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• Intumescent flame retardant (IFR) and zinc oxide (ZnO) were successfully microencapsulated by polysiloxane. • The addition of microencapsulated IFR and ZnO significantly enhanced the flame retardancy of polypropylene (PP). • Water resistance of PP composites was also enhanced by the presence of microencapsulated IFR and ZnO. Intumescent flame retardant (IFR) and zinc oxide (ZnO) were successfully microencapsulated by polysiloxane, resulting in the preparation of Si-IFR and Si-ZnO, respectively. These microencapsulated additives were then incorporated into polypropylene (PP), leading to a synergistic enhancement of the flame retardancy, mechanical properties, and water resistance. By means of limiting oxygen index (LOI), UL-94 vertical burning test, and cone calorimetry test, an assessment was conducted to analyze the combustion characteristics of PP composite materials containing 2% Si-ZnO and 24% Si-IFR additives. The LOI value and UL-94 of PP/24%Si-IFR/2%Si-ZnO achieved to 39.8% and V-0 rating respectively, with significant decreases in both the total heat release (THR) and total smoke production (TSP). Furthermore, the introduction of polysiloxane significantly improved the water resistance of the PP composites. After a 168-hour water immersion test, notable reductions were observed in water absorption, the precipitation of flame retardants, as well as alterations in the mechanical properties of PP/24%Si-IFR/2%Si-ZnO. [ABSTRACT FROM AUTHOR]

• A halogen/phosphorus-free flame retardant phenylboronic acid functionalized chitosan (B-CH) was successfully prepared. • B-CH could effectively improve the flame retardancy of poly(lactic acid). • The char forming ability of PLA composites was also enhanced by the presence of B-CH. A boron-based biological flame retardant phenylboronic acid functionalized chitosan (B-CH) was prepared by reacting chitosan (CH) with 4-formylphenylboronic acids. The structure characterization was carried out by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. B-CH was added into polylactic acid (PLA) by the melt blending method to improve the fire performance of the composite. The results showed that the peak heat release rate (PHRR) of PLA-7% B-CH decreased to 432 kW·m−2 from 564 kW·m−2 of control PLA. The limiting oxygen index (LOI) was increased from 19.1% to 26.2%, and the vertical burning test (UL-94) could reach a V-0 rating. The B-CH participated in the char formation process, which could generate a continuous compact char layer during the combustion to effectively protect the PLA matrix. This work provided an effective strategy to develop environmental friendly flame retardant PLA composites. [ABSTRACT FROM AUTHOR]

• By foam finishing with sodium polyborate, cotton fabric obtains good flame retardancy and maintains softness and breathability. • The flame retardant does not involve Cl or P-containing chemicals. • Foam finishing consume lower water or solvent than dip-padding finishing. The conventional process of imparting flame retardancy to cotton fabrics requires the consumption of large amounts of water, chemicals, and energy, which usually involves halogen-containing and phosphorus-containing chemicals. In this work, an eco-friendly sodium polyborate (SPB) foam was creatively introduced onto the cotton fabric surface by a bladed coater to improve the fire resistant performance. For the cotton sample with only 6.7% weight gain (WG) of SPB coating, the LOI value of cotton fabric (SPB treated cotton-1) was enhanced to 32.6% from 18.5%, the damaged length was decreased to 5.7 cm, and the sample self-extinguished in the vertical burning test. The peak of heat release rate value, total heat release value, and total smoke production (TSP) value decreased by 87.0%, 72.7%, and 22.2% respectively compared with those of the control sample. The TSP was further decreased by 80.6% when the WG of SPB was 16.7%. Besides, the SPB treated cotton showed enhanced antibacterial activities against S.aureus and E.coli. Particularly worth mentioning is in the SPB foam finishing procedure, no organic solvent and P or Cl-containing chemicals were involved, and the processing time was only around 3 min with obviously reduced water consumption, compared with dip-padding finishing. More importantly, SPB treated cotton kept good softness, whiteness, water vapor permeability, and air permeability. The SPB foam finishing in this work shows considerable potential in realize good flame retardancy on cotton fabrics by eco-friendly and high-efficient strategy. [ABSTRACT FROM AUTHOR]

