Effects of annealing temperature on the optical, bonding, structural and electrical properties of nitrogenated amorphous carbon thin films grown by surface wave microwave plasma chemical vapor deposition

We have studied the effects of annealing temperature (AT) on the properties of nitrogenated amorphous carbon (a-C:N) films grown at room temperature (RT) on quartz substrates by surface wave microwave plasma chemical vapor deposition (SWMP-CVD) using camphor alcohol gas as carbon plasma sources. The thickness, optical, bonding, structural and electrical properties of the as-grown (RT) and anneal-treated in range from 100 to 500°C of a-C:N films were measured and compared. The film thickness is decreased rapidly with increasing AT above 350°C. The wide range of optical absorption characteristics is observed depending on the AT. The optical band gap of as-grown a-C:N films is approximately 2.8 eV, gradually decreased to 2.5 eV for the films anneal-treated at 300°C and beyond that it decreased rapidly up to 0.9 eV at 500°C . Visible-Raman Spectroscopy (Raman) revealed the amorphous structure of as-grown a-C:N films and, the growth of nanocrystallinity of a-C:N films upon increase of AT. Raman and Fourier transform infrared spectroscopy (FTIR) analyses respectively shown the structural and composition of the films can be tuned by optimizing the AT. The change of optical, bonding, structural and electrical properties of SWMP-CVD grown a-C:N films with higher AT was attributed due to the fundamental changes in the bonding and band structure of the a-C:N films.     

Behavior of Concrete Beams Strengthened in Shear with Carbon-Fiber Sheets

This paper presents the results of a test program for shear strengthening characteristics of continuous unidirectional flexible carbon-fiber polymer sheets bonded to reinforced concrete (RC) beams. A total of eight 150?mm×200?mm×2,600?mm concrete beams were tested. Various sheet configurations and layouts were studied to determine their effects on ultimate shear strength of the beams. From the tests, it was found that the externally adhesive bonded flexible carbon-fiber sheets are effective in strengthening RC beams in shear. Further, it was observed that the strength increases with the number of sheet layers and the depth of sheets across the beam section. Among the various schemes of wrapping studied, vertical U-wrap of sheet provided the most effective strengthening for concrete beam. Beam strengthened using this scheme showed 119% increase in shear capacity as compared to the control beam without any strengthening. Two prediction models available in literature for computing the shear contribution of carbon-fiber tow sheets to the shear capacity of fiber reinforced polymers bonded beams were compared with the experimental results.     

Bioadhesive ranitidine hydrochloride for gastroretention with controlled microenvironmental pH

Ranitidine hydrochloride is a H(2) receptor blocker used in the treatment of gastric ulcers. Pharmacological factors, in addition to the dosage regimen, favor development of a sustained-release system for ranitidine especially in the therapeutic condition of erosive esophagitis. This investigation delves into the development of bioadhesive type of gastroretentive formulation (tablets) of ranitidine. The effect of mucoadhesive polymers such as Carbopol, hydroxypropyl methyl cellulose, and dextrose were studied. Mucoadhesion, in vitro drug release profile, water uptake, and swelling of the tablet were evaluated. Alkalizing agents were incorporated in an attempt to maintain an alkaline microenvironment within the tablet and improve the stability of the drug in acidic medium. The stability was evaluated using dye test and degradation studies. The drug release profiles were fit into various kinetic models.     

Dimensional stability and mechanical behaviour of wood–plastic composites based on recycled and virgin high-density polyethylene (HDPE)

This paper investigated the stability, mechanical properties, and the microstructure of wood–plastic composites, which were made using either recycled or virgin high-density polyethylene (HDPE) with wood flour (Pinus radiata) as filler. The post-consumer HDPE was collected from plastics recycling plant and sawdust was obtained from a local sawmill. Composite panels were made from recycled HDPE through hot-press moulding exhibited excellent dimensional stability as compared to that made from virgin HDPE. The tensile and flexural properties of the composites based on recycled HDPE were equivalent to those based on virgin HDPE. Adding maleated polypropylene (MAPP) by 3–5 wt% in the composite formulation significantly improved both the stability and mechanical properties. Microstructure analysis of the fractured surfaces of MAPP modified composites confirmed improved interfacial bonding. Dimensional stability and strength properties of the composites can be improved by increasing the polymer content or by addition of coupling agent. This project has shown that the composites treated with coupling agents will be desirable as building materials due to their improved stability and strength properties.     

