Effect of amine-terminated butadiene-acrylonitrile/clay combinations on the structure and properties of epoxy nanocomposites

The effect of the clay content and the method of its combination with amine-terminated butadiene-acrylonitrile (ATBN) on the structure and behavior of epoxy was studied. In the case of the simultaneous addition of both components, the increasing clay content had a very small effect on the size of the reaction-induced phase separation-formed particles at 5% rubber content due to predominant elimination of two major clay effects, i.e., the nucleation due to phase separation and the kinetics. As a result, both the time window between the onset of phase separation and vitrification and the viscosity at the cloud point did not change significantly. The minor change in the particle size/clay content dependences with different curing temperatures indicates that the balance between the two clay effects shifted. The corresponding study of the mechanical behavior indicated that the best balanced mechanical properties were obtained at certain clay/ATBN ratios, and thus, there was synergy between the components. Similar mechanical parameters were obtained for the application of both components in the form of ATBN/montmorillonite intercalate. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of vanadium pentoxide on the mechanical,thermal, and electrical properties of poly(vinyl alcohol)/vanadium pentoxide nanocomposites

In this study, we examined the effect of vanadium pentoxide (V₂O₅) on the mechanical, thermal, and morphological properties of poly(vinyl alcohol) (PVA)/V₂O₅ nanocomposites. The PVA/V₂O₅ nanocomposites were prepared by solution mixing, followed by film casting. The results show that the Young's moduli of the resulting nanocomposites films were higher than the pure PVA modulus with increasing V₂O₅ content, and it reached a maximum point at about 0.4 wt % V₂O₅ content at 8.55 GPa. The tensile strength and stress at break increased with increasing V₂O₅ content. The addition of V₂O₅ did not affect the melting temperature. The crystallization temperatures of PVA were significantly changed with increasing V₂O₅ content. The 5% weight loss degradation temperature of the nanocomposites was measured by thermogravimetric analysis. The degradation temperatures of the V₂O₅ nanocomposites increased with increasing filler content and were higher than the degradation temperature of pure PVA; this showed a lower thermal stability compared to those of the nanocomposites. The results show that the thermal stability increased with the incorporation of V₂O₅ nanoparticles. The dielectric constant of PVA had a tendency to improve when the dispersion of particles was effective. The morphology of the surfaces the nanocomposites was examined by scanning electron microscopy. We observed that the dispersion of the V₂O₅ nanoparticles was relatively good; only few aggregations existed after the addition of the V₂O₅ nanoparticles at greater than 0.4 wt %. In perspective, the addition of 0.4 wt % V₂O₅ nanoparticles into PVA maximized the mechanical, thermal, and electrical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of graphene/poly(vinyl alcohol) nanocomposites

Graphene (GE)‐based nanocomposites are emerging as a new class of materials that hold promise for many applications. In this article, we present a general approach for the preparation of GE/poly(vinyl alcohol) (PVA) nanocomposites. The basic strategy involved the preparation of graphite oxide from graphite, complete exfoliation of graphite oxide into graphene oxide sheets, followed by reduction to GE nanosheets, and finally, the preparation of the GE/PVA nanocomposites by a simple solution‐mixing method. The synthesized products were characterized by X‐ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetry, and differential scanning calorimetry analysis. The GE nanosheets were well dispersed in the PVA matrix, and the restacking of the GE sheets was effectively prevented. Because of the strong interfacial interaction between PVA and GE, which mainly resulted from the hydrogen‐bond interaction, together with the improvement in the PVA crystallinity, the mechanical properties and thermal stability of the nanocomposites were obviously improved. The tensile strength was increased from 23 MPa for PVA to 49.5 MPa for the nanocomposite with a 3.25 wt % GE loading. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of organoclay chemistry and morphology on properties of poly(lactic acid) nanocomposites

Poly(lactic acid) (PLA) nanocomposites with different layered organoclays (variation in the surface treatment of silicate) and one special nanofiller (mixed mineral thixotrope) were melt-compounded using a semi-industrial co-rotating twin-screw extruder. Effects of the silicate surface treatment and shape on the structure as well on processing and utility properties in PLA matrix were investigated. The structural changes in polymer matrix were evaluated from dynamic experiments in the shear flow using low-amplitude oscillatory measurements. Moreover, new approach for morphological investigation of nanocomposites using small-angle X-ray scattering was presented. Concerning utility properties, tests of mechanical and barrier properties were performed to compare enhancement of PLA matrix due to incorporation of different nanoparticles. Surprisingly, filling the PLA matrix with mixed mineral thixotrope resulted into very high material performance (in particular, significant improvement in barrier properties) compared to filling with commercial layered silicates. In this way, new type of nanofiller for PLA applications has been successfully tested.     

