Addition of ammonium polyphosphate for simultaneous enhancement of flame retardancy, mechanical, and viscoelastic properties of PALF-reinforced bio-HDPE composite

This work is focused on reducing the flammability of 25 wt.% pineapple leaf fiber (PALF)-reinforced bio-based high-density polyethylene (bio-HDPE) composites. Varying contents of ammonium polyphosphate (APP) up to 10 wt.%, have been incorporated as a flame retardant while its effects on mechanical and viscoelastic properties are also evaluated. The linear burning rate is reduced by up to 26% for 10% APP content in the horizontal burn test. The incorporation of APP also proved beneficial in arresting the dripping of the polymer matrix during the vertical burn test. Thermal analysis showed that the interaction between APP and natural fibers enhanced the residual char content by up to 9%. Furthermore, dynamic mechanical analysis revealed an increase in the damping factor (loss tangent) with APP addition. The findings recommend incorporating up to 5% APP in PALF/Bio-HDPE composites as optimum. PALF-reinforced Bio-HDPE composite with improved flame retardancy, mechanical, and damping properties is achieved, offering an alternative to conventional composites used in automobile and construction industries.

Highlights

• Flame-retardant composites made from 25% PALF and 10% APP.
• 10% APP base composite showed a 26% reduced UL 94 horizontal burning rate.
• APP incorporation increases residual char content and prevents dripping also.
• APP enhances both the mechanical properties and damping factor of composites.