Cellulose Degradation by Calcium Thiocyanate

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Cellulose aerogels are valuable materials, but their production involves a dissolution step.
• Cellulose degradation during dissolution can compromise the final aerogel quality.

Purpose of the Study:

• To evaluate cellulose degradation, specifically hydrolysis and oxidation, during dissolution using calcium thiocyanate.
• To understand the impact of reaction conditions on cellulose degradation and its effect on aerogel properties.

Main Methods:

• Assessing cellulose hydrolysis by changes in absolute molecular weight.
• Quantifying cellulose oxidation by measuring carboxyl and carbonyl group content.
• Investigating the influence of calcium thiocyanate hydrate number and reaction temperature.

Main Results:

• Significant cellulose hydrolysis was observed during dissolution.
• Hydrolysis rate accelerated with decreased calcium thiocyanate hydrates and increased temperature.
• A 50% loss in cellulose degree of polymerization occurred much faster at higher temperatures (120°C vs. 100°C).
• Oxidation effects were minimal, but Brunauer-Emmett-Teller (BET) surface area decreased with reduced cellulose polymerization.

Conclusions:

• Cellulose hydrolysis is a critical degradation pathway during calcium thiocyanate dissolution.
• Optimizing dissolution conditions (temperature, solvent hydration) is crucial to minimize cellulose degradation.
• Controlling cellulose degradation is essential for producing high-quality cellulose aerogels.