High-efficiency ammonium polyphosphate intumescent encapsulated polypropylene flame retardant

The flame retardant polypropylene containing the micro-envelope core-shell structure flame retardant, which encapsulated ammonium polyphosphate into melamine-formaldehyde resin and sodium silicate through in situ polymerization was prepared with polyamide 6, added as a carbon-forming agent. The composition of ammonium polyphosphate, encapsulated ammonium polyphosphate with melamine-formaldehyde resin and the micro-envelope core-shell structure flame retardant were characterized. The fire safety and thermal stability were investigated and showed an improvement including limiting oxygen index, thermogravimetric analysis, vertical burning tests, and microscale combustion calorimeter. The burned compounds were also studied to confirm the burning mechanism. The results showed the flame retardant performance had been greatly improved, while polyamide 6 had better char-forming effect. Besides, the water solubility of flame retardants and their influence on the mechanical properties of polypropylene were also investigated. The results on the effects of additives demonstrated a high efficiency flame retardant to polypropylene. A core-shell flame retardant that sodium silicate and melamine-formaldehyde resin-coated ammonium polyphosphate had been constructed. The effect of the built flame retardant system on the combustion performance of polypropylene was studied from the mechanism and performance. The LOI of the most flame retardant polypropylene reached 28.6%, and UL-94 reached the V-0 level.     

三聚氰胺-甲醛树脂微胶囊包覆聚磷酸铵阻燃PP的性能

通过原位聚合法制备三聚氰胺-甲醛树脂(MF)微胶囊包覆聚磷酸铵(APP)粒子,研究了APP粒径对微胶囊化APP(MCAPP)结构与性能的影响。将两种MCAPP(APP平均粒径分别为5,15μm)添加至聚丙烯(PP)基体中,研究了PP/MCAPP阻燃材料的性能。结果表明:不同粒径的APP均能成功被MF包覆,且包覆后的APP粒子的水溶性均大幅下降。PP/MCAPP阻燃材料的耐渗析性和极限氧指数均得到一定程度的提高。粒径小的APP有利于MF的包覆,包覆结构层更完整。MF和APP有很好的协同作用,在APP包覆不完全的情况下,能更有效地发挥两者的相互作用,提高PP复合材料的阻燃性。     

硅偶联剂对聚磷酸铵表面改性的研究

用有机硅偶联剂（WD—X）对聚磷酸铵（Ⅰ型-APP）阻燃剂表面进行改性。研究了偶联剂用量、改性时间、改性温度及惰性溶剂等因素对改性效果的影响。改性的最佳工艺条件为：改性剂质量分数1％，反应时间2．5～3．5h，反应温度120～130℃。测试结果表明，改性后的APP粒子表面呈疏水性，在树脂中的分散性得到很大改善。     

笼状磷酸酯微胶囊/聚磷酸铵阻燃聚丙烯

将笼状磷酸酯微胶囊(ET)与聚磷酸铵(APP)复配用于阻燃聚丙烯(PP)。采用氧指数和UL 94评价了阻燃PP的阻燃性能,采用热重分析、扫描电子显微镜照片、傅里叶变换红外光谱及X射线电子能谱研究了阻燃剂的协同效应和阻燃机理。结果表明:ET与APP有较好的复配协同效应,ET/APP的阻燃性能随m(ET)/m(APP)的不同而变化。当m(ET)/m(APP)为1∶2时,阻燃效果最好。w(ET/APP)为30%时,氧指数达29.7%,且达到UL 94 V-0级。     

Effects of ammonium polyphosphate microencapsulated on flame retardant and mechanical properties of the rigid polyurethane foam

