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The widespread industrial applications of thermoplastic polyurethane (TPU) are partially limited by its flammability. The design of high‐performance intumescent flame retardants (IFR) is of great significance for enhancing flame retardant (FR) performance of TPU. In this work, an IFR system consisting of ammonium polyphosphate (APP), double pentaerythritol (DPER), and zinc borate (ZB) is proposed. The optimized experimental parameters with 15 wt.% additive amount of FR, APP‐DPER weight ratio of 2.28:1 and 15.56 wt.% ZB content are regulated based on Box–Behnken design‐response surface methodology (BBD‐RSM) to obtain TPU/FR composite with superior limiting oxygen index value of 30.2%. Noticeably, the design efficiency of TPU/FR composite is significantly improved by utilizing BBD‐RSM. Results of vertical burning test show that the optimized TPU/FR composite passes UL 94 V‐0 rating and peak heat release rate is dramatically reduced from 1355.88 (neat TPU) to 201.01 KW/m2 through cone calorimeter test. In addition, scanning electron microscopy accompanied with Raman spectroscopy are conducted to characterize the morphology and composition of residual char for further exploring the FR mechanism of IFR system in TPU. The as‐prepared TPU/FR composite has provided new potential application in engineering fields. [ABSTRACT FROM AUTHOR]

Linear low‐density polyethylene (LLDPE) and different concentrations (5‐20 wt%) of magnesium hydroxide (MAH) as a filler either with or without the addition of graphene nanoplatelets (GNPs) were peroxide cross‐linked using dicumyl peroxide as a cross‐linking agent in a twin‐screw extruder. The mechanical, thermal stability, flame retardancy, morphological, and rheological properties of the prepared samples were investigated. The mechanical properties of the peroxide cross‐linked LLDPE samples with higher MAH and GNP in the matrix were significantly improvement compared to neat LLDPE. This indicates that the addition of MAH and GNP to the peroxide cross‐linked LLDPE matrix could be suitable reinforcing fillers to achieve better and enhanced mechanical properties, particularly tensile strength. Conversely, a significant decrease in the elongation at break values was found for peroxide cross‐linked LLDPE samples compared to neat LLDPE. Similarly, results of thermogravimetric analysis revealed remarkable thermal stability enhancement in the peroxide cross‐linked LLDPE samples with higher MAH and GNP compared to neat LLDPE. The results from UL94 test demonstrated that the peroxide cross‐linked LLDPE samples comprising higher MAH with GNP exhibited improved V = 0 rating compared to poor no rating (NR) for neat LLDPE. Furthermore, the scanning electron microscope and digital images shown improved flame retardancy properties for these samples because of the formation of protective char layer on the sample surface. The complex viscosity for the peroxide cross‐linked LLDPE samples, at lower frequency, increased with increasing MAH loading and further addition of GNP compared to neat LLDPE. Highlights: Cross‐linked polyethylene with flame retardant (FR) and nanofiller were prepared.Effects of cross‐linking and FR on the final properties of the polymer were studied.20wt% FR with 3 phr nanofiller promoted the final properties of the polymer.Higher filler loading in the polymer improved flame retardancy and thermal stability.Combined effect of cross‐linking and FR has shown major improvement. [ABSTRACT FROM AUTHOR]

Biomass aerogels have attracted wide attention due to their excellent thermal insulation properties, but their low mechanical strength and high susceptibility to combustion limit their application. To address these limitations, a novel composite aerogel was prepared by combining chitosan aerogel (CS) and hydroxyapatite nanowires (HAP) via phytic acid (PA) cross‐linking and freeze‐drying. It was found that the maximum compressive strength and modulus of CS/HAP aerogel were 1.13 and 0.67 MPa, respectively. The minimum thermal conductivity of CS/HAP(0.5) composite aerogel was 0.03921 W m−1 K−1, indicating its good thermal insulating property. Moreover, the CS/HAP composite aerogel also showed excellent flame‐retardant properties. The heat release rate (HRR) and total heat release from combustion (THR) were significantly lower than those of the CS aerogel, with values of 35.2 kW m−2 and 3.7 MJ m−2, respectively, compared to 169.6 kW m−2 and 5.4 MJ m−2. The total smoke release (TSR) was also at a low level, reaches 0.4 m2 m−2. Highlights: Propose a novel chitosan aerogel composited with inorganic nano‐reinforced HAP.High mechanical strength of CS/HAP composite aerogel are illustrated.Exhibit excellent thermal insulation performance of CS/HAP aerogel.HAP and PA largely improves the flame retardancy of the chitosan aerogel. [ABSTRACT FROM AUTHOR]

Epoxy resin (EP)/cyanate ester (CE) copolymer, an important structural material with high temperature resistance and low dielectric constant in aerospace, microelectronics, and related fields, is still of great flammability danger. In this work, copper phenyl phosphonate (CuPP), a flame retardant used in EP/CE copolymer was synthesized by the reaction of phenyl phosphonic acid and copper nitrate trihydrate. The fire and thermal behavior of EP/CE/CuPP composites were studied in detail. The results suggested that the UL-94 rating and limiting oxygen index of EP/CE composite with 5 wt% CuPP (EP/CE/CuPP5) reach V-1 level and 30.6%, respectively. Compared with pure EP/CE copolymer, the peak heat release rate and total heat release values of EP/CE/CuPP5 decreased by 34.5% and 18.9%, respectively. The glass transition temperature of EP/CE/CuPP composite is higher than that of pure EP/CE copolymer, suggesting that the fire-retardant composite has higher work temperature and better heat resistance.

The inflammability of polystyrene (PS) limited its application. In order to improve the flame retardancy of PS, developing reactive-type flame retardants is a promising approach. In this work, a novel N-arylpiperazine phosphoramidate monomer, 2-((phenoxy(4-phenylpiperazin-1-yl)phosphoryl)oxy)ethyl methacrylate (PPPEM), was facilely synthesized and used as a reactive-type flame retardant. The obtained monomer was then copolymerized with styrene through the free radical bulk polymerization. The thermal stability of copolymers was measured by the thermogravimetric analysis. The addition of the PPPEM units increased decomposition temperature of the copolymers, indicating the improvement of the thermal stability. The glass transition temperature of the copolymers remained little changed with varied amount of the PPPEM, implying that the introduction of PPPEM units did not evidently affect the mobility of the PS main chain. The flammability of the copolymers was evaluated by microscale combustion calorimeter (MCC) and limiting oxygen index (LOI). According to the MCC and LOI results, PPPEM unites can contribute to the decrease of the peak heat release rate, the increase of LOI and improvement of the flame retardancy. The novel N-arylpiperazine phosphoramidate monomer show a great potential for application in reactive-type flame retardants. [ABSTRACT FROM AUTHOR]

