Search

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]

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.

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]

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]

Thermal and flame-retardant properties of traditional composites have limitations that are not satisfied for the various applications. Multilayered materials have great potential to improve material properties. The present paper focused on designing new multilayering approach to fabricate flame retardant multilayered materials with a very basic instrument and several simple steps. Montmorillonite nanoparticles filled maleic anhydride grafted polypropylene composites were prepared by the melt-blending method, and the multilayered composites with polypropylene alternating multilayers were fabricated by the quadruple-layering approach. The multilayer structure was characterized by the scanning electron microscopy/energy dispersive spectrometer. The influence of layer structure on the thermal stability, thermal conductivity and flame-retardant properties was investigated by the comparison with the conventional composites. Multilayered composites showed enhanced flame-retardant properties with lower peak heat release rate and better char formation compared to conventional composites with the same mass fraction of montmorillonite. Multilayered composites had higher mass fraction of montmorillonite in filled layers and no fillers in other layers, which caused the unequal distribution of montmorillonite, resulting in changes of thermal and flame-retardant properties of the materials especially in the perpendicular direction to the film surface. This study demonstrates a unique multilayering approach that has potential to be used in variety applications such as food and medical packaging. [ABSTRACT FROM AUTHOR]

• Spherical nickel hydroxystannate (NHS) was prepared by a simple co-precipitation method. • When compared with PP/2PER, the total heat release and total smoke production of PP/2PER/28EG/2NHS were reduced by 87% and 99%, respectively. • The effects of PER, EG, NHS, 2PER/30EG, 2PER/30NHS, 2PER/28EG/2NHS on the thermal degradation properties of PP were studied by the calculated and experimental TG and DTG curves systematically. Spherical nickel hydroxystannate (NiSn(OH) 6 , NHS) particles were successfully prepared by a simple co-precipitation method and added into polypropylene (PP) matrix together with pentaerythritol (PER) and expandable graphite (EG). The flame-retardant, smoke suppressant and thermal degradation properties of PP composites were studied systematically. The results showed that the PP composite with 2phr PER, 28 phr EG and 2 phr NHS (PP/2PER/28EG/2NHS) passed the UL-94 V-0 level, and its total heat release and total smoke production were reduced by 87% and 99% when compared with those of the PP/2PER composite, and reduced by 30% and 67% when compared with those of the PP/2PER/30EG sample. The char residue of PP/2PER/28EG/2NHS composite is composed of the hexagonal Chaoite, rhombohedral graphite, SnO 2 and a little NiO. 2 phr PER has no effect on promoting the char formation of PP; 30phr NHS could accelerate the decomposition and decrease the char formation of PP; 30phr EG could suppress the decomposition and promote the char formation of PP; 2PER/28EG/2NHS could promote the early thermal degradation, slow down the thermal degradation velocity of PP and results in a higher char formation. [ABSTRACT FROM AUTHOR]

The use of metal-free click reactions for the design and synthesis of novel flame retardant reactive monomers for thiol-ene photopolymerization is an intriguing area of research. In this study, we have prepared a new, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based, P- and N-containing reactive flame retardant via the metal-free azide-alkyne click reaction. For this purpose, first, azide-functionalized DOPO (DOPO-N 3) has been synthesized via Atherton–Todd reaction, and then this compound has been reacted with acetylene dicarboxylic acid diallyl ester (ACDAE) to give the flame retardant monomer, namely DOPO-triazole diallyl ester (DTDAE). As prepared flame retardant monomer was characterized by nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy (FTIR) spectroscopies. Thermoset materials prepared by using DTDAE displayed over 90% gel content values. Polar triazole and phosphorous units rendered the surface of the thermosets hydrophilic. The thermal stability of the networks was enhanced, char yields increased and the glass transition temperatures (T g s) were increased. The limiting oxygen index (LOI) values of the crosslinked materials increased up to 27.8% as the DTDAE content was increased in the formulations. The synthetic method described in this study provides a practical approach for the synthesis of a P- and N-containing flame retardant through a metal-free azide-alkyne click reaction Also, the fact that DTDAE is in a liquid state makes this study valuable as it indicates that it can be easily dispersed. It is also believed this promising compound can be used in different polymer structures and formulations to develop new flame retardants in future studies to be applied in industrial applications. [Display omitted] • A liquid reactive flame retardant monomer; DTDAE was synthesized. • DTDAE was prepared via the metal-free azide-alkyne click reaction. • DTDAE was used for the preparation of thiol-ene photocured thermosets. • DTDAE improved the thermal stability of the thermosets. • The LOI value of the thermosets was increased up to 27.8%. [ABSTRACT FROM AUTHOR]

• High P-T method is proved to be the simplest for ZnCO 3 synthesis. • The crystal structure of impurity-free ZnCO3 was determined by single crystal X-ray diffraction. • Accurate thermal expansion of ZnCO 3 was quantified by single crystal X-ray diffraction at different temperatures. Carbonate materials have been increasingly favoured in terms of the development of flame retardants because of the eternal subject of inorganic carbon sequestration. In this regard, anhydrous zinc carbonate (ZnCO 3) has been deemed as suitable candidate thanks to its excellent flame retardancy compared to traditional hydroxid flame retardant. However, the single crystals growth, accurate characterizations of structural and thermal properties are still not entirely clear from previous studies. With this in mind, ZnCO 3 single crystals were synthesized under high-pressure-temperature conditions (high P-T; 3 GPa and 973 K). The crystal structure of impurity-free ZnCO 3 was determined by means of single crystal X-ray diffraction (XRD). The symmetry was identified as R 3 ¯ c , while the unit cell parameters were a= 4.6463(3) Å and c= 15.0015(11) Å with a final R value of 0.0229. The quantitative analyses of Raman spectrum and infrared absorption indicate that the as-synthesized ZnCO 3 is anhydrous phase. Using Thermogravimetric (TG) / Differential Scanning Calorimeter (DSC) measurements, ZnCO 3 was decomposed in the temperature range of 593–773 K, whereas the heat capacity and the endothermic peak were determined. According to the single crystal XRD from 150 K to 383 K, the thermal expansion coefficients were quantified as α a = 7.90 × 10−6 K−1 and α c = 22.8 × 10–6 K−1, as well as α Vunit cell = 38.8 × 10–6 K−1. These findings provide a precise characterisation and obtain important thermal parameters for the evaluation of its flame retardant properties. [ABSTRACT FROM AUTHOR]

This work is devoted to the influence of phosphazene modifiers with different substituents on the curing process, thermal properties and flammability of benzoxazine resin. Novel catalysts with m-toluidine substituents were introduced. The catalytic activity of studied phosphazene compounds decreased in the row: hexachlorocyclotriphosphazene (HCP) > tetra m-toluidine substituted phosphazene PN-mt (4) > hexa m-toluidine substituted phosphazene PN-mt (6) > hexaphenoxycyclotriphosphazene (HPP), where HPP is totally inactive. Two types of catalysis: basic and acid were proposed. A brief study of resulting properties of polybenzoxazines was presented. The addition of any studied modifier caused the decrease of glass transition temperature and thermal stability of polymers. The morphology of cured compositions was characterized by matrix-dispersion phase structure. All phosphazene containing polybenzoxazines demonstrated the improved flame resistance. [ABSTRACT FROM AUTHOR]