Preparation and Properties of 2,6‐Diamino‐3,5‐dinitropyrazine‐1‐oxide based Nanocomposites

With estane as binder, a new nanocomposite energetic material based on 2,6‐diamino‐3,5‐dinitropyrazine‐1‐oxide (LLM‐105) was successfully prepared by the spray drying method. Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), and X‐ray diffraction (XRD) was employed to characterize the nanocomposite samples. The impact sensitivity and thermal decomposition properties of the nanocomposites were also measured and analyzed. The results show that the nanocomposite particles are spherical in shape and range from 1 μm to 10 μm in size. The composite is aggregated of many tiny granules with nucleus/shell structure, in which the shell thickness and crystal size of LLM‐105 are about 20 nm and 50–100 nm. The crystal type of LLM‐105 in the nanocomposite is similar to that of raw LLM‐105, however, the diffraction peaks become weaker and wider mainly due to decreasing of particle size. The nanocomposite has lower impact sensitivity and better thermal stability.     

Correlation between micro/nano-structure,mechanical and tribological properties of copper-zirconia nanocomposites

Fine-grained copper (Cu) and copper-zirconia (Cu–ZrO₂) nanocomposites were produced by high-energy ball milling up to 20 h. Scan Electron Microscope (SEM), Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD), microhardness, wear rate and coefficient of friction measurements were performed to investigate the correlation between micro/nano-structure changes of powder and consolidated samples and the properties of the produced nanocomposites. Cu and Cu–15%ZrO₂ nanocomposites with 49.3 and 24.4 nm crystal size, respectively, were produced after 20 h milling achieving 1.76- and 3-times larger hardness than the as received Cu. The wear rate of milled Cu was slightly decreased than the as received Cu, however, it was highly reduced for Cu–15%ZrO₂ nanocomposites reaching 10-times lower than the as received Cu. SEM, TEM and XRD analysis revealed that four main strengthening mechanisms lead to the great improvement of Cu–ZrO₂ nanocomposites properties. The major strength improvement occurred due to Orowan and dislocation strengthening mechanisms activated by the well dispersion of ZrO₂ nanoparticles in Cu matrix and their impedance to dislocation movement, respectively. Besides these two main strengthening mechanisms, work hardening and grain refinement acted as minor strengthening mechanisms for Cu–ZrO₂ nanocomposites while they are the main strengthening mechanisms of Cu samples.     

Preparation of monodispersed silica spheres and electrospinning of poly(vinyl alcohol)/silica composite nanofibers

In this study, monodispersed silica spheres were successfully synthesized by seed‐growth method and they can be highly dispersed in the poly(vinyl alcohol)(PVA) solution. PVA/silica composite fibers were fabricated by electrospinning the composite solutions containing different amount of silica. Further investigation showed that the size distribution of silica sphere was monodispersed and the spheres were homogeneously dispersed in the fibers individually. The composite fibers showed an uniform and continuous morphology with a average diameter of 298–345 nm. The as‐spun nanofibers were characterized by Field Emission Scanning Electron Microscope (FE‐SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and thermal gravimetric analysis (TGA). POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Synthesis and characterization of styrene butadiene rubber—Bentonite clay nanocomposites

In the present study, naturally occurring unfractionated bentonite clay was used to prepare styrene butadiene rubber/bentonite clay nanocomposite by latex stage blending. The bentonite clay was organo‐modified by in situ resol formation by the reaction of resorcinol and formaldehyde. The latex clay mixture was co‐coagulated with acid. The resulting clay masterbatch was compounded and evaluated by Fourier Transform Infrared spectroscopy, X‐ray diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X‐ray spectroscopy (EDS), Scanning Electron Microscopy, Thermogravimetric analysis, and Differential Scanning Calorimetry. XRD showed that the interplanar distance of the in situ resol‐modified bentonite clay increased from 1.23 to 1.41 nm for the unmodified bentonite. TEM analysis indicated partial exfoliation and/or intercalation. EDS (Si and Al mapping) of the clay revealed the nature of the dispersion in the nanocomposites vis‐à‐vis the conventional styrene‐butadiene rubber (SBR)/bentonite clay composite. Thermogravimetric analysis was used to compare the decomposition trends of the SBR/clay nanocomposites with the SBR/clay composite. The glass transition temperature of SBR/clay nanocomposites increased as compared with that of neat SBR. Substantial improvement in most of the other mechanical properties was also observed in case of the nanocomposites. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Effect of the clay size on the dispersion morphology and emulsion stability of ABS/layered silicate nanocomposites