With the increase in environmental pollution, studies on the use of sustainable resources are increasing day by day. For this purpose, the use of natural fiber-reinforced polymer composites is encouraged in many areas such as automotive, transportation, construction, and home textiles. However, they are flammable and therefore seriously threaten the safety of people and property. Various flame retardant additives have been used to improve the flame retardancy properties of these composites. In this study, silicon dioxide (SD) and zinc borate (ZB) microparticles in different weight percentages (3, 5, 7, and 10%) were reinforced to give flame retardant properties to jute-epoxy composites. In addition, composites containing both SD and ZB microparticles were produced and they were labeled as HB. Then, thermal conductivity, flammability, water absorption, and mechanical properties of these composites were investigated. The burning rate of the composites decreased as the amount of microparticle increased. 5ZB5SD, including %5 SD and %5 SD microparticles, showed 36.60% less burning rate than the neat jute-epoxy composite. 5ZB showed 10.84% higher tensile strength than the neat juteepoxy. The impact strength of the specimens increased with the increase in the filling ratio, and 5ZB5SD showed approximately 2.50 times the impact strength of the jute-epoxy composite. [ABSTRACT FROM AUTHOR]

The results of investigations of the mechanical and thermal properties of the composites modified with a structure-forming agent based on aluminum hydroxide and a high- and low-density polyethylene blend are reported. The properties of the polymer composites, including the fracture stress, relative elongation, melt flow index, heat resistance, thermal stability, and thermomechanics, have been studied. All the composite materials have been based on a titanium dioxide-modified (1 wt %) high- and low-density polyethylene blend (50/50). The aluminum hydroxide content has been varied within 1‒30 wt %. Using the data obtained on the Kanavets device, the temperature dependences of the deformation have been built and the regularities of changes in the thermomechanical curves have been established. It has been shown that, in all the investigated samples, a transition from the solid to viscous-flow state occurs with increasing temperature. The thermal stability has been estimated by the thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

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]

A novel phosphorus- and nitrogen-containing flame retardant (APNTHE) was synthesized through the reaction of N, N, N ′, N ′-tetrakis (2-hydroxypropyl) ethylenediamine, phosphoric acid and urea. Then, the APNTHE solution with a concentration of 120 g/L was used for the preparation of flame retardant cotton (FR-cotton). The elemental compositions, surface morphology, thermal stability and combustion behavior of the cotton before and after modification were investigated. Thermogravimetric (TG) analysis showed that the char residue of the treated fabric at 800°C was as high as 35.09% under a nitrogen atmosphere. Flammability tests after different LCs indicated that FR-cotton had durable flame retardancy. Compared to the blank sample, the peak of heat release rate and total heat release of the FR-cotton decreased by 91.89% and 90.53%, respectively. The char residual and TG-Fourier transform infrared spectroscopy analysis illustrated that APNTHE played a flame retardant role both in the gas phase and the condensed phase. All the results demonstrated that APNTHE can be regarded as a prospective flame retardant for cotton. [ABSTRACT FROM AUTHOR]

• In this work, we report the design, synthesis, and characterization of paracetamol derivatives of cyclotriphosphazene (DSPCT and DSHY) and polycyclotriphosphazenes (DSTPC and DSAC) for the first time. • The thermal decomposition phases can be seen in the TGA curves of DSHY, DSTPC and DSAC, DSTPC polyamide exhibits the greatest solid residue rate at 58.6 % when heated to 700 °C. These polyamides are shown to have considerable promise as heat resistant materials. • The monomer (DSHY) is found to be in crystal resistant materials and the polyamides (DSTPC and DSAC) are found to be amorphous, according to X-Ray diffraction patterns. Polyamides are used as high-performance materials in industry and electronics. Researchers have recently been focusing on this area and trying to synthesize more stable and high-performance molecules by polymerizing various groups into the backbone skeleton. In this work, we report the design, synthesis, and characterization of paracetamol derivatives of cyclotriphosphazene (DSPCT and DSHY) and polycyclotriphosphazenes (DSTPC and DSAC) for the first time. The structures of new products were fully characterized by MALDI-TOF Mass analysis, FT-IR, 1H and 31P NMR spectroscopies and single crystal X-ray (for DSPCT and DSHY) crystallography. The crystallization behaviours of the polyamides were studied by X-ray diffraction, and a scanning electron microscope was used to observe the morphology of the DSTPC and DSAC. Thermal degradation properties for DSHY, DSTPC and DSAC were determined by DSC and TGA techniques. Polyamides and the DSHY compound exhibited superior thermal stability with an initial decomposition temperature range of ca. 251–302 °C. Additionally, spectral characterization and photophysical behaviours (fluorescence quantum yields and lifetimes) of the all new compounds were also comprehensively investigated using UV–Vis and fluorescence spectroscopies (steady-state and time-resolved fluorescence). [Display omitted] [ABSTRACT FROM AUTHOR]

Intumescent fireproof coating (IFC) can effectively slow down the temperature rise of base materials by constructing intumescent heat isolation chars. Expandable graphite (EG), combined with a typical intumescent flame-retardant system, shows an excellent expansion effect. However, it is difficult to be evenly dispersed in the coating system due to its low surface energy, thus limiting its application in IFC. In this research, EG encapsulated by polyvinyl alcohol (PVA) film was used in combination with conventional intumescent flame retardants to prepare a fireproof coating. Due to the increased hydrophilicity caused by the hydroxy groups of the PVA, both the dispersion and adhesion of EG can be greatly improved in the coating. Additionally, PVA also plays the role of a charring agent to further upgrade the quality of the produced carbon layer. The prepared IFC displays a satisfying synergistic effect. The experimental results showed that the back-surface temperature of the steel plate coated by PVA@EG was reduced to 232 °C after 20 min, far lower than the 250 °C of the unmodified EG system, and the thermal insulation performance was enhanced significantly. Compared with the untreated EG coating, the HRR, THR, and TSR decreased by 79.5 %, 86.0 % and 24.8 %, respectively, and combustion and smoke suppression performance were improved greatly. All in all, PVA@EG endows the coating with superior flame-retardant and thermal insulation performance and greatly improves the safety of steel structures in buildings. [Display omitted] • The PVA film was encapsulated on the surface of the EG to enhance the dispersion and adhesion of the EG in the coating. • The PVA in PVA@EG can act as a carbon source and increase the residual char. • The PVA @ EG coating exhibits better flame retardant, heat insulation and smoke suppression 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]

