Moisture Resistance,Thermal Stability and Fire Behavior of Unsaturated Polyester Resin Modified with L-histidinium Dihydrogen Phosphate-Phosphoric Acid

In this paper, the fire behavior of unsaturated polyester resin (UP) modified with L-histidinium dihydrogen phosphate-phosphoric acid (LHP), being a novel intumescent fire retardant (IFR), was investigated. Thermal and thermomechanical properties of the UP with different amounts of LHP (from 10 to 30 wt. %) were determined by thermogravimetric analysis (TG) as well as dynamic mechanical thermal analysis (DMTA). Reaction to small flames was studied by horizontal burning (HB) test, while fire behavior and smoke emission were investigated with the cone calorimeter (CC) and smoke density chamber. Further, the analysis of volatile products was conducted (TGA/FT-IR). It was observed that the addition of LHP resulted in the formation of carbonaceous char inhibiting the thermal decomposition, burning rate and smoke emission. The most promising results were obtained for the UP containing 30 wt. % of LHP, for which the highest reduction in maximum values of heat release rate (200 kW/m²) and total smoke release (3535 m²/m²) compared to unmodified polymer (792 kW/m² and 6895 m²/m²) were recorded. However, some important disadvantage with respect to water resistance was observed.     

Modified montmorillonite combined with intumescent flame retardants on the flame retardancy and thermal stability properties of unsaturated polyester resins

Modified montmorillonite‐containing phytic acid (PA‐MMT) has been prepared by acid treatment and then introduced into unsaturated polyester resin (UPR) with an intumescent flame retardant (IFRs). The flame retardancy and thermal degradation of UPR/IFRs/PA‐MMT were evaluated by a limiting oxygen index (LOI) test, a vertical burning test (UL‐94), a thermogravimetric analysis (TGA), and a cone calorimeter test (CCT). Besides, the mechanical properties were studied by a universal testing machine. The LOI value of UPR/IFRs/PA‐MMT composites was increased to 29.2%. The CCT results indicated that the incorporation of PA‐MMT and IFRs significantly improved the combustion behavior of UPR. The results of the mechanical properties indicated that 1.5 wt% loading of PA‐MMT in UPR/IFRs showed the highest improvement in flexural strength and tensile strength. The flame‐retardant mechanism of PA‐MMT/IFRs was examined and discussed based on the results of combustion behavior and char analysis.     

A review of candidate fire retardants for polyisoprene

Polyisoprene elastomer, as natural rubber (NR) or manufactured synthetically (IR), is used in rubber compounds for applications such as tyres, dampers and suspension elements. NR/IR compounds without fire retardants have a low resistance to burning, and emit large quantities of dense smoke. This is because polyisoprene readily decomposes upon heating, by random chain scission, vaporising into a mixture of small aromatic chemical species, which ignite readily and form smoke particles with negligible char residue formation. The effects of commonly used additives on the thermal decomposition and burning of polyisoprene are reviewed; whilst cross-linking agents have significant effects on physical and ageing properties, they have little effect on thermal decomposition and burning. Fillers such as carbon black and silicas reduce the fuel content by dilution of the polymer and the formation of a stabilising residue.Potential approaches for fire retarding IR are reviewed, identifying two main approaches; halogenated additives, or high loadings of aluminium hydroxide (ATH), neither of which are satisfactory. Other potential approaches are identified, including the use of phosphorus and nitrogen based additives as intumescent char formers, and with zeolites as char catalysts. Alternative inorganic fire retardants to ATH are identified for use, and zinc hydroxystannate and zinc borate are considered as synergists with ATH. Expandable graphite (EG) is identified for use in other elastomers and has potential for polyisoprene. Nano-scale fire retardants such as montmorillonite clay and multi-walled carbon nanotubes are reported typically as a secondary additive to hydrated fillers, but have yet to make a successful transition to industrial processing.     

Effects of kaolin on the thermal stability and flame retardancy of polypropylene composite

Kaolin clay was introduced into an intumescent flame retardant (IFR) system containing ammonium polyphosphate as an acid source and pentaerythritol as a carbonization agent in order to improve the thermal stability and flame retardancy of polypropylene (PP) composite. The flame retardancy and smoke suppression was evaluated by the limiting oxygen index, vertical burning UL‐94, and cone calorimeter (CONE) tests. The limiting oxygen index value was increased from 30 to 33 at the presence of 2 phr kaolin. The peak heat release rate value decreased from 1002 kW/m² of neat PP to 318 kW/m² of PP/40 phr IFR and then to 222 kW/m² of PP/38 phr IFR/2 phr kaolin. The time of the peak heat release rate was significantly prolonged after the introduction of kaolin. The morphology of char after combustion was characterized by a scanning electron microscope, and it revealed more compact char structure that was obtained at the presence of kaolin. The mechanism of kaolin on improving the retardancy and smoke suppression of PP/IFR composite was proposed on the basis of X‐ray photoelectron spectroscopy analysis. Copyright © 2014 John Wiley & Sons, Ltd.     

