1,2,4-Triazole and quinoxaline based polyimide reinforced with neat and epoxide-end capped modified SiC nanoparticles: Study thermal, mechanical and photophysical properties

In this paper, properties of nanocomposite films which were prepared from a new polyimide and SiC nanoparticles via two simple methods are reported: (1) SiC nanoparticles were firstly functionalized with epoxide-end groups (mSiC) and then solution blended with poly(triazole-imide) (PTAI) in DMAc. The homogeneous solution was heated in vacuum to give PTAI/mSiC film. (2) A new diamine containing 1,2,4-triazole ring and a commercial dianhydride was reacted in situ in the presence of native SiC nanoparticles to give a homogeneous poly(amic acid) PAA/SiC mixture which was then heated in vacuum under high temperature thermal process to give PTAI/SiC film. The nanocomposite films were tested for different properties including thermal using TGA and DMTA, mechanical and photophysical. The results showed that strong chemical bonding between SiC nanoparticles and the polymer matrix contributed to the enhanced Tg from 300 °C to >350 °C, tensile strength from 108 MPa to 165 MPa and temperature of 5% weight loss (T5%) from 380 °C to 500 °C. The photoluminescence intensity of the nanocomposites increased and the spectra showed blue shift with increasing SiC content

Synthesis and characterization of new fluorescent polyimides bearing 1,2,4-triazole and 1,2-diaryl quinoxaline: Study properties and application to the extraction/elimination of metallic ions from aqueous media

In this article, synthesis and characterization of triazole-based polyimides for solid-phase extraction of metal cations is described. For this purpose, new aromatic diamines containing 1,2,4-triazole and substituted 1,2-diaryl quinoxaline units were synthesized and used in polycondensation reaction with aromatic dianhydrates to yield poly(triazole-imide)s (PTAI)s. These polymers had inherent viscosities in the range of 0.58-0.62 dL/g and were readily soluble in a variety of organic solvents; they formed low-colored and tough thin films via solution casting. The PTAIs exhibited Tg between 280 and 338 \ub0C, and their 10% weight loss temperatures were in excess of 540 \ub0C with up to 76% char yield at 700 \ub0C in N2. These polymers emitted green or blue fluorescence in dilute NMP solution and in the solid state. The triazole groups in the polymer chain were efficient chelating/host units for heavy metal ions. One of these polymers, PTAI(1b), was investigated for its extraction capability for environmentally deleterious metal ions such as CrVI, CrIII, CoII, Zn II, PbII, CdII, HgII and Mn II from aqueous solutions either individually or in the mixture and at different pH values. \ua9 2012 Elsevier Ltd. All rights reserved

Novel fluorescent light-emitting polymer composites bearing 1,2,4-triazole and quinoxaline moieties: Reinforcement and thermal stabilization with silicon carbide nanoparticles by epoxide functionalization

New diamines bearing substituted 1,2,4-triazole and quinoxaline moieties with OCH3 or Br units were successfully synthesized and used for preparation of novel polyamides (PAs) by direct polycondensation with aromatic and aliphatic dicarboxylic acids. Chemical structure of the diamines as well as the resulting polymers was confirmed by elemental analysis, FT-IR and 1H NMR spectroscopic methods. Inherent viscosities of these PAs were in the range of 0.52–0.56 dL/g, they were readily soluble in a variety of organic solvents and formed low-coloured and tough thin films via solution casting. The aromatic PAs exhibited Tg between 284 °C and 300 °C, and their 10% weight loss temperatures were in excess of 420 °C with up to 70% char yield at 600 °C in N2. These PAs emitted green or blue fluorescence in dilute NMP solution and in the solid state. Silicon carbide (SiC) nanoparticles modified by silane coupling agent were used to prepare SiC/PA particle-reinforced composites by solution blending. Thermal properties of nanocomposites by using DMTA, DSC and TGA and also solubility and optical properties were investigated. The results show that both the uniform particle dispersion and the strong chemical bonding between the nanoparticles and the polymer–matrix contributed to the enhanced Tg, storage modulus and thermal stability