[Display omitted] • A novel six-armed and star-type flame retardant (SCCP) was synthesized. • Flame retardant PAN was prepared by SCCP and chitosan chelated with Cu2+. • Modified PAN has flame retardancy, smoke suppression and antibacterial properties. • The modification is practical, green and environmentally friendly. In this work, a six-armed star-type flame retardant (SCCP) contained phosphorus, nitrogen and sulfur contents was developed, which was then combined with chitosan (CS) to chelate Cu2+ (SCCP@CS-Cu) and blend with polyacrylonitrile (PAN) to produce flame retardant and antibacterial PAN composite (PAN/SCCP@CS-Cu). TG showed that the residual char of PAN/SCCP@CS-Cu in air and nitrogen atmosphere was as high as 16.41 % and 48.48 % at 800 °C, respectively, which were greater than that of PAN. The LOI value of PAN/SCCP@CS-Cu improved to 33.0 % and the peak heat release rate (PHRR) and total heat release (THR) of the composite were all greatly reduced. In addition, the total smoke production (TSP) of PAN/SCCP@CS-Cu decreased by 73.6 % compared to the control sample. Interestingly, the antibacterial properties of PAN/SCCP@CS-Cu against E. coli and S. aureus reached 98.45 % and 99.33 %. This work provides an insight into developing an environmentally friendly PAN composite with flame retardancy, smoke suppression and antibacterial properties, greatly expanding its application field. [ABSTRACT FROM AUTHOR]

In this work, a highly flexible bio-silica reinforced poly (benzoxazine-co-epoxy) hybrid composites have been developed using renewable cardanol based benzoxazine (C-aee), commercially available bisphenol-F epoxy (EP) and functionalized bio-silica (BS). Sustainable C-aee was synthesized with cardanol (C), aminoethoxyethanol (aee), and paraformaldehyde through Mannich condensation reaction. The structure of C-aee monomer was characterized with FT-IR and 1HNMR techniques. Bio-silica (BS) was synthesized from rice husk and functionalized with 3-mercaptopropyl trimethoxysilane (3-MPTMS). Later, the hybrid PC-aee-co-EP/BS composites was prepared with various weight percentages (0, 1, 3, and 5%) of BS reinforced into PC-aee-co-EP. The curing performance of C-aee, C-aee + EP and thermal properties of PC-aee-co-EP/BS composites was characterized using DSC and TGA. Data acquired from thermal studies confirmed that the bio-silica reinforced hybrid composite show improved thermal properties and flame-resistance properties with good flexibility. Hence, the developed PC-aee-co-EP/BS composites are potential material for various applications including marine coating, aerospace, and microelectronics. [ABSTRACT FROM AUTHOR]

In this study, a chitosan-based bioflame retardant additive (referred to as NCS) was prepared by chemically altering CS with silicon dioxide (SiO2) via an ion interchange reaction. The effect of NCS on the thermal stability and mechanical properties of vinyl ester/bamboo fiber (VE/BF) composites was studied. The composites were manufactured by a vacuum-assisted resin transfer molding (VARTM) process. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy and X-ray diffraction analysis were used to characterize the NCS. The spectral results revealed a new peak at 1560 cm−1 corresponding to NH3+–−O Si, indicative of bond between CS and SiO2. The SEM, and XRD results showed a diverse morphology (coarse surfaces) and a significant decrease in the intensity of the diffraction patterns, respectively, which further supported the formation of NCS. The heat release rate (HRR) of NCS was observed to decrease significantly by 76%, and the residual char content increased by 47% compared with CS. The flame retardant and thermal behavior of the NCS-VE/BF composites were examined by UL-94 standards, microcalorimetry, and cone calorimetry and thermogravimetric analysis (TGA). The results showed a 32% delay in burning time, a 14% enhancement in the limiting oxygen index (LOI), and an 18% decrease in the peak heat release rate (pHRR) and total heat release rate (THR) after incorporation of NCS in the VE/BF composites. The addition of NCS into the VE/BF composites also resulted in improved the mechanical properties of the composites, including the tensile, flexural and impact properties. Overall, the synthesized NCS proved to be suitable for the fabrication of sustainable flame-retardant natural fiber (NF) composites suitable for substructural parts in engineering applications without deterioration of mechanical properties. [ABSTRACT FROM AUTHOR]

To improve the flame retardant properties of polyethylene terephthalate (PET), glucose-derived carbon nanospheres (CNSs) were synthesized and introduced into PET matrix. The thermal property and flame retardancy of CNSs/PET composites were thoroughly investigated. Results showed that CNSs displayed good flame-retardant performance for PET. When blended with only 1.0 wt.% of CNSs, CNSs/PET exhibited a limiting oxygen index (LOI) of 26.3 and a vertical combustion class of V-2, and its peak-heat release rate (pk-HRR) was reduced by 41.6%. Importantly, the initial decomposition temperature and the maximum weight loss temperature of CNSs/PET were 52°C and 199°C higher than those of PET, respectively. Furthermore, a condensed phase flame-retardant mechanism appeared in CNSs/PET, which formed a dense and thermally stable protective char layer during combustion. Overall, this study disclosed the flame-retardant potential and possible mechanism of CNSs for polyesters, which would benefit the development of carbon-based materials and flame-retardant polymers.

Aimed at increasing the fire safety of polypropylene (PP), starch-based and green flame retardant (SSPM) have been prepared. Additionally, the employment of starch as bio-based char-forming materials was aimed at replacing the petroleum-based, expensive and unsustainable carbon source. Thermal degradation tests demonstrated that as-prepared SSPM possessed good thermal expansion properties with 44.7% char residue at 600 °C. When 30 phr SSPM was added to PP by melting blending process, PP composites can acquire 26.4% LOI value and UL-94 V-1 rating. Through analyzing the thermal degradation process, the promotion effect of SSPM in char-formation was obtained. Further research on char residue has initially proposed a potential flame retardant mechanism. Therefore, this paper provided a new bio-based route in replacing the petroleum-based char source for decreasing the fire risk of PP materials in actual life. [ABSTRACT FROM AUTHOR]

A series of novel intumescent flame retardant (IFR) based on melamine, neopentyl glycol, and aluminum diethylphosphinate were prepared and tested. In addition, the synergistic effect of the novel IFR and zinc borate (ZB) on the flame retardancy of LLDPE composites was investigated. The structures of novel IFR and ZB were characterized by X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The limiting oxygen index (LOI) increased from 19.3% for the pure LLDPE to 27% for the 25 wt% IFR/5 wt% ZB composites and the composites achieved the desired V‐0 rating in the UL‐94 test. Thermogravimetric analysis showed that the addition of IFR/ZB reduced the pyrolysis rate of the LLDPE composites at high temperatures and increased the amount of the char residues, and the char residue of LLDPE‐5 reached 12.1 wt% at 700°C. Cone calorimetry (CCT) data showed that the peak of total heat release, heat release rate, and fire growth index were comparatively reduced, indicating that the addition of IFR/ZB decreased the fire hazard of LLDPE composites. The formation of a compact and thermally stable char layer on the surfaces of LLDPE composites was revealed from the scanning electrone microscopy images and digital photographs of the char residue after the CCT tests. [ABSTRACT FROM AUTHOR]

