A study of the flame‐retardant properties of polypropylene/Al(OH)3/Mg(OH)2 composites

Polymeric materials are used extensively, but their applications are limited because many of them are flammable. Therefore ways to make them flame retardant have received much attention. In this work, polypropylene (PP) was used as the matrix resin, aluminium hydroxide (Al(OH)₃) and magnesium hydroxide (Mg(OH)₂) as flame‐retardant additives and zinc borate (ZB) as a flame‐retardant synergist. PP/Al(OH)₃/Mg(OH)₂ and PP/Al(OH)₃/Mg(OH)₂/ZB flame‐retardant composites were prepared with a twin‐screw extruder. The flame‐retardant properties, i.e. oxygen index (OI), burning velocity and smoke density, of the composites were measured. The results showed that OI increased with an increase of the filler content and decreased with an increase of the filler particle diameter. The burning velocity decreased with an increase of the filler content, while it first increased and then decreased with an increase of the filler particle diameter. The smoke density decreased with an increase of the filler content and increased with an increase of the filler particle diameter. There was a flame‐retardant synergy between Al(OH)₃/Mg(OH)₂ and ZB in the composites, and the smoke suppression effect was marked when ZB was added. Copyright © 2009 Society of Chemical Industry     

Melt density and volume flow rate of polypropylene/Al(OH)3/Mg(OH)2 flame retardant composites

Polypropylene (PP) flame retardant composites filled with aluminum hydroxide (Al(OH)₃), magnesium hydroxide (Mg(OH)₂) as well as zinc borate (ZB) were prepared with a twin‐screw extruder. The melt volume flow rate (MVR) and density of the composites were measured by means of a melt flow rate instrument under experimental conditions with temperature of 180°C and load varying from 2.16 to 5 kg, to identify the effects of the particle size and content. The results showed that MVR of the composites decreased with an increase of the filler weigh fraction (?_f) when ?_f was more than 10 phr. The MVR decreased first and then increased with an increase of the filler diameter (d). The melt density (ρ_m) of the composites increased linearly with an increase of ?_f and decreased linearly with the increase of d. In addition, the ρ_m increased with an increase of load. Under the same experimental conditions, the MVR decreased slightly while the ρ_m increased somewhat with addition of ZB for the PP/Al(OH)₃/Mg(OH)₂ composite systems. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Heat resistant properties of PP/Al(OH)<Subscript>3</Subscript>/Mg(OH)<Subscript>2</Subscript> flame retardant composites

Vicat softening point temperature (T _V) and heat deflection temperature (T _d) are important parameters for characterization of heat resistant properties of polymeric materials. PP/Al(OH)₃/Mg(OH)₂ flame retardant composites were prepared using a twin-screw extruder, and the T _V and T _d of the composites were measured. The results showed that the T _V and T _d increased nonlinearly with an addition of the weight percentage of the flame retardant additives except for individual data points, while the T _V and T _d decreased with increasing the filler particle size when the content of flame retardant additives was constant. Under the same conditions, filling small amount of zinc borate into the composites might improve the heat resistant properties of the composite systems. Moreover, the morphology of the impact fracture surface of the specimens was observed by means of scanning electron microscope to understand the dispersion and distribution of the filler particles in the PP matrix.     

PP/Al(OH)_3/Mg(OH)_2阻燃复合材料的流动性能

制备了PP/Al(OH)_3/Mg(OH)_2阻燃复合材料,利用熔体流动速率仪测定了复合材料的熔体体积流动速率(MVR),并计算出其密度。结果表明:MVR随着阻燃剂质量分数的增加而减小,随着阻燃剂粒径的增加先降后升;复合材料密度随阻燃剂用量的增加呈近似线性增加,随阻燃剂粒径的增加呈近似线性降低,随着载荷的增加而提高。     

Effect of particle size on flame retardancy of Mg(OH)2‐filled ethylene vinyl acetate copolymer composites

