Comparison of the effects of phenyl dichlorophosphate modified and unmodified β‐iron(III) oxide hydroxide on the thermal,combustion, and mechanical properties of ethylene–vinyl acetate/magnesium hydroxide composites

The objective of this study was to compare the impact of β‐iron(III) oxide hydroxide [β‐Fe(O)OH] and iron hydroxide modified with phenyl dichlorophosphate [β‐Fe(O)OPDCP] on the thermal, combustion, and mechanical properties of ethylene–vinyl acetate (EVA)/magnesium hydroxide (MH) composites. For the EVA/MH composites in combination with these iron‐containing co‐additives, β‐Fe(O)OH and β‐Fe(O)OPDCP both led to an increase in the thermal stability at higher temperatures. The results of microscale combustion calorimetry indicate that the peak heat‐release rate, total heat release, and heat‐release capacity, which are indicators of a material fire hazard, all decreased. Moreover, significant improvements were obtained in the limiting oxygen index (LOI) and Underwriters Laboratories 94 ratings. However, the EVA4 system reached a V‐0 rating, whereas the EVA3 system reached a V‐2 rating. The LOI values for the EVA3 and EVA4 systems were 35 and 39, respectively. A homogeneous and solid structure of char residue caused by β‐Fe(O)OPDCP was observed by scanning electron microscopy. Furthermore, because of the good interfacial compatibility between the fillers and the EVA matrix, the EVA4 system presented better mechanical properties than the EVA3 system. Thermogravimetric analysis/IR spectrometry showed that β‐Fe(O)OPDCP reduced the combustible volatilized products of EVA/MH. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40112.     

In situ synthesis of polystyrene nanocomposites with layered double hydroxide with an unusual anion arrangement: Morphology and thermal and mechanical properties

Today, the steady advance of technology and society makes the development of materials with improved properties of paramount importance. In this article, we contribution to this area by presenting an in situ bulk synthesis of polystyrene (PS) nanocomposites with layered double hydroxide (LDH) as a reinforcement. The LDH that we adopted presented an unusual arrangement of anions and had ZnAl cations intercalated with laurate and palmitate anions. The nanocomposites were analyzed by X‐ray diffraction and transmission electron microscopy to characterize their morphologies. The thermal properties, including the glass‐transition temperature and thermal stability, were measured by differential scanning calorimetry and thermogravimetric analysis, respectively. The mechanical properties and flexural fracture morphologies were also determined, with a bending test. The results demonstrate that the synthesized nanocomposites showed considerable improvements in their thermal stability and mechanical properties compared with the neat PS. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42856.     

Effect of BaTiO3 on the microwave absorbing properties of Co‐doped Ni‐Zn ferrite nanocomposites

Coprecipitation and hydrothermal method were utilized for the synthesis of Co‐doped Ni‐Zn ferrite and barium titanate nanoparticles. The microwave absorption properties of Co‐doped Ni‐Zn ferrite/barium titanate nanocomposites with single layer structure were studied in the frequency range of 8.2–12.4 GHz.The spectroscopic characterizations of the nanocomposites were examined using X‐ ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering measurement. Thermogravimetric analysis indicated the high thermal stabilities of the composites. The composite materials showed brilliant microwave absorbing properties in a wide range of frequency in the X‐band region with the minimum return loss of ?42.53 dB at 11.81 GHz when sample thickness was 2 mm and the mechanisms of microwave absorption are happening mainly due to the dielectric loss. Compared with pure Co‐doped Ni‐Zn ferrite, Co‐doped Ni‐Zn ferrite/BaTiO₃ composites exhibited enhanced absorbing properties. The microwave absorbing properties can be modulated by controlling the BaTiO₃ content of the absorbers and also by changing the sample thicknesses. Therefore, these composites can be used as lightweight and highly effective microwave absorbers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39926.     

