Thermal and combustion behavior of ethylene‐vinyl acetate/aluminum trihydroxide/Fe‐montmorillonite composites

The flammability characterization and synergistic flame‐retardant effect of Fe‐montmorillonite (Fe‐OMT) in the ethylene‐vinyl acetate/aluminum hydroxide (EVA/ATH) compounds were studied using limiting oxygen index (LOI), UL‐94 test, cone calorimeter, microscale combustion calorimetry (MCC), and thermogravimetric analysis (TGA). The results showed that addition of Fe‐OMT increases the LOI value and improves the UL 94 rating. Cone calorimeter data indicate that the addition of Fe‐OMT greatly reduced the heat release rate and carbon monoxide production rate. Furthermore a compact char residue formed on the surface of the sample with a suitable of Fe‐OMT during the combustion. The MCC results indicate that addition of Fe‐OMT reduced the heat release rate and catalyzed the decomposition of EVA. The TGA data showed further evidence that Fe‐OMT can catalyze carbonization reactions. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Synthesis of a magnesium/aluminum/iron layered double hydroxide and its flammability characteristics in halogen‐free,flame‐retardant ethylene/vinyl acetate copolymer composites

Mg–Al–Fe ternary hydrotalcites were synthesized by a coprecipitation method and characterized with powder X‐ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The flame‐retardant effects of Mg/Al–CO₃ layered double hydroxides (LDHs) and Mg/Al/Fe–CO₃ LDHs in an ethylene/vinyl acetate copolymer (EVA) were studied with the limited oxygen index (LOI), the UL‐94 test, and the cone calorimeter test (CCT), and the thermal degradation behavior of the composites was examined by thermogravimetric analysis. The results showed that the LOI values of the EVA/(Mg/Al/Fe–CO₃ LDH) composites were basically higher than those of the EVA/(Mg/Al–CO₃ LDH) composites at the same additive level. In the UL‐94 test, there was no rating for the EVA/(Mg/Al–CO₃ LDH) composite at the 50% additive level, and a dripping phenomenon occurred. However, the EVA/(Mg/Al/Fe–CO₃ LDH) composites at the same loading level of LDHs containing a suitable amount of Fe³⁺ ion reached the V‐0 rating, the dripping phenomenon disappearing. The CCTs indicated that the heat release rate (HRR) of the EVA composites with Mg/Al/Fe–CO₃ LDHs containing a suitable amount of Fe³⁺ decreased greatly in comparison with that of the composites with Mg/Al–CO₃ LDHs. The introduction of a given amount of Fe³⁺ ion into Mg/Al–CO₃ LDHs resulted in an increase in the LOI, a decrease in the HRR, and the achievement of the UL‐94 V‐0 rating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Combustion characteristics of halogen‐free flame‐retarded polyethylene containing magnesium hydroxide and some synergists

Halogen‐free flame‐retarded polyethylene materials have been prepared by using magnesium hydroxide (MH) as a flame retardant combined with red phosphorous (RP) and expandable graphite (EG) as synergists. The effects of these additives on the combustion behavior of the filled linear low density polyethylene (LLDPE), such as a limiting oxygen index (LOI), the rate of heat release (RHR), the specific extinction area (SEA), etc., have been studied by the LOI determination and the cone calorimeter test. The results show that RP and EG are good synergists for improving the flame retardancy of LLDPE/MH formulations. In addition, a suitable amount of ethylene and vinyl acetate copolymer (EVA) added in the formulations can increase the LOI values while promoting the char formation and showing almost no effect on the RHR and SEA values. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 206–214, 2001     

Influence of the pentaerythritol phosphate melamine salt content on the combustion and thermal decomposition process of intumescent flame‐retardant ethylene–vinyl acetate copolymer composites

