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81.
A series of polyurethane resins with varying NCO/OH ratios (0.8–2.0) has been synthesized from the monoglyceride of Mesua Ferrea L. seed oil, poly(ethylene glycol) (Mn, 200 g mol?1) and 2,4‐toluene diisocyanate in the presence of dibutyl tin dilaurate as the catalyst. The effects of the NCO/OH ratios of the synthesized resins on the physical properties, such as hydroxy values, acid values, saponification values, iodine values, specific gravities and isocyanate values have been studied. The formation of the polyurethane resins was confirmed by viscosity measurements, and FTIR, UV and 1H NMR spectroscopic studies. Performance characteristics, such as impact resistance, flexibility, gloss, hardness, adhesive strength and chemical resistance, of the cured resins were investigated as a function of the varying NCO/OH ratios, with an influence of these ratios being observed for most of the above properties. Thermogravimetric analysis (TGA) demonstrated that the thermal stabilities of the cured resins increased with an increase in the NCO/OH ratios. The amounts of char residues at 550 °C were also found to be greater for higher NCO/OH ratios of the oil‐modified polyurethane resins. Copyright © 2005 Society of Chemical Industry 相似文献
82.
An environmentally friendly effective technique was demonstrated to prepare iron oxide/reduced graphene oxide nanohybrid (IO/RGO) at room temperature by using banana peel ash aqueous extract as the base source and Colocasia esculenta leaves aqueous extract as the reducing agent. The nanohybrid was characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, transmission electron microscopy, vibrating sample magnetometry, Raman spectroscopy and thermal studies. The results indicated the decoration of superparamagnetic IO nanoparticles on the surface of the RGO. Both organic and inorganic pollutants were effectively removed from the contaminated water (for Pb2+ and Cd2+ within 10 min, whereas for tetrabromobisphenol A within 30 min) by IO/RGO. The study revealed that adsorption followed pseudo-second order kinetics and isotherms were well described by the Langmuir model in all the cases. The thermodynamics parameters (ΔG°, ΔS° and ΔH°) were calculated from the temperature dependent isotherms and indicated that the adsorptions were endothermic and spontaneous. 相似文献
83.
Mesua ferrea L. seed oil based highly branched polyester resin was modified by methyl methacrylate through grafting polymerization technique. The nanocomposites of this acrylate-modified polyester and 1–5 wt% loadings of organically modified montmorrilonite (OMMT) nanoclay were prepared by an ex situ technique using strong mechanical mixing and ultrasonication. Formation of nanocomposites was confirmed by X-ray diffractometeric (XRD), scanning electron microscopic (SEM) and transmission electron microscopic (TEM) analyses. The absence of d0 0 1 reflections of OMMT in XRD and TEM study revealed the partial exfoliation of OMMT by the polymer chain. The homogeneous surface morphology was also ascertained from SEM. Mechanical and thermal studies of the nanocomposites showed an appreciable improvement in tensile strength and thermal stability by OMMT loading. The enhancement of tensile strength by 2.5 times and thermal stability by 32 °C for 5 wt% OMMT filled nanocomposite was observed compared to that of pristine system. The rheological behavior of the nanocomposites was also investigated and shear thinning was observed. Biodegradation of the nanocomposite films was assayed using two strains of Pseudomonas aeruginosa, SD2 and SD3 and one strain of Bacillus subtilis, MTCC736. The nanocomposites exhibited enhanced biodegradability as compared to pristine acrylate modified polyester. All the results showed the potentiality of the nanocomposites as advanced thin film materials for suitable applications. 相似文献
84.
Sujata Pramanik Rocktotpal Konwarh Kalpana Sagar Bolin K. Konwar Niranjan Karak 《Progress in Organic Coatings》2013
Vegetable oil based hyperbranched poly(ester amide) (HBPEA) has enormous importance because of its unique characteristics. Thus the synthesis of HBPEA using N,N′-bis(2-hydroxy ethyl) castor oil fatty amide, maleic anhydride, phthalic anhydride and isophthalic acid as A2 monomers and diethanol amine, as B3 monomer was reported for the first time. The chemical structure of the synthesized resin was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (1H NMR and 13C NMR) spectroscopic techniques. The degree of branching (DB) (as vouched by 1H NMR analysis) and initial degradation temperature were found to increase with the increment in B3 monomer content. Resins with 5 and 10 wt% of B3 monomer showed shear thinning behavior while rheopectic nature of HBPEA with 15 wt% of B3 content was observed. The evaluation of tensile strength, elongation at break, abrasion resistance, adhesion strength, scratch hardness, gloss, impact strength and chemical resistance complemented by microbial and lipolytic degradation forward the epoxy cured thermosets as advanced biodegradable surface coating materials. 相似文献
85.