Synthesis and characterization of polyurethane/Mg‐Al layered double hydroxide nanocomposites

Layered double hydroxide (LDH) is a new type of nanofiller, which improves the physicochemical properties of the polymer matrix. In this study, 1, 3, 5, and 8 wt % of dodecyl sulfate‐intercalated LDH (DS‐LDH) has been used as nanofiller to prepare a series of thermoplastic polyurethane (PU) nanocomposites by solution intercalation method. PU/DS‐LDH composites so formed have been characterized by X‐ray diffraction and transmission electron microscopy analysis which show that the DS‐LDH layers are exfoliated at lower filler (1 and 3 wt %) loading followed by intercalation at higher filler (8 wt %) loading. Mechanical properties of the nanocomposite with 3 wt % of DS‐LDH content shows 67% improvement in tensile strength compared to pristine PU, which has been correlated in terms of fracture behavior of the nanocomposites using scanning electron microscope analysis. Thermogravimetric analysis shows that the thermal stability of the nanocomposite with 3 wt % DS‐LDH content is ≈ 29°C higher than neat PU. Limiting oxygen index of the nanocomposites is also improved from 19 to 23% in neat PU and PU/8 wt% DS‐LDH nanocomposites, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Morphology,thermal, and mechanical properties of flame‐retardant silicone rubber/montmorillonite nanocomposites

Flame‐retardant methyl vinyl silicone rubber (MVMQ)/montmorillonite nanocomposites were prepared by solution intercalation method, using magnesium hydroxide (MH) and red phosphorus (RP) as synergistic flame‐retardant additives, and aero silica (SiO₂) as synergistic reinforcement filler. The morphologies of the flame‐retardant MVMQ/montmorillonite nanocomposites were characterized by environmental scanning electron microscopy (ESEM), and the interlayer spacings were determined by small‐angle X‐ray scattering (SAXS). In addition to mechanical measurements and limited oxygen index (LOI) test, thermal properties were tested by thermogravimetric analysis (TGA). The decomposition temperature of the nanocomposite that contained 1 wt % montmorillonite can be higher (129°C) than that of MVMQ as basal polymer matrix when 5% weight loss was selected as measuring point. This kind of silicone rubber nanocomposite is a promising flame‐retardant polymeric material. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3275–3280, 2006     

Thermal,mechanical, and dielectric properties of aluminum silicate fiber reinforced aluminum phosphate–poly(ether sulfone) layered composites

In this study, a novel aluminum phosphate (AlPO₄) heat‐resistant layer reinforced with aluminum silicate fiber (ASF) was successfully compounded on a poly(ether sulfone) (PES) matrix via the preparation process of high‐temperature heat treatment and vacuum hot‐pressing sintering technique. The influence of the ASF content on the morphology, thermal, mechanical, and dielectric properties of the as‐fabricated aluminum silicate fiber reinforced aluminum phosphate–poly(ether sulfone) (ASF/AlPO₄–PES) layered composite was investigated. The results reveal that the incorporation of aluminum silicate fiber/aluminum phosphate (ASF/AlPO₄) heat‐resistant layer can significantly improve the thermal stability and mechanical performances of the PES matrix composites. Compared with the pristine PES, the ASF/AlPO₄–PES layered composite containing 8.0 wt % ASF exhibited better high‐temperature resistance properties (300 °C) and a lower thermal conductivity (0.16 W m^?1 K^?1). Furthermore, the dielectric constant and dielectric loss tangent of this PES matrix composite decreased to 2.16 and 0.007, respectively. Meanwhile, the frequency stability of the dielectric properties for the ASF/AlPO₄–PES layered composites was remarkably enhanced with increasing ASF addition at frequencies ranging from 10² Hz to 5 MHz. This was attributed to the existence of microscopic pores within the ASF/AlPO₄ layer and the strong interfacial bonding between the ASF/AlPO₄ layer and the PES matrix. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45542.     