In this article, a flame retardant microcapsule ammonium polyphosphate microencapsulated by polyurea (POAPP) was successfully synthesized by interfacial polymerization method using ammonium polyphosphate (APP) as core and polyurea as shell. The microencapsulation is observed by scanning electron microscopy and characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis and hydroscopicity test, which prove the success in synthesizing microencapsulation. When the POAPP is added into rigid polyurethane foam (RPUF), the flame retardant and mechanical properties are investigated using cone calorimeter, limited oxygen index test, and compressive strength test. The PHRR of RPUF-POAPP20 decreased from 336.52 kW/m² (Ref. RPUF) to 203.84 kW/m² and the THR of RPUF-POAPP20 was only 7.6 MJ/m², which is 33.9% lower than that of Ref. RPUF. Furthermore, the limiting oxygen index of RPUF-POAPP20 reaches 24.8%, which increased by 36.3% compared to Ref. RPUF. Whereas the maximum compressive strength of RPUF-POAPP5 was 7.46 MPa, which is higher than that of RPUF-APP5.     

磷系阻燃剂FR/APP协效阻燃PP

采用氧指数测定仪、热重分析仪和锥形量热仪研究了磷系阻燃剂1,3,5-三(5,5-二甲基-1,3-二氧杂环己内磷酸基)苯(FR)和聚磷酸铵(APP)复配体系对聚丙烯(PP)材料阻燃性能的影响.结果表明,FR/APP提高了PP的极限氧指数(LOI)、热稳定性和残炭率,降低了热释放速率.当w(FR)为15%和w(APP)为10%复配阻燃PP时,复合材料的LOI为29.6%.阻燃级别达到UL 94 V-0级.     

高效阻燃剂聚磷酸铵的合成工艺研究

以磷酸和尿素为原料合成了高聚合度的聚磷酸铵。通过单因素实验对制备工艺进行了优化,考察了原料配比、升温速率、预聚合温度、固化温度和固化时间等对产品质量的影响,采用核磁共振法（NMR）测定了聚磷酸铵的平均聚合度,并用X射线衍射(XRD )和红外(IR)相结合的方法对产品的晶体结构进行了表征,同时测定了聚磷酸铵的溶解度和总磷含量。结果表明,最佳制备工艺条件为：n（磷酸)∶n（尿素）=1∶1.9,预聚合阶段升温速率为2～3 ℃/min,预聚合温度为130 ℃,固化温度为230 ℃,固化时间为90 min。此条件下合成的聚磷酸铵平均聚合度为114,水中溶解度为0.492 g,总磷质量分数为31.75%,XRD表征结果表明,所得产品为Ⅰ型聚磷酸铵。     

聚磷酸铵的合成及其在聚丙烯阻燃中的应用

聚丙烯具有易燃性,限制其进一步应用。以磷酸二氢铵、五氧化二磷、尿素为原料合成聚磷酸铵,然后将其应用于聚丙烯中考察其阻燃性。在氨气压力为0.5 MPa、温度295℃下反应1.5 h,停止加热,降温至150℃,得到聚磷酸铵。红外光谱和X-衍射线表明合成聚磷酸铵是I型和II型混合型。当聚丙烯复合材料中膨胀型阻燃剂质量分数为30%,极限氧指数达30.8%,通过UL-94测试。结果表明,应用聚磷酸铵为原料的阻燃剂具有较好的阻燃性能。     

Polyamide‐enhanced flame retardancy of ammonium polyphosphate on epoxy resin

An attractive intumescent flame retardant epoxy system was prepared from epoxy resin (diglycidyl ether of bisphenol A), low molecular weight polyamide (cure agent, LWPA), and ammonium polyphosphate (APP). The cured epoxy resin was served as carbonization agent as well as blowing agent itself in the intumescent flame retardant formulation. Flammability and thermal stability of the cured epoxy resins with different contents of APP and LWPA were investigated by limited oxygen index (LOI), UL‐94 test, and thermogravimetric analysis (TGA). The results of LOI and UL‐94 indicate that APP can improve the flame retardancy of LWPA‐cured epoxy resins. Only 5 wt % of APP can increase the LOI value of epoxy resins from 19.6 to 27.1, and improve the UL‐94 ratings, reaching V‐0 rating from no rating when the mass ratio of epoxy resin to LWPA is 100/40. It is much interesting that LOI values of flame retardant cured epoxy resins (FR‐CEP) increase with decreasing LWPA. The results of TGA, FTIR, and X‐ray photoelectron spectroscopy (XPS) indicate that the process of thermal degradation of FR‐CEP consists of two main stages: the first stage is that a phosphorus rich char is formed on the surface of the material under 500°C, and then a compact char yields over 500°C; the second stage is that the char residue layer can give more effective protection for the materials than the char formed at the first stage do. The flame retardant mechanism also has been discussed according to the results of TGA, FTIR, and XPS for FR‐CEP. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Inorganic–organic hybrid coating‐encapsulated ammonium polyphosphate and its flame retardancy and water resistance in epoxy resin

