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1.
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.  相似文献   

2.
The rubber nanocomposites containing ethylene vinyl acetate (EVA) having 60 wt % of vinyl acetate content and organomodified layered double hydroxide (DS‐LDH) as nanofiller have been prepared by solution intercalation method and characterized. The XRD and TEM analysis demonstrate the formation of completely exfoliated EVA/DS‐LDH nanocomposites for 1 wt % filler loading followed by partially exfoliated structure for 5–8 wt % of DS‐LDH content. EVA/DS‐LDH nanocomposites show improved mechanical properties such as tensile strength (TS) and elongation at break (EB) in comparison with neat EVA. The maximum value of TS (5.1 MPa) is noted for 3 wt % of DS‐LDH content with respect to TS value of pure EVA (2.6 MPa). The data from thermogravimetric analysis show the improvement in thermal stability of the nanocomposites by ≈15°C with respect to neat EVA. Limiting oxygen index measurements show that the nanocomposites act as good flame retardant materials. Swelling property analysis shows improved solvent resistance behavior of the nanocomposites (1, 3, and 5 wt % DS‐LDH content) compared with neat EVA‐60. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

3.
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  相似文献   

4.
Guo-An Wang  Chuh-Yung Chen 《Polymer》2005,46(14):5065-5074
A new nanocomposite—disorderly exfoliated layered double hydroxides/poly(methyl methacrylate) (LDHs/PMMA)—was prepared by a two-stage process with an in situ bulk polymerization of methyl methacrylate (MMA) in the presence of 10-undecenoate intercalated LDH (LDH-U). The LDH-U was prepared using the co-precipitation method. The structural and compositional details of the LDH-U were determined by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), 27Al and 13C magic-angle spinning nuclear magnetic resonance (27Al and 13C MAS NMR), elemental analysis (EA), inductively coupled plasma-mass (ICP) and transmission electron microscopy (TEM). During the preparation of LDHs/PMMA nanocomposite, XRD and TEM were also employed to monitor the formation of the exfoliated LDHs/PMMA nanocomposite and the dispersion behavior of the LDH layers, respectively. The pre-polymerization process exfoliates LDH layers within pre-polymer, according to the XRD and TEM results. Additionally, the LDHs/PMMA nanocomposite contained 5 wt% LDH-U, indicating that the LDH layers were well exfoliated and dispersed in the PMMA matrix in a disordered fashion.  相似文献   

5.
The preparation of surface-modified layered double hydroxides/unsaturated polyester (LDH/UP) nanocomposites were performed. By in situ coprecipitation, LDHs, modified through grafting of vinyltriethoxysilane (VTS) carrying a double bond using the anionic surfactant sodium dodecyl sulfate (SDS), were used as nanofillers for unsaturated polyester (UP). The morphology of LDH and nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM). Moreover, the thermal properties were determined by thermogravimetric analysis (TGA) and thermal degradation mechanism was discussed.  相似文献   

6.
In this contribution, polyvinylpyrrolidone (PVP) nanocomposites (NCs) with novel chiral diacid intercalated layered double hydroxides (LDHs) as nanofillers were prepared via ultrasonic irradiation. Chiral LDH was synthesized in one step via a co-precipitation reaction in aqueous solution under ultrasonic irradiation. The modified Mg-Al LDH shows an increase in interlayer distance as compared to the unmodified Mg-Al LDH by X-ray diffraction (XRD). Different NCs of organo-modified chiral LDHs and PVP were constructed by means of an ultrasonic process. The structures of these new materials were investigated by XRD, Fourier transform infrared, field emission scanning electron microscopy and transmission electron microscopy techniques. XRD and electron microscopy results confirmed the delaminated state of the LDH in the PVP matrix. Furthermore, thermal analysis was evaluated and the prepared NCs show significantly improved thermal stability at higher temperature because of the homogeneous and good dispersion of modified LDH in polymeric matrix.  相似文献   

7.
The synthesis of poly(ethylene terephthalate) (PET)/layered double hydroxide (LDH) nanocomposites through microwave methods has been investigated. To enhance the compatibility between the PET polymer and the LDH, dodecyl sulfate was intercalated in the lamellar structure. The organo‐LDH structure was confirmed by powder X‐ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR). PET nanocomposites were prepared with 0–10 wt % of LDH content by in situ microwave‐assisted polymerization. PXRD was used to detect the formation of the exfoliated PET/LDH nanocomposites. Transmission electron microscopy was used to observe the dispersed layers and to confirm the exfoliation process. FTIR spectroscopy confirmed that the polymerization process had occurred. TG and DTA are used to study changes in thermal stability of the nanocomposites, which resulted enhanced by well dispersed LDHs layers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