A liquid phosphorous flame retardant combined with expandable graphite or melamine in flexible polyurethane foam

A systematic series of flexible polyurethane foams (FPUF) with different concentrations of flame retardants, bis([dimethoxyphosphoryl]methyl) phenyl phosphate (BDMPP), and melamine (MA) or expandable graphite (EG) was prepared. The mechanical properties of the FPUFs were evaluated by a universal testing machine. The pyrolysis behaviors and the evolved gas analysis were done by thermogravimetric analysis (TGA) and TGA coupled with Fourier-transform infrared (TG-FTIR), respectively. The fire behaviors were studied by limiting oxygen index (LOI), UL 94 test for horizontal burning of cellular materials (UL 94 HBF), and cone calorimeter measurement. Scanning electronic microscopy (SEM) was used to examine the cellular structure's morphology and the postfire char residue of the FPUFs. LOI and UL 94 HBF tests of all the flame retarded samples show improved flame retardancy. BDMPP plays an essential role in the gas phase because it significantly reduces the effective heat of combustion (EHC). This study highlights the synergistic effect caused by the combination of BDMPP and EG. The measured char yield from TGA is greater than the sum of individual effects. No dripping phenomenon occurs during burning for FPUF-BDMPP-EGs, as demonstrated by the result of the UL 94 HBF test. EG performs excellently on smoke suppression during burning, as evident in the result of the cone calorimeter test. MA reduces the peak heat release rate (pHRR) significantly. The synergistic effect of the combination of BDMPP and EG as well as MA offers an approach to enhance flame retardancy and smoke suppression.     

磷化淀粉的合成及其与聚磷酸铵协效阻燃聚乳酸的性能研究

利用9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)和马来酸酐(MA)对淀粉进行改性得到磷化淀粉(DOPOMASt),通过红外光谱(FTIR)、核磁共振谱(1H-NMR)和X射线光电子能谱(XPS)确定其结构.利用DOPOMASt作为碳源,与聚磷酸铵(APP)复配后通过熔融共混制备了阻燃聚乳酸(PLA)...     

Effects of melamine polyphosphate and halloysite nanotubes on the flammability and thermal behavior of polyamide 6

Melamine polyphosphate (MPP) and halloysite nanotubes (HNT) were introduced to polyamide 6 (PA6) by melt blending in order to improve the fire resistance. PA6 composite containing 12% flame retardants with good spinnability was obtained. The flammability of PA6 composite was characterized by limiting oxygen index (LOI), UL‐94 vertical burning and cone calorimeter (CONE) tests. The results indicated that the LOI value could reach 24.0 vol.% and UL‐94 rating could achieve V2 level at the presence of 12% flame retardants. CONE data demonstrated that peak heat release rate was significantly reduced from 554 kW/m² of neat PA6 to 368 kW/m² of the sample containing flame retardants. Thermal analysis indicated that the thermal stability and char formation were improved by the presence of flame retardants. The morphology of residue char was characterized by scanning electron microscopy; and it suggested that a network‐structured protective char layer had been formed. The possible synergism between MPP/HNT and their flame retardant mechanism was also analyzed and discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

Effect of surface chemical modification for aluminum hypophosphite with hexa‐(4‐aldehyde‐phenoxy)‐cyclotriphosphazene on the fire retardancy,water resistance,and thermal properties for polyamide 6