Preparation and characterization of poly(vinyl alcohol) nanocomposites made from cellulose nanofibers

A method using a combination of ball milling, acid hydrolysis, and ultrasound was developed to obtain a high yield of cellulose nanofibers from flax fibers and microcrystalline cellulose (MCC). Poly(vinyl alcohol) (PVA) nanocomposites were prepared with these additives by a solution‐casting technique. The cellulose nanofibers and nanocomposite films that were produced were characterized with Fourier transform infrared spectrometry, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. Nanofibers derived from MCC were on average approximately 8 nm in diameter and 111 nm in length. The diameter of the cellulose nanofibers produced from flax fibers was approximately 9 nm, and the length was 141 nm. A significant enhancement of the thermal and mechanical properties was achieved with a small addition of cellulose nanofibers to the polymer matrix. Interestingly, the flax nanofibers had the same reinforcing effects as MCC nanofibers in the matrix. Dynamic mechanical analysis results indicated that the use of cellulose nanofibers (acid hydrolysis) induced a mechanical percolation phenomenon leading to outstanding and unusual mechanical properties through the formation of a rigid filler network in the PVA matrix. X‐ray diffraction showed that there was no significant change in the crystallinity of the PVA matrix with the incorporation of cellulose nanofibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Surface and electrical characteristics of poly(amide imide)–poly(dimethylsiloxane) nanocomposites

A series of poly(amide imide)–poly(dimethylsiloxane) (PDMS) nanocomposites were fabricated through the reaction of poly(amide imide), epoxysilane (coupling agent), and diethoxydimethylsilane (DEDMS) via a sol–gel process. Nanocomposite films were obtained through the hydrolysis and condensation of DEDMS in poly(amide imide) solutions. The existence of the condensation product of DEDMS in the poly(amide imide) matrix was confirmed with Fourier transform infrared (FTIR). The concentration of PDMS on the surface of the poly(amide imide) matrix was observed through a comparison of FTIR and attenuated total reflection spectra. The contact angle of the poly(amide imide)–PDMS composites increased more than 40° with respect to that of pure poly(amide imide). The alternating‐current (ac) breakdown strength was obtained through the measurement of the ac breakdown voltage at the temperature of liquid nitrogen. As the PDMS concentration in poly(amide imide) increased, the characteristics of the insulation breakdown improved greatly. The best ac breakdown strength was observed in a poly(amide imide)–epoxysilane (30 wt %) nanocomposite with 30 wt % PDMS. The samples at the temperature of liquid nitrogen were brittle, as in a glassy state. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 342–347, 2004     

Thermal and mechanical properties of plasticized poly(L‐lactide) nanocomposites with organo‐modified montmorillonites

Nanocomposites of poly(lactide) (PLA) and the PLA plasticized with diglycerine tetraacetate (PL‐710) and ethylene glycol oligomer containing organo‐modified montmorillonites (ODA‐M and PGS‐M) by the protonated ammonium cations of octadecylamine and poly(ethylene glycol) stearylamine were prepared by melt intercalation method. In the X‐ray diffraction analysis, the PLA/ODA‐M and plasticized PLA/ODA‐M composites showed a clear enlargement of the difference of interlayer spacing between the composite and clay itself, indicating the formation of intercalated nanocomposite. However, a little enlargement of the interlayer spacing was observed for the PLA/PGS‐M and plasticized PLA/PGS‐M composites. From morphological studies using transmission electron microscopy, a finer dispersion of clay was observed for PLA/ODA‐M composite than PLA/PGS‐M composite and all the composites using the plasticized PLA. The PLA and PLA/PL‐710 composites containing ODA‐M showed a higher tensile strength and modulus than the corresponding composites with PGS‐M. The PLA/PL‐710 (10 wt %) composite containing ODA‐M showed considerably higher elongation at break than the pristine plasticized PLA, and had a comparable tensile modulus to pure PLA. The glass transition temperature (T_g) of the composites decreased with increasing plasticizer. The addition of the clays did not cause a significant increase of T_g. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Layer‐structured poly(vinyl alcohol)/graphene oxide nanocomposites with improved thermal and mechanical properties

