The precursor ZrW1.6Mo0.4O7(OH)2(H2O)2 was characterized by IR and XRD methods. δ′-ZrW1.6Mo0.4O8 was prepared by careful controlling the annealing conditions from the precursor and was determined to have the formula as o-ZrW1.6Mo0.4O8·H2O by TG-DSC, IR, and XRD methods. The relation between o-ZrW1.6Mo0.4O8·H2O and o-ZrW1.6Mo0.4O8 was discussed through variable temperature XRD patterns. Further more, the mechanism of the precursor dehydration was suggested. 相似文献
Summary: Macroporous monoliths consisting of silica nanoparticles embedded in poly(methyl methacrylate) (PMMA) were synthesized in supercritical CO2. Well‐dispersed silica particles, pretreated with functional 3‐(trimethoxysilyl)propyl methacrylate (MPS), were to form colloidal PMMA nanocomposites followed by a sol‐gel transition forming interconnected structures resulting in micron‐sized pores with specific areas between 1 and 7 m2 · g−1. SEM and TEM results revealed uniform morphological characteristics of the composite materials and good dispersions of the silica nanoparticles.
SEM micrograph of PMMA/Silica nanocomposites forming interconnected macroporous monolith. The average size of the silica particles is 50 nm. 相似文献
Nano-sized silica particles were modified with methacryloxy-propyltrimethoxysilane(MPS) followed by in situ copolymerization of methyl methacrylate(MMA) and butyl acrylate(BA).These modified nanoparticles were compounded with polypropylene(PP) to prepare PP/silica nanocomposites.PMMA grafted on nano-silica enhances the dispersion of the nanoparticles and interfacial adhesion,decreases the size of PP spherulites in nanocomposites and leads to increasing the Young's modulus and toughness of PP/silica nanoc... 相似文献
Transparent poly(methyl methacrylate) (PMMA)/TiO2 nanocomposites have been prepared by solution mixing PMMA with organically soluble titania xerogel. The organically soluble
titania xerogel in the form of amorphous phase has been synthesized via a simple sol-gel method, involving hydrolysis of tetrabutyl
titanate (TBT) in trifluoroacetic acid (TFA) and gelation. The obtained PMMA/TiO2 nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM),
thermogravimetry (TG) and ultraviolet-visible (UV-vis) absorption spectroscopy. The results showed that the interaction between
titania nanoparticles and PMMA macromolecular chains led to a homogeneous dispersion of TiO2 in PMMA matrix. The resulting PMMA/TiO2 nanocomposites showed improved thermal stability, high transparency and high UV-shielding efficiency with a small amount
of titania xerogel (≤3.0 wt %). The present work is of interest for developing a series of transparent UV-shielding nanocomposites. 相似文献
Graphene oxide (GO) is used as a stabilizer in the Pickering emulsion polymerization of methyl methacrylate (MMA) to prepare PMMA/GO nanocomposites. Transmission electron microscope studies of the emulsion polymerization products showed that the average diameter of nanocomposite particles was about 150 nm, the transparent GO flakes covered the surface of the particles, and were well dispersed in polymer matrix. The influence of GO on the thermal stability of PMMA was investigated by thermogravimetry analysis and differential scanning calorimetry. The results showed that the thermal stability and the glass transition temperature (Tg) of PMMA/GO nanocomposites were improved obviously compared with PMMA. The apparent activation energy (Ea) for the degradation process of PMMA/GO nanocomposites was evaluated by Kissinger method, which indicated that their Eas were much higher than those of PMMA both in nitrogen and air atmosphere. 相似文献
Poly(methyl methacrylate) (PMMA)/silica/titania ternary nanocomposites with covalent bonding interaction between polymer and inorganic phases have been prepared using a novel non-hydrolytic sol-gel method. Transmission electron microscope (TEM) image of silica/titania binary inorganic component indicates a core-shell-like structure. Scanning electron microscope (SEM) images suggest that the well dispersed silica/titania particles in the hybrid are on the nanometer-scale. The transparencies of nanocomposites are maintained in visible region while the absorption band in ultraviolet (UV) region is red shifted with increasing inorganic content. The thermogravimetric analysis (TGA) results show that the thermal stability of PMMA copolymer increases dramatically with the addition of silica/titania moieties both in nitrogen and in air. 相似文献
Poly(methyl methacrylate) (PMMA)/montmorillonite (MMT) nanocomposites were prepared by in situ suspension polymerization. MMT was previously organically modified by three different intercalating agents: methacrylatoethyl trimethyl ammonium chloride (DMC), dodecylamine (12CNH), and hexadecyl allyl ammonium chloride (HADC). The structures of the nanocomposites were investigated by X-ray diffraction and transmission electron microscopy, while the interaction between PMMA and MMT was characterized by Fourier transform infrared spectroscopy. The molecular mass of the extracted PMMA was measured by gel permeation chromatography. The thermal stability of PMMA/MMT nanocomposites was evaluated by thermogravimetric and differential scanning calorimetry. The results indicated that PMMA/MMT nanocomposites were successfully prepared and the interaction between PMMA and MMT of PMMA/MMT–HADC nanocomposites was the strongest. The thermal stability of the nanocomposites was improved and found to be optimal for PMMA/MMT–HADC with T10 increasing to 304 °C, 52 °C higher than that of neat PMMA. 相似文献
Nano-ZnO/poly(methyl methacrylate)(PMMA) composite latex microspheres were synthesized by in-site emulsion polymerization.
The interfacial compatibility between nano-ZnO particles and PMMA were improved by treating the surface of nano-ZnO particles
hydrophobically using methacryloxypropyltrimethoxysilane (MPTMS). TEM indicated that nano-ZnO particles present in nanosphere
and have been encapsulated in the PMMA phase. FT-IR confirmed that MPTMS reacted with the nano-ZnO particle and copolymerized
with MMA. It was clearly found from SEM that ZnO nanoparticles can be homogeneously dispersed in the PVC matrix. The absorbance
spectrum of the nanocomposite polymer suggested that increasing the amount of nano-ZnO in composite particles could enhance
the UV-shielding properties of the polymers. The nano-ZnO/PMMA composite particle could eliminate aggregation of ZnO nanoparticle
and improve its compatibility with organic polymer. This means that the composite particles can be widely applied in lots
of fields. 相似文献