Design of a bio-based flame retardant for polyvinyl alcohol with superior flame retardant, mechanical and UV-blocking properties

In present, during preparing flame retardant polyvinyl alcohol (PVA) composites, most flame retardants present inferior fire retardant efficiency and trend to decrease the mechanical performance of PVA owing to bad dispersibility. Besides, they possess possible threat to human and environmental safety. In order to solve these issues, a bio-based flame retardant (PAE) is synthesized by using phytic acid and ethylenediamine to improve PVA flame retardancy, UV shielding properties and mechanical properties. According to thermographic examination, PVA composites retained its well-performed capacity of char production and thermal stability with the addition of PAE. The limiting oxygen index grows from 18.4% of pure PVA to 29.7% of PVA/PAE-15 composite and vertical burning rating reaches UL-94 V-0. The peak heat release rate and total heat release of PVA/PAE-15 sharply decreased by 68.1% and 31.0% comparing with pristine PVA. More importantly, PVA/PAE composites have outstanding mechanical properties and UV shielding, the addition of 5 wt.% PAE increases the tensile strength from 67.6 MPa to 85.1 MPa compared with pure PVA. Therefore, the results imply that the inclusion of PAE can elevate the flame retardant capability, mechanical properties and UV shielding of PVA.