Layer‐structured poly(vinyl alcohol)/graphene oxide nanocomposites in the form of films are prepared by simple solution processing. The structure and properties of these nanocomposites are studied using X‐ray diffractions, scanning electron microscopy, Fourier‐transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The results indicate that graphene oxide is dispersed on a molecular scale and aligned in the poly(vinyl alcohol) matrix, and there exists strong interfacial interactions between both components, which are responsible for the significant improvement in the thermal and mechanical properties of the nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Morphology and mechanical properties of polymer nanocomposites with a poly(hydroxy ether of bisphenol A) matrix

The poly(hydroxy ether of bisphenol A) (phenoxy (Ph)) has been revealed as a polymeric matrix able to intercalate in, and partially exfoliate a commercial organically modified montmorillonite. Dispersion was attributed to chemical interactions between the Ph and the inorganic clay. A significant increase in the modulus of elasticity (33% with 3.8% montmorillonite (MMT) addition) was observed, together with an unusual increase in ductility attributed to surfactant migration, that should allow tailoring of the processing conditions to widen exfoliation. Ph‐based nanocomposites could be used as a nanostructured masterbatch for producing new polymer nanocomposites by mixing the masterbatch with the polymeric matrices that either miscibilize or are compatible with Ph. Copyright © 2006 Society of Chemical Industry     

Development of poly(dimethylsiloxane)–titania nanocomposites with controlled dielectric properties: Effect of heat treatment of titania on electrical properties

Polymer–ceramic composites were prepared using poly(dimethylsiloxane) as base matrix and normal as well as heat‐treated titania as fillers. Dielectric and mechanical properties of the composites were measured and found that dielectric constant of the composites was increased dramatically with the addition of filler, whereas resistivity was decreased. Hardness and modulus were found to increase but tensile strength, % elongation at break, and tear strength were decreased with the filler loading. Neat titania contains some moisture (physisorbed and chemisorbed) as revealed from thermogravimetric analysis. Both electrical and mechanical properties of the composites were affected by filler heat treatment. Further, untreated titania contains Ti³⁺ and Ti⁴⁺, which on heat treatment, increases the concentration of Ti⁴⁺, as a result electrical properties were affected. Filler dispersion in the composites was studied by field emission scanning electron microscopy and high resolution transmission electron microscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of graphene/poly(vinyl alcohol) nanocomposites with enhanced mechanical properties and water resistance

The control and dispersal of graphene nanosheets in polymer hosts are challenges in the development of high‐performance graphene‐based nanocomposites due to the strong interlayer cohesive energy and surface inertia. Here we report a simple and practical approach to synthesize graphene‐reinforced poly(vinyl alcohol) (PVA) composite films by incorporating graphene oxide and graphene into PVA aqueous solution. The resulting nanocomposites revealed increases of up to 212% in tensile strength and 34% in elongation at break with only 0.5 wt% graphene content. Water absorption measurements showed that the water absorption ratio of the graphene/PVA composites decreased from 105.2 to 48.8%, and the barrier properties were obviously improved. Contact angle measurements showed that the composites were hydrophobic (θ > 90°) in contrast to the highly hydrophilic (θ < 90°) pure PVA. Copyright © 2011 Society of Chemical Industry     

Effect of ZnS nanofiller and temperature on mechanical properties of poly(methyl methacrylate)

This article deals with the study of some mechanical properties of ZnS/poly(methyl methacrylate) nanocomposites prepared by solution casting method. The obtained ZnS/PMMA nanocomposites have ZnS nanoparticles in (0, 2, 4, 6, and 8) wt % and characterized through X‐ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and Fourier transform infrared (FTIR) spectroscopy measurements. Mechanical properties of ZnS/PMMA nanocomposites have been determined at different temperatures (30°C, 50°C, 70°C, and 90°C) through their stress–strain behavior using dynamic mechanical analyzer (DMA). The properties have been found to increase upto 6 wt % of ZnS nanoparticles and then decrease for 8 wt % of ZnS nanoparticles. A theoretical model has also been employed to predict the strain softening and strain hardening of the material. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of organic modification on mechanical properties of melt processed intercalated poly(methyl methacrylate)–organoclay nanocomposites

