Cellulose Formate Filaments with Room-Temperature Esterification
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Solution Overview
Problem
Existing methods for chemically modifying cellulose to improve solubility and processing properties are hindered by strong acidity, leading to degradation and low strength in resulting materials, particularly in high-molecular-weight cellulose.
Innovation Solution
An esterification method using a specific molar ratio of formic acid, zinc chloride, and water at room temperature, followed by filamentation, coagulation, and drying, to produce a high-strength cellulose formate filament material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If concentrated formic acid solution (99 wt%) is used for esterification, then the degree of substitution of formyl can exceed 1.3 and cellulose can be dissolved, but the process takes more than 24 hours and cannot dissolve cellulose with high molecular weight
Solution Approach 1:
The patent changes the parameters of the esterification system by using a mixed solvent system (formic acid, zinc chloride, and water) instead of concentrated formic acid alone, and by controlling the molar ratio and temperature to achieve both high degree of substitution and reasonable processing time
Solution Approach 2:
Zinc chloride acts as an intermediary catalyst in the esterification reaction, accelerating the reaction rate and enabling the process to complete in a reasonable time while maintaining high degree of substitution
2Productivity
If temperature is increased or strong acid catalysts (sulfuric acid, hydrochloric acid, phosphoric acid) are added to accelerate esterification, then the reaction rate increases, but cellulose degradation occurs and homogeneous esterification of high molecular weight cellulose becomes difficult
Solution Approach 1:
Zinc chloride serves as a mild catalyst that accelerates the esterification reaction without causing the severe cellulose degradation associated with strong mineral acids, thereby maintaining both reaction rate and cellulose integrity
Solution Approach 2:
The patent uses a mixed solvent system with specific molar ratios and conducts the reaction at room temperature, changing the reaction conditions to achieve both acceptable reaction rate and preservation of cellulose molecular weight
3Productivity
If strong acid solutions are used for esterification, then the reaction proceeds faster, but homogeneous esterification cannot be achieved and high-strength cellulose renewable materials cannot be obtained
Solution Approach 1:
The patent changes the chemical environment by using a mixed solvent system with formic acid, zinc chloride, and water in specific molar ratios, creating conditions that favor homogeneous esterification while maintaining acceptable reaction speed
Solution Approach 2:
Zinc chloride acts as a mediator that promotes uniform distribution of the esterification reaction throughout the cellulose structure, enabling homogeneous modification without requiring strong acid conditions
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 methods.
Implementation Method 1
Cellulose can undergo esterification when being mixed with a concentrated formic acid solution (99 wt %). When a degree of substitution of formyl exceeds 1.3, the cellulose can be dissolved.
Implementation Method 2
subjecting the reaction solution to filamentation, followed by coagulation, washing, and drying in sequence to obtain the cellulose formate filament material
Implementation Method 3
subjecting the reaction solution to filamentation, followed by coagulation, washing, and drying in sequence to obtain the cellulose formate filament material
Data Source
AI summary
An esterification method of cellulose and a preparation method of a cellulose formate filament material are provided. 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).