8.
In order to investigate whether the particle sizes of inorganic additives in polymer have an influence on the flame‐retardant and other properties of the polymer, five types of Mg3Al–CO3 layered double hydroxide (LDHs) with particle diameters of 80–100, 200–350, 500–550, 550–600, and 700–900 nm were synthesized using a hydrothermal method. The obtained Mg3Al–CO3 LDHs were treated using the aqueous miscible organic solvent treatment method to give highly dispersed platelets in Polypropylene (PP). The thermal stability, flame retardancy, and mechanical properties of the PP/AMO–LDH nanocomposites were investigated systematically. The results showed that the thermal stability and flame retardancy of PP could be improved after incorporating AMO–LDHs. The temperature at 50% weight loss (T0.5) of PP/LDH (700–900 nm) nanocomposites with a LDH loading of 15 wt % was increased by 57 °C. When the LDHs loading was 40 wt %, the peak heat release rate (PHRR) of the PP/LDH nanocomposites with small LDHs particle sizes (<350 nm) was decreased by ca. 58%. The limiting oxygen index was increased by 5% for PP/LDH (80–100 nm) nanocomposites. The response surface regression results also indicated that both LDH particle size and loading have influence on PHRR, heat release capacity, tensile strength, and elongation at break. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46204.  相似文献   

9.
The focus of the current study is to investigate the influence of Co–Al layered double hydroxide (LDH) on the morphological, thermal, and mechanical features of poly(methyl methacrylate) (PMMA)‐based nanocomposites. Sodium dodecyl sulfate modified Co–Al LDH was synthesized by single step coagulation method. The PMMA nanocomposites containing different loadings of nanofiller (1–7 wt %) and polystyrene‐grafted maleic anhydride compatibilizer (5 wt %) were melt intercalated via twin screw extruder and later subjected to injection molding to prepare mechanical testing samples. The different properties of PMMA nanocomposites were studied by using XRD, TEM, FTIR, DSC, TGA, tensile, flexural, impact, and flammability analysis. The result of XRD analysis suggested the exfoliated morphology of the nanocomposite while the TEM demonstrated the intercalated structure at higher loading of LDH. The thermal characterization results revealed that thermal properties were improved by the addition of Co–Al LDH, whereas the flammability test exposed that dripping was minimum at 7 wt % loading. The mechanical properties exhibited that optimum results were obtained at 1 wt % loading of Co–Al LDH. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45774.  相似文献   

10.
Ethylene propylene diene terpolymer (EPDM)/MgAl layered double hydroxide (LDH) nanocomposites have been synthesized by solution intercalation using organically modified LDH (DS-LDH). The molecular level dispersion of LDH nanolayers has been verified by the disappearance of basal XRD peak of DS-LDH in the composites. The internal structures, of the nanocomposite with the dispersion nature of LDH particles in EPDM matrix have been studied by TEM and AFM. Thermogravimetric analysis (TGA) shows thermal stability of nanocomposites improved by ≈40 °C when 10% weight loss was selected as point of comparison. The degradation for pure EPDM is faster above 380 °C while in case of its nanocomposites, it is much slower.  相似文献   

11.
Nanocomposites of poly(vinyl alcohol) (PVA) with Mg‐Al layered double hydroxides (LDHs) were prepared with different compositions, viz., 2, 4, 6, and 8 wt %, of LDH, by solution‐intercalation method. The effect of LDH contents on thermal, physicomechanical, and morphological property of PVA films were investigated. Differential scanning calorimetric analysis reveals that LDH layers promote a new crystalline phase for PVA. The tensile analysis of PVA/LDH nanocomposites indicates reduction in tensile strength and modulus with change in LDH concentration and moisture. The microstructure analysis by optical microscopy and scanning electron microscopy demonstrates exfoliation and dispersion of LDHs in the PVA matrix in a disorderly fashion. The primary focus of the present investigation is to explore the potential of LDHs as nanofiller in a polyhydroxy polymer without surface modification. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

12.
A series of poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) loaded with various contents of layered double hydroxides (LDHs) nanoparticles were prepared via a melt mixing method. Detailed investigations on LDH dispersion state in the polymeric matrix conducted by TEM revealed intercalated/exfoliated, and agglomerated structures at low (1 wt %) and high (>3 wt %) loadings of LDH contents, respectively. Wide angle X‐ray scattering and DSC results showed that incorporation of LDH into PVDF‐HFP matrix reduced its overall crystallinity and helped to form polar crystallites, while the crystal size at 020 crystallographic directions was found to be most affected by presence and dispersion state of LDH in the matrix. TGA results showed LDH improved thermal stability of matrix however, unlike many other nanomaterials it significantly reduced the residual mass which highlights catalytic role of LDH in degradation of residual carbon char. Detailed analysis on creep and recovery data over wide range of selected temperatures revealed that the creep compliance of nanocomposites are basically controlled by crystallinity and presence of LDH at low and high temperatures, respectively. Based on obtained storage modulus and creep compliance master curves it was also found that the influence of LDH on decreasing the creep compliance and improving viscoelastic properties of PVDF‐HFP over long time period and over high frequency ranges becomes more pronounced. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46352.  相似文献   

