Nickel-Aluminum Hydrotalcite for Improving Flame Retardancy and Smoke Suppression of Intumescent Flame Retardant Polypropylene: Preparation,Synergy, and Mechanism Study

Intumescent flame retardants (IFR) are widely used in the field of flame retardant polypropylene (PP), but their flame retardant efficiency and smoke suppression properties need to be further improved. Herein, a Ni-Al LDH (layered double hydroxide) is obtained successfully by coprecipitation and microwave hydrothermal technique and used as a synergist to improve the flame-retardant and smoke-suppression properties of triazine-based IFR. The results showed that IFR/Ni-Al LDH exhibited the best synergistic effect when the IFR is replaced by 5 wt% Ni-Al LDH. 17 wt% IFR/Ni-Al LDH enabled the PP composites to achieve UL-94 V-0 rating with a high LOI of 29.8%. Besides, the introduction of Ni-Al LDH effectively decreased the heat and smoke release of the PP/IFR composites due to its catalytic charring effect. This is mainly attributed that the introduction of metal ions in Ni-Al LDH effectively improved the strength and crosslinking degree of char layer and promoted the formation of a cohesive and dense char layer. The formed high-quality char layer effectively exerted the barrier effect in condensed phase. Therefore, the PP/IFR/Ni-Al LDH composites exhibited excellent flame-retardant and smoke-suppression performance. This investigation provided a facile way to prepare environment-friendly and high-performance flame retardant PP composites with wide application prospects.     

Synergistic Effect of Montmorillonite and Intumescent Flame Retardant on Flame Retardance Enhancement of ABS

The synergistic effects of organic montmorillonite (OMMT) and intumescent flame retardant (IFR) based on the ammonium polyphosphate (APP) and pentaerythritol (PER) on flame retardant enhancement of acrylonitrile-butadiene-styrene copolymer (ABS) were investigated by using the limiting oxygen index (LOI), the UL-94 (vertical flame) test, thermogravimetric analysis (TGA), x-ray diffractometry (XRD) and scanning electron microscopy (SEM). The LOI data and vertical flame tests show that OMMT has a synergistic flame retardant effect with IFR and the LOI value of ABS/OMMT/IFR (96/4/20) reaches 28.7%. The TGA data demonstrate that the incorporation of OMMT and IFR is very effective in enhancing the thermal stability of ABS/OMMT/IFR system at high temperature (T > 500°C). The results of XRD show that the composite of ABS/OMMT is a kind of intercalated nanocomposite and the gallery height of ABS/OMMT nanocomposite is 3.5 nm. The microstructures observed by SEM demonstrate that a suitable amount of OMMT with IFR can promote formation of compact intumescent charred layers in ABS blends.     

Flammable,thermal, and mechanical properties of intumescent flame retardant PP/LDH nanocomposites with different divalent cations

The flammable, thermal, and mechanical properties of intumescent flame retardant (IFR) polypropylene/layered double hydroxide (PP/IFR/LDH) nanocomposites with the LDHs of different divalent cations and IFR system of ammonium polyphosphate/pentaerythritol (APP/PER) have been studied by X-ray diffraction (XRD), cone calorimeter test (CCT), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), limiting oxygen index (LOI), UL-94 test, and mechanical measurements. The XRD results show that the exfoliated PP/IFR/LDH nanocomposites possess the nanoscaled dispersion characteristic. The data from the CCT tests show the synergistic effect of LDHs with IFR can decrease considerably the HRR, MLR, and EHC values of the PP/IFR/LDH nanocomposites, in which the pk-HRR, pk-MLR, and pk-EHC values of the PP/IFR/ZnAl-LDH sample decrease to 318 kW/m², 0.081 g/m² s, 61.8 MJ/kg from the corresponding values 506 kW/m², 0.115 g/m² s, 71.8 MJ/kg of the PP/IFR sample. The LOI and UL-94 data further support the evidence that the flame retardant synergistic effects of LDHs with IFR increase the LOI values and UL-94 rating, especially for the LDHs with the transition ions (Zn, Cu) the LOI values can reach 33% and the UL-94 pass the V-0 rating. The TGA results demonstrate the LDHs can greatly improve the thermal stabilities of PP/IFR/LDH nanocomposites by increasing the thermo-oxidation decomposition temperature and charred residues. The morphological structures observed by SEM have demonstrated the LDHs can promote formation of compact charred layers. The data from the mechanical tests show the tensile strength and elongation at break of the PP/IFR/LDH samples are basically unchanged compared with the PP/IFR sample. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

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.     

