A novel high phosphorus-content phosphonate enables polylactide with superior fire safety, mechanical properties, and...

In developing durable polylactide (PLA) composites, balancing fire safety with mechanical strength and transparency remains crucial for electronic applications. To overcome this hurdle, a novel high phosphorus-content (15.9%) BDPMPP (bis[(diphenylphosphoryl)methyl] phenylphosphonate) was successfully synthesized, and the PLA/BDPMPP composites with different BDPMPP contents were fabricated. As anticipated, the incorporation of merely 2 wt% BDPMPP endows PLA/2.0BDPMPP composite with the UL-94 V-0 rating (vertical burning test V-0 rating) while increasing the LOI (limiting oxygen index) to 26.0%. The synergy between free radical trapping and interruption of heat exchange was the main reason for superior fire safety. Surprisingly, the tensile, flexural, and unnotched impact strength of PLA/2.0BDPMPP composite were increased from 63.9 MPa, 78.8 MPa, and 11.2 kJ/m² of pure PLA to 72.6 MPa, 90.5 MPa, and 15.0 kJ/m², respectively. The improvement of mechanical properties was closely related to the enhancement of the crystallinity of PLA/BDPMPP composites, the favorable compatibility between BDPMPP and PLA matrix, and the introduction of a rigid structure in the PLA matrix. More importantly, the transmittance of PLA/2.0BDPMPP composite decreased by only 3.4% compared to pure PLA. In conclusion, this research provides a PLA composites with excellent comprehensive performance that has enormous application potential in the fields of electronics.