Synthesis and characterization of ethylene vinyl acetate/Mg–Al layered double hydroxide nanocomposites

Mg–Al layered double hydroxide (LDH)/Ethylene vinyl acetate (EVA‐28) nanocomposites were prepared through solution intercalation method using organically modified layered double hydroxide (DS‐LDH). DS‐LDH was made by the intercalation of sodium dodecyl sulfate (SDS) ion. The structure of DS‐LDH and its nanocomposites with EVA‐28 was determined by X‐ray diffraction (XRD) and transmission electron microscope (TEM) analysis. XRD analysis shows that the original peak of DS‐LDH shifted to lower 2θ range and supports the formation of intercalated nanocomposites while, TEM micrograph shows the presence of partially exfoliated LDH nanolayers in addition to orderly stacked LDH crystallites in the polymer matrix. The presence of LDH in the nanocomposites has been confirmed by Fourier transform infrared (FTIR) analysis. The mechanical properties show significant improvement for the nanocomposite with respect to neat EVA‐28. Thermogravimetric (TGA) analysis shows that thermal stability of the nanocomposites is higher than that of EVA‐28. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1845–1851, 2007     

Improving the flame‐retardant efficiency of aluminum hydroxide with fullerene for high‐density polyethylene

The influence of fullerene (C₆₀) on the flame retardancy and thermal stability of high‐density polyethylene (HDPE)/aluminum hydroxide (ATH) composites was studied. After the addition of three portions of C₆₀ to an HDPE–ATH (mass ratio = 100:120) composite, a V‐0 rating in the UL‐94 vertical combustion test was achieved, and the limiting oxygen index increased by about 2%. The results of cone testing also showed that the addition of C₆₀ effectively extended the time to ignition and the time to maximum heat‐release rate while cutting down the peak heat‐release rate. Thus, fewer flame retardants were needed to achieve a satisfactory flame retardance. Consequently, the adverse effects on the mechanical properties because of the high level of flame‐retardant loading was reduced, as evidenced by the obvious enhancements in the tensile strength, elongation at break, and flexural strength. Electron spin resonance spectroscopy proved that C₆₀ was an efficient free‐radical scavenger toward HO· radicals. Thermogravimetric analysis coupled to Fourier transform infrared spectroscopy demonstrated that in both N₂ and air atmospheres, C₆₀ increased the onset temperature of the matrix by about 10 °C because of its enormous capacity to absorb free radicals evolved from the degradation of the matrix to form crosslinked network, which was covered by aluminum oxide. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44551.     

The effects of APP,APP/MMT nanocomposites on the thermal degradation of ABS resin

The thermal degradation of acrylonitrile‐butadiene‐styrene (ABS) added ammonia polyphosphate (APP) or APP/montmorillonite (MMT) nanocomposite was studied. The whole degradation progress of ABS could be regarded as the combination of the thermal degradation of polystyrene (PS) and polybutadiene (PB). The PB influences the formation of char while PS influences the maximum mass loss rate and its decomposition temperature. APP or APP/MMT nanocomposite could decrease the maximum mass loss rate and promotes the formation of char. A SiO₂ network was formed on the char surface of the ABS‐APP/MMT composite which could improve the strength of the char and flame retardancy of ABS. It was found that when APP/MMT mixture or APP/MMT nanocomposite are added to ABS, NH₃ (the gas product of APP) was buried in the residue and released until full degradation of ABS. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40704.     

Fabrication and properties of carbon nanotube/styrene–ethylene–butylene–styrene composites via a sequential process of (electrostatic adsorption aided dispersion)‐plus‐(melt mixing)

Carbon nanotube (CNT)/styrene–ethylene–butylene–styrene (SEBS) composites were prepared via a sequential process of (electrostatic adsorption assisted dispersion)‐plus‐(melt mixing). It was found that CNTs were uniformly embedded in SEBS matrix and a low percolation threshold was achieved at the CNT concentration of 0.186 vol %. According to thermal gravimetric analysis, the temperatures of 20% and 50% weight loss were improved from 316°C and 352°C of pure SEBS to 439°C and 463°C of the 3 wt % CNT/SEBS composites, respectively. Meanwhile, the tensile strength and elastic modulus were improved by about 75% and 181.2% from 24 and 1.6 MPa of pure SEBS to 42 and 4.5 MPa of the 3 wt % CNT/SEBS composite based on the tensile tests, respectively. Importantly, this simple and low‐cost method shows the potential for the preparation of CNT/polymer composite materials with enhanced electrical, mechanical properties, and thermal stability for industrial applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40227.     

