Polyaniline-multiwalled carbon nanotube composites: Characterization by WAXS and TGA

Polyaniline/carboxylated multi-walled carbon nanotube (PAni/c-MWNT) nanocomposites have been synthesized by micellar aided emulsion polymerization with various c-MWNTs compositions, viz., 0.5, 1, 5, and 10 wt %. The microcrystalline parameters such as the nanocrystal size (〈N〉), lattice strain (g), interplanar distance (d_hkl), width of the crystallite size distribution, surface weighted crystal size (D_s), and volume of the ordered regions were calculated from the X-ray data by using two mathematical models, namely the Exponential distribution and Reinhold distribution methods. The effects of heat ageing on the microcrystalline parameters of the PAni/c-MWNT nanocomposites were also studied and the results are correlated. The thermal stability and electrical resistivity of the PAni/c-MWNT nanocomposites were examined with thermogravimetric analysis (TGA) and a conventional two-probe method. The TGA data indicate that the thermal stability of the nanocomposites improved after the incorporation of c-MWNTs. The influence of temperature on the resistivity of the nanocomposites was also measured. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Physico-Mechanical Properties of Nano Silica-Filled Epoxy-Based Mono and Hybrid Composites for Structural Applications

Silicon - This research article describes the results of nano-silica (nSiO2) filled epoxy (Ep) mono composites with different contents (0.5, 1.0, 1.5, 3, and 5 wt.%) and carbon...     

Synthesis and characterization of polyurethane/poly(vinylidene chloride) interpenetrating polymer networks

A series of polyurethane (PU)/poly(vinylidene chloride) (PVDC) interpenetrating polymer networks (IPNs) were synthesized through variations in the amounts of the prepolyurethane and vinylidene chloride monomer via sequential polymerization (80/20, 60/40, 50/50, 40/60, 30/70, and 20/80 PU/PVDC). The physicomechanical and optical properties of the IPNs were investigated. Thermogravimetric analysis (TGA) studies of the IPNs were performed to establish their thermal stability. TGA thermograms showed that the thermal degradation of the IPNs proceeded in three steps. Microcrystalline parameters, such as the crystal size and lattice disorder, of the PU/PVDC IPNs were estimated with wide‐angle X‐ray scattering. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1375–1381, 2007     

Modelling the viscoelastic stress relaxation of glass fibre reinforcements under constant compaction strain during composites manufacturing

Viscoelastic stress relaxation of glass fibre reinforcements is commonly encountered in the manufacture of glass fibre reinforced polymer composites. A better understanding of the phenomenon, coupled with an ability to predict this behaviour, will aid improved manufacturing process control and tooling design. Finished product quality may also be bettered by virtue of increased knowledge of stresses acting within the composite product. This paper presents a simple Maxwell element-based model to both simulate and help explain the viscoelastic stress relaxation of glass fibre reinforcements under compressive strain compaction of layers during composites manufacturing. The model was validated against experimental data for reinforcement materials of different architecture, and good-to-reasonable predictions of the stress relaxation response were obtained.     

Assessment of the performance of different compost models to manage urban household organic solid wastes

The environmental, cultural, socio-economic and political conditions of each community greatly affect the municipality’s effort and decision-making in managing household wastes. Composting at home can be used as a sound method of SWM, can manage the waste at source itself thereby can increase their recycling. And vermicomposting is a viable and completely feasible option at household level, provided it is acceptable to family members to handle the worms and to remove worm-casts subsequently. In this regard, the present paper gives a methodological framework for assessing the management of urban household organic wastes using different compost models to influence the actual efficiency and effectiveness of a municipality’s collection and management services. The current study also deals with the challenges of solid waste management with a focus on the segregation of compostable wastes from the non-compostable ones and their composting, recycling or disposal. The non-compostable wastes can be left for recycling and re-use by the concerned authorities. The composting behavior and the efficiency of different compost models have been dealt with, and it is concluded that vermicomposting model is the best option. Urban residents can be educated to vermicompost not only their entire kitchen wastes but also garden wastes to reduce the burden on the municipal councils.     

Microscopic order parameter of two nematogenic compounds using X-rays

X-ray Laue type diffraction patterns were recorded using the image plate system at different temperatures in the nematic phase for two nematogenic compounds. Micro-orientational order parameters have been computed using different methods. These are compared with the microscopic orientational order parameters obtained from refractive index data. Higher order parameters have also been computed and compared. Distribution function at various temperatures for the two nematogenic compounds from Deutsch method has been reported.     

Studies on residual aryl amine content on discharge printed silk fabrics

Degummed and bleached tabby silk fabric was dyed with easily dischargeable azo dyes and discharge printed with zinc sulphoxylate-formaldehyde. The aryl amines released during the discharge printing were quantitatively recovered and identified by using gas chromatography mass spectrometry. Quantitative analysis by HPLC of the regenerated aryl amines shows that the initial soaking and one rinsing removes more than 43% of the amines in the case of benzidine-based azo dyes. The quantity of the residual amine (benzidine) retained by the benzidine-based dyes even after fourth rinsing was in the range of 300–780 mg/kg. This compared with acid dye (CI Acid Red 114) based on o -toluidine, released 70% of the regenerated amine in the first rinsing itself and 84% after the fourth rinsing.     

Inhibition of Rhizomucor miehei and Candida rugosa lipases by D-glucose in esterification between L-alanine and D-glucose

A detailed kinetic study of the esterification of D-glucose with L-alanine catalyzed by lipases from Rhizomucor miehei (RML) and Candida rugosa (CRL) showed that both lipases follow the Ping-Pong Bi-Bi mechanism, in which L-alanine and D-glucose bind in subsequent steps releasing water and L-alanyl-D-glucose, with competitive substrate inhibition by D-glucose at higher concentrations leading to the formation of dead-end lipase.D-glucose complexes. An attempt to obtain the best fit of this kinetic model through curve fitting yielded good approximates of the apparent values of four important kinetic parameters: for RML-k(cat)=0.29+/-0.028x10(-3) M h(-1) mg(-1), K(m L-alanine)= 4.9+/-0.51x10(-3) M, K(m D-glucose)=0.21+/-0.018x10(-3) M, and K(i D-glucose)=1.76+/-0.19x10(-3) M; for CRL-k(cat)= 0.75+/-0.08x10(-3) M h(-1) mg(-1), K(m L-alanine)=56.2+/-5.7x10(-3) M, K(m D-glucose)=16.2+/-1.8x10(-3) M, and K(i D-glucose) =21.0+/-1.9x10(-3) M.     

Influence of inherent strain on the curie temperature of rare earth ion-doped bismuth vanadate

X-ray line broadening is found to be an effective parameter to estimate the strain associated with rare earth ion (Gd³⁺)-doped polycrystalline bismuth vanadate(Bi₂VO_5·5). The strain increases with increasing Gd³⁺ concentration. It is anisotropic and found to be maximum in (111) plane. The Curie temperature which is known to decrease with increase in the rare earth ion concentration in these compounds is correlated with increase in strain.