A flame-retardant jute/PP composite with excellent flame retarding and mechanical properties was prepared by the surface powder spraying process. The flame-retardant layer used the green and pollution-free β-cyclodextrin as a char agent. To improve the char forming ability of β-cyclodextrin, ammonium polyphosphate (APP) and melamine (MEL) were also used as acid source and a blowing agent, respectively. The results indicated that the char forming ability of β-CD could be improved by the reaction between β-CD and APP. The composite with 20% flame retardants containing β-CD, APP and MEL (1:2:1) showed the better flame-retardant properties. The LOI value of the composite increased to 27.8%, which reached the second fire resistance according to Japan's JISD 1201-77 standard, and the self-extinguishing time reached to 37 s. Compared with pure jute/PP, the PHRR value and Av-EHC value of the composites were reduced by 50% and 21%, respectively. The carbon residual at 700 °C was increased by 10.9%. The tensile strength and bending strength were increased by 5% and 19%. These results revealed that the flame retardancy, thermal stabilities and mechanical properties of composites containing β-CD/APP/MEL system were significantly improved by the surface powder spraying method. [ABSTRACT FROM AUTHOR]

Polyolefins used in building materials and furniture require the use of flame-retardant (FR) additives to improve their fire safety. Such additives should be safe to humans and the environment, and preferably bio-based. In the present work, the FR performance of unmodified and chemically modified technical lignins was compared to that of the ammonium polyphosphate/pentaerythritol (APP/PER) intumescent system in a polypropylene (PP) matrix. Micro-scale combustion calorimetry (MCC) was used to study the peak heat release rate (PHR), temperature at PHR (TPHR), total heat release (THR) and char yield upon thermal decomposition of milligram-scale specimens. The PP/lignin composites showed up to 41% lower PHR and up to 36% lower THR compared to pure PP as well as large char residues. Based on the same parameters, especially the PP/lignin composites made with modified lignins outperformed the reference PP/APP/PER system and the PP/APP/lignin composites where unmodified lignin was used with APP. The most promising PP/lignin composites were prepared with partially demethylated/demethoxylated and depolymerised kraft lignin ('CatLignin'), modified by the Mannich reaction to a nitrogen content of 13.5%. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this work was to develop a new trispiperazido phosphate-based reactive diluent (diphosphate-piperazine hydroxyl acrylate [DPHA]) and used as a flame retardant with an epoxy acrylate (EA) in ultraviolet (UV)-curable wood coating. Design/methodology/approach: The concentration of reactive diluent was varied from 0% to 20% in the UV-curable formulation with constant photoinitiator concentration. The effect of DPHA concentration on film properties was studied by differential scanning calorimetry and thermogravimetric analysis, gel content, water absorption and limiting oxygen index. Findings: The results showed that the viscosity of the prepared formulation decreased by increasing reactive diluent (DPHA) concentration which leads to improving the coating efficiency. A high concentration of reactive diluent (DPHA) of the cured films shows good resistance against stain, mechanical and thermal properties, which results in an increased glass transition temperature (Tg) and cross-linking density of the films. Originality/value: The new trispiperazido phosphate-based reactive diluent was used in wood coating formulation, which resulted in excellent flame-retardant properties with higher cross-linked density with good stain resistance. This material can provide a wide range of application for coating industries to produce a glossy finish. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to manufacture composites from sawdust and polymer high-density polyethylene (HDPE) with different loading from alum as natural and cheap flame retardant and subsequently characterized using standard analytical tools. Design/methodology/approach: Artificial wood plastic composites (WPCs) were prepared by mixing HDPE with sawdust as a filler with constant ratio (2:1) using hot press. Polyethylene-graft-maleic anhydride (PE-g-MAH) used as a coupling agent between two parents of the composites with different ratios (2.5, 5, 7 and 10). Alum as a flame retardant was incorporated into HDPE with 5 phr polyethylene grafted with maleic anhydride (PE-g-MAH) with different ratios (10, 15 and 20). Flame retardant efficiency was investigated using differential scanning calorimetry, thermal gravimetric analysis and the technique of ASTM E162. Findings: The results revealed that the composite containing 5 phr from (PE-g-MAH) exhibited higher mechanical properties and this proved that (PE-g-MAH) act as an efficient coupling agent using the aforementioned ratio. The results also revealed that incorporation of alum as a flame retardant increased the thermal stability of the composites. Originality/value: Artificial WPCs are ecofriendly materials with a wide range of applications in the constructions field. Moreover, they have high mechanical and physical properties with low cost. Evaluate alum as a natural and cheap flame retardant. [ABSTRACT FROM AUTHOR]

Octa-N-phenylaminopropyl-POSS (Octa-NAPA-POSS), DOPO and paraformaldehyde were used to synthesize Octa-DOPO-POSS through the Kabachnik-Fields reaction. It was added into epoxy resin with different ratio to prepare a series of modified epoxy resin composites. The results proved that the addition of flame retardant Octa-DOPO-POSS significantly improved the thermal property, flame retardant performance and moisture resistance of epoxy resin without weakening the mechanical properties. When the addition amount of Octa-DOPO-POSS was 5 wt%, the LOI value of the cured EP/Octa-DOPO-POSS composite increased to 33.9%. Its UL-94 level reached V-0 rating, and the THR and PHRR were significantly reduced. Meanwhile, the flexural modulus and breaking elongation were improved. Moreover, as the adding amount increased the residual char yield of EP/Octa-DOPO-POSS composites also increased, while the maximum thermal weight loss rate gradually decreased. The real-time FTIR and SEM analysis of the char residue after high temperature pyrolysis proved that Octa-DOPO-POSS could promote the char formation and produce a denser char layer. Overall, the combination of POSS and DOPO at a molecular level rather than physical mixing has a positive and significant effect on the flame retardancy of epoxy resin. [ABSTRACT FROM AUTHOR]

The acrylic adhesives with the flame-retardant property are necessary to meet the safety requirement in electrostatic flocking. In this study, acrylic emulsion chemically modified with phosphorus and silicone, PSE, with core–shell structure, was synthesized by introducing the vinyl silicone oil and phosphor-containing monomer (PAM-100) onto the molecular chain of acrylic ester polymer in the core and shell layer, respectively. Subsequently, the silicone-acrylic adhesive with flame retardation (FR-SA) was prepared by mixing PSE with inorganic flame-retardant, Al(OH)3. The acrylic adhesive obtains the excellent flame retardation under a low addition of Al(OH)3 when the ratio of PAM-100 is 5%, while the commercial adhesive needs a high addition of the inorganic flame retardant to realize the satisfactory performance. FR-SA in this work has a great potential application as intrinsically flame-retardant electrostatic flocking adhesive. [ABSTRACT FROM AUTHOR]

A (poly) piperazine pyrophosphate (PIPP) was synthesized and its chemical structure was confirmed via Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, and 31P nuclear magnetic resonance. PIPP was used together with melamine polyphosphate (MPP) as an ammonium polyphosphate (APP)‐free intumescent flame retardant (IFR) to prepare several flame‐retardant polypropylene (FRPP) composites. The flame retardancy and burning behaviors of the composites were investigated via limiting oxygen index (LOI) determination, vertical burning tests (UL‐94), and cone calorimeter tests. The thermal properties were investigated by means of thermogravimetric analysis under nitrogen and air atmosphere. Use of PIPP and MPP together yielded an increase in the LOI value, a UL‐94 V‐0 rating, and a decrease in both the values of PHRR and THR in cone calorimetric analysis. Visual observations and scanning electronic microscopy confirmed the occurrence of char formation, which acted as a heat and fire barrier in the condense phase. [ABSTRACT FROM AUTHOR]

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.