A novel encapsulated ammonium polyphosphate (APP) with an inorganic–organic hybrid coating (MAPP) was prepared by a sol–gel method using tetraethoxysilane and octyltriethoxysilane as precursors. The properties of MAPP were investigated by water solubility, hydrophobicity, and morphological determination. The structure of MAPP was characterized by X‐ray photoelectron spectroscopy. The flame retardancy of epoxy resin composite with MAPP was evaluated by limiting oxygen index, UL‐94 test, and cone calorimetry test. The results showed that both tetraethoxysilane and octyltriethoxysilane hydrolyze and condense to form a dense polysiloxane layer structure on the surface of APP. The water solubility of MAPP was reduced from 0.64 to 0.13 g/100 mL of water, and the water resistance of epoxy resin composites filled with MAPP was also greatly improved. The limiting oxygen index, UL‐94 test, and cone calorimeter results showed that the epoxy resin composites filled with MAPP had better flame retardancy, probably because of a synergistic effect between polysiloxane and APP. Copyright © 2013 John Wiley & Sons, Ltd.     

Preparation and characterization of double shell microencapsulated ammonium polyphosphate and its flame retardance in polypropylene

Microencapsulated ammonium polyphosphate (MUFAPP) with a double shell is prepared by in situ polymerization, and is characterized by FTIR, XPS and SEM, etc. The microencapsulation of APP can increase its flame retardance and water resistance in PP. The flame retardant action of MUFAPP and APP in PP are studied using LOI and UL 94 test, and their thermal stability is evaluated by TG. The LOI value of the PP/MUFAPP composite at the same loading is higher than that of PP/APP composite. The LOI values of the PP/MUFAPP/ dipentaerythritol are higher than that of the PP/MUFAPP, and UL 94 ratings of most ternary composites are raised to V-0 at 30 wt.% loading. The results of the cone calorimeter also indicate that MUFAPP is an effective flame retardant in PP. The thermal degradation behaviors of APP and MUFAPP are studied using TG and dynamic FTIR.     

新型磷氮溴复合阻燃剂的制备及其阻燃聚丙烯的研究

以氢溴酸三聚氰胺盐（MHB）、聚磷酸铵（APP）、阻燃增效协同剂2、3-二甲基-2、3-二苯基丁烷( DMDPB )3种物质为原料复配成一种新型磷溴氮复合阻燃剂,将不同复配比例的复合阻燃剂添加到聚丙烯（PP）中,对阻燃PP材料的阻燃性能、力学性能及熔体流动速率进行测试,探讨3种物质的最佳复配比;并研究了该复合阻燃剂的添加量对材料阻燃性能的影响。结果表明,当MHB：APP：DMDPB的配比为10:10:1时,为最佳复配比;当磷氮溴复合阻燃剂的添加量为2.0 %（质量分数,下同）时,其极限氧指数值为30.8 %,燃烧等级为UL 94 V-1。     