ABS/layered silicate nanocomposites were synthesized through an emulsion polymerization with different sizes of silicates. The particle sizes of Laponite, Cloisite‐Na and Kunipia‐F are about 20–30, 70–150, and 300–500 nm, respectively. When ABS was synthesized by the emulsion polymerization in the presence of Laponite and Cloisite‐Na, ABS/layered silicate nanocomposite emulsion showed a stable suspension without the precipitation of solid particle. On the other hand, ABS/layered silicate nanocomposite synthesized with Kunipia‐F showed the precipitation of large aggregated particles and the phase separation. Smaller sizes of silicates like Laponite and Cloisite‐Na than polymerized particle worked as resided barrier preventing the emulsion particle from coagulation. Larger size of silicate like Kunipia‐F than emulsion particle was not able to enclose the emulsion particle delicately because of its stiffness and large aspect ratio. The monomers inserted into the intercalated Kunipia‐F connected the ABS particles and clay particles. The Kunipia‐F particles anchored ABS particles around them inducing the aggregation and precipitation of ABS particles. ABS copolymer emulsion and aqueous silicate dispersion were mixed to compare with synthesized ABS/layered silicate nanocomposites and showed a stable suspension. With small amount of Laponite or Cloisite‐Na, nanocomposite emulsion of Kunipia‐F was also stabilized. Laponite and Cloisite‐Na worked as a steric stabilizer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Composites based on EVA and barium titanate submicrometric particles: Preparation by high‐energy ball milling and characterization

Ethylene vinyl acetate copolymer, a thermoplastic semicrystalline polymer, has been blended with barium titanate submicrometric particles (BaTiO₃) by means of high‐energy ball milling (HEBM) for obtaining composites in the form of films by hot pressing. Two different milling conditions have been considered: (i) milling at room temperature and (ii) milling under the temperature of the liquid nitrogen (cryomilling). The resulting composites have been fully characterized by spectroscopic and microscopic techniques to study the structure and morphology as a function of the processing conditions. A very good dispersion of the particles is attained under cryogenic conditions and, irrespective of the milling method, structural modifications were not observed in any of the materials used. Cross‐contamination of iron from the milling tools is also reduced to acceptable values for HEBM standards, especially in the case of cryomilling, an important issue for the use of these composites in electrical applications. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Effect of organic modifiers and silicate type on filler dispersion,thermal, and mechanical properties of ABS‐clay nanocomposites

Acrylonitrile–butadiene–styrene (ABS)–clay composite and intercalated nanocomposites were prepared by melt processing, using Na‐montmorillonite (MMT), several chemically different organically modified MMT (OMMT) and Na‐laponite clays. The polymer–clay hybrids were characterized by WAXD, TEM, DSC, TGA, tensile, and impact tests. Intercalated nanocomposites are formed with organoclays, a composite is obtained with unmodified MMT, and the nanocomposite based on synthetic laponite is almost exfoliated. An unintercalated nanocomposite is formed by one of the organically modified clays, with similar overall stack dispersion as compared to the intercalated nanocomposites. T_g of ABS is unaffected by incorporation of the silicate filler in its matrix upto 4 wt % loading for different aspect ratios and organic modifications. A significant improvement in the onset of thermal decomposition (40–44°C at 4 wt % organoclay) is seen. The Young's modulus shows improvement, the elongation‐at‐break shows reduction, and the tensile strength shows improvement. Notched and unnotched impact strength of the intercalated MMT nanocomposites is lower as compared to that of ABS matrix. However, laponite and overexchanged organomontmorillonite clay lead to improvement in ductility. For the MMT clays, the Young's modulus (E) correlates with the intercalation change in organoclay interlayer separation (Δd₀₀₁) as influenced by the chemistry of the modifier. Although ABS‐laponite composites are exfoliated, the intercalated OMMT‐based nanocomposites show greater improvement in modulus. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel kind of functional gradient poly(ε‐caprolactone) polyurethane nanocomposite: A shape‐memory effect induced in three ways

