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     

Morphology and mechanical properties of PP/POE/nano‐CaCO3 composites

The mechanical properties including tensile, flexural, and impact of the nanometer on calcium carbonate (nano‐CaCO₃) filled polypropylene (PP)/poly (ethylene‐co‐octene) (POE) composites were measured at room temperature to identify the effects of the POE content on the mechanical properties. It was found that the Young's modulus, tensile strength, and tensile elongation at break decreased nonlinearly while the tensile fracture strength varied slightly with increasing the POE weight fraction; the V‐notched and unnotched Izod impact fracture strength increased nonlinearly with an increase of the POE weight fraction; the flexural modulus and strength decreased roughly linearly with increasing the POE weight fraction. Furthermore, the impact fracture surface of the specimens was observed by means of a scanning electronic microscope to discuss the toughening mechanisms. POLYM. COMPOS., 37:539–546, 2016. © 2014 Society of Plastics Engineers     

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     

Effects of zinc borate and microcapsulated red phosphorus on mechanical properties and flame retardancy of polypropylene/magnesium hydroxide composites

In this paper, the mechanical properties and flame retardancy of zinc borate (ZB) and microcapsulated red phosphorus (MRP) with modified magnesium hydroxide (MH) in flame-retardant polypropylene (PP) were studied by mechanical properties test, UL-94 test, and thermogravimetric analysis (TGA). The crystallization behaviors of the composites were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). The addition of ZB could improve tensile strength and elongation at break of PP/MH composite. The MRP powders had a little effect on the mechanical properties of the PP composites. DSC results showed the addition of ZB and MRP weakened the heterogeneous nucleation effect of MH on PP. The addition of ZB and MRP had a great effect on the flammability of the PP/MH/EG composites. The thermal stability of PP/MH/ZB and PP/MH/ZB/MRP composites was better than that of PP/MH composite.     

Effect of matrix graft modification using acrylic acid on the PP/Mg(OH)2 composites and its possible mechanism

The matrix graft modification using an acrylic acid (AAc) was employed on the polypropylene/Mg(OH)₂ flame-retardant composite. The graft modification of PP matrix was carried out via an in-situ reactive extrusion by a twin-screw extruder. The tensile strength of the composites was analyzed using an equation developed by Pukanszky from which both matrix tensile strength σ₀ and interfacial adhesion strength were found to be increased. The enhancement of σ₀ is due to the intermolecular crosslinking of PP by AAc grafting. This crosslinking causes increases of tensile strength, Young’s modulus, impact resistance, and thermal resistance, but decreases the elongation at break of the composites.     

表面改性方法对PP/Mg(OH)2无卤阻燃体系性能的影响

以聚丙烯(PP)为基体树脂,加入采用不同表面改性方法处理的氢氧化镁[Mg(OH)2]制备无卤阻燃PP复合材料。探讨了化学法和辐射法对PP/Mg(OH)2无卤阻燃复合材料阻燃性能和力学性能的影响。结果表明,用烷烃类偶联剂Ao-03进行表面改性的PP/Mg(OH)2具有较好的阻燃性能和力学性能,氧指数可以达到23.8%;拉伸强度变化不大,断裂伸长率达20%,是未处理PP/Mg(OH)2的9.5倍;冲击强度也最高,为未处理PP/Mg(OH)2的7倍。     

Effects of High-Energy Electron Beam Irradiation on the Properties of Flame-Retardant HDPE/EVA/Mg(OH)2 Composites

The mechanical properties of flame-retardant high-density polyethylene/ethylene vinyl-acetate copolymer/magnesium hydroxide (HDPE/EVA/Mg(OH)₂) composites for cable materials are usually poor due to the high loading of the filler. In this study, high-energy electron beam irradiation was applied to HDPE/EVA/Mg(OH)₂ composites in the presence of triallylisocyanurate, an irradiation sensitizer. The effects of high-energy electron beam irradiation on the properties of irradiated HDPE/EVA/Mg(OH)₂ composites were investigated through the measurements of gel content, limiting oxygen index, tensile testing, thermogravimetric analysis, and scanning electron microscope. The results showed that the thermal, mechanical and flame-retardant properties of the HDPE/EVA/Mg(OH)₂ composites were improved by using high-energy electron beam irradiation.     