The influence of organic modifiers on intercalation extent, structure, thermal and mechanical properties of poly(methyl methacrylate) (PMMA)–clay nanocomposites were studied. Two different organic modifiers with varying hydrophobicity (single tallow versus ditallow) were investigated. The nanocomposites were prepared from melt processing method and characterized using wide angle X‐ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. Mechanical properties such as tensile modulus (E), break stress (σ_brk), and % break strain (ε_brk) were determined for nanocomposites at various clay loadings. Extent of PMMA intercalation is sufficient and in the range 9–15 Å depending on organoclay and filler loading. Overall thermal stability of nanocomposites increases by 16–30°C. The enhancement in T_g of nanocomposite is merely by 2–4°C. With increase in clay loading, tensile modulus increases linearly while % break strain decreases. Break stress is found to increase till 4 wt % and further decreases at higher clay loadings. The overall improvement in thermal and mechanical properties was higher for the organoclay containing organic modifier with lower hydrophobicity and single tallow amine chemical structure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Thermal and mechanical properties of poly(butylene succinate) nanocomposites with various organo‐modified montmorillonites

Nanocomposites based on biodegradable poly(butylene succinate) (PBS) and layered silicates were prepared by melt intercalation. Nonmodified montmorillonite (MMT) and MMTs (DA‐M, ODA‐M, ALA‐M, LEA‐M, and HEA‐M) organo‐modified by protonated ammonium cations {i.e., those of dodecylamine, octadecylamine, 12‐aminolauric acid, N‐lauryldiethanolamine, and 1‐[N,N‐bis(2‐hydroxyethyl)amino]‐2‐propanol, respectively} were used as layered silicates. From morphological studies using transmission electron microscopy, DA‐M, ODA‐M, and LEA‐M were found to be dispersed homogeneously in the matrix polymer, whereas some clusters or agglomerated particles were observed for ALA‐M, HEA‐M, and MMT. The enlargement of the difference in the interlayer spacing between the clay and PBS/clay composite, as measured by X‐ray diffraction, had a good correlation with the improvement of the clay dispersion and with the increase in the tensile modulus and the decrease in the tensile strength of the PBS composites with an inorganic concentration of 3 wt %. Dynamic viscoelastic measurements of the PBS/LEA‐M nanocomposite revealed that the storage modulus and glass‐transition temperature increased with the inorganic concentration (3–10 wt %). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1463–1475, 2004     

Interface adjustment between poly(ethylene terephthalate) and graphene oxide in order to enhance mechanical and thermal properties of nanocomposites

There is great interest in the use of graphene and derivatives in the production of polymer nanocomposites as it provides improvements in the properties of the materials to which they are associated. Such improvements depend heavily on filler dispersion and the interaction between the nanomaterials and the matrix. This work aimed to study the compatibility of graphene oxide (GO) with a poly(ethylene terephthalate) matrix. For this, graphite was modified using Hummers method, using reaction times of 3 and 6 h. The obtained GO was functionalized with amine, amide, and magnetite groups (FGO). The effects of the oxidation degree, functionalization and concentration of the nanofillers on the dispersion and consequently on the properties of the polymer nanocomposites were evaluated. The nanocomposites were synthesized by the solid–solid deposition method followed by the melt mixing technique. It was observed that lower concentrations of nanofiller associated with the lower degree of oxidation and functionalization improved the interaction of the nanofillers with the matrix, which resulted in better mechanical properties under tensile stresses for strain at break, maximum stress, Young's modulus and toughness. It was also observed that the glass transition and crystallization of nanocomposites increased due to a nucleating effect of the nanofillers.     