13.
Layered double hydroxides/epoxy (LDHs/EP) nanocomposites were prepared from organo-modified LDHs, a diglycidyl ether of bisphenol A monomer (DGEBA) and amine curing agents. The organo-modified LDHs were obtained by ionic exchange of a magnesium-aluminum carbonate LDH in an acid medium. X-ray diffraction and transmission electron microscopy showed a dispersion of the layers at a nanometer scale, indicating the formation of LDH/EP nanocomposites. The thermal degradation and flame resistance properties of LDH/EP nanocomposites, montmorillonite-epoxy (MMT/EP) nanocomposites, LDH/EP microcomposites and aluminum hydroxide-epoxy microcomposites were compared by thermogravimetrical analyses, simultaneous thermal analyses, UL94 and cone calorimeter tests. Only LDH/EP nanocomposites showed self-extinguishing behavior in the horizontal UL94 test; LDH/EP microcomposites and MMT/EP nanocomposites samples burned completely showing that the unique flame resistance of LDH/EP nanocomposites is related to both the level of dispersion and the intrinsic properties of LDH clay. Furthermore, cone calorimeter revealed intumescent behavior for LDH/EP nanocomposites and a higher reduction in the peak heat release rate compared to MMT/EP nanocomposites.  相似文献   

14.
Polystyrene (PS)/ZnAl layered double‐hydroxide (LDH) nanocomposites were synthesized via in situ emulsion and suspension polymerization in the presence of N‐lauroyl‐glutamate surfactant and long‐chain spacer and characterized with elemental analysis, Fourier transform infrared spectrum, X‐ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis. The XRD and TEM results demonstrate that the exfoliated ZnAl–LDH layers were well dispersed at molecular level in the PS matrix. The completely exfoliated PS/LDH nanocomposites were obtained even at the 20 and 10 wt % LDH loadings prepared by emulsion polymerization and suspension polymerization, respectively. The PS/LDH nanocomposites with a suitable amount of LDH showed apparently enhanced thermal stability. When the 50% weight loss was selected as a comparison point, the decomposition temperature of the exfoliated PS/LDH sample prepared by emulsion polymerization with a 5 wt % LDH loading was about 28°C higher than that of pure PS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3758–3766, 2006  相似文献   

15.
Polystyrene (PS)/layered double hydroxide (LDH) nanocomposites were synthesized by in situ free radical bulk polymerization. LDH formed by magnesium and aluminum (Mg:Al—molar ratio of 2:1) was prepared by coprecipitation method and intercalated with sodium dodecyl sulfate (DDS). The nanocomposites were characterized by X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and flammability test. The XRD and TEM demonstrated that synthesized nanocomposites in all compositions studied showed a high global dispersion of LDH in PS, suggesting exfoliation. The results of TGAs (when 50% mass loss was selected as a comparison point) and flammability tests for synthesized nanocomposites, presented a significant improvement in thermal stability and flammability property when compared with pure PS. This behavior and properties indicate application of the surfactant intercalated LDH reinforced PS in fields where thermal stability is an important characteristic. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers  相似文献   

16.
《Polymer Composites》2017,38(8):1680-1688
Various layered double hydroxides (LDHs), including MgAl, CoAl, NiAl, and ZnAl‐LDHs, were synthesized and modified using sodium dodecyl benzene sulfonate. Nonhalogen flame‐retardant PS/LDHs nanocomposites were prepared via melt mixing method. The structure of PS/LDHs nanocomposites was investigated by Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD) pattern technique, and scanning electronic microscope. Results from XRD indicated that intercalated/exfoliated structure was achieved in the polystyrene matrix. Dynamic mechanical thermal analysis suggested that the storage modulus and T g for the PS/LDHs nanocomposites was efficiently improved. Thermal and flammability properties of PS nanocomposites were investigated using thermogravimetry and cone calorimetry. Thermal analysis was evaluated and the prepared nanocomposites showed slightly lower thermal stability probably due to the presence of LDH, which starts to decompose at a lower temperature. Compared with neat PS, the peak heat release rate of PS/MgAl and PS/ZnAl‐LDHs nanocomposites filled with 5 wt% LDHs is reduced by 7% and 12%, respectively. Among all LDHs, MgAl, and ZnAl‐LDHs had a better smoke suppression effect with a reduction of peak smoke production rate and CO release rate of 37% and 44%, respectively. POLYM. COMPOS., 38:1680–1688, 2017. © 2015 Society of Plastics Engineers  相似文献   