Four kinds of magnesium hydroxide (Mg(OH)₂) with different particle sizes are chosen and mixed with ethylene vinyl acetate copolymer (EVA) to investigate the effect of particle size on the flame retardancy of composites, which is evaluated by limiting oxygen index (LOI) testing, horizontal fire testing, and cone calorimeter. When Mg(OH)₂ filling level changes from 35 to 70 wt %, the composites filled with nano‐Mg(OH)₂ do not always possess the best flame retardancy, and among the composites filled with micro‐Mg(OH)₂, the composites filled with 800 mesh Mg(OH)₂ show the best flame retardancy; however, the composites filled with 1250 mesh presents the worst one. So the effect of particle size on the flame retardancy of micro‐Mg(OH)₂‐filled EVA is not linear as expected. All the differences are thought to result from both particle size effect and distributive dispersion level of Mg(OH)₂. To prepare the composites with better mechanical properties and flame retardancy, authors suggested that Mg(OH)₂ of smaller size should be chosen as flame retardant, and good dispersion of Mg(OH)₂ particles also should be assured. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4461–4469, 2006     

Thermal oxidative degradation kinetics of PP and PP/mg (OH)2 flame‐retardant composites

The thermal stability and thermal oxidative degradation kinetics of polypropylene (PP) and flame‐retardant PP composites filled with untreated and treated magnesium hydroxide (MH) in air were studied by thermogravimetric analysis (TGA). The effect of the heating rate in dynamic measurements (5°C–30°C/min) on kinetic parameters such as activation energy was also investigated. The Kissinger and Flynn–Wall–Ozawa methods were used to determine the apparent activation energy for the degradation of neat PP and flame‐retardant PP composites. The results of TGA showed that the addition of untreated or treated MH improved the thermal oxidative stability of PP in air. The kinetic results showed that the apparent activation energy for degradation of flame‐retardant PP composites was much higher than that of neat PP, suggesting that the flame retardant used in this work had a great effect on the mechanisms of pyrolysis and combustion of PP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1978–1984, 2007     

Mg(OH)_2表面处理对阻燃PP性能的影响

分别采用硬脂酸和硅烷偶联剂对阻燃剂Mg(OH)2进行表面处理,研究了Mg(OH)2的表面处理方法对聚丙烯(PP)复合材料熔体流动性能和阻燃性能的影响。结果表明,经表面处理的Mg(OH)2与PP组成的复合材料的加工性能得到明显改善,对材料的阻燃性能没有明显影响。相同条件下,硅烷偶联剂比硬脂酸的改性效果更好,酸化水解条件对硅烷偶联剂的改性效果没有影响。     

Effect of particle size on the flame retardancy of poly(butylene succinate)/Mg(OH)2 composites

Poly(butylene succinate)/magnesium hydroxide (PBS/Mg(OH)₂) composites were prepared by melt compounding to investigate the effect of particle size on the flame retardancy of PBS. Their flammability properties were investigated by limiting oxygen index, UL‐94, and cone calorimeter tests, which suggested that the medium‐sized Mg(OH)₂‐5 µm displayed the best flame retardancy. The residual char structure were analyzed and indicated that Mg(OH)₂‐5 µm could form a better protective layer than other sized particles, leading to the better flame retardancy to PBS. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.     

Physical and mechanical properties of Al(OH)3/polypropylene composites modified by in situ‐functionalized polypropylene

Al(OH)₃/polypropylene (PP) composites modified by in situ‐functionalized polypropylene (FPP) were prepared by a one‐step melt‐extrusion process. The effect of in situ FPP on the crystallization and melting behavior, melt‐flow index, limiting oxygen index, thermal degradation, mechanical properties, and fracture morphology of Al(OH)₃/PP composites was studied. Formation of in situ FPP resulted in a decreased crystallization temperature and melting point of PP in the composites, an increased melt‐flow index, and improved tensile and flexural strengths of Al(OH)₃/PP composites, whereas the thermal degradation behavior and limiting oxygen index was not been influenced. The impact strength of the Al(OH)₃/PP composites modified by in situ FPP depended upon the content of the initiator, dicumyl peroxide, and the monomer, acrylic acid. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2850–2857, 2002; DOI 10.1002/app.10269     

