Preparation and Characterization of Carboxymethyl Hydroxypropyl Cellulose

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Carboxymethyl cellulose (CMC) is a widely used polymer with limitations in solubility and salt tolerance.
• Combining carboxymethyl and hydroxypropyl substitutions creates Carboxymethyl hydroxypropyl cellulose (CMHPC) with enhanced properties.

Purpose of the Study:

• To develop an optimized synthesis route for CMHPC via homogeneous hydroxypropylation of CMC.
• To investigate the impact of reaction parameters on CMHPC structure and properties.
• To evaluate CMHPC's performance in modifying recycled coarse aggregate (RCA).

Main Methods:

• Homogeneous hydroxypropylation of CMC under alkaline conditions.
• Systematic investigation of propylene oxide amount and reaction time.
• Characterization using FTIR, solid-state ¹³C NMR, and SEM.
• Evaluation of CMHPC-modified RCA properties.

Main Results:

• Optimized synthesis achieved with 5% NaOH and 4% CMC, balancing yield and fluidity.
• CMHPC demonstrated significantly faster dissolution (3-5 min) compared to CMC (>30 min).
• Enhanced salt and acidity tolerance observed in CMHPC due to steric hindrance.
• CMHPC improved RCA surface compactness, structural integrity, and water resistance.

Conclusions:

• The study successfully optimized CMHPC synthesis, yielding a material with superior solubility and stability.
• CMHPC shows significant potential for enhancing the properties of recycled coarse aggregate.
• This research provides a pathway for producing high-value, tailored cellulose derivatives for construction and other applications.