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• Poly-siloxane encapsulated EG (Si@EG) was prepared and introduced into PP composites. • The Si@EG significantly improved flame retardancy of PP composites. • Finite element analysis was used to evaluate burning behavior of PP composites. Expandable graphite (EG) was encapsulated by a poly-siloxane (Si@EG) and introduced into polypropylene (PP) composite as flame retardant additives. Compared with that of PP/EG composite, PP/Si@EG composite achieved the V-0 rating with a loading of 25 wt.%. Additionally, the total heat release of PP/Si@EG composite was decreased by 42% compared with that of control PP in the cone calorimeter test. To investigate the burning behavior of PP/Si@EG, a burning rate measurement was designed and finite element analysis was introduced to evaluate influences brought by char volume and shape formed by EG. The temperature field was calculated among EG and Si@EG expanding in the PP matrix. Additionally, Fourier transforms infrared spectroscopy and scanning electron microscope observation were operated to investigate the char residues. It was proposed that the outstanding flame retardancy brought by Si@EG was owing to the compact and dense char. [ABSTRACT FROM AUTHOR]

• Poly-siloxane coated IFR (Si-IFR) was prepared and introduced into TPO composites. • The Si-IFR significantly improved flame retardancy of TPO composites. • The water resistance of TPO composite was enhanced by the presence of Si-IFR. The flammability of thermoplastic polyolefins (TPO) is a prior concern related to fire disasters. The fire safety strategy for TPO has not been settled because of serious waterproof property deteriorations caused by the presence of flame retardant additives. This work reported an encapsulation of conventional intumescent flame retardant (IFR) additives by a poly-siloxane (Si-IFR) and its application in TPO composites. The fire behavior characterization revealed that the peak heat release rate and smoke density of the TPO/Si-IFR sample was decreased by 26.5% and 24.0% respectively compared with that of the TPO/IFR sample. The flame retardant mechanism analysis suggested that the poly-siloxane coated IFR formed compact char layers through Si-O structures and nano-silica attachment on the carbonous layer. Notably, the flame retardancy and mechanical property for the TPO/Si-IFR sample were almost unchanged after being soaked in water for 7 days at 70°C. Consequently, this work proved that the poly-siloxane encapsulated IFR was an effective additive for producing flame retardant and water resistant TPO composites. [ABSTRACT FROM AUTHOR]

• A silicone resin/EG surface coated RPUF was prepared via brush painting. • The coated RPUF showed outstanding flame retardancy with an add on of 8.5 mg/cm2. • The mechanical property of coated PRUF was enhanced by the coating. • The durability was investigated under artificial harsh weather conditions. High loading of flame retardants are usually required to prepare fire safety rigid polyurethane foam (RPUF), which often leads to deterioration of its mechanical properties. In this work, a silicone resin (poly-DDPM) was synthesized and coated on the surface of RPUF in association with expandable graphite (EG) via brush painting in order to improve its flame retardancy with minimal damage to the inherent mechanical property. The flammability characterization by limiting oxygen index (LOI), UL 94 and cone calorimeter tests revealed that the fire resistance of the foam samples was significantly improved by the presence of poly-DDPM/EG coating with an average add on of 8.5 mg/cm2. The LOI value was increased to 32.3 from 18, the UL 94 grade was upgraded to V-0, the peak heat release rate and the peak smoke release rate was reduced 55% and 59% respectively compared with that of the control RPUF sample. Additionally, the coated sample could not be ignited when it was exposed to a butane burner for 10 min. The compressive strength of the coated RPUF was impressively increased 10%. Furthermore, the fire resistance of the coating was durable under artificial harsh weather conditions. The poly-DDPM/EG coating adhered on the RPUF surface tightly, and transformed into expanded graphite flakes loaded nano-silica to achieve a protective char layer upon combustion. The demonstrated coated RPUF has great potential for commercial products. [ABSTRACT FROM AUTHOR]

This work reports our recent effort on the preparation of α-Phenyl-N-(2-propyl-2-hydroxymethyl-1, 3-dihydroxy)-imine-Nickel (Ⅱ) (Ni-MOF) containing polyhydroxy groups and its application in improving the fire performance of PLA composites in combination with ammonium polyphosphate (APP). The flame retardant evaluation revealed that the presence of 1.7% Ni-MOF and 3.3% APP in PLA increased the LOI value to 31.0%, upgraded the UL-94 level to V-0, decreased the peak heat release rate (pHRR), total heat release (THR) and total smoking production (TSP) by 27%, 19% and 50%, respectively, and substantially delayed the time to ignition (TTI) from 67 to 97 s. It was proposed that the flame retardants take effect in both vapor and condensed phases, and Ni-MOF nanosheets can synergistically improve the flame resistance of PLA with APP. The incorporation of Ni-MOF effectively inhibited the deterioration of mechanical properties for PLA composites caused by the presence of APP. • The Ni-MOF nanosheets containing polyhydroxy groups was prepared. • APP and Ni-MOF nanosheets significantly improved the fire safety of PLA composite. • The possible synergistic flame-retardant mechanism of Ni-MOF and APP was proposed. • Ni-MOF effectively improved the mechanical properties of PLA composites. [ABSTRACT FROM AUTHOR]

