Abstract
A novel polyol (Poly-PDT) containing phosphorus and nitrogen was synthesized from Phenyl phosphoryl dichloride (PPDC), dipropylene glycol (DPG), and Triethanolamine (TEA) by condensation polymerization. Poly-PDT and polymethylene polyphenyl polyisocyanate (PM-200) with different ratios were prepared into RPUF-PNs. The tertiary amine in the Poly-PDT structure initiates an autocatalytic operation. This process gradually enlarges the bubble pore structure of RPUF-PNs. As a result, the density of RPUF-PNs decreases, impacting their mechanical properties. The test results indicate that due to the nitrogen-phosphorus synergistic effect of Poly PDT, the flame retardant performance of polyurethane materials can be significantly improved. The LOI of RPUF-PN50 can reach 23.3%. The materials tested with conical calorimeters test (CCT) show significant improvements in combustion properties. The heat release rate (HRR) curve and the total heat release rate (THR) curve for the sample containing Poly-PDT was lower than the blank sample, RPUF-PN40 showed the lowest peak heat release rate at 126 Kw/m2, representing an approximate 48% decrease compared to RPUF and RPUF-PNs. These improvements are due to an increased crosslinking density and a synergistic flame retardant effect from nitrogen-phosphorus. This enhances the ability of RPUF-PNs to obstruct gases after combustion. Moreover, it improves the matrix carbon burning capacity and strengthens the carbon layer of RPUF-PNs.
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