Multiwalled carbon nanotube (MWCNT) crosslinked polyurethane nanocomposites filled with iron (Fe) powders were synthesized by an in situ polymerization method. The Fe powders were deposited on one side of the nanocomposites during sample formation. Because of the gradient distribution of the Fe powders, the polymer part was affected little; this resulted in good mechanical properties of the nanocomposites. The electrical conductivities on each side of the nanocomposites were different. Because of the good magnetic properties and high electrical conductivities of the nanocomposites, the shape‐memory effect could be induced by temperature heating (temperature = 45°C), electrically resistive Joule heating (voltage (U) = 30 V), and magnetic field heating (frequency (f) = 45 kHz, intensity of magnetic field (H) = 46.5 kA/m). The shape‐memory properties were dependent on the location of the side that contained the most Fe powders (Fe side), and the nanocomposites showed better shape‐memory properties when the Fe side was located inside of the folded samples. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40220.     

Effect of cryomilling on the thermal behaviors of poly(ethylene terephthalate)

We have studied the effect of cryomilling (high‐energy ball milling under cryogenic temperature) on the thermal behaviors of poly(ethylene terephthalate) (PET) by comparing with original PET and quenched PET. Cryomilling induced the amorphization of crystalline PET, but the thermal behaviors of amorphous PET obtained from cryomilling are significantly different to those of amorphous PET obtained from quenching. Unlike amorphous PET obtained from quenching, the heating curve of amorphous PET obtained from cryomilling shows no cold crystallization peak, but evidences are found that its cold crystallization occurs within a wide temperature range. In addition, the stability of amorphous PET obtained from cryomilling is higher than that of amorphous PET obtained from quenching. The difference is proved to be attributed to the stored energy in cryomilled PET. The hot crystallization behaviors of PET improve a lot after cryomilling, and the heat stability of cryomilled PET is also better than those of original PET during reheating. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Electrical and mechanical properties of acrylonitrile‐butadiene‐styrene/multiwall carbon nanotube nanocomposites prepared by melt‐blending

The electrical properties in polymer/carbon nanotube (CNT) nanocomposites are governed not only by the degree of dispersion but also to a greater extent on the aspect ratio of the CNTs in the final composites. Melt‐mixing of polymer and CNTs at high shear rate usually breaks the CNTS that lowers the aspect ratio of the nanotubes. Thus, homogeneous dispersion of CNTs while retaining the aspect ratio is a major challenge in melt‐mixing. Here, we demonstrate a novel method that involves melt‐blending of acrylonitrile‐butadiene‐styrene (ABS) and in situ polymerized polystyrene (PS)/multiwalled CNT (MWCNT) nanocomposites, to prepare electrically conducting ABS/MWCNT nanocomposites with very low CNT loading than reported. The rationale behind choosing PS/MWCNT as blending component was that ABS is reported to form miscible blend with the PS. Thus, (80/20 w/w) ABS/(PS/MWCNT) nanocomposites obtained by melt‐blending showed electrical conductivity value ≈1.27 × 10^?6 S cm^?1 at MWCNT loading close to 0.64 wt %, which is quite lower than previously reported value for ABS/MWCNT system prepared via solution blending. Scanning electron microscopy and differential scanning calorimetry analysis indicated the formation of homogenous and miscible blend of ABS and PS. The high temperature (100°C) storage modulus of ABS (1298 MPa) in the nanocomposites was increased to 1696 MPa in presence of 0.64 wt % of the MWCNT. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Structural,mechanical, and thermal properties of 3D printed L‐CNC/acrylonitrile butadiene styrene nanocomposites