Three commercialized flame retardants, 1,2‐bis(diphenylphosphinoyl)ethane (EDPO), 6,6‐(1,2‐phenethyl)bis‐6H‐dibenz[c,e][1,2]oxaphosphorin‐6,6‐dioxide (HTP‐6123), and hexa‐phenoxy‐cyclotriphosphazene (HPCTP), were used to prepare the flame retardant diglycidyl ether of bisphenol A (DGEBA) epoxy resin (EP) under the same experimental conditions. The effects of Tg, thermal stability, and water absorption properties of EP caused by the three flame retardants were investigated and compared, together with their flame retardant efficiency. Results showed that the introduction of the three flame retardants improved the flame retardant performance of EP but led to decreases in Tg and decomposition temperature. EDPO showed higher flame retardant efficiency than the other two flame retardants. EP/EDPO showed higher thermal stability, better flame retardant performance, higher Tg value, and lower water absorption than EP/HTP‐6123 and EP/HPCTP. The study discovered that EDPO and HTP‐6123 primarily act through the gas phase flame retardant mechanism, while HPCTP is primarily driven by the condensed phase mechanism. [ABSTRACT FROM AUTHOR]

Rigid polyurethane foam/aluminum diethylphosphinate (RUPF/ADP) composites were prepared by one-step water-blown method. Furthermore, scanning electron microscope (SEM), thermal conductivity meter, thermogravimetric analysis (TGA), limiting oxygen index, Underwriters Laboratories vertical burning test (UL-94) and microsacle combustion calorimetry were applied to investigate thermal conductivity, thermal stability, flame retardancy and combustion behavior of RPUF/ADP composites. Thermogravimetric analysis–Fourier transform infrared spectroscopy (TG–FTIR) was introduced to investigate gaseous products in degradation process of RPUF/ADP composites, while SEM and X-ray photoelectron spectroscopy were used to research char residue of the composites. It was confirmed that RPUF/ADP composites presented well cell structure with density of 53.1–59.0 kg m−3 and thermal conductivity of 0.0425–0.0468 W m−1 K−1, indicating excellent insulation performance of the composites. Flame retardant test showed that ADP significantly enhanced flame retardancy of RPUF/ADP composites, RPUF/ADP30 passed UL-94 V-1 rating with LOI of 23.0 vol%. MCC test showed that ADP could significantly decrease peak of heat release rate (PHPR) of RPUF/ADP composites. PHPR value of RPUF/ADP20 was decreased to 158 W g−1, which was 21.8% reduced compared with that of pure RPUF. TG–FTIR test revealed that the addition of ADP promoted the release of CO2, hydrocarbons and isocyanate compound in first-step degradation of RPUF matrix while inhibited the release of CO in second step degradation. Char residue analysis showed that the addition of ADP promoted polyurethane molecular chain to form aromatic and aromatic heterocyclic structure, enhancing strength and compactness of the char. This work associated a gas–solid flame retardancy mechanism with the incorporation of ADP, which presented an effective strategy for preparation of flame retardant RPUF composites. [ABSTRACT FROM AUTHOR]

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A novel flame-retardant additive, 6,6′,6″-((1,3,5-triazine-2,4,6 triyl) tris (azanediyl)) tris (dibenzo[c,e][1,2]oxaphosphinine 6-oxide) (DOPO-M), was synthesized from melamine and 9,10-dihy-dro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO). The structure of DOPO-M was characterized by Fourier transform infrared (FTIR) spectroscopy, proton (1H) and phosphorous (31P) nuclear magnetic resonance (NMR) spectroscopies, and electrospray ionization mass spectroscopy (ESI-MS). DOPO-M was blended into epoxy resin (EP) to prepare flame-retardant EPs. The flame-retardant and thermal properties of EPs cured with triethylenetetramine (TETA) were investigated by thermogravimetric analysis (TGA), the UL-94 test, and the limiting oxygen index (LOI) test. The results revealed that the epoxy thermosets exhibited excellent flame retardancy and passed the V-0 rating of the UL-94 test with an LOI of 29.3% when the phosphorus content was 2.57 wt%. The scanning electron microscopy (SEM) results showed that DOPO-M in the EP/TETA system obviously accelerated the formation of a stronger, phosphorus-rich sealing char layer to improve the flame-retardant properties of the matrix during combustion. [ABSTRACT FROM AUTHOR]

The structure, thermal stability, and mechanical properties of electrospun nanofiber mats obtained from poly(ethylene terephthalate) (PET) solutions in trifluoroacetic acid/dichloromethane were evaluated. The electrospun PET nanofibers were characterized by means of attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, limiting oxygen index, and tensile testing. PET-3-hydroxyphenylphosphinyl-propanoic acid (HPP) copolymer was used as the flame-retardant (FR) agent to improve the thermal stability and flammability of the nanofiber mats. HPP is a commercial FR for polyesters which was studied from the viewpoint of chemical reactivity and reaction mechanism. To enhance the tensile strength of the nanofiber mats, the nanofibers were collected on high-speed rotating drum. The results showed that the nanofibers were oriented, and their strength was enhanced by increasing the velocity of the collector. The average diameter of electrospun nanofibers was in the range of 110–240 nm, decreasing with the increasing drum speed. Also the mean pore size of the mats decreased significantly with increasing orientation of the nanofibers. The results showed that HPP improved the flame retardancy of PET. [ABSTRACT FROM AUTHOR]

• Powder characteristics of flame-retardant powder were investigated. • Various properties of flame-retardant laser-sintered specimens were evaluated. • Flame-retardant laser-sintered specimens attained V0 rating (2-mm thickness). The effects on powder characteristics and various properties of selective-laser-sintering (SLS) specimens when flame-retardant (FR) materials (10-wt% polypentabromobenzyl acrylate (PPBBA) and 5-wt% antimony trioxide (ATO)) were added to copolymer poly(butylene terephthalate) (cPBT) were evaluated. It was found that acting as a crystal-nucleating agent for cPBT, the ATO powder increases the crystallization temperature of cPBT. It was also found that the combustion characteristics of the powders differ according to whether or not the ATO embeds in the PPBBA. Comparing the flame-retardant IM specimens and the SLS specimens revealed that all the mechanical properties of the SLS specimens tended to be degraded because they contained more porosity than the IM specimens. On the other hand, the SLS specimens showed higher heat-deflection temperatures because they had higher crystallinity than that of the IM specimens. Comparing the various SLS specimens revealed that the specimens in which with ATO was coated on cPBT and PPBBA showed higher mechanical and thermal properties than the specimens with ATO embedded in PPBBA. Furthermore, it was confirmed that the SLS specimens attained a UL94 test rating of grade V0 (with a thickness of 2 mm). [ABSTRACT FROM AUTHOR]