Pentaerythritol phosphate melamine salt (PPMS) as a single‐molecule intumescent fire retardant was synthesized and characterized. The influence of the PPMS content on the combustion and thermal decomposition processes of intumescent‐flame‐retardant (IFR) ethylene–vinyl acetate copolymer (EVA) composites was studied by limiting oxygen index (LOI) measurement, UL 94 rating testing, cone calorimetry, thermogravimetric analysis, and scanning electron microscopy. The LOI and UL 94 rating results illustrate that PPMS used in EVA improved the flame retardancy of the EVA composites. The cone calorimetry test results show that the addition of PPMS significantly decreased the heat‐release rate, total heat release, and smoke‐production rate and enhanced the residual char fire performance of the EVA composites. The IFR–EVA3 composite showed the lowest heat‐release and smoke‐production rates and the highest char residue; this means that the IFR–EVA3 composite had the best flame retardancy. The thermogravimetry results show that the IFR–EVA composites had more residual char than pure EVA; the char residue yield increased with increasing PPMS content. The analysis results for the char residue structures also illustrated that the addition of PPMS into the EVA resin helped to enhance the fire properties of the char layer and improve the flame retardancy of the EVA composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42148.     

Effect of rubbers on the flame retardancy of EVA/ultrafine fully vulcanized powdered rubber/nanomagnesium hydroxide ternary composites

Two flame retardant ternary composites of ethylene‐vinyl acetate copolymer (EVA)/ultrafine fully vulcanized powdered rubber (UFPR)/nanomagnesium hydroxide (MH) were studied in this article. It has been found that carboxyl acrylonitrile butadiene UFPR (CNB‐UFPR) and acrylonitrile butadiene UFPR (NB‐UFPR) have different effect on the flame retardancy of related materials when they are used together with nano‐MH. CNB‐UFPR is in favor of lowering the material's heat release rate during its combustion, while NB‐UFPR benefits the material on the resistance to ignition. Observation on the microstructure of the composites by transmission electron micrograph revealed that the aforementioned two ternary composites have quite different morphology. EVA/CNB‐UFPR/nano‐MH composite exhibits partial encapsulation structure, while EVA/NB‐UFPR/nano‐MH composite has full separation structure. POLYM. COMPOS., 28:479–483, 2007. © 2007 Society of Plastics Engineers     

Flame‐retarded polyethylene terephthalate with carbon microspheres/magnesium hydroxide compound flame retardant

A novel compound flame retardant (carbon microspheres/magnesium hydroxide, abbreviated as CMSs/MH) was used to improve the fire performance of polyethylene terephthalate (PET). LOI, UL94, and Cone test results showed that CMSs/MH/PET composites obtained the best fire performance at the mass ratio of CMSs to MH, which was 5:5, where the CMSs/MH content was 1.0 wt. % of PET. The Py‐CS‐MS, TGA‐DSC results, and morphology of char residue revealed the flame‐retardant mechanism. CMSs/MH increased the thermal stability of PET by increasing the activation energy at the initial combustion stage. At the second stage of combustion, CMSs/MH increased the chance of recombination of free radicals and slowed the combustion. Additionally, CMSs/MH promoted the cross‐linking of pyrolysis products and further improved the continuity of the char layer. Thus, a dense and continuous char layer of CMSs/MH/PET composites was produced; this char layer reduced the heat release rate and increased the amount of char residue.     

Flame retardancy and mechanical properties of EVA nanocomposites based on magnesium hydroxide nanoparticles/microcapsulated red phosphorus

The flame retardancy and mechanical properties of ethylene vinyl acetate (EVA) polymer nanocomposite based on magnesium hydroxide (MH) nanoparticles with lamellar‐shape morphological structures and synergistic agent microcapsulated red phosphorus (MRP) have been studied by limiting oxygen index (LOI), cone calorimeter test (CCT), UL‐94 test, tensile strength (TS), and elongation at break (EB). Results showed that LOI values of lamellar‐like nanosized MH (50 × 350 nm²) samples were 1–7 vol. % higher than those of the common micrometer grade MH (1–2 μm) in all additive levels. When 1–3 phr MRP substituted for nanosized MH filler, LOI value increased greatly from original 37 to 55, and met the V‐0 rating in the UL‐94 test. The values of TS for MH nanoparticles composites increased from 10.4 to 17.0 MPa as additive loading levels increased from 80 to 150 phr, respectively, while the corresponding values for common micrometer MH composites decreased steadily from 9.7 to 7.1 MPa. Thermogravimetric analysis (TGA) and dynamic Fourier‐transform infrared spectroscopy (FTIR) results revealed two‐step flame‐retardant mechanism. First, MH particles decompose endothermically with the release of 30.1% hydration water in the 320–370°C temperature range. Second, MRP promote the formation of compact charred layers slowly in the condensed phase in the 450–550°C temperature range. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