3D printing has been extensively applied in human‐related activities, and therefore the 3D printed nanocomposites became more popular and important in end‐use products. In the present study, we use lignin‐coated cellulose nanocrystal (L‐CNC) to reinforce 3D printed acrylonitrile butadiene styrene (ABS) and explore the effect of L‐CNC on the structural, mechanical, and thermal properties of 3D printed L‐CNC/ABS nanocomposites. The results indicate that the addition of L‐CNC foams the ABS and decreases the density of 3D printed L‐CNC/ABS nanocomposites. However, the tensile modulus and storage modulus increase by adding 4% L‐CNC. The thermal stability of 3D printed L‐CNC/ABS nanocomposites is also significantly improved as indicated by an increase in the maximum degradation temperature. The morphology of the nanocomposites reveals good dispersion and interfacial adhesion between L‐CNC and ABS. The finding indicates that the 3D printed nanocomposites become lighter and stiffer with addition of L‐CNC, which will have great potential to be applied in end‐use products. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45082.     

Preparation and mechanical properties of acrylonitrile‐butadiene‐styrene copolymer/clay nanocomposites

Bis(3‐triethoxysilylpropyl) tetrasulfane (TSS) was reacted with the silanol groups of the commercially available clay, Closite®25A (C25A) to prepare TSS‐C25A, which was melt‐compounded with acrylonitrile‐butadiene‐styrene copolymer (ABS). The tetra sulfide groups of TSS‐C25A may chemically react with the vinyl groups of ABS to enhance the interaction between the clay and ABS. The ABS/clay composites exhibited much higher tensile strength and elongation at break than the neat ABS. Especially the elongation at break of ABS/TSS‐C25A composite was 5 times higher than that of neat ABS. The X‐ray diffraction patterns of the clay showed that the d₀₀₁ basal spacing was enlarged from 1.89 nm to 2.71–2.86 nm as a result of the compounding with ABS. According to the thermogravimetric analysis, the thermal decomposition of the composite took place at a slightly higher temperature than that of neat ABS. Intercalated/exfoliated coexisting structures were observed by transmission electron microscopy for the ABS/clay composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of poly(2‐hydroxyethyl methacrylate)‐functionalized Fe‐Au/core‐shell nanoparticles

Disulfide‐bearing poly(2‐hydroxyethyl methacrylate) (DT‐PHEMA) was synthesized by atom transfer radical polymerization technique, which was subsequently immobilized onto core‐shell structured Fe‐Au nanoparticles (Fe‐AuNPs) by applying a “grafting to” protocol to afford new PHEMA‐grafted Fe‐AuNPs (PHEMA‐g‐Fe‐AuNPs). The Fe‐AuNPs having the iron core of 20–22 nm and the gold layer of 1–2 nm were initially prepared by inverse micelle technique and characterized by XRD and high‐resolution transmission electron microscopy (HR‐TEM). The grafting of DT‐PHEMA on the Fe‐AuNPs was confirmed by Fourier transformed infrared spectrophotometer, thermogravimetric (TGA), X‐ray photoelectron spectroscopy, and energy dispersive X‐ray analyses. The average diameter of polymer coated Fe‐AuNPs was determined to be 28 nm by HR‐TEM analysis. The amount of the polymer on the surface of Fe‐AuNPs was calculated to be about 50% by TGA analysis. The studies of magnetic property by the superconducting quantum interference devices indicate the superparamagnetic property of Fe‐AuNPs and PHEMA‐g‐Fe‐AuNPs. The optical property of the PHEMA‐g‐Fe‐AuNPs was recorded by UV–visible absorption spectroscopy, and a redshift in the absorption was observed, which further suggests the PHEMA attachment on the surface of Fe‐AuNPs. The magnetic nanocomposites demonstrate good dispersibility in common polar solvents. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Soy Oil-Based Rigid Polyurethane Biofoams Obtained by a Facile One-Pot Process and Reinforced with Hydroxyl-Functionalized Multiwalled Carbon Nanotube

