Synergistic flame‐retardant effect of halloysite nanotubes on intumescent flame retardant in LDPE

Synergistic flame‐retardant effect of halloysite nanotubes (HNTs) on an intumescent flame retardant (IFR) in low‐density polyethylene (LDPE) was investigated by limited oxygen index (LOI), vertical burning test (UL‐94), thermogravimetric analysis (TGA), cone calorimeter (CC) test, and scanning electronic microscopy (SEM). The results of LOI and UL‐94 tests indicated that the addition of HNTs could dramatically increase the LOI value of LDPE/IFR in the case that the mass ratio of HNTs to IFR was 2/28 at 30 wt % of total flame retardant. Moreover, in this case the prepared samples could pass the V‐0 rating in UL‐94 tests. CC tests results showed that, for LDPE/IFR, both the heat release rate and the total heat release significantly decreased because of the incorporation of 2 wt % of HNTs. SEM observations directly approved that HNTs could promote the formation of more continuous and compact intumescent char layer in LDPE/IFR. TGA results demonstrated that the residue of LDPE/IFR containing 2 wt % of HNTs was obviously more than that of LDPE/IFR at the same total flame retardant of 30 wt % at 700°C under an air atmosphere, and its maximum decomposing rate was also lower than that of LDPE/IFR, suggesting that HNTs facilitated the charring of LDPE/IFR and its thermal stability at high temperature in this case. Both TGA and SEM results interpreted the mechanism on the synergistic effect of HNTs on IFR in LDPE, which is that the migration of HNTs to the surface during the combustion process led to the formation of a more compact barrier, resulting in the promotion of flame retardancy of LDPE/IFR. In addition, the mechanical properties of LDPE/IFR/HNTs systems were studied, the results showed that the addition of 0.5–2 wt % of HNTs could increase the tensile strength and the elongation at break of LDPE/IFR simultaneously. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40065.     

Synergistic effect of intumescent flame retardant and zinc borate on linear low-density polyethylene

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.     

Halogen‐free intumescent flame‐retardant ethylene‐vinyl acetate copolymer system based on organic montmorillonite and graphene nanosheets

Halogen‐containing flame retardants are not preferred for environmental reasons. Herein, a halogen‐free intumescent flame‐retardant ethylene‐vinyl acetate copolymer (EVA/IFR) system containing organic montmorillonite (OMMT) and graphene nanosheets (GNSs) is fabricated with well dispersion structure, enhanced thermal‐oxidative resistance at high temperature. Interestingly, the amount of residual chars from thermogravimetric analysis is increased to 12.7 wt % at 700 °C, the EVA/IFR composite containing both OMMT and GNSs exhibits the best flame retardancy with the lowest peak heat release rate value of 529.58 kW m^?2, and the highest limited oxygen index value of 24.8%. The excellent flame retardancy is attributed to the formation of complete and compact protective char layer. Furthermore, the decreases of the mechanical properties caused by the addition of IFR are relieved and a high volume resistivity is maintained when combining OMMT and GNSs in the EVA/IFR system together. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46361.     

Reactive,intumescent, halogen‐free flame retardant for polypropylene

A reactive, intumescent, halogen‐free flame retardant, 2‐({9‐[(4,6‐diamino‐1,3,5‐triazin‐2‐yl)amino]‐3,9‐dioxido‐2,4,8,10‐tetraoxa‐3,9‐diphosphaspiro[5.5]undecan‐3‐yl}oxy)ethyl methacrylate (EADP), was synthesized through a simple three‐step reaction from phosphorus oxychloride, pentaerythritol, hydroxyethyl methacrylate, and melamine. EADP exhibited excellent thermal stability and char‐forming ability, as revealed by thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The TGA results show that the temperature at 5% weight loss was 297.8°C and the char yield at 700°C was 51.75%. SEM observation revealed that the char showed a continuous and compact surface and a cellular inner structure with different sizes. Composite of polypropylene (PP) with a 25 wt % addition of EADP (PP/EADP25) passed the UL‐94 V‐0 rating and showed a limiting oxygen index value of 31.5. Compared with those of neat PP, the flexural strength and modulus values of PP/EADP25 were somewhat improved, the tensile strength was basically unchanged, and the notched Izod impact strength was slightly decreased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40054.     