The surface chemical modified aluminum hypophosphite (AHP) defined as MAHP was successful prepared through P–H bonds on AHP surface reacted with the aldehyde groups in hexa‐(4‐aldehyde‐phenoxy)‐cyclotriphosphazene made in our lab. The wettability of the flame retardants was evaluated by water contact angle tests, and the water contact angle of the prepared MAHP dramatically increased from 0° for AHP to 145°, which indicated the surface modification made the superhydrophilic AHP into superior hydrophobic MAHP. The prepared MAHP and AHP, respectively, incorporated into polyamide 6 (PA6) matrix to prepare flame retardant PA6 composites and the fire retardancy and thermal degradation behavior of flame retardant PA6 composites were investigated by limiting oxygen index, vertical burning test (UL‐94), cone calorimeter, and thermogravimetric analysis tests. The morphologies and chemical compositions of the char residues for PA6 composites were investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy, respectively. The water resistant properties of flame retardant PA6 composites were evaluated by putting the samples into distilled water at 70°C for 168 hr, and the mechanical properties for flame retardant PA6 composites were investigated by the tensile, flexural, and Izod impact strength tests. The results demonstrated that the PA6/MAHP composites successfully passed UL‐94 V‐0 flammability rating, and the limiting oxygen index value was 27.6% when the loading amount of MAHP was 21 wt%. However, there is no rating in vertical burning tests for PA6/AHP composite with the same amount of AHP, which indicated the surface modification of AHP enhanced the flame retardancy efficiency for PA6 composites. The morphological structures and analysis of X‐ray photoelectron spectroscopy of char residues revealed that the surface modification of AHP benefited to the formation of a sufficient, flame retardant elements rich, more compact and homogeneous char layer on the materials surface during combustion, which prevented the heat transmission and diffusion, limit the production of combustible gases, inhibit the emission of smoke and then led to the reduction of the heat release rate and smoke produce rate. The mechanical properties results revealed that the surface modification of AHP enhanced the mechanical properties, especially the Izod impact strength comparing with that of PA6/AHP composites with the same amount of flame retardant. After water resistance tests, the PA6/MAHP composites remained superior flame retardancy and presented continuous and compact char layer after cone calorimeter tests; however, the fire retardancy for PA6/AHP composite obviously decreased, and the char layer was discontinuous with big hole caused by the extraction of AHP by water during water resistance tests. Copyright © 2017 John Wiley & Sons, Ltd.     

Enhancing the flame-retardant and smoke suppression properties of transparent intumescent fire-retardant coatings by introducing boric acid as synergistic agent

A series of novel phosphorus-boron flame retardants (BPEAs) were successfully synthesized by introducing boric acid (BA) into cyclic phosphate ester acid (PEA) via the esterification and thoroughly characterized by ¹H nuclear magnetic resonance spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Five kinds of transparent fire-retardant coatings applied to wood substrates were produced by thoroughly mixing amino resin with PEA and BPEAs. The effects of BA on the optical transparency, thermal stability, fire performance and smoke emission characteristics of the coatings were investigated by various analytical instruments. The transparency analysis reveals that the transparency value of the coatings gradually decreases with increasing BA loading, and MPEA4 with the highest BA content still exhibits a high degree of transparency. The results from fire protection, cone calorimeter and smoke density tests show that the introduction of BA greatly decreases the flame spread rating, mass loss, char index, heat release rate, smoke production rate, total heat release, total smoke release and specific optical density of the coatings concomitant with the increase in the residual mass and intumescent factor, which is ascribed to the formation of a more dense and continuous intumescent char judging by digital photographs and scanning electron microscope images. Thermo-gravimetric analysis indicates that the onset decomposition temperature, high-temperature stability and residual mass of the coatings greatly improve with increasing BA content. FTIR analysis shows that the introduction of BA into the coatings contributes to generate more phosphorus-rich cross-linked structures and aromatic structures and then create a compact and intumescent char layer, thereby effectively enhancing the flame retardancy and smoke suppression properties of the coatings.     

新型单组分磷氮膨胀阻燃剂的合成

以新戊二醇与三氯氧磷为原料,合成了5,5-二甲基-1,3-二氧杂己内磷酰氯;进而将5,5-二甲基-1,3-二氧杂己内磷酰氯分别与苯并咪唑类衍生物反应,得到三种新型单组分磷氮膨胀阻燃剂(Ⅲa-c).利用IR1、HNMR、质谱及元素分析等表征了Ⅲa-c三种化合物的结构;并利用热重分析考察了三种化合物的热稳定性能.结果表明,目标产物Ⅲa-c均有较好的成炭性和热稳定性,600℃时残炭质量分数分别达26.93%、23.62%及18.75%.     