卡拉胶-纳米氢氧化铝协同阻燃天然橡胶

将BaCl2分级的k型卡拉胶(KC)和纳米氢氧化铝〔Al(OH)3〕构成的协同阻燃体系添加到天然橡胶(NR)中制备KC-Al(OH)3/NR复合材料。通过TG、极限氧指数(LOI)、锥形量热(CCT)以及SEM考察了不同质量比的KC和Al(OH)3对复合材料力学性能和阻燃性能的影响。结果表明,当KC与Al(OH)3以1∶1的质量比加入到NR时,KC-Al(OH)3/NR复合材料的热稳定性、阻燃性能最优,复合材料的LOI达到25%。与纯天然橡胶相比,复合材料总热释放量(THR)、热释放速率峰值(pHRR)、总烟释放量(TSP)和平均质量损失率(AMLR)分别降低了12%、65%、23%和62%。相比于单独添加Al(OH)3体系,复合材料拉伸强度和断裂伸长率分别增加了11%和17%。     

Effect of stearic acid and epoxy silane on the structure and flame‐retardant properties of magnesium hydroxide/ethylene vinyl acetate copolymer/very low density polyethylene composites

Ethylene vinyl acetate copolymer (EVA) and very low density polyethylene (VLDPE) blends filled with magnesium hydroxide (MH) were compounded by melt blending. Two kinds of surface treatments were used in this research, including stearic acid and epoxy silane. The composites were analyzed by scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, limiting oxygen index (LOI), and cone calorimeter testing to study the effects of stearic acid and epoxy silane on the structure and flame‐retardant properties of the MH/EVA/VLDPE composites. The results indicate that stearic acid and epoxy silane had different effects on the interfacial interaction of the MH/EVA/VLDPE composites; this made a difference in the condensed phase of the physical process. Thus, the composites with different surface treatments had different flammability characteristics, thermal degradation processes, char yields, and LOIs. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effects of silicon additive as synergists of Mg(OH)2 on the flammability of ethylene vinyl acetate copolymer

The present work dealt with the effects of nine kinds of silicon additives on flame retardancy of ethylene‐vinyl acetate copolymer (EVA)/magnesium hydroxide [Mg(OH)₂] composites, as well as mechanical properties. The limiting oxygen index (LOI) test, horizontal fire test, vertical fire test, and cone calorimeter test were employed to evaluate flame retardancy of the composites. It was found that different silicon additives had different synergistic effects with Mg(OH)₂ on flame retardancy of the EVA matrix and exerted different influences on mechanical properties of the composites. The incorporation of organic montmorillonite (MMT) clay or silicone rubber not only made the composite reach FH‐1 rating in the horizontal fire test and FV‐1 rating in the vertical fire test, respectively, but also dramatically reduced the peak rate of heat release (Peak RHR) and increased the fire performance index (FPI) and ignition time (IT). The composites filled with precipitated SiO₂ exhibited the longest IT, the highest FPI, and FV‐1 rating. However, only the composites filled with silicone rubber could attain a balance between mechanical properties and flame retardancy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Effect of OMMTs on flame retardancy and thermal stability of poly(ethylene‐co‐vinyl acetate)/LDPE/magnesium hydroxide composites