硼酸锌在膨胀型无卤阻燃ABS中的协同作用

采用熔融共混法制备了丙烯腈-丁二烯-苯乙烯共聚物(ABS)/膨胀型阻燃剂(IFR)/硼酸锌(ZB)无卤阻燃复合材料。利用热重分析仪、氧指数测定仪、扫描电子显微镜等研究了ZB对复合材料热失重行为、阻燃性能、微观结构及力学、加工性能的影响。较低含量的ZB与IFR存在较好的阻燃协同作用,且ZB可促进IFR成炭,使ABS/IFR复合材料的氧指数及其残炭量分别由未加ZB时的27.4%、21.29%提高到30.1%和23.05%。ZB的加入能够提高ABS/IFR复合材料的弯曲性能和加工性能,但对复合材料的冲击、拉伸性能产生了不利影响。     

Synergistic flame retardant effect of piperazine salt and ammonium polyphosphate as intumescent flame retardant system for polypropylene

Amino trimethylene phosphonic acid piperazine (ATPIP) salt, as a novel charring agent, is prepared via a simple ionic reaction in distilled water using amino trimethylene phosphate (ATMP) and piperazine as raw materials. The synergistic flame retardant effect of ATPIP and ammonium polyphosphate (APP) as an intumescent flame retardant (IFR) is investigated by various characterization and testing methods. The results show that the polypropylene (PP)/modified APP with piperazine (MAPP)/ATPIP ternary blend passes UL-94 V-0 rating and achieve a limiting oxygen index (LOI) of 30% at a loading level of 25 wt% IFR (MAPP:ATPIP = 3:1). Meanwhile, the total smoke production (TSP) value of IFR-PP samples is 3.3 m², which decreases by 93.2% compared with that of pure PP, exhibiting excellent smoke suppression performance. Besides, the analysis of gaseous pyrolysis products and char residue indicates that the IFR-PP samples show a synergistic flame-retardant mechanism including the gas phase and the condensed phase.     

Synergistic flame retardant effect of cerium oxide in ethylene‐vinyl acetate/aluminum hydroxide blends

The flammability characterization and synergistic flame retardant effect of cerium oxide (CeO₂) in the ethylene‐vinyl acetate/aluminum hydroxide blends were studied using limiting oxygen index (LOI), UL‐94 test, and cone calorimeter test (CCT). The results showed that the addition of a given amount of CeO₂ apparently increased the LOI value and UL‐94 rating. The data obtained from the CCT indicated that the addition of CeO₂ greatly decreased the heat release rate and prolonged the combustion time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synergistic effect of mesoporous silica SBA‐15 on intumescent flame‐retardant polypropylene

Mesoporous silica SBA‐15 synthesized from Pluronic P123 and tetraethoxysilane was used as a synergistic agent on the flame retardancy of polypropylene (PP)/intumescent flame‐retardant (IFR) system. Limiting oxygen index (LOI), UL‐94 rating and thermogravimetric analysis were used to evaluate the synergistic effect of SBA‐15 on PP/IFR system. It showed that PP/IFR system could reach V‐0 with loading of SBA‐15 ranging from 0.5 to 3 wt%, while without SBA‐15 it had no rating at UL‐94 test. The LOI value increased from 25.5 to 32.2 when the loading of SBA‐15 was 1 wt%. The thermal stability of PP/IFR was improved in the presence of SBA‐15 and the amount of the char residue at 600° C was increased from 8.96 to 16.42 wt% when loading of SBA‐15 varied from 0.5 to 5 wt%. Laser Raman spectroscopy (LRS) and scanning electron microscopy were employed to study the morphology of the char residue of PP/IFR system with and without SBA‐15. Copyright © 2010 John Wiley & Sons, Ltd.     