Highly conductive, thermally insulating, and three-dimensional (3D) macromolecular network-structured nanocomposite biofoams with very low density were designed from soy oil-based polyurethane (PU) and hydroxyl-functionalized multiwalled carbon nanotubes (MWCNT-OH) using a facile one-pot process with water as the sole blowing agent. Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and Fourier Transform Infrared spectroscopy (FTIR) analyses revealed homogeneous dispersion as well as interaction or reaction of MWCNT-OH with the PU biofoam matrix or a polymeric methylene diphenyl diisocyanate (MDI) to form a 3D macromolecular network structure. Mechanical properties and electrical conductivity were remarkably enhanced with the increase of MWCNT-OH. Dynamic mechanical analysis and thermogravimetric analysis results showed that all the nanocomposite PU biofoam products had good thermal stability properties. Hence, the prepared nanocomposites hold promise as rigid biopolyurethane (BioPU) foams, serving the needs of the conductive composite material fields.     

硅烷偶联剂对聚甲基丙烯酸甲酯/二氧化硅纳米复合材料结构与性能的影响

采用乙烯基三乙氧基硅烷(WD-20)作为偶联剂,通过溶胶-凝胶法合成了聚甲基丙烯酸甲酯(PMMA)/二氧化硅(SiO₂)纳米复合材料,采用紫外-可见光谱、红外光谱、扫描电子显微镜和热机械分析等研究了材料的结构和性能.结果表明,WD-20的加入对纳米复合材料透明性、耐热性能和微观形态结构有较大影响,随着WD-20用量的增加,纳米复合材料透明性增加,SiO₂分散相尺寸变小,玻璃化转变温度增加.当WD-20与四乙基原硅酸盐（TEOS）之比为0.2时,所制备的纳米复合材料的溶胶分数为6%、玻璃化转变温度为250 ℃以上、可见光透过率在80％以上、SiO₂分散相尺寸小于100 nm.     

超细红粘土/白炭黑/硅橡胶复合材料的制备及细胞相容性的研究

硅橡胶是一类以聚硅氧烷为主链,在生物医用领域应用广泛的医用高分子材料。本研究制备了新型超细红粘土/白炭黑改性的硅橡胶材料,采用激光粒度仪测定了红粘土的粒径分布,并结合红外光谱(FTIR)、透射电镜(TEM)对其表面化学结构和形态结构进行了表征;同时采用扫描电镜(SEM)对复合材料表面形貌进行了分析;水接触角的改变表明了复合材料表面亲水性的变化,利用细胞黏附性实验对复合材料的细胞相容性进行评价。结果表明,红粘土具有独特的空穴结构,呈不规则形状,加入了红粘土复配填料后,复合材料的亲水性以及细胞相容性均有提高。由此可知,红粘土作为较好改善硅橡胶生物相容性的填料,可为新型生物材料提供新的思路和方向。     

Preparation and properties of nano‐CaCO3/acrylonitrile‐butadiene‐styrene composites

CaCO₃/acrylonitrile‐butadiene‐styrene (ABS) and CaCO₃/ethylene‐vinyl acetate copolymer (EVA)/ABS nanocomposites were prepared by melting‐blend with a single‐screw extruder. Mechanical properties of the nanocomposites and the dispersion state of CaCO₃ particles in ABS matrix were investigated. The results showed that in CaCO₃/EVA/ABS nanocomposites, CaCO₃ nanoparticles could increase flexural modulus of the composites and maintain or increase their impact strength for a certain nano‐CaCO₃ loading range. The tensile strength of the nanocomposites, however, was appreciably decreased by adding CaCO₃ nanoparticles. The microstructure of neat ABS, CaCO₃/ABS nanocomposites, and CaCO₃/EVA/ABS nanocomposites was observed by scanning electron microscopy. It can be found that CaCO₃ nanoparticles were well‐dispersed in ABS matrix at nanoscale. The morphology of the fracture surfaces of the nanocomposites revealed that when CaCO₃/EVA/ABS nanocomposites were exposed to external force, nano‐CaCO₃ particles initiated and terminated crazing (silver streak), which can absorb more impact energy than neat ABS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal and anti‐corrosion analysis of nano‐porous phenolic‐novolac‐Zn composite materials