Synergistic effect of dual nanofillers (MWCNT and Ni–Al LDH) on the electrical and thermal characteristics of polystyrene nanocomposites

The advantage of using 3D hybrid filler containing carboxylic acid functionalized multiwalled carbon nanotubes (c‐MWCNTs) and sodium dodecyl sulfate modified Ni–Al layered double hydroxide (sN‐LDH) over c‐MWCNTs and sN‐LDHs acting alone was investigated. PS/c‐MWCNT composites proved to be good for improvement of properties, but not to an appreciable level, especially in case of electrical conductivity, flame retardancy, rheology, and water vapor permeability. Hence, a combination of 0.3 wt % of c‐MWCNT and 3 wt % of sN‐LDH was optimized as additives to assist in the full expression of the filler traits in the nanocomposite and to obtain a versatile nanocomposite with properties specific to both the fillers. This approach slightly decreases the dispersion challenge faced with handling high loadings of CNT and also the intrinsic limitations specific to the individual fillers (i.e., inertness of CNTs and low conductivity of LDHs). Moreover, the anion/anionic repulsion of organically modified CNT/LDH facilitates effective dispersion of the additive opposing adhesion. FTIR and Raman spectroscopy provided evidence for incorporation and proper dispersion of the additives in the polymer matrix, with XRD and TEM confirming a well‐dispersed morphology of the nanocomposites. In this work, focus is made on the improvement of thermal stability, flame retardancy, melt rheology, hardness, electrical conductivity, and water vapor permeability of PS/0.3 wt % c‐MWCNT/3 wt % sN‐LDH nanocomposites over PS/0.3 wt % c‐MWCNT, making use of the synergistic effect of c‐MWCNT coupled with sN‐LDH on polystyrene. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46513.     

Effect of bilayered stearate ion‐modified Mg?Al layered double hydroxide on the thermal and mechanical properties of silicone rubber nanocomposites

The homogeneous dispersion of nanofillers in polymer matrices to form polymer nanocomposites remains a challenge in the development of high‐performance polymer materials for various applications. In the work reported, a stearate ion‐modified Mg? Al layered double hydroxide (St‐LDH) as nanofiller was incorporated in a silicone rubber (SR) matrix by solution intercalation and subsequently characterized. X‐ray diffraction and transmission electron microscopy studies confirm the formation of a predominantly exfoliated dispersion of St‐LDH layers of 75–100 nm in width and about 1–2 nm in thickness in the SR. Thermogravimetric analysis shows that the thermal degradation temperature of the exfoliated SR/St‐LDH (1 wt%) nanocomposites is about 80 °C higher than that of pure SR. Differential scanning calorimetric studies indicate that the melting and crystallization temperatures are higher by 4 and 10 °C for 5 and 8 wt% St‐LDH‐loaded SR nanocomposites compared to neat SR. A significant improvement of 97% in tensile strength and 714% in storage modulus and a reduction of 82% in oxygen permeability have been achieved at 3 wt% St‐LDH loading in SR. Copyright © 2011 Society of Chemical Industry     

Synthesis and characterization of diamide–diimide–diamines based on p‐amino benzoic acid and their curing and thermal behavior with epoxy blends containing phosphorus/silicon in the main chain