不同芳基磷酸酯与膨胀型阻燃剂复配阻燃PP的研究

采用间苯二酚双(二苯基)磷酸酯(RDP)、双酚A双(二苯基)磷酸酯(BDP)、磷酸三甲苯酯(TCP)和异丙苯基磷酸酯(IPP)作为阻燃协效剂与膨胀型阻燃剂(IFR)复配阻燃聚丙烯(PP)。研究了芳基磷酸酯的种类对PP/IFR复合材料阻燃性能、热稳定性能和力学性能的影响,并通过热重分析(TGA)、扫描电镜(SEM)等对材料进行了表征。结果表明:芳基磷酸酯对PP/IFR复合材料具有一定的协同阻燃作用。当芳基磷酸酯用量为5.0%时,PP/IFR/TCP、PP/IFR/IPP、PP/IFR/RDP和PP/IFR/BDP复合材料的氧指数(OI)由PP/IFR的28.5%分别提高到29.5%、30.0%、30.5%和29.5%,垂直燃烧级别由UL 94V-1级提升至UL 94V-0级;同时,RDP和BDP可提高PP/IFR复合材料的热稳定性能,500℃时的残余率分别高达15.4%和12.9%。此外,RDP和BDP的加入有利于IFR粒子的分散,从而改善了材料的力学性能。     

Influence of nano silica hybrid expandable graphite on flammability,thermal stability,and mechanical property of polypropylene/polyamide 6 blends

Silica (SiO₂) nanohybrid expandable graphite (nEG) particles fabricated through one-step method are used as an efficient flame retardant for polypropylene (PP)/polyamide 6 (PA6) blends. The effect of nEG on the flammability, thermal stability, crystallization behaviors, and mechanical properties of PP/PA6 composites is investigated by using limit oxygen index (LOI), UL-94 test, cone calorimeter test (CCT), thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared, scanning electron microscopy, and mechanical tests. Compared with pure expandable graphite (EG), nEG improves the flame retardancy of composites. The results of LOI show that LOI of PP/PA6/nEG10 and PP/PA6/nEG15 composites are 26.0% and 27.2%, respectively. But the LOI values of PP/PA6/EG10 and PP/PA6/EG15 composites are 25.7% and 26.9%, respectively. The UL-94 test results show that PP/PA6/nEG10 composites reach V-1 level when the nEG content is only 10%. However, the PP/PA6 composites with 10% EG does not pass the UL-94 test. In addition, PP/PA6 composites with 15% nEG can reach V-0 level. The CCT results further show that nEG has a higher flame-retardant efficiency than pure EG for PP/PA6 blends. The thermal stability of PP/PA6/nEG composites is better than that of PP/PA6/EG composites. The mechanical property tests indicate that nEG is more conducive to maintain the tensile and impact strengths of PP/PA6 blends than EG due to the enhanced compatibility and interfacial adhesion.     

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.     

阻燃LGFPP的阻燃性能研究

将有机蒙脱土(OMMT)和水滑石(LDH)分别与膨胀阻燃剂(IFR)构成阻燃体系,对长玻纤增强聚丙烯(LGFPP)复合材料进行阻燃改性,通过极限氧指数(LOI)和锥形量热仪(CONE)测试,对比研究了两种体系阻燃LGFPP的阻燃性能及阻燃机理。结果表明:当OMMT质量分数为2%时,复合材料的LOI达到最大值24.2%,且垂直燃烧达到了UL-94 V-0级;当LDH质量分数为1%时,LOI达到最大值23.3%,而垂直燃烧等级仍为V-1级。以炭层阻隔的IFR/OMMT体系比以稀释阻燃的IFR/LDH体系更加有效地改善LGFPP的阻燃性能。     

