Graft‐interpenetrating polymer networks of epoxy with polyurethanes derived from poly(ethyleneterephthalate) waste

Polyester polyurethanes derived from poly(ethyleneterephthalate) (PET) glycolysates were blended with epoxy to form graft‐interpenetrating networks (IPNs) with improved mechanical properties. Microwave‐assisted glycolytic depolymerization of PET was performed in the presence of polyethylene glycols of different molecular weights (600–1500). The resultant hydroxyl terminated polyester was used for synthesis of polyurethane prepolymer which was subsequently reacted with epoxy resin to generate grafted structures. The epoxy‐polyurethane blend was cured with triethylene tetramine under ambient conditions to result in graft IPNs. Blending resulted in an improvement in the mechanical properties, the extent of which was found to be dependant both on the amount as well as molecular weight of PET‐based polyurethane employed. Maximum improvement was observed in epoxy blends prepared with polyurethane (PU1000) at a loading of 10% w/w which resulted in 61% increase in tensile strength and 212% increase in impact strength. The extent of toughening was quantified by flexural studies under single edge notch bending (SENB) mode. In comparison to the unmodified epoxy, the Mode I fracture toughness (K_IC) and fracture energy (G_IC) increased by ～45% and ～184%, respectively. The underlying toughening mechanisms were identified by fractographic analysis, which generated evidence of rubber cavitation, microcracking, and crack path deflection. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40490.     

2D graphene supported nickel oxide nano-composite for fiber optic ethanol gas sensing,removal of azo dye,and biological activity

Journal of Materials Science: Materials in Electronics - Green synthesis of multifunctional metal oxide nanoparticles and its composites are widely evaluated for their efficacy in environmental and...     

Effect of crosslink density on transport of industrial solvents through polyether based polyurethanes

Polyurethanes based on PPG 2000 with variable concentrations of TDI and TMP were prepared and used for sorption studies, employing homologous series of hydrocarbons such as benzene, toluene and xylene. The sorption was observed to be non-Fickian in nature. The solubility parameter of the polyurethane series was observed to be 9·7(calcm^-3)^1/2. The polymer solvent interaction parameter χ was found to be lowest in benzene, suggesting higher interaction with it. The sorption and diffusion coefficients were observed to increase with a decrease in the degree of crosslinking. Molecular weights between crosslinks were calculated using the Flory–Rehner equation and compared with those obtained theoretically. © 1998 Society of Chemical Industry     

Structure–property relationship studies in amine functionalized multiwall carbon nanotubes filled polypropylene composite fiber

Amine functionalized multiwalled carbon nanotubes (a‐MWNT) based polypropylene (PP) composite fibers were prepared in the presence of polypropylene‐g‐maleic anhydride (PP‐g‐MA) by melt‐mixing followed by melt‐spinning with subsequent post‐drawing of the as‐spun fibers of varying draw ratio (DR). In order to enhance the interfacial interaction, a‐MWNT were utilized in combination with PP‐g‐MA during melt‐mixing. Fourier transform infrared spectroscopic analysis revealed the formation of imide bonds between MA functionality of PP‐g‐MA and amine functional group of a‐MWNT. Higher tensile properties of PP/a‐MWNT/PP‐g‐MA composite fibers were registered with varying DR of the as‐spun fiber. Orientation factors of a‐MWNT and PP chains along the fiber axis were correlated with the higher tensile modulus and tensile strength of PP/a‐MWNT/PP‐g‐MA composite fiber of varying DR. Crystallization studies indicated the role of hetero‐nucleating action of a‐MWNT in PP/a‐MWNT/PP‐g‐MA composite fiber. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Mechanism of microemulsion polymerization of methyl methacrylate: Experimental evidence

Free radical polymerization of methyl methacrylate in emulsion and microemulsion media was studied for the understanding of the mechanism of the polymerization process. Average particle size of the poly(methyl methacrylate) (PMMA) latex formed during microemulsion polymerization was observed to be ≈ 45 nm. Nuclear magnetic resonance data indicated a larger number of interactions for β-methylene protons of PMMA synthesized in microemulsion, indicating dominant isotaciticity in the polymer. Activation energy of degradation of the products was calculated by Broido's method and was found to be 44.70 kJ/mol and 65.47 kJ/mol for PMMA synthesized from microemulsion and emulsion media, respectively. Solution properties of the above polymers were also studied. Intramolecular expansion factors indicate a more rigid structure for PMMA synthesized from microemulsion medium. © 1996 John Wiley & Sons, Inc.     

Structure recognition and information extraction from tabular documents

We present a system for the extraction of the structural information of a table from its image. Following the initial binarization and deskewing operations, the image is scanned to extract all horizontal and vertical lines that may be present. The table's dimensions are estimated based on these lines. Unlike other systems, the procedure described here does not depend on the sole existence of lines to mark the item blocks. White streams are recognized in both the horizontal and vertical directions as substitutes for any missing demarcation lines. A structure interpretation procedure uses the extracted demarcation information to identify each of the item blocks in the table. Subsequently, the interrelations of these item blocks are used to recognize the structure of the tabulated data. The interpretation can be done for one-dimensional as well as two-dimensional tables. Interpretation of the tabular document involves character recognition, which in turn depends on the structure of the table. The above procedure to extract the structural information of the tabular document can be used to extract useful information from different types of tabular drawings. In this article, we focus our attention on interpreting telephone company central office drawings. These drawings contain additional information in the form of crossed-out entries and repeated entries, which must be detected and recognized to interpret the document completely. Hence, after extracting the basic structure of the drawing, the additional information is extracted and cell block location is obtained in order to develop a data base representing the tabular document. The telephone company drawings are very large in size, resulting in images as large as 15,000 x 10,000 pixels. Thus, designing efficient and fast algorithms is an important criterion in this research. © 1996 John Wiley & Sons, Inc.     

Solving general multi-class closed queuing networks using parametric decomposition

This paper presents a new approach to evaluate the performance of general multi-class closed queuing networks. The approach uses parametric characterization of the traffic processes to derive two-moment approximations for performance measures at individual nodes. Based on these approximations, linkage equations are derived to establish the relationships between the various nodes in the network. These relationships result in a system of non-linear equations that is solved using an iterative procedure. Numerical studies comparing the performance of the approach with detailed simulations suggest that the approach yields fairly accurate estimates of performance measures without significant computational complexity.     

Nickel oxyhydroxide/manganese dioxide composite as a candidate electrode material for alkaline secondary cells

Nickel hydroxide and manganese dioxide are used in alkaline cells as positive electrode materials. Positive electrodes comprising a nickel oxyhydroxide/manganese dioxide composite, with modification by Bi₂O₃, deliver a combined reversible discharge capacity of 2.25e per metal atom (650 mAh g⁻¹ metal content), which is higher than that realized from electrodes of either component taken singly. The composite discharges with two potential plateaux, the first appearing at 325 mV corresponds to the discharge of the nickel component, whereas the second at −600 mV is due to the manganese component. Composites of NiO(OH)/MnO₂ can be used as a new electrode material with higher discharge capacity than conventional electrodes.