Simultaneously enhancing the fire retardancy and crystallization rate of biodegradable polylactic acid with piperazine-1, 4-diylbis(diphenylphosphine oxide). (1st December 2020)

• Record Type: Journal Article
• Authors: Liu, Lubin; Xu, Yue; Di, Yifan; Xu, Miaojun; Pan, Yu; Li, Bin
• Is Part Of: Composites. Number 202(2020)
• Publication Date: 2020-12-01
• Subjects: Polylactic acid -- Piperazine-phosphamide derivative -- Fire retardancy -- Crystallization; Composite materials -- Periodicals; Materials science -- Periodicals; Composite materials; Periodicals; Electronic journals; 620.118
• DOI: 10.1016/j.compositesb.2020.108407
• Languages: English
• ISSNs: 1359-8368

Abstract

Abstract: The simultaneous improvement of flame retardancy and crystallization rate for polylactic acid (PLA) has always been a challenge in the field of engineering applications. In this paper, a piperazine-phosphamide derivative (PPDO) was successfully synthesized from diphenylphosphinyl chloride and piperazine and its chemical structure was confirmed. The PPDO was served as a multi-functional additive to simultaneously improve the fire safety and crystallization rate of PLA. The fire retardancy, crystallization behaviors, mechanical properties and flame-retardant mechanism of PLA biocomposites were systematically investigated. With the incorporation of mere 3 wt% PPDO, the PLA biocomposites fulfilled UL-94 V-0 rating with the LOI of 27.8%. The outstanding fire retardancy of PPDO in PLA was ascribed to the shielding effect of compact and dense char layer in condensed phase, and the suppression function of benzene- and phosphorus-containing free radicals and the dilution role of inert gases in vapor phase. Thus, the effective heat combustion and total heat release of PLA biocomposites were prominently depressed. Meanwhile, PPDO was a good nucleating agent for PLA, which effectively increased the crystallinity and crystallization rate of PLA. Besides, PLA biocomposites still maintained remarkable transparency and mechanical properties due to the low addition of PPDO and excellent compatibility with the PLA matrix, which endowed flame-retardant PLA biocomposites with the enormous application prospect in the field of advanced optoelectronic devices. Graphical abstract: Image 1 Highlights: A piperazine-phosphamide derivative (PPDO) was synthesized by diphenylphosphinyl chloride and piperazine. PPDO endowed PLA with high fire retardancy and crystallization rate. PPDO exerted flame-retardant effect both in condensed and vapor phase. PLA/PPDO biocomposites retained superior mechanical properties and transparency.