A Flame-Retardant Phytic-Acid-Based LbL-Coating for Cotton Using Polyvinylamine

Area of Science:

• Materials Science
• Polymer Chemistry
• Textile Finishing

Background:

• Flame retardants are crucial for textile safety.
• Developing eco-friendly and effective flame-retardant finishes is a key research area.
• Phytic acid (PA) offers a sustainable phosphorus source, while polyvinylamine (PVAm) provides a nitrogen-rich polymer.

Purpose of the Study:

• To develop a partly bio-based flame-retardant finish for cotton using phytic acid and polyvinylamine.
• To investigate the flame-retardant properties and mechanisms of the PA/PVAm coating on cotton.
• To assess the impact of the coating on the thermal decomposition and volatile emissions.

Main Methods:

• Layer-by-layer (LbL) assembly of phytic acid and polyvinylamine onto cotton fabric.
• Vertical flame tests to evaluate flame retardancy.
• Microscale combustion calorimetry (MCC) to assess heat release rate.
• Thermogravimetric analysis (TGA) coupled with FTIR to study pyrolysis and volatile products.

Main Results:

• A coating of 15 bilayers (BL) achieved effective flame retardancy with no afterflame or afterglow.
• The finish contained 2% phosphorus and 1.4% nitrogen, with a molar P:N ratio of 3:5.
• MCC showed a >60% reduction in peak heat release rate (pkHRR).
• TGA/FTIR indicated char formation and reduced emission of toxic volatiles like formaldehyde and acrolein.

Conclusions:

• The PA/PVAm coating provides excellent flame retardancy to cotton.
• Phytic acid catalyzes cellulosic dehydration, promoting protective char formation.
• This approach offers a sustainable and effective method for creating flame-retardant textiles with reduced toxicity.