Mesua ferrea L. seed oil based hyperbranched polyurethane/multi‐walled carbon nanotube nanocomposites were prepared by solution polymerization technique. The multi‐walled carbon nanotubes were modified with the polyoxyethylene octyl phenyl ether (Triton X‐100). The transmission electron microscopy and Fourier transform infrared spectroscopic study revealed the homogeneous distribution of the multi‐walled carbon nanotubes in the polymer matrix and the presence of strong interfacial interaction between them, respectively. The tensile strength (5.5–21.5 MPa) and scratch resistance (3–6.1 kg) increase with the increase of the content of carbon nanotubes (0 to 2 wt%). The thermo‐gravimetric analysis result showed the increment of thermal stability (240–275°C) of the nanocomposites. All the prepared nanocomposites exhibited the excellent shape fixity and shape recovery. The shape recovery time decreases (127–73 s) with the increase of the concentration of carbon nanotubes in the nanocomposites. Thus the prepared nanocomposites might be utilized as advanced shape memory applications. POLYM. COMPOS., 35:636–643, 2014. © 2013 Society of Plastics Engineers 相似文献
86.
The bio‐based hyperbranched polyurethanes (HBPUs) have generated immense interest as advanced shape memory materials. In the present investigation, HBPUs were synthesized from poly(ε‐caprolactone)diol as a macroglycol, butanediol as a chain extender, monoglyceride of Mesua ferrea L. seed oil as a bio‐based chain extender, triethanolamine as a branch‐generating moiety (at different percentages), and toluene diisocyanate by a prepolymerization technique using A2 + B3 approach. The structure of the synthesized HBPU was characterized by different techniques. Nuclear magnetic resonance (proton) study indicated the formation of highly branched structure with degree of branching 0.9. The increment of thermal stability from 225 to 260°C and melting point from 50 to 53.5°C with the increase of triethanolamine content was observed. Tensile strength 4–8 MPa, elongation at break 614–814%, impact resistance 0.8–0.95 m, and scratch hardness 2–6 kg increased with the increase of multifunctional moiety content from 0 to 5 wt%. The shape recovery ratio increased with the increase of multifunctional moiety content from 0.21 to 0.95. Thus, the studied HBPUs have the potential to be used as advanced thermoresponsive shape memory materials. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers 相似文献
87.
One of the most important textile materials, poly(ethylene terephthalate) (PET) fiber, was coated with a semi-conductive polyfuran (PFu) by in situ oxidative polymerization using FeCl3 oxidant in solvent mixture of acetonitrile–chloroform. The effects of polymerization conditions such as volume ratios of acetonitrile/chloroform, monomer concentration, and oxidant/monomer mol ratio were investigated on PFu content (%) of the composites. It was observed that pretreatment of PET in dichloromethane increased PFu content and its coating continuity before polymerization. The highest PFu content (12.0%) was obtained using FeCl3/furan mol ratios of 3.5 in acetonitrile/chloroform mixture (5/1). The density values of the composites with different PFu contents were measured. Composite fibers were also subjected to doping processes with HCl and I2 vapors, separately, and it was observed that the surface resistivity of PFu/PET (1012 Ω/cm2) reached to 53 Ω/cm2 after doping with I2. The structural, thermal, and morphological characterization was performed with FTIR, XRD, TGA, and SEM, respectively. 相似文献
88.
Exfoliated graphite nanoplates (xGnPs)/polystyrene-b-poly(ethylene-r-butylene)-b-polystyrene (SEBS) nanocomposites have been prepared by the simple melt-compounding approach. The structural, mechanical and viscoelastic properties of these composites were studied and compared. Wide-angle X-ray diffraction (WAXD) studies indicated that the processing of nanocomposites did not change the original d-spacing of xGnPs. Scanning electron microscopy observation on the fracture surfaces of the composites shows a uniform dispersion of xGnPs throughout SEBS matrix and strong interfacial adhesion between oxidized xGnPs and the matrix, which are responsible for the considerable enhancement of mechanical properties of the composites. It is found that the addition of xGnPs particles improved both the elastic modulus and storage modulus of pure SEBS significantly and the higher the xGnPs content, the higher the modulus of the nanocomposite. Moreover, the effects of dispersed xGnPs on the microphase separation of SEBS have also been investigated using small angle X-ray scattering (SAXS). 相似文献
89.
Scientometrics - While a large majority of scientific publications get most of their citations within the initial few years after publication, there is an interesting number of papers—termed... 相似文献
90.
Mobile Networks and Applications - Changes in the BAN topology are caused due to the body movement induced by repeated activities like walking, running, twisting, turning and waving arms. In such... 相似文献