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Phosphated cellulose (PCF) was synthesized based on urea, phosphated acid and cellulose. The structure of the PCF was confirmed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy coupled with the Energy Dispersive Spectrometer (SEM-EDS). Benzoxazine (Ba)/PCF hybrid materials were fabricated and thermally cured to prepare polybenzoxazine composites (PBa/PCF). The effects of PCF on the curing temperature of Ba were analyzed through differential scanning calorimetry (DSC). The thermogravimetric (TGA) results demonstrated an increased char residue of 50% for the PBa composites incorporating PCF-5% compared with the pure PBa. The peak heat release rate (PHRR) and total heat release (THR) values of the PBa/PCF-5% composites clearly decreased by 58.1% and 16.5% compared to those of the pristine PBa. The smoke released from the PBa/PCF system significantly reduced with the loading of PCF. Moreover, the limited oxygen index (LOI) and vertical burning test level (UL-94) of PBa/PCF-5% reached up to 31 and V0. The flame retardant mechanism of the PCF in the PBa matrix was investigated TG-FTIR and char residues analysis. Finally, the dynamical mechanical analysis (DMA) results demonstrated that the Tg of the PBa/PCF composites was approximately 230 °C, which does not affect further applications of PBa composites.

Melamine–formaldehyde resin-coated bamboo fiber (MFBF) and ammonium polyphosphate (MFAPP) were prepared, and then flame-retardant polypropylene (PP)/bamboo fiber composites based on MFBF/MFAPP were obtained by melt blending. The water resistance, flame retardant, and thermal properties of the composites were studied. The results show that MFBF and MFAPP have excellent water resistance with the water contact angles 130.85° and 119.78°, respectively. Compared with pure PP, the limit oxygen index (LOI) of the prepared composite increased from 18.5 to 25.5% with the UL-94V-0 rating. The peak heat release rate of the composite decreased from 1011.8 to 344.3 kW·m−2 and the total heat release decreased from 100.6 to 58.8 MJ·m−2. Meanwhile, the total smoke release decreased from 1453.3 to 922.0 m2·m−2. After soaking in 70 °C water for 36 h, the composite still reached the V-0 rating in UL-94 test, demonstrating a good water resistance. This work provides an effective method to improve the water resistance and flame retardancy of PP/bamboo fiber composites. Melamine–formaldehyde resin-coated bamboo fibers (MFBF) and ammonium polyphosphate (MFAPP) were prepared, then flame-retardant PP/BF composites were obtained based on MFBF/MFAPP. The results show that prepared composite exhibited excellent water resistance and flame-retardant properties. [ABSTRACT FROM AUTHOR]

The more efficient and hydrophobic modificated ammonium polyphosphate (M-APP) and charring agent (M-CA) were prepared based on sol–gel method, and they were used in the preparation of water-resistant and flame-retardant polypropylene (PP) composites. The results showed that the contact angles of M-APP and M-CA were 135.11° and 137.89°, respectively. The flame-retardant and thermal properties of the PP composites were also studied. The results showed that the flame retardancy of PP loaded with 30 mass% intumescent flame retardant (M-APP/M-CA = 3:1) was significantly increased. The limiting oxygen index (LOI) reached 36.8% and passed UL-94 V-0. The peak heat release rate and total heat release of the PP composite decreased from 1011.77 to 134.43 kW·m−2 and 100.58 to 6.86 MJ·m−2, respectively. The peak smoke production rate and total smoke release decreased from 0.13 to 0.0056 m2·s−1 and 1453.09 to 74.82 m2·m−2. The PP composite with M-APP/M-CA = 3:1 also exhibited excellent water resistance, and it could still reach UL-94 V-0 after soaking in 70 ℃ water for 168 h. [ABSTRACT FROM AUTHOR]

A novel bio-flame retardant (PA-B) was prepared based on green materials--banana peel powder (BPP) and phytic acid (PA), then PA-B was used to prepare flame retardant poly(lactic acid) (PLA) composites. The flame retardancy and thermal property of PLA composites were studied. It can be found that the limiting oxygen index (LOI) of PLA composite with 15.0 wt% BPP is 22.1%, showing the heavy dripping during the combustion and failing to reach the vertical burning tests (UL-94) V-0 rating. However, when 15.0 wt% PA-B is added, the LOI is significantly increased to 37.5%, and the composite can reach UL-94 V-0 rating with the dripping problem is obviously reduced. Furthermore, PA-B is helpful to ameliorate the thermal property of PLA composites under the high temperature. The char residue of PLA/PA-B15 is 10.9 wt% at 550.0 °C, showing much higher value than that of PLA/B15 (3.3 wt%) and pure PLA (almost nothing left). From flammability analysis, PA-B not only is a crucial part of promoting the formation of char layer with high quality in the solid phase, which can play a "barrier effect" role to protect the underlying matrix and retard combustion process, but also has the flame retardant effect in the gaseous phase on the basis of PO· free radical. This work provides an efficient way to prepare bio-based flame retardant PLA composites, and also offers a new method to reuse agricultural wastes like banana peel. [ABSTRACT FROM AUTHOR]