The phenolic‐novolac‐Zinc composite materials with hexamethylenetramine (HMTA) 8 wt% at Zinc powder content weight from 2% to 11% are investigated by Scanning Electron Microscope, Differential Scanning Calorimetry, Thermogravimetric analysis, and Kissinger method. It is found that a nano‐porous structure is synthesized in phenolic‐novolac porous with 8 wt% HMTA and 5 wt% Zn powder. The thermal and anti‐corrosion analysis shows that the composite with nano‐pores structure produces the highest glass‐transtion temperature, decomposition temperature, and the best anti‐corrosion property comparing with other samples. Furthermore, it introduces a novel method to prepare the nano‐porous phenolic‐novolac‐Zn composite material which can be used as the functional material. POLYM. COMPOS., 36:1346–1351, 2015. © 2014 Society of Plastics Engineers     

Synthesis and properties of poly(methyl methacrylate)/clay nanocomposites using natural montmorillonite and synthetic Fe‐montmorillonite by emulsion polymerization

In this article, Fe‐montmorillonite (Fe‐MMT) was synthesized by hydrothermal method. For the first time, Fe‐MMT was modified by cetyltrimethyl ammonium bromide (CTAB), and poly(methyl methacrylate)(PMMA)/Fe‐MMT nanocomposites were synthesized by emulsion polymerization. Then poly(methyl methacrylate)(PMMA)/natural montmorillonite (Na‐MMT) and PMMA/Fe‐MMT nanocomposites were compared by Fourier transform infrared (FTIR) spectra, X‐ray diffraction (XRD) patterns, transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA). By XRD and TEM, it was found out that the morphology of PMMA/Fe‐MMT nanocomposites was different from that of the PMMA/Fe‐MMT nanocomposites when the content of two types of clay was same in the PMMA matrix. It was possible that the presence of iron may lead to some radical trapping, which enhances intragallery polymerization to be developed to improve layer dispersion in PMMA/Fe‐MMT systems. In TGA curves, the thermal stability and residue at 600°C of PMMA/Fe‐MMT nanocomposites were higher than those of PMMA/Na‐MMT nanocomposites. Those dissimilarities were probably caused by structural Fe ion in the lattice of Fe‐MMT. POLYM. COMPOS., 27:49–54, 2006. © 2005 Society of Plastics Engineers     

Toughening of PA6 nanocomposites by reactive acrylonitrile–butadiene–styrene core–shell rubber particles

The effect of addition of organoclay and the reactive ABS‐g‐MA core‐shell particles on the mechanical properties and morphology of blends of polyamide (PA6) were reported. The reactive rubber particles with core‐shell structure were selected as modifier instead of conventional reactive bulk rubber. The microstructure of the ternary nanocomposites was characterized by X‐ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Impact strength and stress–strain behavior of blends were measured as a function of organoclay content and core/shell ratio of ABS‐g‐MA. The organoclay plates affected the interfacial adhesion between polyamide and the core‐shell particles because of a shielding effect of organclay on the interacting of amine end groups of PA6 with the MA groups of ABS‐g‐MA. The poor dispersion behavior of ternary nanocomposites was observed when the core/shell ratio is 80/20, and with an increase of organoclay content, the core/shell dispersed phase size increased. Blends based on the maleated elastomer with the core/shell ratio 60/40 gave a more beneficial balance of toughness versus stiffness. POLYM. COMPOS., 35:864–871, 2014. © 2013 Society of Plastics Engineers