Mechanical,thermal and combustion properties of intumescent flame retardant biodegradable poly (lactic acid) composites

ABSTRACT

Despite extraordinary mechanical properties and excellent biodegradability, poly (lactic acid) (PLA) still suffers from a highly inherent flammability, restricting its applications in the electric and automobile fields. Although a wide range of flame retardants have been developed to reduce the flammability, they normally compromise the mechanical strength of PLA. In this study, a series of composites based on PLA, have been prepared by melt-blending with intumescent flame retardants (IFRs). The morphology, thermal stability and burning behaviour of the composites were investigated using a scanning electron microscope–energy dispersive spectrometer (SEM–EDS), thermogravimetric analysis (TGA), the limiting oxygen index (LOI), vertical burning (UL-94) and the cone calorimeter test (CCT). The LOI value reached 38.5% and UL-94 could pass V-0 for the PLA/IFR composite containing only 12 wt-% IFR. The dispersion of IFR in PLA was observed using SEM–EDS. A significant improvement in fire retardant performance was observed for the PLA/IFR composite from the CCT (reducing the heat release rate and the total heat release). More importantly, compared to pure PLA, the addition of IFR did not seriously deteriorate the mechanical properties of the material.     

Linking the flame‐retardant mechanisms of an ethylene‐acrylate copolymer,chalk and silicone elastomer system with its intumescent behaviour

In this paper the flame‐retardant mechanisms of a flame‐retardant system consisting of ethylene‐acrylate copolymer, chalk and silicone elastomer are linked to its foaming process and to its formation of a final intumescent structure. Thermocouples were placed inside and at the surface of cone calorimeter test specimens in order to measure the temperature at different depths during the formation of the intumescent structure. The temperature and visual observations of the foaming process were then linked to chemical reactions seen with thermogravimetric analysis and also coupled with earlier knowledge of the flame‐retardant mechanism. A correlation is seen between the chemical reactions, the temperature (inside and at the surface of a cone calorimeter test specimen) as measured by thermocouples and visual observations in the intumescent process. Further, the outcome of this study provides useful information for achieving a deeper understanding of the flame‐retardant mechanisms of the ethylene‐acrylate copolymer, chalk and silicone elastomer system. Copyright © 2005 John Wiley & Sons, Ltd.     

Synergistic effects of fumed silica on intumescent flame‐retardant polypropylene

The synergistic effects of fumed silica on the thermal and flame‐retardant properties of intumescent flame retardant (IFR) polypropylene based on the NP phosphorus‐nitrogen compound have been studied by Fourier transfer infrared (FTIR) spectroscopy, cone calorimeter test (CCT), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), limiting oxygen index (LOI), and UL‐94 tests. The LOI and UL‐94 data show that when ≤1 wt % fumed silica substituted for the IFR additive NP can increase 2 to 4% LOI values of the PP blends and keep the V‐0 rating. The data obtained from the CCT tests indicate the heat release rates (HRR) reduce by about 23% for the PP/NP sample with 0.5 wt % fumed silica, whereas the mass loss rates (MLR) and total heat release (THR) values are much lower than those of the PP/NP samples without fume silica. The TGA data demonstrate that a suitable amount of fumed silica can increase the thermal stability and charred residue of the PP/IFR/SiO₂ blends after 500°C. The morphological structures of charred residues observed by SEM give positive evidence that a suitable amount of fumed silica can promote the formation of compact intumescent charred layers and prevent the charred layers from cracking, which effectively protects the underlying polymer from burning. The dynamic FTIR spectra reveal that the synergistic flame‐retardant mechanism of a suitable amount of fumed silica with IFR additive is due to its physical process in the condensed phases. However, a high loading of fumed silica restricts the formation of charred layers with P? O? P and P? O? C complexes formed from burning of polymer materials and destroys the swelling behavior of intumescent charred layers, which deteriorates the flame retardant and thermal properties of the PP/IFR blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Optimization of intumescent flame retardant system based on ammonium polyphosphate,double pentaerythritol,and zinc borate for thermoplastic polyurethane composite

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.     