A facile approach to incorporate an intramolecular 6-membered ring hydrogen bond into a benzoxazine monomer containing 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) moiety has been developed, leading to a novel monobenzoxazine, ODOPB-pa. This monobenzoxazine was successfully synthesized via a Mannich condensation from 2-(6-oxido-6 H -dibenz-[ c , e ][1,2]oxaphosphorin-1,4-dihydroxy phenylene (ODOPB), propargylamine and paraformaldehyde. The newly obtained ODOPB-pa possesses a relatively lower polymerization temperature than most commercialized benzoxazine resins. In addition, the intramolecular 6-membered ring hydrogen bond is identified as an essential feature in its polymerization behavior. The cured product, poly(ODOPB-pa) , exhibits high thermal stability with a 5% weight loss temperature of 327 °C, and good flame retardant properties with a heat release capacity value of 119 Jg−1 K−1 and a total heat release value of 41 kJg−1. Moreover, ODOPB-pa was also applied to mix in different amounts (5, 10, 15 and 20 wt%) with a tri-functional benzoxazine bearing propargyl group, TH-pa. Notably, it has been demonstrated that the TH-pa/ODOPB-pa blend derived thermoset with 10 wt% ODOPB-pa exhibits the best thermal and flame retardant properties in consideration of the high glass transition temperature (312 °C) and very low heat release capacity value (56.5 Jg−1 K−1). These combined advantages highlight the potential of intramolecular 6-membered ring hydrogen bond-containing ODOPB-based benzoxazine in the producing of high-performance thermosetting systems. [Display omitted] • A novel phosphaphenanthrene-based benzoxazine (ODOPB-pa) has been synthesized. • The intramolecular hydrogen bond in ODOPB-pa has been investigated. • The performance of a tri-functional benzoxazine can be enhanced by blending with ODOPB-pa. • The thermoset blends show excellent thermal and flame retardant properties. [ABSTRACT FROM AUTHOR]

Lyocell fabrics are widely applied in textiles, however, its high flammability increases the risk of fire. Therefore, to resolve the issue, a novel biomass-based flame retardant with phosphorus and nitrogen elements was designed and synthesized by the reaction of arginine with phosphoric acid and urea. It was then grafted onto the lyocell fabric by a dip-dry-cure technique to prepare durable flame-retardant lyocell fabric (FR-lyocell). X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analysis demonstrated that the flame retardant was successfully introduced into the lyocell sample. Thermogravimetric (TG) and Raman analyses confirmed that the modified lyocell fabric featured excellent thermal stability and significantly increased char residue. Vertical combustion results indicated that FR-lyocell before and after washing formed a complete and dense char layer. Thermogravimetric Fourier-transform infrared (TG-FTIR) analysis suggested that incombustible substances (such as H2O and CO2) were produced and played a significant fire retarding role in the gas phase. The cone calorimeter test corroborated that the peak of heat release rate (PHRR) and total heat release (THR) declined by 89.4% and 56.4%, respectively. These results indicated that the flame retardancy of the lyocell fabric was observably ameliorated.

The inherently poor flame retardancy and comparatively low tensile strength of poly(lactic acid) (PLA) have limited its wide adoption as alternative 'green' engineering plastic in many fields. This manuscript reports the synthesis of a new phosphorus flame retardant - phenylphosphonic 3(2-aminobenzothiazole) (P-TAB) and its combination with recycled short wool fibers (WF) for improving the flame retardancy and the mechanical properties of PLA. Fourier transform infrared (FTIR), 1H, and 13C nuclear magnetic resonance (NMR) spectra proved that P-TAB was effectively synthesized. Considerable reductions in heat release rate, total heat released, CO and CO2 produced were attained with 3 wt% P-TAB and various WF loadings. The fire performance index (FPI), and fire growth index (FGI) improved by 38.2 and 48.1% respectively. The composite achieved a V-0 rating at 20 wt% WF loading and an LOI value of 28.5%. TG-IR results showed substantial reductions in evolved gaseous products. The tensile strength and Young's modulus improved significantly with the increasing content of WF in the composite. [ABSTRACT FROM AUTHOR]

The flame‐retarded epoxy resin with improved thermal properties based on environmentally friendly flame retardants is vital for industrial application. Hereby, a novel reactive‐type halogen‐free flame retardant, 10‐(3‐(4‐hydroxy phenyl)‐3,4‐dihydro‐2H‐benzo[e] [1,3] oxazin‐4‐yl)‐5H‐phenophosphazinine 10‐oxide (DHA‐B) was synthesized via a two‐step reaction route. Its structure was characterized using 1H, 13C, and 31P NMR and HRMS spectra. For 4,4′‐diaminodipheny ethane (DDM) and diglycidyl ether of bisphenol A (DGEBA)‐cured systems, the epoxy resin with only 2 wt% loading of DHA‐B passed V‐0 rating of UL‐94 test. Significantly, its glass transition temperature (Tg) and initial decomposition temperature (T5%) were as high as 169.6°C and 359.6°C, respectively, which were even higher than those of the corresponding original epoxy resin. Besides, DHA‐B decreased the combustion intensity during combustion. The analysis of residues after combustion suggested that DHA‐B played an important role in the condensed phase. [ABSTRACT FROM AUTHOR]

In this study it was aimed to improve the fire retardant performance of halogen free flame-retardant polypropylene by increasing limiting oxygen index value. Ammonium polyphosphate, pentaerythritol, and ulexite were used to improve flame retardancy of polypropylene. Ulexite powder filled (1, 2, and 4 wt%) polypropylene composites were obtained by using a twin-screw extruder and injection molding method. Thermal, mechanical, and flame retardant performances of polypropylene composites were investigated by several characterization techniques. Limiting oxygen index value was obtained higher than 45% when ulexite was added into polypropylene at 1–4 wt%. It was observed that flame retardant additives do not change the mechanical properties considerably. The effect of ulexite addition on melting and crystallization temperatures of polypropylene-based composite is not pronounced. [ABSTRACT FROM AUTHOR]