Flammability and mechanical properties of Al(OH)3 and BaSO4 filled polypropylene

The flammability and mechanical properties of Al(OH)₃/BaSO₄/polypropylene (PP) composites were investigated. The flow, morphological, and thermal properties were also analyzed by melt flow index (MFI), Scanning electron microscopy (SEM), and Differential scanning calorimeter (DSC) studies, respectively. Total filler amount was fixed at 30 wt % to optimize physical characteristics of the composites. In addition to the flame retardant filler Al(OH)₃, BaSO₄ was used to balance the reduction in impact strength at high filler loadings. Substantial improvement in mechanical properties was achieved for 20 wt % Al(OH)₃ (i.e., 10 wt % BaSO₄) composition while maximum flammability resistance was obtained for 30 wt % Al(OH)₃ composite. SEM studies showed that the presence of aggregated Al(OH)₃ particles led to low interfacial adhesion between them and PP matrix ending up with decreased mechanical strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Al（OH）3和Mg（OH）2阻燃EVA性能的研究

选用形貌、粒径尺寸及分布相近的两种无机阻燃剂氢氧化铝（Al（OH）3）和氢氧化镁（Mg（OH）2），研究了二者用量对乙烯-醋酸乙烯酯共聚物（EVA）复合材料的力学性能和阻燃性能的影响，并比较了添加红磷的复合材料的力学性能和阻燃性能。研究表明：Al（OH）3和Mg（OH）2用量对复合材料性能影响比较相似，随着阻燃剂用量的增加，复合材料的阻燃性能提高，拉伸强度增加，但断裂伸长率下降；通过锥形量热仪数据看出：Al（OH），的点燃时间短，最大热释放速率和平均热释放速率低，火行为指数大，阻燃效果比Mg（OH）2好；红磷的加入对复合材料力学性能影响不大，而对阻燃性能影响较大。Mg（OH）2与红磷复配能提高复合材料的氧指数，但是，从水平和垂直燃烧角度考虑，Al（OH）3与红磷之间的阻燃协效效果更好。     

Flame‐retardant and mechanical properties of rigid polyurethane foam/MRP/mg(OH)2/GF/HGB composites

Some rigid polyurethane foam (RPUF) composites modified with microencapsulated red phosphorus (MRP), magnesium hydrate (Mg(OH)₂), glass fiber (GF), and hollow glass bead (HGB) were prepared. The influence of the MRP, Mg(OH)₂, GF, and HGB on the flame‐retardant, combustion, and mechanical properties of the filled RPUF composites was investigated. The results showed that the flame‐retardant and the combustion properties of the composites were obviously improved, the limiting oxygen index, half burning time and the residual mass/original mass ratio increased with increasing MRP/Mg(OH)₂ weight fraction, especially in case of MRP/Mg(OH)₂ weight fraction of 8 wt %; the carbon monoxide (CO) concentration decreased with increasing MRP/Mg(OH)₂ weight fraction, When the composites were loaded appreciate content of the HGB and the GF, the maximum torque and compressive strength of the composites were improved. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46551.     

Mechanical properties of Mg(OH)2/polypropylene composites modified by functionalized polypropylene

Modified Mg(OH)₂/polypropylene (PP) composites were prepared by the addition of functionalized polypropylene (FPP); and acrylic acid (AA) and by the formation of in situ FPP. The effects of the addition of FPP and AA and the formation of in situ FPP on the mechanical properties of Mg(OH)₂/PP composites were investigated. Experimental results indicated that the addition of Mg(OH)₂ markedly reduced the mechanical properties of PP. The extent of reduction in notch impact strength of PP was higher than that in flexural strength and tensile strength. However, tensile modulus and flexural modulus increased with increased Mg(OH)₂ content. The addition of FPP facilitated the improvement in the flexural strength and tensile strength of Mg(OH)₂/PP composites. The higher the Mg(OH)₂ content was, the more significant the effect of FPP was. The incorporation of AA resulted in further increased mechanical properties, in particular the flexural strength, tensile strength, and notch impact strength of Mg(OH)₂/PP composites containing high levels of Mg(OH)₂. It not only improved mechanical properties but also increased the flame retardance of Mg(OH)₂/PP composites. Although the mechanical properties of composites modified by the formation of in situ FPP were lower than those of composites modified by only the addition of AA in the absence of diamylperoxide, the mechanical properties did not decline with increased Mg(OH)₂ content. Moreover, the mechanical properties increased with increasing AA content. The addition of an oxidation resistant did not influence the mechanical properties of the modified Mg(OH)₂/PP composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2139–2147, 2003     