Synergistic effect of THEIC‐Based charring agent on flame retardant properties of polylactide

A novel charring agent tris(2‐hydrooxyethyl) isocyanurate terephthalic acid ester, tetramer (TT4) was synthesized using tris(2‐hydrooxyethyl) isocyanurate and terephthalic acid as raw materials, and it was characterized by Fourier transformed infrared spectrometry and ¹H‐NMR spectrum. It was combined with ammonium polyphosphate (APP) to form intumescent flame retardants for polylactide (PLA). The combustion properties and thermal stability of PLA/APP/TT4 composites were evaluated by UL‐94 burning tests, limiting oxygen index (LOI), and thermogravimetric analyses (TGA). It was found PLA with 30 wt % of APP/TT4 (5 : 1) achieved UL‐94 V‐0 rating and a 40.6 LOI value. Results from TGA demonstrated that APP/TT4 composites could retard the degradation of PLA above 410°C. The char residue at 500°C is higher than 24%, showing a good char forming ability. Moreover, the continuous and expansionary char layer observed from the SEM images proved good charring forming ability of TT4. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41218.     

膨胀型阻燃剂在橡胶中的应用

介绍了膨胀型阻燃剂的组成及功能改进,总结了膨胀型阻燃剂在天然橡胶、三元乙丙橡胶、丁苯橡胶及氯丁橡胶中的应用进展,并对膨胀型阻燃剂的发展方向做了展望。     

Synergistic effects of molybdenum disulfide on a novel intumescent flame retardant polyformaldehyde system

A novel intumescent flame retardant (IFR) composed of ammonium polyphosphate (APP), benzoxazine containing trialkoxysilane (BA-a-Si) and melamine (ME), is compounded with different specifications of MoS₂ as synergist to flame retard polyformaldehyde (POM). The flame retardancy and mechanism of the composites are analyzed by limiting oxygen index (LOI), vertical combustion (UL-94) and cone calorimeter. At the same time, the mechanical properties and lubricating properties are tested by electromechanical testing machine and wear testing machine. The experimental results show that MoS₂ has a good synergistic effect with IFR, and the smaller the average particle size of MoS₂ is, it seems to be more beneficial to improve the flame retardancy of POM composites. Only a small amount of MoS₂ (0.8 wt%) is needed to synergize with IFR, the flame retardant POM composite (FR-POM) can achieve UL-94 (3.2 mm) V-0 rating, LOI of 62.5%, and heat release rate reduction of 25.3%, total smoke release decreased by 29.5%. In addition, from the mechanical properties analysis, it is found that the microscale MoS₂(M2) can better improve the bending and tensile properties of the FR-POM composites, while the nanoscale MoS₂(N80) is more helpful to improve the lubricating properties.     

Thermal degradation and combustion behavior of intumescent flame‐retardant polypropylene with novel phosphorus‐based flame retardants

The objective of this study was to develop an environmentally friendly fire‐retardant polypropylene (PP) with significantly improved fire‐retardancy performance with a novel flame‐retardant (FR) system. The system was composed of ammonium polyphosphate (APP), melamine (MEL), and novel phosphorus‐based FRs. Because of the synergistic FR effects among the three FRs, the FR PP composites achieved a V‐0 classification, and the limiting oxygen index reached as high as 36.5%. In the cone calorimeter test, both the peak heat‐release rate (pHRR) and total heat release (THR) of the FR PP composites were remarkably reduced by the incorporation of the novel FR system. The FR mechanism of the MEL–APP–FR–PP composites was investigated through thermogravimetric analysis and char residue characterization, and the results reveal that the addition of MEL–APP–FRs promoted the formation of stable intumescent char layers. This led to the reduction of pHRR and THR and resulted in the improvement of the fire retardancy. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45962.     