Influences of flame-retardant fillers on fire protection and mechanical properties of intumescent coatings

A combination of acrylic binder and flame-retardant ingredients was used to synthesize the solvent-borne intumescent coatings designed for steel substrates. The influences of individual and various combinations of flame-retardant fillers on the fire protection and mechanical properties of the coatings were characterized by using Bunsen burner, thermogravimetric analysis, limiting oxygen index, field emission scanning electron microscopy, freeze–thaw cycles, static immersion and pull-off type equipment. It was found that the combination of aluminium hydroxide (Al(OH)₃) and titanium dioxide (TiO₂) has significantly improved the fire protection, thermal stability and water resistance of the coating. This formulation had an LOI value of 34, which indicated good flammability resistance of the coating. The adhesion strength tests showed that the coating added with magnesium hydroxide (Mg(OH)₂) exhibited maximum bonding strength to the metal surface due to its effective interface adhesion. Hence, the findings from this study revealed that the selection of appropriate combinations of flame-retardant fillers strongly influenced the physical and chemical properties of the coatings.     

Interface modification and characterization in linear low-density polyethylene highly loaded with aluminium hydroxide

Fire-retardant linear low-density polyethylene (LLDPE) composites were prepared by combining this polymer with uncoated and surface treated forms of aluminum hydroxide (Al(OH)₃). The poor toughness and ductility of polyethylene highly filled with Al(OH)₃ can be significantly improved by addition of a small amount of silicon oil. It is found that silicon oil improves elongation at break of the composite remarkably, but this is accompanied by the deterioration of tensile strength. Silane crosslinked polyethylene substituting for polyethylene as the matrix in Al(OH)₃-filled polyethylene improves the tensile strength of the composite. Fractured surface analysis and limiting oxygen index (LOI) of the composites were also studied. Possible mechanisms accounting for these effects are discussed.     

Dielectric properties of γ‐irradiated POE highly filled with aluminum hydroxide

The influence of γ irradiation on the dielectric and physicochemical properties of polyethylene‐octene elastomer (POE) containing 120 phr aluminum hydroxide (Al(OH)₃) as fillers has been investigated. The dielectric properties of the γ‐irradiated POE highly filled with Al(OH)₃ have been measured over a wide range of frequencies (70 kHz–3 MHz). It was found that γ irradiation strongly influences the dielectric properties of the POE composite in the dose range 0–250 kGy. POLYM. ENG. SCI. 46:1721–1727, 2006. © 2006 Society of Plastics Engineers     

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     

Mg(OH)2及其与红磷复配阻燃聚丙烯复合材料的性能研究

研究了Mg(OH)2和Mg(OH)2/红磷复配体系阻燃聚丙烯材料的性能,选用热塑性弹性体POE对阻燃聚丙烯复合材料进行了增韧改性,结果表明:Mg(OH)2与红磷复配可以减少Mg(OH)2用量,降低对材料力学性能的损耗;POE较好地改善了材料的冲击性能,其添加量为15份时,材料的冲击强度可由8.14kJ/m2增大至12.83kJ/m2。最后利用锥形量热仪验证了Mg(OH)2/红磷复配体系的协同阻燃效应。     

原位生成甲基丙烯酸铝对POE的补强

用氢氧化铝和甲基丙烯酸（MAA）经原位反应生成了甲基丙烯酸铝[Al（MAA）3],并将其作为补强剂用于补强聚烯烃热塑性弹性体（POE）,研究了过氧化二异丙苯（DCP）用量、Al（OH）3和MAA的物质的量比和Al（MAA）3理论生成量对POE硫化胶力学性能的影响。结果表明,当DCP用量为3份、Al（OH）3/MAA的物质的量比为1∶3时,原位生成Al（MAA）3能够显著地提高POE硫化胶的力学性能。随着Al（MAA）3理论生成量的增加,硫化胶的拉伸强度先增加后减少,当Al（MAA）3理论生成量为30份时,拉伸强度达到最大值为24.31 MPa,而扯断伸长率保持在500%以上。另外,Al（MAA）3补强的POE硫化胶还具有较好的耐热氧老化性能和较高的邵A硬度。     

聚丙烯／纤维级Mg（OH）2／P复合材料研究

以聚丙烯（PP）为基料,通过与纤维级Mg(OH)2、红磷（P）以及其他助剂改性制备阻燃材料。实验结果表明：当PP、纤维级Mg(OH)2和P的比例为100：95：5时,共混体系的阻燃性能和力学性能均能满足使用要求,通过与PP／球状Mg(OH)2/P体系对比,发现PP／纤维级Mg(OH)2/P体系的拉伸性能优异。     