Ammonium polyphosphate/montmorillonite nanocompounds in polypropylene

Ammonium polyphosphate (APP)/montmorillonite (MMT) nanocompounds were prepared. The crystal forms and morphologies of the nanocompounds were studied by XRD, FTIR, SEM, and TEM. The APP/MMT nanocompounds were applied to intumescent flame‐retarded polypropylene (PP) composites. The PP composites were studied by using oxygen index measurements, UL‐94 flame testing, thermogravimetric analysis, and mechanical measurement. It was found that the APP/MMT nanocompounds enhanced the flame retardancy of the IFR/PP compared with the form II APP and its mixture with micro‐MMT. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synergistic effect of ammonium polyphosphate and expandable graphite on flame‐retardant properties of acrylonitrile‐butadiene‐styrene

A new intumescent flame‐retardant (IFR) system consisting of expandable graphite (EG) and ammonium polyphosphate (APP) was applied in acrylonitrile–butadiene–styrene (ABS) resin. A synergistic effect between EG and APP on the flame retardancy of ABS was observed. Fixing the total loading of flame retardant at 15 wt %, the limited oxygen index (LOI) could reach 31 vol % at a weight ratio of 3 : 1 for EG and APP. While LOI values of EG‐ and APP‐filled ABS were only 26.0 and 21.5 vol % at the same loading, respectively. The UL‐94 vertical burning test suggested that samples with different ratios of EG and APP could all pass V‐0 rating while the samples containing EG and APP alone only passed V‐1 rating. Thermogravimetric analysis indicated that the addition of EG and APP (3 : 1 by weight) to ABS led to an increase in the amount of high‐temperature residue by 11.8 wt %, and a decrease of mass loss rate by 0.7%/°C compared with pure ABS. Scanning electronic microscopy revealed a homogeneous compact intumescent char layer of ABS/EG/APP samples. Based on our experiment and combined with others' previous studies, the synergistic mechanism is inferred. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Enhanced flame retardancy of unsaturated polyester resin composites containing ammonium polyphosphate and metal oxides

Three metal oxides (MOs) (Fe₂O₃, Sb₂O₃, Al₂O₃) were incorporated into blends of unsaturated polyester resin (UPR)/ammonium polyphosphate (APP) composites with the aim of studying and comparing their synergistic effect on flame retardancy with APP. The UPR-APP/MOs composites were prepared, then the thermal stability and flame-retardant properties of the UPR composites were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning test (UL-94), and cone calorimetry test (CCT). Besides, residues after CCT were characterized by scanning electron microscopy and laser Raman spectroscopy. The LOI values of the UPR composites with 0.5 wt% MOs increased to around 40%. However, the CCT results indicated that the incorporation of Sb₂O₃ brought an increase in the total heat release. Moreover, these three MOs had different effects on the process of thermal degradation of UPR composites from the TGA results. Based on the above results, Al₂O₃ provided a best promotion on flame retardancy among three MOs.     

聚丙烯/聚磷酸铵复合材料的等温结晶行为

采用差示扫描量热法研究了聚丙烯(PP)聚/磷酸铵(APP)复合材料的等温结晶过程。引入APP后,PP/APP复合材料的平衡熔点升高,结晶速率大幅度提高。采用Avrami方程研究了该体系的结晶动力学,发现PP/APP复合材料呈现明显的异相成核特征,随w(APP)的增加,Avrami结晶速率常数增大,半结晶时间降低。     

Influence of ammonium polyphosphate modified with 3‐(methylacryloxyl) propyltrimethoxy silane on mechanical and thermal properties of wood flour–polypropylene composites

In this article, the influence of ammonium polyphosphate (APP) and ammonium polyphosphate modified with 3‐(Methylacryloxyl) propyltrimethoxy silane (M‐APP) on mechanical properties, flame retardancy, and thermal degradation of wood flour–polypropylene composites (WF/PP composites) have been investigated. Polypropylene grafted with m‐isopropenyl‐α,α‐dimethylbenzyl‐isocyanate (m‐TMI‐g‐PP) was used to improve the adhesion of WF/PP composites. APP and M‐APP were used as flame retardants. The experimental results demonstrated that addition of M‐APP obviously enhanced mechanical properties of WF/PP composites. According to cone calorimetry results, M‐APP is also an effective flame retardant for WF/PP composites, compared to that of APP. It was also found that M‐APP decreased the 1% weight loss temperature and increased char residue. The thermal degradation of wood flour based upon the first peak temperature of wood decreased from 329.3 to 322.9°C and the thermal degradation of PP based upon the second peak temperature of PP improve from 518.0 to 519.6°C, when M‐APP was added to the WF/PP composites. From SEM results the char layer of the 25% M‐APP systems is much more intumescent than that of the 25% APP systems, indicating that 3‐(Methylacryloxyl) propyltrimethoxy silane can improve the char‐forming ability of WF/PP composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