• A 3D boron nitride skeleton was fabricated by the ice template method. • The thick skeleton layer provides a more efficient heat transfer path. • The synergistic flame retardant mechanism of boron nitride and ammonium polyphosphate was revealed. • The char residue left in the combustion can support weights more than 1100 times of its own mass. Epoxy (EP) is widely used in the field of high-speed communication and microelectronics. However, its poor thermal conductivity and high flammability bury the hidden danger of fire accident. In this work, the hexagonal born nitride (h-BN) combined with ammonium polyphosphate (APP) constructs a three-dimensional skeleton (3D-BN) via bidirectional freezing technology. The 3D-BN skeleton is immersed into the EP matrix to obtain the EP/3D-BN composite, which is endowed with high thermal conductivity and flame retardancy. When the loading of hexagonal born nitride (h-BN) is 9.1 vol%, the thermal conductivity of EP/3D-BN 3 composite reaches 1.67 W m−1 K−1, which is increased by 944 % compared with that of the control EP. The peak heat release rate (PHRR) and total heat release (THR) of EP/3D-BN 3 are significantly reduced by 54 % and 34 % respectively. This EP/3D-BN composite provides potential applications toward the industrial production for microelectronic devices. In this work, the hexagonal born nitride (h-BN) combined with ammonium polyphosphate (APP) constructs a three-dimensional scaffold (3D-BN) via bidirectional freezing technology. The 3D-BN scaffold is immersed into the epoxy (EP) matrix to obtain the EP/3D-BN composite, which is endowed with high thermal conductivity and flame retardancy. [Display omitted] [ABSTRACT FROM AUTHOR]

• An eco-friendly coating (APP-LA) was prepared based on ammonium polyphosphate (APP) and tyramine (LA). • The APP-LA treated lyocell showed improved flame retardancy. • The possible flame retardant mechanism of APP-LA was proposed. Low-carbon emissions are a sustainable development approach, among which lyocell is a renewable and zero carbon biodegradable cellulose fiber. The flammability of lyocell fabric poses a threat to people's lives and property. In response to this issue, a bio-based flame retardant, tyramine polyphosphate (APP-LA), was synthesized and applied to the treatment of lyocell fabrics. The synthesis of APP-LA adopted an eco-friendly and organic solvent-free method. In the combustion test, the limiting oxygen index of APP-LA treated lyocell fabrics increased to 35.8% compared to control lyocell (18.5%), and the damage length was only 6.7 cm. Meanwhile, the peak heat release rate and total heat release decreased by 92.9% and 58.7% respectively, compared to the control lyocell. Besides, the P-containing compounds generated by APP-LA accelerated the decomposition of the matrix to produce a dense char layer. The fewer flammable volatiles and more non-flammable gases were released. This work provided a low-cost and eco-friendly strategy for the simple preparation of commercial flame-retardant lyocell fabrics. [ABSTRACT FROM AUTHOR]

• A novel DOPO derivative was synthesized and employed as a multi-functional additive for EP. • The EP composite with superior fire-retardancy, mechanical properties and anti-aging performance was obtained. • HP-DOPO shows good compatibility, while accelerate the curing procedure and do not sacrifice the transparency of cured EP. Aiming to develop high performance flame-retardant epoxy resin (EP), a novel phosphorus-containing flame retardant named 6-(3-(2-hydroxyphenyl)propyl)dibenzo-[1,2]oxaphosphinine 6-oxide (HP-DOPO) was synthesized and employed as a multi-functional additive for EP with simultaneously excellent flame retardancy, transmittance, mechanical enhancement and anti-aging. With 5 wt.% loading of HP-DOPO, EP composites showed outstanding flame retardancy with a high limiting oxygen index of 35.6 % and V-0 rating in UL-94 test, while the cone calorimetric test results demonstrated that HP-DOPO could efficiently restrain the heat and smoke release. Compared with pure EP, the resultant EP/5 %HP-DOPO exhibited superior mechanical properties with 27.9 % and 56.2 % increase in tensile and impact strengths, respectively. Furthermore, HP-DOPO accelerated the curing procedure and did not sacrifice the transparency of cured EP, while anti-aging performance was obtained at the same time. The exploration of this novel multi-functional additive provided a powerful basis for the technologies and potential industrial applications of epoxy materials. [ABSTRACT FROM AUTHOR]

