Papers by Keyword: In Situ Polymerization

Abstract: The MWCNT-COOH and CTAB modified MMT were hybridized by the ultrasonic method, and the nylon 66/MMT/WMCNT composite was prepared by in-situ polymerization to study the effect of the introduction of MMT and MWCNT on the properties of nylon 66. A scanning electron micrograph of the composite cross-section shows that the CNTs were uniformly dispersed in the nylon 66 matrix. The XRD patterns show that the introduction of MMT and MWCNT-COOH caused the ratio of α1 and α2 of nanocomposites. The TGA results show that the heat resistance and residual carbon content of the composite material are improved. The mechanical properties of nanocomposites show that the mechanical properties of the material are improved relative to pure PA66.

Abstract: Polyaniline has attracted a lot of attention for thermoelectric (T.E) applications, however their drawback materials is that they possess low power factors than the state-of-the-art materials such as BiTe-based, BiSb-based, PbTe-based, etc. ^[1-4]. Currently, in order to enhance the T.E properties, hybrids between the polymer and other components such as carbon materials, other polymers, and even inorganic materials are being investigated. In this work, the effect of MoS₂ addition on the T.E properties of polyaniline was investigated. The MoS₂ nanoflowers were first synthesized via hydrothermal process at 200 °C for 24 hrs after which they were used for templated in situ polymerization of polyaniline. The scanning electron microscope (SEM) image showed that the MoS₂ nanoflowers were covered with the polyaniline during the polymerization process and this was confirmed from the X-ray diffraction (XRD) analysis which showed existence of both the polyaniline and MoS₂ in the synthesized material. The electrical conductivity of polyaniline was reported to be 10^-3 S cm^-1 and it was noticed that addition of minute amounts of MoS₂ into polyaniline resulted in an enhancement of the electrical conductivities of up to two orders of magnitude. Nanocomposite with 5 % MoS₂ (PMX-5) showed optimized power factor values ranging from 6.30 x 10^-2 - 1.12 x 10^-3 μW m^-1 K^-2 for the temperature range studied. This study therefore provides a facile approach for synthesis of polyaniline-molybdenum disulphide nanocomposites and the results obtained confirm that transition metal dichalcogenides (TMDs) have a potential for the enhancement of T.E properties of polyaniline.

Abstract: A series of polyethylene terephthalate (PET) hybrid materials with high-load TiO₂ content were prepared via in situ polymerization by dispersing unmodified titanium dioxide (TiO₂) in Ethylene Glycol (EG), and the influence of load TiO₂ nanofillers on the physical properties of PET masterbatch was investigated. The intrinsic viscosities of the prepared PET hybrid materials were affected by the addition of the nanoparticles and in both cases a slight decrease was observed. In addition, the thermal behavior of these PET hybrid materials and neat PET was investigated using Differential Scanning Calorimetry (DSC). The chemical structures of PET hybrid materials were characterized by Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). The TiO₂ nanoparticles show well dispersibility in PET matrix. The PET hybrid material with 40wt.% TiO₂ content was used as master batch to prepare full dull PET fiber with 2.5 wt.% TiO₂. The melt flow ability of PET hybrid materials shows good winding and drawing performance, and also the resulted fiber has better mechanical properties than neat PET fiber. It suggests that this PET/TiO₂ masterbatch by in situ polymerization may find good application for delustered fiber preparation.

Abstract: Containing phosphorus compound is widely used in the modification of flame retardant polyester due to the excellent flame retardant properties. But it is difficult to solve the droplet problems, especially the polyester fiber. In this paper the copolyesters and fiber with flame retardant and anti-droplet were prepared using reaction containing phosphorus flame retardant [(6-Oxido-6H-dibenz [c, e] [1, 2] oxaphosphorin-6-yl) methyl] butanedioic acid (DDP) and silica sol by in-situ polymerization. The structure and properties of modification flame retardant were measured by nuclear magnetic resonance (NMR), thermal gravity analysis (TGA). The results indicated that the modification flame retardant was more suitable for polymerization. The TGA, limiting oxygen index (LOI), vertical flame test, and scanning electron microscope (SEM) were devoted to discuss the flame retardant properties. It suggested that the nanoSiO₂ particles increased char residue, and the nanoSiO₂ particles were conducive to the formation of dense stable carbon layer, inhibiting the expansion of the carbon layer to form holes, the nanoSiO₂ particles improved the droplet of copolyester. The highest LOI of copolyester is 34.8±0.1%, the UL94 is V-0 grade. The copolyester fiber has excellent mechanical, flame retardant and anti-droplet. This can meet the requirement of household textile decoration and use.