Effect of particle size on the properties of Mg(OH)2‐filled rubber composites

A novel nanomagnesium hydroxide powder and three kinds of micro‐Mg(OH)₂, with different particle sizes, were chosen as fillers and mixed with ethylene–propylene–diene monomer rubber (EPDM) to form a series of composites by a traditional rubber‐processing technique. The results showed that the mechanical properties of composites improved with decreasing particle size. The nanocomposites were far stronger than the microcomposites, which also supported the view that rubber reinforcement requires nanoreinforcement. The effect of particle size on the fire resistance of composites was investigated by cone calorimetry and limiting oxygen index analysis, which showed that the particle size of powder had an impact on the fire resistance of composites. For the composites filled with untreated powder, the peak value of heat release rate decreased and T_ign increased with decreasing particle size. In conclusion, the fire resistance of nanocomposites was better than that of microcomposites. Surface modification of particles sometimes substantially improved the mechanical properties of nanocomposites, but had no effect on either the mechanical properties of microcomposites or the fire resistance of nanocomposites and flame retardance. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2341–2346, 2004     

Interfacial interaction in AI(OH)3/polypropylene composites modified by insitu‐functionalized polypropylene

To investigate the interfacial interaction of AI(OH)₃/polypropylene (PP) composites modified by in situ‐functionalized polypropylene (FPP), AI(OH)₃/polypropylene (PP) composites containing a low AI(OH)₃ content, modified by in situ‐grafted acrylic acid, were prepared by a one‐step melt‐extrusion process. The effect of in situ FPP on the crystallization and melting behavior, crystalline morphology of the composites, and interfacial interaction between the filler and PP was investigated. The crystallization and melting behavior and crystalline morphology of PP in the composites depended upon the interfacial physical [heterogeneous nucleation of AI(OH)₃; cocrystallization and compabilitization of PP with in situ FPP] and the interfacial chemical interaction between both the components in the composites. FTIR results indicated that there exists a chemical reaction between AI(OH)₃ and in situ FPP. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 110–120, 2002; DOI 10.1002/app.10270     

Fracture morphology of Mg(OH)2/polypropylene composites modified by functionalized polypropylene

The morphologies of the fracture surface under impact and flexural testing of Mg(OH)₂/Polypropylene (PP) composites and their modified composites were investigated by scanning electron microscopy. Experimental results indicated that addition of functionalized polypropylene (FPP) and acrylic acid (AA) and the formation of in situ FPP changed the fracture morphologies of Mg(OH)₂/PP composites. We believe that addition of these modifiers improved the interfacial interaction and enhanced the interface adhesion between the particle and the matrix in Mg(OH)₂/PP composites. The degree of improvement was more significant in Mg(OH)₂/PP composites modified by the formation of in situ FPP. At low Mg(OH)₂ content, 2 phr AA exhibited a marked effect, but at high Mg(OH)₂ content, 4 phr AA afforded good effect. Due to the improved interface adhesion by interface interactions the fracture mechanism transformed from interface debonded fracture into a matrix fracture. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2148–2159, 2003     

Mechanical properties and fracture morphology of Al(OH)3/polypropylene composites modified by PP grafting with acrylic acid