Using maleic anhydride grafted poly(lactic acid) as a compatibilizer in poly(lactic acid)/layered‐silicate nanocomposites

The goal of this work was to prepare exfoliated poly(lactic acid) (PLA)/layered‐silicate nanocomposites with maleic anhydride grafted poly(lactic acid) (PLA–MA) as a compatibilizer. Two different layered silicates were used in the study: bentonite and hectorite. The nanocomposites were prepared by the incorporation of each layered silicate (5 wt %) into PLA via solution casting. X‐ray diffraction of the prepared nanocomposites indicated exfoliation of the silicates. However, micrographs from transmission electron microscopy showed the presence of intercalated and partially exfoliated areas. Tensile testing showed improvements in both the tensile modulus and yield strength for all the prepared nanocomposites. The results from the dynamic mechanical thermal analysis showed an improvement in the storage modulus over the entire temperature range for both layered silicates together with a shift in the tan δ peak to higher temperatures. The effect of using PLA–MA differed between the two layered silicates because of a difference in the organic treatment. The bentonite layered silicate showed a more distinct improvement in exfoliation and an increase in the mechanical properties because of the addition of PLA–MA in comparison with the hectorite layered silicate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1852–1862, 2006     

The effect of processing routes on the thermal and mechanical properties of poly(urethane‐isocyanurate) nanocomposites

A systematic investigation of four processing routes was implemented so as to evaluate the thermal and mechanical properties of nanosilica (NS) reinforced poly(urethane‐isocyanurate) nanocomposites (NC). The NS dispersion in the Polmix and the Isomix routes was performed in the polyol and the isocyanate precursor, respectively. The Isopol and the Solvmix routes consisted on the dispersion of the filler after the mixing of the precursors and with the aid of solvents, respectively. The NS dispersion, fractography (SEM, TEM), flexural and tensile mechanical properties, thermogravimetric analysis and FTIR analysis of NCs was performed as a function of processing route, isocyanate index, and NS concentration. Each route produced a NC with distinct properties, which were correlated to the NS agglomeration degree and how the NS affected the thermal transitions of the HS and the relative ratio of urethane and isocyanurate chemical groups. For example, the NC prepared with the Polmix route had substantial improvements of σ_t and ε_t of around +40 and +52%, respectively and an improved thermal resistance of the Hard Segments. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42750.     

Processing and properties of carbon nanotube/poly(methyl methacrylate) composite films

A systematic study of the reinforcement of single‐walled carbon nanotubes (SWNTs), multiwalled carbon nanotubes, and vapor‐grown carbon nanofibers (VGCNFs) in poly(methyl methacrylate) (PMMA) is reported. SWNT/PMMA composite films with various SWNT concentrations (from 0.5 to 50 wt % with respect to the weight of PMMA) were processed from nitromethane. Two types of SWNTs were used: SWNT‐A, which contained 35 wt % metal catalyst, and SWNT‐B, which contained about 2.4 wt % metal catalyst. Properties of different nanotubes containing composites were compared with 15 wt % carbon nanotubes (CNTs). Property enhancement included electrical conductivity, mechanical properties, and solvent resistance. The thermal degradation of PMMA in the presence of CNTs in air and nitrogen environments was studied. No variation in the thermal degradation behavior of PMMA/CNT was observed in nitrogen. The peak degradation temperature increased for the composites in air at low CNT loadings. Dynamic and thermomechanical properties were also studied. At a 35 wt % SWNT loading, a composite film exhibited good mechanical and electrical properties, good chemical resistance, and a very low coefficient of thermal expansion. Property improvements were rationalized in terms of the nanotube surface area. Composite films were also characterized with Raman spectroscopy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

环氧树脂/蒙脱土纳米复合材料的制备和性能

利用插层法制备了环氧树脂/蒙脱土纳米复合材料。X射线衍射分析表明,改性使蒙脱土层间距变大,制备出的环氧树脂/蒙脱土纳米复合材料剥离结构较好。性能测试表明,复合材料的力学性能和热性能均比纯环氧树脂有所提高:拉伸强度提高了70.8%,无缺口冲击强度提高了64.5%,热变形温度提高了17.7℃。     

PP/黏土纳米复合材料的结构与性能

采用熔体插层法制备聚丙烯（PP）/有机黏土（OMMT）纳米复合材料。XRD和TEM的测试结果表明,采用熔体插层法制备的PP/OMMT复合材料是剥离型纳米复合材料。力学性能实验结果表明,相容剂的加入提高了PP与OMMT之间的相互作用,使其各项力学性能都得到了提高;PP/OMMT纳米复合材料的各项力学性能在有机黏土含量较小的情况下,就可以有较大幅度的提高;与纯PP相比,相容剂含量为10 phr、有机黏土用量为1 phr的聚丙烯基纳米复合材料具有最好的各项力学性能。