The aim of this study was to prepare poly (ethylene‐co‐vinyl acetate) (EVA)/ low density polyethylene (LDPE)/magnesium hydroxide (MH) composites applicable in cable industry with required flame retardancy. For this reason, two types of organo‐modified montmorillonites (OMMT) with different surface polarites (Cloisite 15A and Cloisite 30B) at various concentrations, and also combination of these two OMMTs with overall loadings of 2 wt % and 5 wt % were used. The samples were compounded using a twin screw extruder with total (MH + OMMT) feeding of 55 wt % and 60 wt %. Limiting oxygen index (LOI) of the samples containing 2 wt % of OMMTs increased about 16% and dripping was suppressed according to vertical burning test (UL‐94V). Thermogravimetric results of EVA/LDPE/MH samples containing OMMT showed that the beginning of second step degradation was shifted about 50°C to higher temperatures. The composite tensile strength results showed enhancement by incorporating some amount of nanoclays with EVA/LDPE/MH composites. Scanning electron microscopy images confirmed that MH particles had better wetting by EVA matrix in presence of nanoclays. Oxidative induction time of the EVA/LDPE/MH/OMMT nanocomposites was 140 min, which was more than that of the samples without OMMT (20 min). Employing the equal weight ratios of the two OMMTs demonstrated a synergistic effect on flame retardancy of the samples according to the both tests results (LOI, UL‐94V). X‐ray diffraction analysis of the samples confirmed the intercalation/semiexfoliation structure of nanosilicate layers in the bulk of EVA/LDPE matrix. This led to longer elongation at break and thermal stability of Cloisite 15A based nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40452.     

Synergistic flame retardant effects of ammonium polyphosphate in ethylene‐vinyl acetate/layered double hydroxides composites

Mg–Al–Fe ternary layered double hydroxides (LDH) were synthesized based on bayer red mud by calcination‐rehydration method, and characterized using X‐ray diffraction and thermogravimetric analysis (TGA). The synergistic flame retardant effects of ammonium polyphosphate (APP) with LDH in ethylene‐vinyl acetate (EVA) composites were studied using limiting oxygen index (LOI), UL 94 test, cone calorimeter test (CCT), and smoke density test (SDT). The thermal degradation behavior of EVA/LDH/APP composites was examined by thermal gravimetric analysis‐fourier transform infrared spectrometry (TG‐FTIR). The results showed that LOI values decreased by incorporation of APP together with LDH; and, a suitable amount of APP in EVA/LDH composites can apparently improve UL 94 rating. The CCT results indicated that heat release rate (HRR) of the EVA/LDH/APP composites with APP decreased in comparison with that of the EVA/LDH composites. The SDT results showed that APP was helpful to suppress smoke. The TG‐FTIR data showed that the composites with APP had a higher thermal stability than the EVA/LDH composites at high temperature. POLYM. ENG. SCI., 54:766–776, 2014. © 2013 Society of Plastics Engineers     

Synergistic effects of expandable graphite with magnesium hydroxide on the flame retardancy and thermal properties of polypropylene

In this study, the flammability characterization and synergistic effects of different particle size of expandable graphite (EG) with modified magnesium hydroxide (MH) in flame‐retardant polypropylene (PP) composites were studied by limiting oxygen index (LOI), UL‐94 test, thermogravimetric analysis (TGA), and fourier transform infrared (FTIR) spectroscopy. The results showed that the particle size of EG had a great effect on the flammability of the PP/MH/EG composites. The EG2 with smaller particle size could apparently increase the LOI value and improved the UL‐94 flammability properties rating of the PP composites. The data obtained from the TGA and FTIR curves indicated that the thermo‐oxidative stability of PP/MH/EG composites increased with decreasing particle size of EG. And the smaller the particle size of EG, the higher the residues of the composite. POLYM. ENG. SCI., 47:1756–1760, 2007. © 2007 Society of Plastics Engineers     

Effect of different metallic hydroxides on flame‐retardant properties of low density polyethylene/melamine polyphosphate/starch composites