17.
Wan Duk Lee  Hyung-Mi Lim 《Polymer》2006,47(4):1364-1371
Thermal, rheological and mechanical properties of layered double hydroxide (LDHs)/PET nanocomposites were investigated. To enhance the compatibility between PET matrix and LDHs, organic modification of parent LDH having carbonate anion was carried out using various anionic surfactants such as dodecylsulfate (DS), dodecylbenzenesulfonate (DBS), and octylsulfate(OS) by rehydration process. Then, PET nanocomposites with LDH content of 0, 1.0, and 2.0 wt% were prepared by direct melt-compounding. The dispersion morphologies were observed by transmission electron microscopy and X-ray diffraction, indicating that LDH-DS were exfoliated in PET matrix. From the rheology study, there are some network structures owing to filler-filler and/or filler-matrix interactions in nanocomposite systems. Consequently, DS intercalated LDH provided good compatibility with PET molecules, resulting in exfoliated LDH-DS/PET nanocomposites having enhanced thermal and mechanical properties as compared to other nanocomposites as well as homo PET.  相似文献   

18.
The terephthalate‐intercalated LDHs (TA‐LDHs) are used to improve the barrier properties of poly(ethylene terephthalate) (PET) for their application in liquid food packaging. First, TA‐LDHs were synthesized from freshly prepared metal hydroxides. PET/LDH nanocomposites were then prepared by a masterbatch process. The structures and morphologies of TA‐LDHs and PET/LDH nanocomposites were characterized using X‐ray diffractometer, transmission electronic microscopy, and scanning electron microscope. The mechanical performances and the oxygen permeability of the PET/LDH composites were measured using a precision universal tester and differential pressure gas permeameter, respectively. The influence of TA‐LDH content on their structures and properties was studied. PET/LDH nanocomposites with 1 and 2 wt% of TA‐LDHs are partially exfoliated nanocomposites, while PET/LDH with 5 wt% of TA‐LDHs is an intercalated nanocomposite. The PET/LDH nanocomposites prepared by a masterbatch process show better mechanical properties and gas barrier properties. PET/LDHs‐m2 with 2 wt% of TA‐LDHs could offer up to a 29.4% improvement in tensile strength over PET and the Young's modulus is increased by 38.9%. The O2 permeation of PET/LDHs‐m2 with 2 wt% of TA‐LDHs is decreased by 46.2%. POLYM. ENG. SCI., 59:E366–E371, 2019. © 2019 Society of Plastics Engineers  相似文献   

19.
The synergistic effects of exfoliated layered double hydroxides (LDH) with some halogen‐free flame retardant (HFFR) additives, such as hyperfine magnesium hydroxide (HFMH), microencapsulated red phosphorus (MRP), and expandable graphite (EG), in the low‐density polyethylene/ethylene vinyl acetate copolymer/LDH (LDPE/EVA/LDH) nanocomposites have been studied by X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermal analysis (TGA and DTG), mechanical properties, limiting oxygen index (LOI), and UL‐94 tests. The XRD results show that EVA as an excellent compatilizer can promote the exfoliation of LDH and homogeneous dispersion of HFMH in the LDPE/EVA/HFMH/LDH nanocomposites prepared by melt‐intercalation method. The TEM images demonstrate that the exfoliated LDH layers can act as synergistic compatilizer and dispersant to make the HFMH particles dispersed homogeneously in the LDPE matrix. The results from the mechanical, LOI, and UL‐94 tests show that the exfoliated LDH layers can also act as the nano‐enhanced and flame retardant synergistic agents and thus increase the tensile strength, LOI values, and UL‐94 rating of the nanocomposites. The morphological structures of charred residues observed by SEM give the positive evidence that the compact charred layers formed from the LDPE/EVA/HFMH/LDH nanocomposites with the exfoliated LDH layers play an important role in the enhancement of flame retardant and mechanical properties. The TGA and DTG data show that the exfoliated LDH layers as excellent flame retardant synergist of MRP or EG can apparently increase the thermal degradation temperature and the charred residues after burning. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

20.
Francis Reny Costa 《Polymer》2005,46(12):4447-4453
Low density polyethylene (LDPE)/Mg-Al layered double hydroxide (LDH) nanocomposites have been synthesized with different compositions by melt-mixing technique using maleic anhydride grafted polyethylene as compatibilizer. LDH has been modified by sodium dodecylbenzene sulfonate using reconstruction method and characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The nanocomposites are characterized by different techniques such as, transmission electron microscopy (TEM), XRD and rheology. The TEM analysis shows a complex nature of particle dispersion in the polymer matrix with wide distribution of particles sizes and shapes. The rheological analysis showed significant changes in linear viscoelastic responses of the composites, even at very low concentration (2 phr) of LDH materials, in comparison to the pure polymer in low frequency regime in dynamic frequency sweep experiments. These changes are related to the LDHs-polymer chains interactions resulting in network-like structure.  相似文献   

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