Synergistic effects of aluminium hypophosphite on the flame retardancy and thermal degradation behaviours of a novel intumescent flame retardant thermoplastic vulcanisate composite

ABSTRACT

The synergistic effects of aluminum hypophosphite (AHP) on the flame retardancy, thermal degradation behaviors of a novel intumescent flame retardant thermoplastic vulcanizate (TPV/IFR) composite were investigated. The results showed that the combination of AHP with IFR showed evident synergistic effects on the increase in the LOI value and reduction of the combustion parameters for the TPV/IFR/AHP composites at the optimum weight ratio of IFR/AHP (6/1) as evidenced by LOI, UL-94 and CCT. The TGA data revealed that AHP could change the degradation behavior of TPV/IFR composites and enhance the thermal stability of the TPV/IFR composites at high temperature. The results of FTIR, EDXS, LRS and SEM demonstrated that TPV/IFR/AHP composites could form more continuous, dense and stable char layer on the materials surface, and consequently improving the flame retardancy. Based on these results, the possible condensed flame retardant mechanism of TPV/IFR/AHP composites was concluded in detail.     

芳基磷酸酯/膨胀型阻燃剂协同阻燃PP的制备及性能研究

以间苯二酚双(二苯基)磷酸酯(RDP)为阻燃协效剂,与三聚氰胺焦磷酸盐(MPP)和季戊四醇(PER)组成的膨胀型阻燃剂(IFR)复配,制备了具有良好阻燃性能的无卤阻燃聚丙烯(PP)。研究了RDP的用量对PP/IFR体系阻燃性能和力学性能的影响,并通过热重分析(TGA)和动态热机械分析(DMA)等手段对阻燃材料进行了表征。结果表明:RDP与IFR具有明显的协同阻燃作用。当RDP质量分数为5.0%时,阻燃PP的氧指数(LOI)从28.5%提高至30.5%,UL-94由V-1级提升至V-0级;此外,体系的缺口冲击强度也有较大幅度提高。     

有机蒙脱土对聚丙烯复合材料阻燃性能和抗冲击性能的影响

随着膨胀型阻燃剂(IFR)用量的增加,聚丙烯(PP)复合材料的冲击强度会不断降低。为提高PP/IFR复合材料的抗冲击韧性,使用了少量有机蒙脱土(OMMT)和聚烯烃弹性体(POE)协同增韧。结果表明,所制备的PP/IFR/POE/OMMT复合材料的极限氧指数最高为29.3%,达到UL94 V-0等级。当OMMT的质量分数为0.5%,POE质量分数为15%时,复合材料的冲击强度达到21.8 kJ/m~2,几乎是PP/IFR复合材料的6倍。此外,PP/IFR/POE/OMMT复合材料的熔体质量流动速率大于9.5 g/10min,具有良好的流动性。这种PP阻燃复合材料在汽车、家电、工业与民用建筑等领域具有广阔的应用前景。     

有机化坡缕石黏土-膨胀型阻燃聚丙烯复合材料的制备及性能

制备了优异阻燃性能(LOI36%)兼具良好力学性能的膨胀型阻燃聚丙烯复合材料OPGS/PA-APP/PP。将有机化坡缕石黏土引入到哌嗪-多聚磷酸铵(PA-APP)膨胀型阻燃(IFR)聚丙烯(PP)复合材料中,通过极限氧指数(LOI)、垂直燃烧(UL-94)、热重分析法(TGA)、扫描电子显微镜(SEM)、通用电子万能试验机研究了有机化坡缕石黏土添加量对PA-APP阻燃聚丙烯复合材料阻燃性能和力学性能的影响。结果表明,添加质量分数为2%的有机化坡缕石黏土提高了该复合材料的阻燃性能和力学性能。此外,所制备样品经垂直燃烧测试可达到阻燃V-0级别。实验证明,有机化坡缕石黏土在膨胀型阻燃聚丙烯复合材料中具有明显的协效阻燃作用。     