Synergistic effect of combined dimethyl methylphosphonate with aluminum hydroxide or ammonium polyphosphate retardant systems on the flame retardancy and thermal properties of unsaturated polyester resin

A series of flame-retardant unsaturated polyester resin (UPR) were prepared by the addition of dimethyl methylphosphonate (DMMP) with various amounts of aluminum hydroxide (ATH) or ammonium polyphosphate (APP) as the flame retardants. The combustion resistance effects of ATH/DMMP and APP/DMMP systems were evaluated by limiting oxygen index test and vertical burning test (UL-94). The thermal properties of UPR were investigated by thermogravimetric analysis. The structure of char was observed by scanning electron microscopy. DMMP incorporated with ATH or APP improved the flame retardancy and thermal properties of UPR. However, the fire-retardant mechanism of these two systems were different: The ATH/DMMP system provided synergistic effect in charring property of the UPR, produced great amount of residual char, and thus revealed the excellent flame retardancy. The APP/DMMP system further improved the flame retardancy of the UPR due to the change in the residual char structure rather than the increase in the production of char.     

Thermal and flame retardant properties of novel intumescent flame retardant polypropylene composites

Novel intumescent flame retardant polypropylene (PP) composites were prepared based on a char forming agent (CFA) and silica-gel microencapsulated ammonium polyphosphate (Si-MCAPP). The thermal and flame retardancy of flame retardant PP composites were investigated by limiting oxygen index, UL-94 test, cone calorimetry, thermogravimetric analysis, scanning electron micrograph, and water resistance test. The results of cone calorimetry show that the flame retardant properties of PP with 30 wt% novel intumescent flame retardants (CFA/Si-MCAPP = 1:3) improve greatly. The peak heat release rate and total heat release decrease, respectively, from 1,140.0 to 156.8 kW m^?2 and from 96.0 to 29.5 MJ m^?2. The PP composite with CFA/Si-MCAPP = 1:3 has the excellent water resistance, and it can still obtain a UL-94 V-0 rating after 168 h soaking in water.     

An efficiently halogen-free flame-retardant long-glass-fiber-reinforced polypropylene system

In order to solve the “candlewick effect” caused by glass fibers, which results in the decrease of flame retardancy of flame-retardant long-glass-fiber-reinforced polypropylene (LGFPP) systems, and the deterioration of mechanical properties caused by adding an additional amount of flame retardants compared with flame-retardant non-glass-fiber-reinforced polypropylene systems so as to keep a same flame retardancy, a novel intumescent flame retardant (IFR) system, which is composed of a charring agent (CA), ammonium polyphosphate (APP) and organically-modified montmorillonite (OMMT), was used to flame retard LGFPP. The thermal stability, combustion behavior, char formation, flame retardant mechanism and mechanical properties of the IFR-LGFPP samples were investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 test, cone calorimeter test, scanning electronic microscopy, and mechanical property tests. When the content of IFR is 20 wt%, the LOI value of IFR-LGFPP reaches 31.3, and the vertical burning test reaches UL-94 V-0 rating, solving the “candlewick effect” caused by long glass fiber without additional amount of the IFR. All the relevant cone calorimeter parameters also show that IFR-LGFPP has much better flame-retardant behaviors than LGFPP. Furthermore, the mechanical properties of IFR-LGFPP almost remain unchanged in comparison with those of LGFPP containing no IFR. The flame retardant mechanism was also discussed.     

An efficient halogen-free flame retardant for glass-fibre-reinforced poly(butylene terephthalate)

Compared with poly(butylene terephthalate) (PBT), glass-fibre-reinforced poly(butylene terephthalate) (GF-PBT) is difficult to flame retard with halogen-free flame retardants. In the present study, the aluminium salt of hypophosphorous acid (AP) was used as a flame retardant for GF-PBT. A series of flame-retardant GF-PBT composites was prepared via melt compounding. The flame retardance and combustion behaviour of the composites were studied by limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimetric test. Thermal behaviours and thermal decomposition kinetics were investigated by thermogravimetric analysis (TGA) under N₂ atmosphere. The addition of AP to the composites could result in an increased LOI value, a UL-94 V-0 (1.6 mm) classification and a better fire performance in cone calorimetric tests. The char morphology observation after flame-retardant tests, calculation of decomposition kinetics, X-ray photoelectron spectroscopy (XPS) and infra-red spectral analysis of the char residue confirmed the condensed-phase flame-retardant mechanism. Furthermore, the mechanical properties of the flame-retardant composites were not deteriorated, retaining an acceptable level.     