In order to guarantee fire safety and water resistance of the butyl acrylate (BA) coating, an integrated intumescent flame retardant (IFR) was fabricated. At first sodium tri-polyphosphate (STPP) was selected as acid source, and melamine (MEL) was gas source. STPP and MEL were connected by ionic bond. In the obtained product of melamine tri-polyphosphate (MTP), the amounts of hydrophilic groups was obviously reduced. BA coating containing 10 wt% MTP showed 37.3% reduction on water absorption, and the surface looked smoother with little folds. The limiting oxygen index (LOI) of BA coating is 22%; comparatively, LOI for BA/10 wt% MTP increased to 27%. The heat release rate (HRR), smoke production rate (SPR), CO production rate decreased by 20.1%, 5.4% and 33.3% respectively. The flame retardancy mechanism was tried to deduce by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) observation. It was proposed that MTP promoted the formation of compact char and the release of nonflammable gases. [Display omitted] • Melamine reacted with sodium tri-polyphosphate, the product MTP was used as flame retardant. • By 10% adding of MTP, butyl acrylate (BA) coating achieve self-extinguish. • By 10% MTP, heat and smoke release of BA coating was reduced by 38.3% and 27.8%, respectively. • By 10% MTP, the water absorption of BA coating was reduced by 37.3%. [ABSTRACT FROM AUTHOR]

The demand for eco-friendly poly (lactic acid) (PLA) nonwovens grows at a high rate in the past several decades, however, only a little attention has been received for flame retardant PLA nonwoven fabrics. In this work, a novel halogen-free self-intumescent polyelectrolyte tris (hydroxymethyl)-aminomethane polyphosphate (APTris) was synthesized by reacting ammonium polyphosphate with tris (hydroxymethyl) aminomethane, and was then used to improve the fire resistance of PLA nonwovens via a dip-nip process. The flammability characterization indicated the limiting oxygen index value was increased to 30.0% from 18.3%, and the damaged area in the vertical burning test was reduced by about 87.0% by the presence of APTris. The cone calorimeter test results revealed that the peak heat release rate and total heat release of the treated sample were decreased by 41.0% and 28.2% respectively compared with that of the control PLA nonwoven sample. The char residue was increased to 12.3 from 1.7 wt % at 800 °C. It is suggested that the dense char barrier formed at the presence of APTris prevents heat, smoke, and gas transfer, and hence enhance thermal dilatability and flame retardancy of PLA nonwovens. This simple sustainable halogen-free treatment has great potential to produce cleaner commercialized flame-retardant PLA nonwovens. Image 1 • An intumescent polyelectrolyte (APTris) was prepared by ion exchange reaction. • The APTris significantly improved the flame retardancy of PLA nonwovens. • The molten droplet of treated PLA nonwovens was reduced. • The APTris was carbonized to form compact protective layer during combustion. [ABSTRACT FROM AUTHOR]

• Two reactive flame retardants were obtained through transesterification. • The flame retardants improved the flame retardancy of rigid polyurethane foam. • The mechanical properties and low heat conductivity were well maintained. The reactive type flame retardants have been applied in rigid polyurethane foams (RPUF) owing to their excellent durability and minimal negative effect on the physical properties, however, their flame retardant efficiency cannot meet the requirements in many practical application scenarios. In this work, two reactive-type flame retardants with several hydroxyl groups were synthesized by a solvent-free transesterification between erythritol and dimethyl methyl phosphonate (DMMP), and they were then introduced into RPUF by reacting with isocyanate respectively. The flammability of the as-prepared RPUF samples was evaluated by limiting oxygen index (LOI) and cone calorimeter tests. With the presence of 10 phr as prepared flame retardant, the LOI value of RPUF was improved from 18.3% to 29.8%, and the peak heat release rate (pHRR) and total heat release (THR) were reduced by 31.4% and 47.8% respectively in contrast to that of control RPUF. Furthermore, the compressive strength and thermal conductivity of RPUF containing reactive flame retardants were similar to those of control RPUF. This study provides an innovative method for the clean production of commercial RPUF with fire safety by using a modified phosphorus ester. [ABSTRACT FROM AUTHOR]