EG与IFR复合阻燃ABS的动态燃烧性和协同效应

将可膨胀石墨(EG)与P-N型膨胀阻燃剂(IFR)复合阻燃丙烯腈-丁二烯-苯乙烯共聚物(ABS)树脂,阻燃剂添加量为20%(质量分数,下同),通过极限氧指数(LOI)仪、垂直燃烧测试(UL-94)仪、锥形量热(CONE)仪和扫描电镜(SEM)研究了EG与IFR复合阻燃ABS的协同效应。结果表明,EG/IFR质量比为1/1为最佳配比,阻燃ABS的LOI达到29%,UL-94为V-0级;EG与IFR复合阻燃ABS,表现出一定的协同作用;通过SEM观察ABS/EG/IFR试样燃烧后样品发现,EG与IFR起到协同阻燃作用。     

Kinetics of thermo-oxidative degradation of zinc borate/microcapsulated red phosphorus with magnesium hydroxide in flame retarded polypropylene composites

The flammability and the thermo-oxidative degradation kinetics of zinc borate (ZB) and microcapsulated red phosphorus (MRP) with magnesium hydroxide (MH) in flame-retardant polypropylene (PP) composites were studied by limiting oxygen index (LOI), TGA, and FTIR spectroscopy. The results show that ZB/MRP is a good synergist for improving the flame retardancy of the PP composites. The Kissinger and Flynn-Wall-Ozawa methods were used to determine the activation energy (E) for degradation of PP composites. The results from the TGA curves indicate that the thermal stability of PP/MH/ZB and PP/MH/ZB/MRP composites is better than that of PP/MH composites. The kinetic results show that the values of E for degradation of PP/MH/ZB/MRP composites is much higher than those of PP/MH and PP/MH/ZB composites. The FTIR spectra data show that the incorporation of MH improves the thermo-oxidative stability of PP, especially for PP/MH composites with suitable content of MRP at higher temperatures. These data indicate that the synergistic flame retardants used in this work have a great effect on the mechanisms of pyrolysis and combustion of PP/MH composites.     

Influence of polyamide 6 as a charring agent on the flame retardancy,thermal, and mechanical properties of polypropylene composites

In this work, polyamide 6 (PA6) as a charring agent has been used in combination with thermoplastic polyurethane (TPU)‐microencapsulated ammonium polyphosphate (MTAPP) forming intumescent flame retardants (IFRs) which applies in polypropylene (PP). The effects of the IFRs on the flame retardancy, morphology of char layers, water resistance, thermal properties and mechanical properties of flame‐retardant PP composites are investigated by limiting oxygen index (LOI), UL‐94 test, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mechanical properties test. The results show that the PP/MTAPP/PA6 composites exhibit much better flame‐retardant performances than the PP/MTAPP composites. The higher LOI values and UL‐94 V‐2 of the PP/MTAPP composites with suitable amount of PA6 are obtained, which is attributed to the thick and compact char layer structure evidenced by SEM. The results from TGA and DSC demonstrate that the introduction of PA6 into PP/MTAPP composites has a great effect on the thermal stability and crystallization behaviors of the composites. Furthermore, the mechanical properties of PP/MTAPP/PA6 composites are also improved greatly due to the presence of PA6 as a charring agent. POLYM. ENG. SCI., 55:1355–1360, 2015. © 2015 Society of Plastics Engineers     

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.     