Joint‐aggregation intumescent flame‐retardant effect of ammonium polyphosphate and charring agent in polypropylene

In order to explore the structure mode of intumescent flame retardants (IFRs) with higher efficiency, IFR particles with joint‐aggregation structure (@IFR) were obtained through the treatment of ammonium polyphosphate (APP) and a charring agent (PT‐Cluster) in their aqueous solution. Then, the joint‐aggregation IFR effect was researched using its application in polypropylene. In case of 20 wt% IFR loading, the limiting oxygen index (LOI) value of @IFR/PP was 1.1% higher than that of 15APP/5PT‐Cluster/PP mixture, and a 1.6 mm‐thick @IFR/PP composite passed the UL 94 V‐2 rating test, while 15APP/5PT‐Cluster/PP demonstrated no flame‐retardant rating in UL 94 vertical burning tests. In a cone calorimeter test, @IFR also had a better inhibition effect on heat release. The average heat release rate (av‐HRR) value during 0 to 120 seconds of @IFR/PP was only 41 kW m^?2, which was 33.9% lower than that of the 15APP/5PT‐Cluster/PP. Furthermore, the peak heat release rate (pk‐HRR) of @IFR/PP was 20.5% lower than that of 15APP/5PT‐Cluster/PP, and the time to pk‐HRR of @IFR/PP was 710 seconds, while that of 15APP/5PT‐Cluster/PP was 580 seconds. The better inhibition effect on HRR and the delay of time to pk‐HRR were caused by the joint‐aggregated structure of @IFR, which can rapidly react to form stable and efficient char layers. This kind of join‐aggregation IFR effect has great significance in suppressing the spread of fire in reality. In addition, @IFR also increased the mechanical properties of PP composites slightly compared with the APP/PT‐Cluster mixture.     

协效剂对膨胀阻燃聚丙烯基木塑复合材料的阻燃增效研究

赋予木塑复合材料(WPC)的阻燃性能成为近年来该领域国内外的研究热点之一。本文通过两轮正交试验,研究8种常见的协效剂对膨胀型阻燃剂(IFRs,m(聚磷酸铵,APP)∶m(季戊四醇,PER)=2∶1)的阻燃增效作用,筛选出具有显著协效作用的协效剂组MgO/EG(可膨胀石墨)/SiO_2,其组成为m(MgO)∶m(EG)∶m(SiO_2)=1∶5∶5,其与IFRs的最佳配比为m(IFRs)∶m(MgO/EG/SiO_2)=1∶0.18,得到性能良好的阻燃型聚丙烯基木塑复合材料。通过热重分析(TGA)和锥形量热分析(CONE)评价IFRs及协效剂组对聚丙烯(PP)基木塑复合材料(WPC)热稳定性能和阻燃性能的影响。结果表明,IFRs及MgO/EG/SiO_2的加入可以有效提高WPC的热稳定性,WPC/IFRs/MgO/EG/SiO_2600℃的残炭率达到22.42%。WPC/IFRs的热释放速率峰(PHRR)、总热释放量(THR)和总烟释放量(TSP)相比于WPC分别降低了21.9%、8.7%和22%。MgO/EG/SiO_2的加入可以进一步提高IFRs的阻燃效率,WPC/IFRs/MgO/EG/SiO_2的PHRR和THR相比于WPC分别降低了33.0%和13.8%。     

An efficient halogen-free flame retardant for polyethylene: piperazinemodified ammonium polyphosphates with different structures

In this study, piperazine-modified ammonium polyphosphates(PA-APPs) with hierarchical structure were synthesized through ion exchange reaction. ~1H nuclear magnetic resonance(~1H-NMR), Fourier transform infrared spectra(FTIR), elemental analysis(EA), and inductively coupled plasma atomic emission spectroscopy(ICP-AES) confirmed that the PA-APPs with different structures were prepared successfully. Then these flame retardants were used alone as monocomponent intumescent flame retardant for low-density polyethylene(LDPE). Combustion tests demonstrated that the flameretardant efficiency of PA-APP containing about 7 wt% carbon(PA-APP_7) was significantly higher than that of the other PAAPPs with more or less carbon. The flame-retarded LDPE system with 30 wt% PA-APP_7 passed the UL-94 V-0 rating, and had the oxygen index(LOI) of 33.0%. Thermal analysis illustrated that the thermal decomposition behavior of PA-APP changed with incorporating different contents of PA. For all these PA-APPs, PA-APP_7 showed higher thermal stability than the other PA-APP flame retardants. All the experimental results proved that PA-APP_7 could reach the balance of an acid source, a blowing source, and a charring source as a mono-component intumescent flame retardant for LDPE. Further, it led to the formation of a compact intumescent char layer containing the structures of rich P―O―P, P―N―C, C=C, etc. during burning which in turn resulted in the excellent flame-retardant efficiency of PA-APP_7.     