Room temperature polymerization of vinylic monomers by azo initiator

The azo initiator, sodium‐{4‐(4‐hydroxy‐phenylazo)‐benzenesulfonate (SHPBS)}, has been synthesized by coupling reaction with sodium‐(p‐sulfonate benzene diazonium chloride) and phenol. Unsymmetrical azo group leading to weak azo bond in case of SHPBS resulted in dissociation at lower temperature (25°C) to produce free radicals. Its versatile solubility (soluble in aqueous and organic solvents), generation of free radicals at 25°C, and its application without mechanical stirring are the added greater advantage over commercially available azo initiators (AIBN, etc.). The SHPBS has been characterized by FTIR, ¹H‐NMR spectroscopies, and thermal analysis. It has been observed that various monomers such as AM, AA, IPAM, and AMPS which have been polymerized with SHPBS have led to high molecular weight polymers at shorter reaction time. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Proactive role of carbon nanotube-polyaniline conjugate support for Pt nano-particles toward electro-catalysis of ethanol in fuel cell

Uniformly dispersed Pt over CNT-Pani hybrid support, shows considerable proficiency in energy conversion for ethanol electro-oxidation in acid medium. Thermal stability of the configuration was studied by thermo gravimetry while the functional moieties within the close packed composite structure were identified through FTIR spectroscopy. The size, shape and distribution of Pt NPs over the polymer modified CNT support were investigated through XRD and TEM analysis and the morphology was obtained from FESEM studies. The much improved functional property of Pt decorated CNT-Pani composite with respect to Pt over bare CNT, for direct ethanol fuel cell (DEFC), is attributable to the simultaneous effect of several promoting factors like creation of active electrochemical centers, charge tunneling and proton gliding within the composite structure, ensuring faster reaction kinetics and propagation of the reaction to considerable extent.     

Synthesis,characterization, and flocculation characteristics of polyacrylamide‐grafted glycogen

The synthesis of glycogen‐g‐polyacrylamide (Gly‐g‐PAM) was carried out by a ceric ion‐induced solution polymerization technique. Six grades of graft copolymers were synthesized by the variation of catalyst and monomer concentrations. These graft copolymers were characterized by intrinsic viscosity measurements, FTIR spectroscopy, and X‐ray diffraction techniques. Flocculation performance of these graft copolymers were done in kaolin suspension. Of the above grades, the graft copolymer Gly‐g‐PAM 5, which has longer PAM chains, showed best flocculation performance. The flocculation performance of the graft copolymer was compared with commercial flocculants and other PAM‐grafted flocculants developed so far in the authors' laboratory. In all the cases, it was found that the graft copolymer performed the best. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 773–778, 2007     

Integral backstepping sliding mode control for underactuated systems: Swing-up and stabilization of the Cart–Pendulum System

In this paper an integral backstepping sliding mode controller is proposed for controlling underactuated systems. A feedback control law is designed based on backstepping algorithm and a sliding surface is introduced in the final stage of the algorithm. The backstepping algorithm makes the controller immune to matched and mismatched uncertainties and the sliding mode control provides robustness. The proposed controller ensures asymptotic stability. The effectiveness of the proposed controller is compared against a coupled sliding mode controller for swing-up and stabilization of the Cart–Pendulum System. Simulation results show that the proposed integral backstepping sliding mode controller is able to reject both matched and mismatched uncertainties with a chattering free control law, while utilizing less control effort than the sliding mode controller.     

Preparation of ultra‐high‐molecular‐weight polyacrylamide by vertical solution polymerization technique

A straightforward and novel methodology has been developed for the synthesis of ultra‐high‐molecular weight polyacrylamide (PAM) by vertical solution polymerization technique. By varying the concentrations of acrylamide monomer, three different grades of polymers (PAM‐V₁, PAM‐V₂, and PAM‐V₃) have been synthesized and compared with the series of different grades of PAM (PAM‐C₁, PAM‐C₂, and PAM‐C₃) synthesized through conventional solution polymerization technique. The synthesized grades PAM‐V₁, PAM‐V₂, PAM‐V₃, PAM‐C₁, PAM‐C₂, and PAM‐C₃ have been characterized by ¹H NMR, infrared spectroscopy, intrinsic viscosity measurement, molecular weight determination by gel permeation chromatography, and thermal analysis. Rheological analysis has been carried out on the aqueous solutions of various grades of PAMs. Swelling behavior of ultra‐high‐molecular weight PAMs has also been investigated. The flocculation performances of all grades have been investigated in kaolin suspension by settling and jar test methods. POLYM. ENG. SCI., 59:1175–1181 2019. © 2019 Society of Plastics Engineers