The flame retardancy of synthesized melamine polyphosphate (MPP) in combination with starch (ST) and different metallic hydroxides was investigated in low density polyethylene (LDPE) by limiting oxygen index (LOI) and vertical burning test. The results indicated that the LOI value of composite comprising Al(OH)₃(ATH) was higher than those of composites at the same additive loading with Mg(OH)₂(MH)or Fe(OH)₃(FH), which increased from 22 to 27%. And the composite comprising ATH passed V1 rating without causing molten drops. In addition, thermostability and morphology were characterized by differential scanning calorimeter (DSC), thermogravimetry (TG), derivative thermogravimetry (DTG), and scanning electron microscope (SEM). The results demonstrated that the crystallization of the composites remained unaffected after the incorporation of metallic hydroxide. The thermal degradation behavior of LDPE composites and the morphology of residual charred layer were changed. It also can be concluded that there was a synergy between certain metallic hydroxide and MPP after analyzing the residual charred layer using X‐ray diffraction (XRD). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Evaluation of nonconventional additives as fire retardants on polyamide 6,6: Phosphorous‐based master batch, α‐zirconium dihydrogen phosphate,and β‐cyclodextrin based nanosponges

The influence of new types of additives, such as halogen‐ and antimony‐free flame‐retardant master batches based on phosphorus, α‐zirconium dihydrogen phosphate, and β‐cyclodextrin nanosponges, on the flame retardancy of polyamide 6,6 (PA6,6) by means of cone calorimetry and limiting oxygen index (LOI) tests was investigated. A significant decrease of the heat release rate, depending by the type of additive used, was observed. Furthermore, with the consideration that the life safety during the fire could be improved by a decrease in the fire hazard, a decrease in the quantity of the smoke and its toxicity, depending also on the type of additive, was revealed. With regard to the LOI test, neat PA6,6 showed a slight increase in the LOI value in comparison with the PA6,6 composites. However, all of the PA6,6/composites showed a slower burning velocity and antidripping effects at oxygen concentrations corresponding to the LOI value. To understand the flame‐retardancy mechanism of these novel PA6,6 composites, we thoroughly investigated their thermal decomposition behavior and microstructure/elemental analysis by scanning electron microscopy/energy‐dispersive X‐ray spectroscopy. Furthermore, the combustion behavior of these novel PA6,6 composites was compared with that of conventional nanofillers (e.g., modified montmorillonite clay and carbon nanotubes). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Combustion characteristics and synergistic effects of red phosphorus masterbatch with expandable graphite in the flame retardant HDPE/EVA composites

In this work, the flammability behaviors and synergistic effects of red phosphorus masterbatch (RPM) with expandable graphite (EG) in flame‐retardant high‐density polyethylene/ethylene vinyl‐acetate copolymer (HDPE/EVA) composites have been investigated by limiting oxygen index (LOI), UL‐94 test, cone calorimeter test (CCT), thermogravimetric analysis (TGA), Fourier‐transform infrared (FTIR) and scanning electron microscopy (SEM). The data obtained from LOI, UL‐94 test and CCT showed that suitable amount of RPM had synergistic effects with EG in the HDPE/EVA/EG/RPM composites. The addition of RPM greatly increased the LOI values by 3.4%, obtained UL‐94 V‐0 rating, decreased the heat release rates and total heat release, and prolongated the ignition time when 6.7 phr RPM substituted for EG in the HDPE/EVA/EG/RPM composites. The data from TGA and FTIR spectra also indicated the synergistic effects of RPM with EG considerably enhanced the thermal degradation temperatures. The morphological observations after UL‐94, CCT, and SEM images presented positive evidences that the synergistic effects took place for RPM with EG, and the flame‐retardant mechanism has been changed in flame‐retardant HDPE/EVA/EG/RPM composites. The formation of stable and compact charred residues promoted by RPM acted as effective heat barriers and thermal insulations, which improved the flame‐retardant performances and prevented the underlying polymer materials from burning. POLYM. ENG. SCI., 55:2884–2892, 2015. © 2015 Society of Plastics Engineers     