Al(OH)₃/polypropylene (PP) composites modified by polypropylene grafted with acrylic acid (FPP) were prepared by melt extrusion. Effect of PP grafting with acrylic acid on mechanical properties and fracture morphology of Al(OH)₃/polypropylene composites were investigated. Although incorporation of Al(OH)₃ reduced the mechanical properties of PP, addition of FPP increased the mechanical properties of Al(OH)₃/PP composites. It is suggested that addition of FPP improve the dispersion of Al(OH)₃ and the interfacial interaction between filler and matrix. Mechanical properties of Al(OH)₃/FPP/PP composites depend on the grafting rate and the content of FPP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2617–2623, 2001     

Crystallization and melt behavior of Mg(OH)2/PP composites modified by functionalized polypropylene

The crystallization and melting behavior of Mg(OH)₂/PP composites modified by the addition of functionalized polypropylene (FPP) or acrylic acid (AA) and the formation of in situ FPP were investigated by DSC. The results indicated that addition of FPP increased the crystallization temperatures of PP because of the nucleation effect of FPP. The formation of in situ FPP resulted in a reduced crystallization rate, melting point, and degree of crystallization attributed to the decreased regularity of the PP chain. For Mg(OH)₂/PP composites, the addition of Mg(OH)₂ increased the crystallization temperatures of PP resulting from a heterogeneous nucleation effect of Mg(OH)₂. The addition of FPP into Mg(OH)₂/PP composites further enhanced the crystallization temperatures of PP. It is suggested that there is an activation of FPP to the heterogeneous nucleation effect on the Mg(OH)₂ surface. The addition of AA also increased the crystallization temperatures of PP in Mg(OH)₂/PP composites, although the crystallization temperature of PP was not influenced by the AA content, which is explained by the heterogeneous nucleation effect of the Mg(OH)₂ surface activated by FPP and AA. A synergistic effect on the crystallization of PP in Mg(OH)₂/PP composites further increased the crystallization temperatures of PP. However, The crystallization temperatures of Mg(OH)₂/PP composites modified by in situ FPP were lower than those of Mg(OH)₂/PP composites modified by addition of either FPP or AA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3610–3621, 2004     

Mg(OH)2/Al(OH)3/包覆红磷阻燃SEBS/PS共混物

研究了Al(OH)3,Mg(OH)2包覆红磷(10份)对苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物(SEBS)/聚苯乙烯(PS)阻燃性能的影响.结果表明,Mg(OH)2用量为80份时阻燃级别达V-2,氧指数达到29%,但力学性能较差;AI(OH)3用量为80份时阻燃效果不很理想,但对力学性能影响较小;Mg(OH)2/Al(OH)3/包覆红磷体系中Mg(OH)2用量大于Al(OH)3时综合阻燃效果最好.阻燃体系的热释放速率降低,有效燃烧热出现峰值延后.     

Low‐temperature synthesis of Mg(OH)2 nanoparticles from MgO as halogen‐free flame retardant for polypropylene

Mg(OH)₂ (MH) nanoparticles were synthesized by hydration of the light‐burned MgO at low temperature (70°C). Effects of additives, such as magnesium nitrate and magnesium acetate, on the size, morphology and agglomeration of MH particles were investigated. MH nanoparticles have platelet‐like structure and approximately 20–40 nm in thicknesses. The supersaturation degree plays an important role in magnesia hydration and is defined. When magnesium acetate was used as the additive, the hydroxyl ion can be homogeneously introduced into the solution. The size and morphology of MH nanoparticles are more homogeneous. Modified by titanate coupling agent, MH nanoparticles were used as the flame retardant for polypropylene (PP). The combustibility, mechanical properties and thermal behaviors of the PP/MH composites were characterized. The mechanical properties of PP/MH composites are not seriously deteriorated with increasing MH content. When the amount of MH fraction reached 65, the limiting oxygen index (LOI) value and UL 94 testing result of MH65 are 33.8 and V‐0 grading, respectively. The onset temperature (T_10%) and the maximum thermal decomposition temperature (T_max) of MH65 separately increased by approximately 100°C and 77°C than those of neat PP. Copyright © 2012 John Wiley & Sons, Ltd.