Diimide–diacid ( I ) having an imide group in its rigid structure was synthesized by the refluxing of 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride [4,4′‐carbonyldiphthalic anhydride (BTDA)] and p‐amino benzoic acid in a mixture of acetic acid and pyridine (3 : 2 v/v). The chloroderivative of the diacid ( I ) was synthesized by its reaction with thionyl chloride, this was followed by condensation with different diamines with phenyl, naphthyl, ether, sulfide, and cardo groups to generate a series of diamide–diimide–diamines (DADIDAs). The resultant DADIDAs were characterized by elemental analysis and spectroscopic techniques, namely, Fourier transform infrared spectroscopy and NMR spectroscopy, and were used as epoxy curing agents to impart flame retardancy to the epoxy system. Two epoxy blends (designated as ES and EP) were prepared by the homogeneous mixing of diglycidyl ether of bisphenol A (DGEBA) with 1,3‐bis(3‐glycidyloxypropyl)tetramethyl disiloxane and DGEBA with tris(glycidyloxy)phosphine oxide: each in a ratio of 3 : 2 respectively. The synergistic effect of phosphorus/silicon with nitrogen on the thermal properties of the modified epoxy system was studied. The curing behavior of the epoxy resins formulated by the reaction of stoichiometric amounts of ES/EP with the synthesized DADIDAs were determined by differential scanning calorimetry, and the thermal stabilities of the cured epoxies were evaluated by thermogravimetric analyses (TGAs) under nitrogen and air. TGA indicated that the residual weight percentage of polymers at 800°C was in the range 36.4–60.0 in nitrogen, and in air, it was up to 6.5. However, the major loss in weight in air occurred at elevated temperature; this demonstrated their potential use as flame‐retardant epoxy systems for electronic/electrical encapsulants. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of zinc‐oxide‐free natural rubber nanocomposites using nanostructured magnesium oxide as cure activator

The effect of sol–gel synthesized magnesium oxide (MgO) nanoparticles as cure activator is studied for the first time in the vulcanization of natural rubber (NR) and compared with conventional zinc oxide (ZnO) in terms of cure, mechanical, and thermal properties. The NR vulcanizate with 1 phr (Parts per hundred parts of rubber) nano MgO shows an excellent improvement in the curing characteristics and the value of cure rate index is about 400% greater for NR vulcanizate containing 1 phr nano MgO in comparison to the NR vulcanizate with 5 phr conventional ZnO. Both mechanical and thermal properties of NR vulcanizate are found to be satisfactory in the presence of 1 phr nano MgO as cure activator in comparison to conventional NR vulcanizate. This study shows that only 1 phr nano MgO can successfully replace 5 phr conventional ZnO with better resulting properties in the sulfur vulcanization of NR. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42705.     

Preparation of submicrometer mesoporous iron–tin oxide hydroxide and its flame‐retardant and smoke‐suppressant properties on flexible poly(vinyl chloride)

A submicrometer mesoporous structured iron–tin oxide hydroxide [FeSnO(OH)₅] was synthesized via a hydrothermal method and characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and the Brunauer–Emmett–Teller method. Blank poly(vinyl chloride) (PVC) and a flexible PVC treated with FeSnO(OH)₅ were investigated by limiting oxygen index (LOI) testing, cone calorimetry testing (CONE), tensile properties testing, and thermogravimetric analysis (TGA)–differential scanning calorimetry. The PVC sample treated with 5 phr FeSnO(OH)₅ (PVC5) showed the best integration properties among the studied samples. Compared with those of the untreated PVC sample, the LOI value of PVC5 increased 5.6%, and its tensile strength also improved; the average heat‐release rate, average specific extinction area, and total smoke production of PVC5 decreased about 13.4, 28.0, and 48.8%, respectively. The char residue of PVC5 after CONE contained oxides and chlorides and was dense; this reduced the release of hydrogen chloride. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46218.     