改性赤泥协同膨胀型阻燃剂阻燃聚乙烯

以聚磷酸铵（APP）、季戊四醇（PER）和三聚氰胺（MEL）复配的膨胀型阻燃体系（IFR）为主要阻燃剂,表面改性后的赤泥（Ti-MRM）作为协效剂阻燃聚乙烯（PE）,采用熔融共混法制备PE基阻燃复合材料（PE/IFR-Ti-MRM）。通过热重分析仪（TGA）、垂直燃烧仪（UL-94）、极限氧指数测定仪（LOI）及扫描电镜（SEM）等对其热氧稳定性、燃烧等级、阻燃性能和残炭形貌进行了表征与分析。结果表明：加入改性赤泥的PE/IFR-Ti-MRM复合材料形成的炭层更加致密和连续,当最优配比时,复合材料的极限氧指数达到32.2,燃烧等级达到V-0级;而PE/IFR阻燃复合材料的极限氧指数只能达到27.5,燃烧等级为V-2级。     

不同膨胀型阻燃剂改性聚丙烯/聚乳酸复合材料

用两种不同的膨胀型氮磷阻燃剂(IFR1和IFR2)阻燃改性聚丙烯(PP)/聚乳酸(PLA)复合材料。结果表明:两种阻燃剂在PP/PLA基体中都具有良好的分散性和界面粘合性。阻燃剂的加入降低了材料的力学性能,而含有25%阻燃剂的PP/PLA复合材料就能到达垂直燃烧试验(UL-94)的V0等级。燃烧过程中阻燃剂通过在材料表面形成致密的炭层来提高材料的阻燃性,其中IFR1对PP/PLA体系的阻燃改性效果更好。从力学性能和阻燃效果的双重考虑,质量含量25%的阻燃剂适合于PP/PLA材料的阻燃改性。     

Curing behavior,mechanical, and flame-retardant properties of epoxy-based composites filled by expandable graphite and ammonium polyphosphate

In this study, 4,4′-Diaminodiphenyl methane (DDM) was exploited as hardener for diglycidyl ether of daidzein (DGED) and epoxy resin mixture (E-D). The composites were produced by blending with different contents of ammonium polyphosphate (APP) and expandable graphite (EG) into E-D resin, named E-D/A-E composites. Firstly, E-D/A-E blends were analyzed by Fourier transform infrared spectroscopy and DSC to evaluate their curing behavior. The TGA was performed on the E-D/A-E composites to analyze their thermal stability, and the thermal properties of the composites were enhanced by adding APP-EG (A-E) flame retardants. The mechanical properties and the fractured surfaces of the E-D/A-E composites were studied by tensile, impact tests and scanning electron microscopy. Finally, through torch burning test, limiting oxygen index (LOI), vertical burning (UL-94) and micro-calorimetry tests, the influence of A-E flame retardants contents on flammability of composites were evaluated. The results showed that the UL-94 V-0 rating was obtained for the E-D/A-E composites and the composites exhibited a self-extinguishing phenomenon. When A-E flame retardants content reached 9.1 wt%, the LOI value reached 34.5%, and total heat release (Total HR) was reduced by 20.2% compared with E-D/A-E 1.     

Investigation of the influence of red phosphorus,expansible graphite and zinc borate on flame retardancy and wear performance of glass fiber reinforced PA6 composites

The flame retarded materials were prepared which used wear‐resistant PA6 composite (PA6/GF/PTFE/UHMWPE/CG, 85/15/5/5/5 by weight) as matrix, red phosphorus (RP), expansible graphite (EG), and zinc borate (ZB) as fire retardant. The flame retarded properties were characterized by LOI and UL‐94 testing. PA6 composite with 15 wt% RP reached V0 rating and had a high LOI value (27.3 vol%). When a combination of 7 wt% ZB and 8 wt% RP was added, increases in LOI (27.9 vol%) and UL‐94 rating(V0) were both observed. Thermogravimetric analysis (TGA) and char residue characterization showed that the combination of RP and ZB can promote the formation of char barrier, reduce the mass loss rate, and thus improve the flame retardancy of PA6 composites. The wear test showed that, the composite filled by 15 wt% RP or a combination of 7 wt% ZB and 8 wt% RP both possessed a low wear rate and a much stable friction coefficient. The presence of EG could also improve the flame retardance but was harmful to the mechanical property as well as wear performance. The results indicated that ZB and RP had synergy effect on improving both flame retardance and wear performance of PA6 composites. POLYM. COMPOS., 38:2090–2097, 2017. © 2015 Society of Plastics Engineers