Polyurethane‐imide (PUI) foams containing both polyimide and polyurethane segments combined the advantage of fine mechanical properties as well as high thermal stability of the two polymers. To further improve the thermal stability and flame resistance of PUI foams, a series of PUI composite foams with different content of SiC (silicon carbide) as fillers were prepared. The cell structure, mechanical properties, flame resistance, and thermal properties of resulting PUI/SiC composite foams were characterized in detail. The experimental results showed that the cell size distribution became uneven, the apparent density was increased, and the compressive strength decreased with the increase in silicon carbide content. Meanwhile, the limiting oxygen index (LOI) showed an increase from 24.7% to 28.1% with increasing of SiC content from 0% to 9.6%. The thermogravimetric analysis showed that the addition of SiC could significantly enhance the thermal stability and flame retardancy of PUI foams. [ABSTRACT FROM AUTHOR]

In order to improve the mechanical, thermal and flame-resistant properties of polyimide foams (PIFs), in the present study, flexible polyimide (PI)/graphite composite foams were prepared with dianhydride and isocyanate as the starting materials and graphite as the filler. The experimental results showed that most cells of PIFs possessed an open cell structure, and the open cell content decreased by graphite incorporation. While with the increase in graphite, the distribution of cellular size became uneven and the size distribution became broad. The compressive strength increased initially and then decreased and reached the maximum value of 26.4 kPa when the graphite content was 1.98 wt%, but all the composite foams exhibited higher strength than the neat PIF. In addition, the limiting oxygen index increased from 31% to 34.8% with the increase in graphite from 0 wt% to 3.25 wt%. The peak heat release rate of composite foams was 2.3% to 24.7% lower than the neat PIF and reached a minimum value of 42.36 kW m−2 with the graphite content of 1.98 wt%. Considering the above analysis, it is feasible to improve mechanical properties, thermal stability and flame-resistant properties of PIFs by graphite addition. [ABSTRACT FROM AUTHOR]

Abstract In this work we have performed a comprehensive study on synthesis, processing, detailed material characterization and preliminary assessment of toxicity of relatively new flame retardant (FR) additives as a key for developing environmentally friendly fire safe polyesters. Two 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) based FR additives were synthesized using principles of green chemistry and incorporated via thermal processing in high temperature polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). The green synthesis strategies included (i) the use of N-chlorosuccinimide as a sustainable chlorinating agent for DOPO and (ii) a solvent and catalyst free microwave-assisted synthesis. Atomistic molecular dynamics (MD) simulations were employed in order to calculate the solubility parameters of these additives so as to estimate their compatibility in the polyesters. Detailed rheological measurements of the polyester/FR blends were carried out and the results indicated a clear difference in all three additives tested. Based on these analyses, 6H-dibenz[c,e][1,2]oxaphosphorin,6-[(1-oxido-2,6,7-trioxa-1-phosphabicyclo[2.2.2]oct-4-yl)methoxy]-, 6-oxide (DOPO-PEPA) exhibited the highest compatibility with both polyesters and their blends and showed the highest thermal-oxidative stability guaranteeing stable and steady processing at high temperatures. All polyester/FR formulations exhibited higher flame retardancy compared to the virgin polyesters in the small scale fire tests. The FR additives were evaluated for their potential toxicity using a well-established in vitro platform. Our results indicate no acute cytotoxic potential for all FRs analyzed in two different cell types (the human lung epithelial cell line A549 and macrophages derived from the monocytic cell line THP-1) and under the chosen experimental conditions. Highlights • New DOPO based flame retardant (FR) additives were synthesized using principles of green chemistry. • Molecular dynamics simulations confirmed their compatibility in the polyesters. • DOPO-PEPA exhibited the highest thermal-oxidative stability and compatibility with both polyesters. • All polyester/FR formulations exhibited higher flame retardancy compared to the virgin polyesters. • Well-established in vitro experiments indicate no acute cytotoxic potential for all FRs analyzed. [ABSTRACT FROM AUTHOR]

Cellulose has attracted considerable attention as a potential substitute for plastics. However, the flammability and high thermal insulation properties of cellulose contradict the unique requirements for highly integrated and miniaturized electronics i.e., rapid thermal dissipation and efficient flame retardancy. In this work, cellulose was first phosphorylated to achieve intrinsic flame-retardant properties, and subsequently treated with MoS 2 and BN, ensuring efficient dispersion throughout the material. Via chemical crosslinking, a sandwich-like unit was formed, in the order of BN, MoS 2 , and phosphorylated cellulose nanofibers (PCNF). The sandwich-like units were further self-assembled, layer-by-layer, to successfully create BN/MoS 2 /PCNF composite films exhibiting excellent thermal conductivity and flame retardancy, and comprised a low MoS 2 and BN loading. The thermal conductivity of the BN/MoS 2 /PCNF composite film containing 5 wt% BN nanosheets was higher than that of neat PCNF film. The combustion characterization of BN/MoS 2 /PCNF composite films revealed highly desirable properties that were far more superior than the BN/MoS 2 /TCNF (TCNF, TEMPO-oxidized cellulose nanofibers) composite films. Moreover, the toxic volatiles that escaped from flaming BN/MoS 2 /PCNF composite films were significantly reduced compared to that of the BN/MoS 2 /TCNF composite film alternative. The thermal conductivity and flame retardancy of BN/MoS 2 /PCNF composite films have promising application prospects in highly integrated and eco-friendly electronics. [Display omitted] [ABSTRACT FROM AUTHOR]

The preparation of flame-retardant encapsulated electrospun core-shell fibrous membrane (ECSFM) is the key to ensure both high performance and safety of battery separator. However, there are lacks of simulation analysis on the thermal deformation behaviour of core-shell fibers, and stable, controllable, and batch preparation method of ECSFM, which makes it difficult to efficiently prepare ECSFM with higher safety. Here, the thermal deformation process of core-shell fiber was simulated to analyze the core and shell ratio with the best flame retardancy and thermal shutdown performance. The results showed that a high ratio of shell layer would make it difficult for the flame retardant in core layer to spill out in time, causing insufficient flame retardancy, while the low ratio would lead to the insufficient thermal shutdown performance of the ECSFM. The ECSFM was prepared by coaxial electrospinning with the optimal proportion of shell and core layer, in which the shell layer was polyvinylidene fluoride (PVDF) and the core layer was triphenyl phosphate (TPP), and the optimized one (TPP@PVDF) had shutdown temperature (177 °C), a membrane rupture temperature (227 °C), and a short self-extinguishing time (1.82 s), while the unoptimized one could not thermal shutdown and had longer self-extinguishing time (2.13 s). Moreover, the batch preparation of TPP@PVDF was realized by sheath focusing multi-nozzle coaxial electrospinning, the output increased by 20.33 times compared with single coaxial electrospinning, and the comprehensive performance was better than commercial battery separator. This work provides a convenient method for the rapid fabrication of safe and high-performance battery separators. [Display omitted] • Core-shell nanofibrous membrane with both flame retardancy and thermal shutdown properties. • Simulation analysis on the thermal deformation behaviour of core-shell fibers. • Sheath focusing multi-nozzle coaxial electrospinning core-shell fibers. • Stable, controllable, and batch preparation method of core-shell fibers. [ABSTRACT FROM AUTHOR]

