From a bio-based polyphenol diol intermedia to high-performance polyurethane elastomer: Thermal stability,...

Area of Science:

• Polymer Chemistry
• Materials Science
• Flame Retardant Technology

Background:

• Polyurethane elastomers often require improved flame retardancy for various applications.
• Developing sustainable and effective flame retardants is a key challenge in materials science.

Purpose of the Study:

• To synthesize a novel bio-based polyphenol diol intermediate (VDP) for enhanced flame retardancy in polyurethanes.
• To investigate the impact of VDP incorporation on the flame retardant properties, thermal stability, and mechanical performance of polyurethane elastomers.

Main Methods:

• Synthesis of VDP via aldimine condensation and addition reactions using vanillin, 4,4'diamino diphenylmethane (DDM), and 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO).
• Covalent incorporation of VDP into the polyurethane backbone at various concentrations.
• Evaluation of flame retardancy using Limiting Oxygen Index (LOI) and UL-94 vertical burning tests.
• Analysis of thermal stability through decomposition activation energy (Eα) measurements.
• Assessment of mechanical properties, rebound resilience, and reprocessability.

Main Results:

• The incorporation of VDP significantly improved flame retardancy, increasing LOI from 23% to 30% and achieving a V-0 rating in UL-94 tests.
• Flame retardancy enhancement is attributed to radical scavenging (PO·, PO₂∙) and non-flammable gas release during combustion.
• VDP incorporation increased decomposition activation energy (Eα) from 109.3 to 227.6 KJ/mol, enhancing thermal stability due to rigid benzene structures.
• The modified elastomer retained 98.6% of its original mechanical properties after multiple re-molding and solvent casting cycles, demonstrating excellent reprocessability.

Conclusions:

• The novel bio-based VDP is an effective flame retardant for polyurethane elastomers.
• VDP enhances flame retardancy and thermal stability without compromising mechanical properties or reprocessability.
• This study presents a promising route for developing sustainable, high-performance flame-retardant polymers.