微胶囊化膨胀阻燃剂及膨胀阻燃聚丙烯性能的研究

通过微胶囊化技术合成了新型磷氮体系无卤膨胀型阻燃剂(IFR),采用IFR提高聚丙烯(PP)的阻燃性能。运用扫描电子显微镜、氧指数仪和垂直燃烧仪等对IFR阻燃PP体系的表面形态和性能进行分析。结果表明,聚磷酸铵经包覆后粒度增大;当IFR的质量分数达到30%左右时,PP/IFR体系可以获得良好的阻燃效果,其氧指数达到32%,燃烧等级为FV-0级,抑烟效果较明显;力学性能下降不大;断裂面形态良好。     

Effects of expandable graphite and ammonium polyphosphate on the flame‐retardant and mechanical properties of rigid polyurethane foams

In this work, the effect of expandable graphite (EG) and ammonium polyphosphate (APP) on the flame retardancy and mechanical properties of the rigid polyurethane foam (RPUF) was studied. The results indicated that both EG and APP could effectively improve the flame retardancy of RPUF, while the retardancy of EG was better than APP. When the flame‐retardant loading was 15 wt %, the limited oxygen index (LOI) values of APP‐ and EG‐filled RPUF were 24.5 and 32 vol %, respectively. According to the LOI test, the optimal ratio of APP to EG in RPUF composites was 1 : 1 by weight, at which the LOI value of 15 wt % (APP + EG)/RPUF was 30.5 vol %. Thermal degradation test of RPUF composites by thermogravimetric analysis indicated that the addition of APP and EG to RPUF could lead to an increase in the amount of high‐temperature residue. Under the same conditions, the residue amount of EG/RPUF was less than that of APP/RPUF at the same temperature. Compression test and dynamic thermal mechanical analysis indicated that both the compressive strength and modulus decreased at a certain extent with the EG‐ or APP‐filled into RPUF, respectively, but with the mixture of EG and APP added into RPUF, the mechanical properties of these materials increased. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of morphology and ammonium polyphosphate dispersion on the flame retardancy of polystyrene/nylon‐6 blends

The influences of the distribution of ammonium polyphosphate (APP) in polystyrene/nylon‐6 [PS/polyamide‐6 (PA6)] blends and the continuity of the (PA6 + APP) phase on flame retardancy were investigated. The flame retardant properties were evaluated by limiting oxygen index (LOI), vertical flammability test and cone calorimeter tests. The results showed that APP is exclusively dispersed in the PA6 phase, and (PA6 + APP) phase formed a continuous state when the content of PA6 in PS/PA6 blends was higher than 32% (w/w). For blends with a continuous (PA6 + APP) phase, the decrease of PA6 content caused an increase in LOI values from 26% to 33% and a reduction of peak heat release rate. The improvement of flame retardancy was attributed to the increase of APP concentration in the PA6 phase, which benefited the fast formation of a continuous intumescent charred layer. The transformation of (PA6 + APP) phase morphology from a continuous state to a discontinuous state at a PA6 content of below 32% (w/w) caused a decrease in LOI. Results of thermo‐gravimetric and cone calorimeter tests indicated that the discontinuous intumescent charred layer thus formed could be responsible for the deterioration of flame retardant properties, which was also confirmed by scanning electron microscopy. Copyright © 2013 John Wiley & Sons, Ltd.