Abstract: In this research solid-solid microencapsulated phase change material (SSMePCM) with high thermal energy storage density (177.6 Jg/1) was synthesized successfully by in situ polymerization using biodegradable natural polymer chitosan as shell and polyethylene glycol (PEG-1000) as core. The morphology, chemical structure and thermal properties were characterized by optical microscopy (OM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The results show that the obtained SSMePCM dispersed individually with a spherical shape. Author (s) recommends the all set thermal and chemically steady microcapsule for thermal energy storage purposes as novel synthesized SSMePCM with latent heat storage capacities.

Abstract: The BaFe₁₂O₁₉ nanoparticles was prepared by sol-gel method in different temperature (750°C,850°Cand 950°C), and then BaFe₁₂O₁₉/polyaniline nanocomposites was synthesized by in situ polymerization. The XRD, FTIR spectra, SEM and vector network analyzer were used to analyze the "" chemical component, morphology and microwave absorption property of the nanocomposites. The result show that BaFe₁₂O₁₉ can be generated at 750°C without any impurity ,and its size increased with increase of calcination temperature.BaFe₁₂O₁₉ nanoparticle was coated with polyaniline partially, and we can get it have interaction with polyaniline through FTIR spectra. While the ferrite calcined at 850°C,the thickness of the absorbing material is 4.5mm,the nanocomposites have the largest reflection loss of-17.6 dB at 6 GHz,and its reflection loss values less than−10 dB in the range of 5-7.4GHz.

Abstract: Microcapsules with silicone oil as core and poly (urea-formaldehyde) as shell were prepared by direct in-situ polymerization process. The influences of formaldehyde-urea molar ratios on microcapsules morphologies were investigated by scanning electron microscope (SEM). The microcapsules were characterized by fourier transform infrared spectrometer (FT-IR), particle size analyzer, simultaneous thermal analyzer. The results showed that well dispersive microcapsules were obtained with average particle size of 2.5 μm when formaldehyde-urea molar ratio was 1.8:1.0 and that the weight ratio of silicon dioxide to microcapsule was 15.4%, which produced from pyrolysis of core material silicone oil. The prepared microcapsules were expected to a kind of high-efficiency erosion inhibitor when used in propellant.

Abstract: Acorus calamus Linn. extract containing the active compounds were known for insect repellent and antimicrobial activity. The encapsulation of A. calamus extract has potential for application as insect repellent agent or antimicrobial finishing textile. The aim of this study was to encapsulate the extract of A. calamus by in situ polymerization of urea-formaldehyde. Microcapsules containing A.calamus extract were prepared by varying the weight ratio of extract to urea into four ratios (W_extract/W_urea); 0:5, 1:5, 3:5, and 5:5. The prepared microcapsules were characterized using FT-IR, SEM, particle analyzer and TGA to confirm the existing of A. calamus extract in microcapsules.

Abstract: A novel sulfur/polypyrrole/graphene nanosheet composite (S/PPy/GNS) was synthesized and investigated as a promising cathode material. This ternary composite was prepared via in situ polymerization of pyrrole monomer with nanosulfur and GNS aqueous suspension followed by heat-treatment. Scanning electronic microscopy observation revealed the formation of a highly porous structure consisting sulfur and polypyrrole coating on the GNS surface. In this composite, GNS works as nanocurrent collector and enhances the conductivity of the composite, and polypyrrole with its high adhesion ability to GNS could act as a binder to connect sulfur and GNS. The resulting S/PPy/GNS composite cathode exhibits high and stable specific discharge capacities of 991 mAh g^-1 after 50 cycles at 0.1 C and good rate capability.

Abstract: Carbon fiber reinforced composites (CFRCs) have been used in various high-end industries due to their outstanding specific mechanical properties. Recently, carbon nanotube (CNT)-grafted carbon fibers (CFs) made via direct growth has emerged as an advanced and hierarchical reinforcement that can improve the reinforcing effect of CFs in CFRCs. On the other hand, CF reinforced thermoplastic composites (CFRTPs) have attracted much attention because of their quick and mass production capability, e.g., which is important for automotive part manufacturing. Here, we report on the manufacture of CFRTPs using CNT-grafted CFs and their mechanical properties. First, the interfacial shear strength of CNT-grafted CFs with thermoplastic resins was characterized to demonstrate improved interfacial properties due to the CNTs grafted on CFs. Then, the composites were manufactured in two ways; polymer nanoparticles and in-situ polymerization. Polymer nanoparticles were used to improve the interfacial properties due to their small size and good mechanical locking with CF surfaces. In-situ polymerization was also used to manufacture CFRTPs, i.e., monomers with catalyst were transferred into CNT-grafted CF fabric preform using vacuum assisted resin transfer molding and then polymerized into solid matrix. This in-situ polymerization enabled the manufacture of CNT-grafted CF thermoplastic composites by overcoming the difficulties of filling the surface of CNT-grafted CFs with thermoplastic polymers. Finally, the mechanical, thermal, electrical, and damping properties of CNT-grafted CF thermoplastic composites were characterized and compared with their thermoset composites.