Thermogravimetry as a tool for measuring of fracturing fluid absorption in shales

A series of flame-retardant ethylene–vinyl acetate (EVA) composites with different contents of aluminum phosphate (AHP) and Trimer were prepared. The synergistic flame-retardant effects of the Trimer with AHP in EVA/AHP blends were studied by limiting oxygen index (LOI) tests, UL-94 tests, cone calorimeter tests, thermogravimetric analysis, and scanning electron microscopy (SEM). The LOI and UL-94 results showed that the system containing AHP and Trimer was very effective in improving the flame retardancy of EVA. When the mass ratio of AHP and Trimer was 3:1, the highest flame retardancy could be obtained, and when the flame-retardant loading was 30 wt%, the EVA/AHP/Trimer (7.5%) sample could achieve the V-0 rating in UL-94 tests, at the same time, its LOI value was 24.4%. The TG and DTG results showed that the addition of flame retardants catalyzes EVA decomposition in the first stage and generates a more stable char residue in the second stage. Consequently, an efficient reduction in the flammability parameters, such as heat release rate, total heat release, smoke production rate, and total smoke production could be observed. In addition, it was observed from the SEM observations of the morphological features that the AHP and Trimer combination, at the optimum proportion, could promote the formation of compact charred layers and prevent their cracking, which effectively protected the underlying materials from burning.     

三聚氰胺聚磷酸盐/季戊四醇配比、协效剂组及表面改性对聚丙烯基木塑复合材料的膨胀阻燃影响

通过极限氧指数(LOI)、线性燃烧速率(LBR)、热重分析和锥形量热分析等技术手段研究膨胀型阻燃剂(IFRs)中三聚氰胺聚磷酸盐(MPP)和季戊四醇(PER)的质量比、组成为m(MgO):m(可膨胀石墨,EG):m(SiO₂)=1:5:5的协效剂组(MgO/EG/SiO₂)和硅烷偶联剂(KH550)对聚丙烯基木塑复合材料(WPC)阻燃性能的影响。 结果表明,当IFRs中m(MPP):m(PER)=23:2(IFRs-M1)、质量分数为25%时的阻燃性能最佳,膨胀阻燃复合材料WPC/IFRs-M1的LOI和LBR分别为27.1%和3.89 mm/min,较未添加的WPC分别提高48.1%和下降89.79%,燃烧时的热释放速率、总热释放量、总烟释放量和CO₂释放量分别降低了76.2%、50.1%、6.9%和65.4%,600 ℃时的残炭率提高了498.3%。 协效剂组和KH550表面处理均可进一步改善WPC/IFRs-M1的阻燃性能,均对IFRs-M1具有良好的阻燃增效作用。 相比于WPC/IFRs-M1,同时用这两种阻燃增效手段的WPC/IFRs-M1/MgO/EG/SiO₂/KH550,其LOI提高了3.7%,LBR降低了20.3%;材料的热稳定性明显提高,热失重降低;燃烧时的热释放速率、总热释放量、总烟释放量和CO₂释放量分别降低了36.5%、37.6%、57.5%和33.33%,600 ℃时的残炭率提高了84.02%,显示出二者更好的协同效应。     

Preparation of a novel phosphorus‐containing organosilicon and its effect on the flame retardant and smoke suppression of polyethylene terephthalate

A novel phosphorus‐containing silicone flame retardant (PDPSI) was prepared by Mannish reaction, and a series of PDPSI/PET composites were prepared by melt blending method. The nuclear magnetic resonance (¹H NMR), Fourier transformation infrared (FTIR), and the thermogravimetric analyzer (TGA) results indicated that PDPSI showed network structure and owned good thermal stability, with the char residue of 62.2% at 800°C. The flame retardancy of PDPSI/PET composites was characterized by limiting oxygen index (LOI), vertical burning tests (UL‐94), and cone calorimeter (CCT). The results revealed that the addition amount of PDPSI was 5%, the LOI value of PDPSI/PET composites increased to 27.3%, and UL‐94 test passed V‐0 rating. When the PDPSI loading was 3%, PET composites showed excellent flame retardancy and smoke suppression, with a decrease in the peak heat release rate (PHRR) by 71.19% and the total smoke release (TSP) reduced from 14.4 to 11.1m². The scanning electron microscopy (SEM) and FTIR results of char residue demonstrated that the flame‐retardant mechanism of PDPSI was solid phase flame retardant. PDPSI catalyzed the aromatization reaction of PET to promote the formation of a dense and continuous carbon layer, finally improving the flame retardancy and smoke suppression properties of PET.