• A flame retardant diphenylphosphinyl vanillin diamino triazole (DPPVA) is synthesized. • The limit oxygen index of EP/4%wt DPPVA is 34.5%, and the sample passes UL-94 V-0. • The mechanical properties of EP/4%wt DPPVA are similar as that of the control EP. • The EP/4%wt DPPVA is transparent, and exhibits repellence to E. coli and S. aureus. A flame retardant DPPVA was synthesized through a Schiff-base reaction of vanillin, 3,5-diamino-1,2,4-triazole, and diphenylphosphinyl chloride, which was used to improve the thermal stability, flame retardancy, and antibacterial activity of the cured epoxy resin (EP). The EP/4% DPPVA sample looked yellow, but it was still transparent, and it passed the V-0 rating with a limit oxygen index (LOI) of 34.5%. The presence of 4wt% DPPVA in EP decreased the peak heat release rate (pHRR), total heat release (THR), and total smoke production (TSP) by 32.5%, 25.2%, and 29.3%, respectively. Compared with that of the control EP, the char residue was increased to 14.9wt% from 9.6wt%. In TGA the max mass loss rate of the EP/4% DPPVA sample was reduced to 0.86%/ °C from 1.75%/ °C of the control sample, which means the pyrolysis of EP was slowed down by DPPVA. The EP/4% DPPVA sample exhibited effective repellence to E. coli and S. aureus. The addition of 4% DPPVA to EP decreased the impact strength to 8.5 kJ/m2 from 9.9 kJ/m2, which was acceptable for many industrial scenarios. This work provided a potential strategy with an easy process for manufacturing flame retardant, antibacterial and transparent EP composites. [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]

• The flame retardancy and thermal degradation behavior of iPP and sPP has been investigated. • IPP can achieve better flame retardancy with the equal amounts of IFR compared with sPP. • The reason for the difference of iPP and sPP in flame retardancy was discussed through viscosity, melt point, crystallization and thermal degradation. This work investigated the difference in flame retardancy and degradation behavior of polypropylene (PP) composites with different configurations. The piperazine pyrophosphate (PAPP) was combined with melamine polyphosphate (MPP) to construct an intumescent flame retardant system, before incorporating into the PP system by melt blending. It showed that by the introduction of equal amounts of flame retardant, isotactic polypropylene composites (iPP-IFR) can achieve better flame retardancy with a desirable UL-94 V-0 rating, whereas syndiotactic polypropylene (sPP-IFR) shows poor fire performance. Melt index tests show that sPP-IFR sample is easy to flow and prone to melt drops. Differential scanning calorimetry results show that iPP-IFR has a higher degree of crystallinity. The thermogravimetric infrared coupling results show that sPP-IFR produces more small molecule hydrocarbon gases during combustion, making the system more difficult to achieve satisfied flame retardancy. The burning properties of iPP-IFR have been proven to be somewhat better compared to that of sPP-IFR, and sPP is more difficult for flame retardant modification. [ABSTRACT FROM AUTHOR]

• Divinylbenzene-maleic anhydride microsphere (DM) was used as a synergistic flame retardant and compatibilizer. • By incorporation of 16wt% intumescent flame retardant (IFR) and 1wt% DM, the bio-based and degradable polyester P34HB reached UL-94V-0 grade. • The smoke and toxic gas release were obviously reduced by 1wt% DM. • The degradation rate of P34HB/16wt%IFR/1wt%DM was more than 5 times faster than the control P34HB. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB), as a bio-originated and biodegradable polyester, is expected to be developed to substitute traditional petroleum-based plastics. However, its flammability restrains its application, intumescent flame retardant (IFR) has been used in P34HB. Herein, a rigid microsphere divinylbenzene-maleic anhydride (DM) copolymer was used as a synergistic agent with IFR together in P34HB. The LOI of the 83wt% P34HB/16wt% IFR/1wt% DM reached 30.0%, and the composite also passed the UL-94V-0 rating. In the cone calorimeter test, the peak heat release rate (PHRR) of the control P34HB was 727 kW/m2, which was reduced to 281 kW/m2 for the 83wt% P34HB/16wt% IFR/1wt% DM. The total smoke production (TSP) of the control P34HB was 12.1 m2, however, the TSP value of 83wt% P34HB/16wt% IFR/1wt% DM was reduced to 8.4 m2. The results showed that DM acted as an ideal synergist flame retardant. For the 75wt% P34HB/25wt% IFR, the tensile strength and impact strength were 13.7 MPa and 4.2 KJ/m2, respectively and for the 83wt% P34HB/16wt% IFR/1wt% DM, they were increased to 18.1 MPa and 9.1 KJ/m2, respectively. In the degradation process, the weight loss rate of control P34HB was 0.1 mg/h, and that was 0.56 mg/h for 83wt% P34HB/16wt% IFR/1wt% DM, which indicated that the IFR/DM accelerated the degradation of P34HB. All the work documented that DM improved the flame retardant, mechanical properties, and degradation rate of P34HB. [ABSTRACT FROM AUTHOR]