Synergistic flame retardant effects of Fe-OMMT with LDH in EVA/LDH composites

Abstract

The synergistic effects of Fe organic modified montmorillonite (Fe-OMMT) with layered double hydroxides (LDHs) in ethylene vinyl acetate copolymer/LDH (EVA/LDH) composites have been studied using thermal analysis [thermogravimetric analysis (TGA)], limiting oxygen index (LOI), UL-94 test and cone calorimeter test (CCT). The results showed that the addition of a given amount of Fe-OMMT apparently increased the LOI value and the rating in the UL-94 test. The results from the LOI and UL-94 tests show that Fe-OMMT can act as flame retardant synergistic agents in EVA/LDH composites. The CCT data indicated that the addition of Fe-OMMT in the EVA/LDH system can greatly reduce the heat release rate. The TGA data show that Fe-OMMT, as an excellent flame retardant synergist of LDH, cannot increase the thermal degradation temperature and the charred residues.     

Synergism between hydrotalcite and silicate‐modified expandable graphite on ethylene vinyl acetate copolymer combustion behavior

Influence of independent Mg–Al‐layered double hydroxide (LDH), silicate modified expandable graphite (EG), mixture of LDH and EG at various ratios on ethylene vinyl acetate copolymer (EVA) combustion behavior and thermal stability was detected in sequence through the limiting oxygen index (LOI), vertical combustion (UL‐94) level, microscale combustion calorimeter (MCC) tests and thermal gravimetric/differential thermal gravimetric (TG/DTG) analysis. Results show that the 30 wt % LDH can improve the LOI of 70EVA/30LDH to 27.0%, but the combustion accompanies with serious melt‐dropping. While, the same amount of the EG can increase the LOI, UL‐94 level to 28.5%, V‐0 respectively. However, the combination of LDH and EG can further enhance the 70EVA/20LDH/10EG flame retardancy, it presents the LOI of 29.7%, UL‐94 level of V‐0, and total heat release of 29.5 kJ g^?1. The excellent flame retardancy is attributed to its compact residue. Compared with residue mass, the residue compactness plays a more important role in improving flame retardancy. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44634.     

Synergistic flame retardant effect of cerium oxide in ethylene‐vinyl acetate/aluminum hydroxide blends

The flammability characterization and synergistic flame retardant effect of cerium oxide (CeO₂) in the ethylene‐vinyl acetate/aluminum hydroxide blends were studied using limiting oxygen index (LOI), UL‐94 test, and cone calorimeter test (CCT). The results showed that the addition of a given amount of CeO₂ apparently increased the LOI value and UL‐94 rating. The data obtained from the CCT indicated that the addition of CeO₂ greatly decreased the heat release rate and prolonged the combustion time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synergistic effect of aluminum hydroxide and nanoclay on flame retardancy and mechanical properties of EPDM composites

The composites based on ethylene–propylene–diene monomer rubber (EPDM) with aluminum hydroxide (ATH), nanoclay, vulcanizing agent, and curing accelerator were prepared by conventional mill compounding method. The thermal stability and the flame retardant properties were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL‐94 test, cone calorimeter, and smoke density chamber tests. The results indicated that the substitution of the nanoclay in the EPDM/ATH composites increased the 50% weight loss temperature and the LOI value, and reduced the peak heat release rate (pk‐HRR), the extinction coefficient (Ext Coef), the maximal smoke density (Dm), and the whole smoke at the first 4 min (VOF4) of the test specimens. The synergistic flame retardancy of the nanoclay with ATH in EPDM matrix could imply that the formation of a reinforced char/nanoclay layer during combustion prevents the diffusion of the oxygen and the decomposed organic volatiles in the flame. The mechanical properties of the composites have been increased by replacing more of the nanoclays into the EPDM/ATH blends. The best loading of the nanoclay in EPDM/ATH composites is 3 wt %, which keeps LOI in the enough value, the V‐0 rating in the UL‐94 test, and the improved mechanical properties with better dispersion and exfoliation of the nanoclays shown by transmission electron microscopy (TEM) micrographs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2042–2048, 2013