Influence of methacryl polyhedral oligomeric silsesquioxane on the thermal and mechanical properties of methylsilicone resin

A methacryl polyhedral oligomeric silsesquioxane (POSS)‐reinforced methylsilicone resin was prepared in this work. The structures of the obtained products were confirmed with Fourier transform infrared and atomic force microscopy. The influence of methacryl‐POSS on the thermal behavior of the methylsilicone resin was studied by thermogravimetric analysis and isothermal thermogravimetric analysis. The results showed that the thermal stability of the methylsilicone resin was improved, and the degree of thermooxidative degradation was lowered; this was due to the retardation of polymer chain motion and the formation of a protective layer of SiO₂. The interlaminar shear strength and flexural strength of quartz fiber/methylsilicone resin composites were tested to determine the effects of methacryl‐POSS on the mechanical properties of methylsilicone resin. The results revealed that the mechanical properties of the methylsilicone composites also increased obviously after the incorporation of methacryl‐POSS because of the increase in the cure degree and rigidity of the resin. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Sb‐intercalated layered double hydroxides–poly(vinyl chloride) nanocomposites: Preparation,characterization, and thermal stability

In this study, a novel ‐intercalated layered double hydroxide (Sb‐LDH) was prepared by simultaneous recovering of LDH structures and intercalation of into LDH layers. The prepared Sb‐LDH composites remain the hydrotalcite structure with layered geometry and show higher thermal property than that of LDH. When applied to poly(vinyl chloride) (PVC) composites, Sb‐LDH showed limited thermal stability for PVC at the early stage of thermal and thermooxidative degradation processes. However, Sb‐LDH could retard the thermal cracking of the carbonaceous conjugated polyene of PVC which may hinder further degradation, and the moderate amount of Sb‐LDH (1, 2, and 5 wt %) in PVC resin can retard the process of decarbonation and enhance char formation. Sb‐LDH also promoted the transparency of PVC but darkened the color. With the advantages of transparency promotion, high temperature resistance, and long‐term stability, the prepared Sb‐LDH is a potential thermal stabilizer for PVC resins. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42524.     

Effect of nano‐titanium nitride on thermal insulating and flame‐retardant performances of phenolic foam

In this work, titanium nitride (TiN) nanoparticles were employed to achieve enhanced thermal insulation and flame retardance of phenolic foam (PF)/TiN nanocomposites (PFTNs) via in situ polymerization. The morphologies of PFTNs were observed by scanning electron microscope and the images showed that the PFTNs have more uniform cell morphologies compared with pure PF. Thermal insulating properties of PFTNs were evaluated by thermal conductivity tests. The introduction of TiN obviously decreased the thermal conductivities of PF over a wide temperature range (?20 to 60 °C). Significantly, the thermal conductivity of PFTNs gradually decreased as the temperature increased from 30 to 60 °C, showing a contrary tendency with that of pure PF. Moreover, the thermal stability and flame‐retardant properties of PFTNs were estimated by thermogravimetric analysis (TGA), UL‐94 vertical burning and limited oxygen index (LOI) tests, respectively. The TGA and LOI results indicated that PFTNs possess enhanced thermal stabilities and fire‐retardant performances with respect to the virgin PF. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43765.     

Clay‐Assisted dispersion of carbon black in thermoplastic nanocomposites

The poor dispersion of carbon black (CB) in thermoplastic polymers has provided a space for improving the various properties of nanocomposites. In this study, nanoclay (NC) was introduced into CB/thermoplastic composites to improve the dispersion of CB and, finally, to improve the thermal or mechanical performance. We noticed that there was a simultaneous enhancement in the mechanical and thermal performances of the nanocomposites because of the combination of the NC and CB. The information obtained from the mechanical and thermal studies indicated that the properties were improved to an appreciable extent because of the plastic–plastic/CB/NC combination. The tensile strength of polycarbonate (PC) was observed to be enhanced by 9.4% only because of the addition of CB, although when poly(methyl methacrylate) (PMMA) was used as a matrix material along with PC, the tensile strength improved by 25%, although the tensile strength of PMMA is much lower than that of PC. This confirmed that the tensile properties of the polymer composites also depended on the plastic–plastic interaction phenomenon. Moreover, the tensile strengths of the different blended nanocomposites system increased by around 42.5% with the addition of NC. A significant improvement of 22% was achieved in the thermal stability of the PMMA composites with the addition of CB. However, the addition of NC provided further improvement in the thermal decomposition temperature by only 3.7%. This showed that the thermal stability of the polymer nanocomposites was slightly affected by the addition of NC. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41477.     

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.