• Phosphorylated histidine-amino triazine-diaminopropane (PHTD) copolymer was synthesized and used as bifunctional additives of flame retardant and binder. • PHTD can improve the flame retardancy and smoke suppression of EPS foams significantly. • The hard shell formed by PHTD can improve the compressive strengths of EPS foams. A novel intumescent flame retardant, phosphorylated histidine-amino triazine-diaminopropane (PHTD) was synthesized and utilized as both a flame retardant and a binder addition. Flame retardant expanded polystyrene (EPS) foams containing PHTD was successfully prepared by coating method. The limited oxygen index (LOI) and vertical burning (UL-94) tests were used to determine the flammability of EPS/PHTD composite foams, and an apparent flame retardant effect could be obtained with up to 28.8% LOI value and UL-94 V-0 rating when 41.9 wt.% PHTD was added. The cone calorimetric test results showed that the treat EPS sample showed significantly depressed peak heat release rate (pHRR) by 74.9% and peak smoke production rate (pSPR) by 77.3%. Additionally, the flame retardant could be evenly coated on the surface of EPS beads. Even though part of the foam was damaged, it could still keep good flame retardant performance. Furthermore, the thermal conductivity of coated foam was not affected and remained at a comparatively low level, and the compressive strength was increased by 20.0%. [ABSTRACT FROM AUTHOR]

• The Ni-Fe layered double hydroxides as synergistic flame retardant fillers were synthesized. • The excellent flame retardant and smoke suppression of TPU was obtained. • The mechanisms for the flame retardancy and smoke suppression were proposed. Aluminum hypophosphite (AHP), as an effective phosphorus-based flame retardant used in thermoplastic polyurethane (TPU), released a large amount of smoke and toxic gasses during combustion. In this work, a flame retardant filler, Ni-Fe layered double hydroxides (NiFe-LDHs), was synthesized and applied in TPU together with AHP. The limiting oxygen index (LOI) of the TPU/6AHP/1NiFe-LDH composite reached 30.7% with a V-0 rating in the UL-94 test. Compared with neat TPU, the peak heat release rate (pHRR) and total heat release (THR) values of TPU/6AHP/1NiFe-LDH sample were reduced by 67.9% and 40.8%, respectively. Moreover, both the smoke production and CO/CO 2 yield were also decreased sharply. It was proposed that NiFe-LDH provided the effect of catalyzing char formation, and the obtained dense char layer was able to block both heat and smoke release. In addition, the addition of NiFe-LDH had little effect on the mechanical properties of TPU, and the tensile strength and elongation at break only decreased by 6.0% and 6.9%, respectively. This work provides a new strategy for fillers and flame retardants to improve the flame retardant properties and smoke suppression of TPU. [ABSTRACT FROM AUTHOR]

• 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]

• An organic-inorganic hybrid coating was constructed on T/C fabrics. • The hybrid coating improved greatly the flame retardancy of T/C fabrics. • The coated fabrics showed antibacterial property against S. aureus and E. coli. • The flame retardant and antibacterial mechanism was proposed. In this work, an organic-inorganic hybrid coating was used to improve the fire safety and antibacterial property of polyester/cotton blend fabrics. The hybrid coating was constructed by two steps, including the in-situ growth of zirconium phosphate nanosheets, and the preparation of polyelectrolyte complex with phytic acid and poly(hexamethylene guanidine hydrochloride) via spraying method. The flame retardancy and antibacterial activity of treated fabrics were completely investigated. A self-extinguishing behavior was observed in vertical burning test and the damaged length was only 5.4 cm. The LOI value of treated fabrics was increased from 19.0% of pristine fabrics to 27.8%, and the peak heat release rate and total heat release were decreased by 42% and 27%, respectively. Besides, thermogravimetric analysis revealed that the char residue increased from 8.3% to 26.3% at 800 °C, confirming a great char-forming ability of coated fabrics. Tensile strength test indicates that the introduction of coating had no seriously damage to the mechanical properties of fabric. Moreover, an excellent antibacterial property of treated fabrics was proved by using agar diffusion method. This research provides an environmentally friendly path for the flame retardant and antibacterial modification of polyester/cotton blend fabrics. [ABSTRACT FROM AUTHOR]