Structure‐property relationships of LLDPE—highly filled with aluminum hydroxide

The mechanical performance, rheological behavior, and phase morphology of linear low‐density polyethylene (LLDPE) highly loaded with aluminum hydroxide [Al(OH)₃] were investigated. It was found that titanate surface‐active agent and ethylene‐vinyl acetate copolymer (EVA) improve the processing and ductile properties of the composite remarkably but are accompanied by the deterioration of the tensile strength. Addition of vinyl triethoxy silane (VTEO) and dicumyl peroxide (DCP) improves the tensile strength of the composite because of the silane crosslinking structure introduced. A synergistic effect of interface modifying and silane crosslinking method in improving mechanical performance of the composite is presented. Phase morphology of the LLDPE/Al(OH)₃ composites was studied by means of scanning electron microscopy (SEM) technique. SEM micrographs indicate that a core‐shell type with Al(OH)₃ as a core and EVA as a shell is formed in the composite. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2485–2490, 2002     

Deformation mechanism of polypropylene composites filled with magnesium hydroxide

The fracture behavior and deformation mechanism of polypropylene (PP) composites filled with magnesium hydroxide [Mg(OH)₂] were investigated. The incorporation of Mg(OH)₂ particles into the PP matrix led to an increase in Young's modulus and a significant reduction in the tensile yield strength and elongation at break. Surface modification on filler particles with stearic acid could reduce the interfacial adhesion between the filler and PP matrix and improve the stress transferability. The deformation mechanism of the Mg(OH)₂/PP composites depended on the interfacial adhesion and the deformability of ligaments between microvoids caused by debonding. The deformability of the ligaments could be significantly improved by surface modification on the particle surface. The dependence of the deformation behavior of the Mg(OH)₂/PP composites on the filler content was in accordance with percolation theory. The agglomeration of microvoids and fibrillation of ligaments in the PP composites with excessive filler content indicated the weak resistance of the polymer matrix to crack propagation and premature fracture in a brittle manner. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1922–1930, 2005     

PP/nano-CaCO_3/POE复合材料性能研究

采用熔融共混法制备了PP/nano-CaCO3/POE复合材料,分别研究了nano-CaCO3和POE的加入量对复合材料力学性能的影响。结果表明:随着nano-CaCO3用量的增加,复合材料的冲击强度和拉伸强度均呈现出先增加后降低的趋势,弯曲模量呈增加趋势;随着POE用量的增加,复合材料的冲击强度先显著增加而后稍有降低,拉伸强度和弯曲模量均呈下降趋势。     

阻燃抑烟软PVC材料的研究

主要探讨了阻燃抑烟软PVC材料的配方设计，通过改变AJ(OH)3／Mg(OH)3的配比，及包覆红磷、硼酸锌的用量，观察PVC阻燃效果的变化，并综合其力学性能与流动性能的变化情况，最终确定阻燃剂的最佳组合及最佳配比。     

汽车拉索护套用增韧PP的性能

研究了聚丙烯(PP)基体树脂、增韧剂种类对增韧PP复合材料撕裂力和热氧老化性的影响。结果表明:PP K8003/三元乙丙胶(EPDM)撕裂力高于PP B8101/EPDM,而耐热氧老化性劣于PP B8101/EPDM;三种增韧剂EPDM,乙烯–辛烯共聚物(POE)和苯乙烯–乙烯–丁烯–苯乙烯三嵌段共聚物(SEBS)对增韧PP的撕裂力和热氧老化性影响不同,PP/SEBS复合材料的撕裂力和热氧老化性最好,PP/POE次之、PP/EPDM最差;当POE质量百分数为35%时,PP/POE复合材料的撕裂力为217 N,经140℃×1 000 h热氧老化后拉伸强度和断裂伸长率保持率分别为131%和82%;采用PP/POE复合材料挤出成型的汽车拉索护套各项性能可满足使用要求,达到客户的预期目标。     

Tailoring of interphase structure in highly filled poly(propene) block copolymer via reactive processing

Summary The effect of the of the reactive modifier 1,3-phenylene dimaleimide (BMI) on the interphase structure of poly(propene) block copolymer (PPBC)/magnesium hydroxide (Mg(OH)₂) composites has been investigated. DRIFTS and DSC studies on hot decane extracted composites confirmed preferential encapsulation of the filler particles with the ethene based elastomeric phase of the PPBC. This elastomeric interphase structure, formed efficiently via reactive processing of untreated Mg(OH)₂, PPBC and BMI, conferred excellent strength and toughness to the composites. The tensile strength and elongation of a BMI modified composite containing 60% w/w Mg(OH)₂, exceeded the yield stress and strain of the unfilled matrix. Received: 17 March 2000 /Revised version: 23 October 2001/ Accepted: 23 October 2001