Study on flame‐retardancy and thermal degradation behaviors of intumescent flame‐retardant polylactide systems

Two intumescent flame‐retardant (IFR) additives, IFR‐I and IFR‐II, were synthesized and their structure was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance. Polylactide (PLA) was modified by the two IFRs to obtain flame‐retardant composites. The flammability of the PLA/IFR composites was characterized by the vertical burning test UL‐94 and limiting oxygen index. The limiting oxygen index values of the PLA composites increased with increase of IFR content. The PLA composite with 20 wt% IFR‐I could pass the UL‐94 V0 rating, while the composite with 30 wt% IFR‐II could not. The results of pyrolysis combustion flow calorimetry showed that the heat release capacity of PLA composites with 30 wt% IFR‐I decreased 43.1% compared with that of pure PLA. The thermal degradation and gas products of PLA/IFR‐I systems were monitored by thermogravimetric analysis and thermogravimetric analysis infrared spectrometry. Scanning electron microscopy was used to investigate the surface morphology of the char residue. Copyright © 2011 Society of Chemical Industry     

Thermal property improvement of ethylene‐octene copolymer through the combined introduction of filler and silane crosslink

In many applications, e.g., wire and cable insulation, hot water pipe, high‐temperature properties of polymer are essential. This article presents the use of silane crosslinking together with the addition of particular filler in improving the thermal and mechanical properties of ethylene‐octene copolymer (EOC). The effects of filler surface characteristics on siloxane network structure developed and final properties of the crosslinked products are discussed. The results show an increase in the decomposition temperature of EOC more than 50°C after modification. Only crosslinked composites are able to withstand the high‐temperature environment of aging test which is beyond the melting temperature of the matrix polymer. The crosslinked composites filled with calcium carbonate show superior properties to those with silica, due to a higher crosslink density and tighter network structure formed. The silane coupling mechanism and the presence of bound polymer on silica surfaces cause difficulties for the crosslink formation in the silica filled systems. However, an advantageous influence of both silane coupling and crosslink reaction in the silica filled composites is seen on the enhanced tensile strength and modulus of the materials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermal and flame retardant properties of ethylene‐vinyl acetate copolymer/modified multiwalled carbon nanotube composites

The synthesized flame retardant 9,10‐dihydro‐9‐oxa‐10‐phosphaphanthrene‐10‐oxide/vinyl methyl dimethoxysilane (DV) was used to modify multiwalled carbon nanotubes (MWNTs). The results of FTIR, ¹H‐NMR, and TGA measurements show that DV has been covalently grafted onto the surfaces of MWNTs, and the MWNTs‐g‐DV is obtained successfully. Transmission electron microscopy images show that a core‐shell nanostructure appears with MWNTs as the core and the DV thin layers as the shell, and the modified MWNTs with DV can achieve better dispersion than unmodified MWNTs in EVM matrix. Thermogravimetric analysis and cone calorimeter tests indicate that the thermal stability and flame retardant are improved for the presence of the MWNTs in EVM matrix. Moreover, the improvement is more evident for EVM/MWNTs‐g‐DV composite compared to unmodified MWNTs‐based composite, which can be attributed to the better dispersion of the DV‐modified MWNTs and to the chemical structure of the combustion residue. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

膨胀型阻燃剂在聚丙烯中的应用研究

使用磷酸、季戊四醇、三聚氰胺合成了一种膨胀型阻燃剂。采用热重分析（TGA）、红外光谱分析（FTIR）、氧指数晨6定和垂直燃烧实验，研究了所合成的膨胀型阻燃剂对聚丙烯的阻燃作用。与普通的膨胀型阻燃剂和包覆型膨胀阻燃剂的对比研究表明，该阻燃剂对聚．丙烯的阻燃性能优良，达到相同的阻燃效果（聚丙烯氧指数达到34％）时，用量较其它两种膨胀型阻燃剂明显减少。抗析出和防湖性能较其它两种膨胀型阻燃剂也有明显改善。