Novel chlorinated acrylonitrile butadiene rubber (Cl‐NBR) was prepared from NBR by the alkaline hydrolysis of chloroform by using phase‐transfer catalysis. The formation of Cl‐NBR was monitored by 1H‐NMR, UV‐Vis, and Fourier transform infrared spectroscopic techniques. The percentage of chlorine attached to the rubber chain was estimated by Volhard method. The effect of polar groups on the structural and thermal properties of Cl‐NBR was analyzed by scanning electron microscopy, X‐ray diffraction analysis, differential scanning calorimetry, and thermogravimetric analysis studies. The flame retardant, oil resistance, cure behavior, and mechanical properties of chlorinated elastomer were also analyzed. The proton NMR revealed the attachment of chlorine in the backbone of NBR with new chemical shift values. The C‐Cl stretching of chlorinated NBR was confirmed from Fourier transform infrared. The UV spectrum also supported the formation of chlorinated unit in the NBR chain through the shifts and broadening of absorption peaks. The X‐ray diffraction analysis pattern indicated a decrease in the amorphous domain of NBR with an increase in the level of chemical modification. The increased glass transition temperature obtained from differential scanning calorimetry confirms the increased molecular rigidity of the chlorinated NBR and thermal transitions increased with increase in the level of chemical modification. The thermal stability of Cl‐NBR decreased with an increase in chlorine content. The flame and oil resistance of Cl‐NBR was greatly higher than pure NBR due to the increased polarity of modified rubber. The superior tensile strength of Cl‐NBR (4 times higher than pure NBR) and higher oil resistance find applications in pump diaphragms, aircraft hoses, oil‐lined tubing, and gaskets materials with the excellent flame resistant property. [ABSTRACT FROM AUTHOR]

In order to improve the flame retardancy of polystyrene (PS), a phosphorus and nitrogen comonomer, named AC2NP2, was synthesized and then incorporated into various amounts of PS by seeded emulsion polymerization. The modified methacrylate (AC2NP2) was used as the core phase, the styrene as the shell phase, then flame-retardant effect copolymers with core-shell structure were prepared successfully. The particle size was ranged from 40 to 60 nm, and the structure and properties of the copolymers were characterized in detail. Notably, despite a few amounts of the AC2NP2 units in the copolymers, all the copolymers exhibited significantly enhanced thermal stability and reduced flammability as compared with pure PS. Furthermore, from differential scanning calorimetry test, it was observed that the glass transition temperature was tinily influenced with the incorporation of commoner. The incorporation of P-N comonomer into PS backbone did not lead to negative effect on the glass transition behavior of PS. [ABSTRACT FROM AUTHOR]

An intumescent flame retardant (IFR) system was prepared by 2 ways. Firstly, bis(2,6,7-trioxa-1-phosphabicyclo[2,2,2]octane-1-oxa-4-hydroxymethyl) phosphonate methyl (bis-PM) was synthesized and characterized by 1H nuclear magnetic resonance (NMR), 31P NMR, and Fourier transform infrared spectroscopies. This carbonization agent was mixed with melamine (ME), ammonium polyphosphate (APP), and pentaerythritol (PER) to constitute an IFR system. Secondly, an IFR system by reaction was prepared by reaction, and the presence of compositions in product was confirmed by 1H NMR and Fourier transform infrared. Both of systems enhanced the flammable retardation of ethylene vinyl acetate (EVA) and polypropylene (PP). Flammability and thermal behaviors of IFR-EVA and IFR-PP were investigated by vertical burning test (UL-94 V) and thermogravimetric analysis. Results indicated that the IFR systems performed excellent flame retardancy and antidripping ability for PP. At 30 wt% loading, the optimum flame retardant formulations that are bis-PM/ME: 4/1, bis-PM/ME/PER: 3/1/1, APP/ME/PER: 3/1/1, and bis-PM/ME/PER/APP: 1.5/1.5/1/1 give UL-94 V-0 rating. However, V-0 rating results were only obtained for EVA when systems contain bis-PM/ME: 4/1 and bis-PM/ME/PER: 3/1/1. The char yield from decomposition of the IFR-EVA and IFR-PP has effects on the flame retardancy and antidripping behaviors of EVA and PP. [ABSTRACT FROM AUTHOR]

The effect of zinc borate (ZnB) was studied on the flame retardant and thermal properties of thermoplastic polyurethane containing huntite-hydromagnesite. The flame retardant properties of thermoplastic polyurethane-based composites were investigated using limiting oxygen index, vertical burning test (UL 94), thermogravimetric analysis, and mass loss calorimeter. No remarkable effect of ZnB was observed on the flammability properties of composites. UL 94 rating did not change regardless of the added amount of ZnB, and the slight increase in limiting oxygen index value was observed at ratio of 1:1. The adjuvant effect of ZnB was observed during the mass loss calorimeter studies by increasing the barrier effect of the residue in the condensed phase and by increasing the formation of incombustible gasses in the gas phase. The highest fire performance was achieved at ratio of 1:1. [ABSTRACT FROM AUTHOR]

Flame retardant viscose fibers of different contents of chemical fire retardant were prepared and the thermal properties, structures, LOI and mechanical properties of flame retardant viscose fibers were tested to study influences of different chemical fire retardant content for structures and properties of flame retardant viscose fibers. Research showed that the crystal structure of flame retardant viscose fibers were still kept the cellulose fiber cellulose II whether chemical fire retardant addition or not. However, the properties of thermal and flame retardation were both increased with contents of chemical fire retardant rising except the mechanical properties. It was believed that the properties of flame retardant viscose fibers were optimum as contents of chemical fire retardant between 5% and 25% by using this kind chemical fire retardant which was made in laboratory. [ABSTRACT FROM AUTHOR]

The effects of sepiolite on fire behavior of ammonium polyphosphate-based intumescent flame retardant (IFR)/polypropylene (PP) were investigated. The disaggregation of sepiolite bundles has been provided by wet-milling as the zeta potential value decreased from - 9.6 to - 31.3 mV. PP and additives were compounded by a twin-screw extruder and molded by injection. A total additive content of 20 wt% in PP and various proportions of sepiolite (1.0-10.0 wt%) in flame retardant (FR) formulation were studied. The flammability of the samples was measured by limit oxygen index (LOI) test and cone calorimetry. The LOI of neat PP (19%) was increased to 32.2% when sepiolite and IFR were used. The peak heat release rate of neat PP (1566.4 kW/m2) was also significantly reduced (94.7 kW/m2) when sepiolite was added with IFR. Thermal analyses results showed that, at higher temperature (700°C), IFR and sepiolite increased the char residue (9 wt%) compared to neat PP (0 wt%). [ABSTRACT FROM AUTHOR]