an intermediary catalyst in the esterification system, mediating between formic acid and cellulose to achieve rapid reaction without the harsh conditions required by traditional strong acids. The zinc chloride-water-formic acid complex provides a milder yet effective catalytic environment that prevents degradation.
3Stability of the object's composition
If degree of substitution of formyl exceeds 1.3, then cellulose dissolution is achieved, but the process cannot be completed in reasonable time and high molecular weight cellulose cannot be dissolved
Solution Approach 1:
The patent modifies the esterification system parameters by incorporating zinc chloride and water with formic acid in specific molar ratios. This enables achievement of degree of substitution exceeding 1.3 with complete dissolution of high molecular weight cellulose within 1-12 hours, simultaneously improving both dissolution completeness and reaction efficiency.
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 achieves homogeneous esterification of cellulose, resulting in a cellulose formate filament material with a tensile strength of not less than 1 GPa, overcoming the limitations of prior art.
Implementation Method 1
a strong acidity of the mixed solvent causes the degradation of a cellulose macromolecular structure... hydrogen bonding interaction investigation
Implementation Method 2
Cellulose can undergo esterification when being mixed with a concentrated formic acid solution (99 wt%)... cellulose can be dissolved
Implementation Method 3
subjecting the reaction solution to filamentation, followed by coagulation, washing, and drying in sequence
Data Source
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AI summary
An esterification method of cellulose and a preparation method of a cellulose formate filament material are provided, belonging to the technical field of cellulose renewable materials. The esterification method of cellulose includes the following steps: mixing cellulose with an esterification system to obtain a mixture, and subjecting the mixture to esterification, where the esterification system includes formic acid, zinc chloride, and water at a molar ratio of (2-4): 1: (1-2). An esterification system with a specific molar ratio can homogeneously esterify cellulose macromolecules at room temperature. Cellulose formate samples in examples all show a degree of substitution of not less than 0.6, thereby promoting the preparation of a high-strength cellulose formate filament material.