Curing of DGEBA/ZnO nanocomposite with new fluorinated curing agents: Study of kinetics, water absorption, thermal and photophysical properties

In this study, two new fluorinated curing agents bearing imidazole-bisphenol and imidazole-diamine groups in their structures, namely: 4,4′-(2-(4-(trifluoromethyl)phenyl)-1H-imidazole-4,5-diyl)diphenol (TFIDO) and 4,4′-(4,4′-(2-(4-(trifluoromethyl)phenyl)-1H-imidazole-4,5-diyl)bis(4,1-phenylene)bis(oxy)bis (3-(trifluoromethyl)aniline) (TFIA) were synthesized, fully characterized and used to cure diglycidylether of bisphenol-A (DGEBA)-based epoxy resin and blend of DGEBA with nano ZnO (NZ) particles. Two mechanisms were anticipated to play roles in the curing reactions based on adducts formation and ionic complexes. The DGEBA/TFIDO system was more reactive than the DGEBA/TFIA system, whereas the thermal stability of DGEBA/TFIA was higher than that of DGEBA/TFIDO. These results can be explained by the increase in cross-linking density and more CF3 groups in TFIA. The results indicated that cured materials showed red shift in absorption and fluorescence emission spectra and significant improvements in the water repellency and thermal stability. The NZ particles as catalyst increased the rate of cure reaction by decreasing the activation energy (Ea) and increasing the rate constant values

The Effect of Shoe Outsole Containing Nanoclay Particles on Knee Joint Power during the Stance Phase of Running

The popularity of running and consequently of running injuries has increased tends to develop shoe sole constructions aiming at preventing different injuries. The purpose of this study was to investigate the effect of shoe outsole containing nanoclay particles on knee joint power during stance phase of running. Fourteen healthy male shod runners run 3 times at 3.5 m.s-1 under three shoe conditions manufactured by polyurethane (PU), 1% Polyurethanes-clay nano-composites (NPU1) and 2% Polyurethanes-clay nano-composites (NPU2). The joint power (Pj) was calculated by multiplying the joint moment (Mj) and the joint angular velocity (ωj). Knee joint peak power in the three dimensional planes were compared between the shod conditions during the stance phase of running using repeated measurement ANOVA (P< 0.05). The results showed that the negative peak of knee joint power in sagittal plane was significantly different between the PU and NPU2 conditions. No significant differences were noted in other positive and negative peaks. It is concluded that using Polyurethanes-clay nano-composites can change shock absorbing ability of knee joint​

Removal of Metal Ions from Water Using Poly(MMA-<i>co</i>-MA)/Modified-Fe₃O₄ Magnetic Nanocomposite: Isotherm and Kinetic Study

Magnetic Fe₃O₄ nanoparticles were synthesized, surface modified with an amino-terminated silane coupling agent, 3-amino­propyl­tri­methoxy­silane (APTMS), and characterized by Fourier transform infrared spectroscopy (FT-IR), field scanning electron microscopy (FESEM), and X-ray diffraction (XRD). A copolymer of methyl methacrylate (MMA) and maleic anhydride (MA), poly­(MMA-<i>co</i>-MA), was synthesized by radical polymerization and transformed into magnetic nanocomposite (MNC) by chemical immobilization of APTMS-Fe₃O₄ with the anhydride groups of poly­(MMA-<i>co</i>-MA) chains. The MNC was characterized by FT-IR, XRD, FESEM, TEM, and atomic force microscopy (AFM) and used for the removal of metal ions from water. Various factors influencing adsorption capacity such as contact time, absorbent dosage, pH, and initial concentration of ions were investigated. The adsorption kinetics showed a pseudo-second-order rate law, indicating chemical sorption as the rate-limiting step mechanism. Sorption of metal ions to MNC agreed well with the Langmuir adsorption model with the maximum adsorption capacity of 90.09, 90.91, 109.89, and 111.11 mg g^–1 for Co²⁺, Cr³⁺, Zn²⁺, and Cd²⁺, respectively