Influence of surface treatment on properties of Cocos nucifera L. Var typica fiber reinforced polymer composites

Natural fibers are a powerful competitor in the polymer composite market due to their availability, sustainability, obtainability, cost, and biodegradability. The surface of natural fibers was changed to increase mechanical qualities, hydrophobicity, and bonding with polymer matrix. This study exposes the influence of several surface treatments of coconut tree peduncle fibers (CTPFs) on the thermomechanical and water absorption properties of CTPF-reinforced polymer composites. The CTPFs were treated with sodium hydroxide, benzoyl peroxide, potassium permanganate and stearic acid at a constant 40 wt% and individually reinforced in an unsaturated polyester resin matrix containing 60 wt% CTPFs. Chemically treated CTPFs improved reinforcement-matrix adhesion and enhanced composite mechanical characteristics. In addition, the scanning electron microscope fractographical study of stressed composite specimens shows improved reinforcement-matrix bonding. Moreover, the treated CTPFs have a higher cellulose wt%, which improves the composites crystalline nature, hydrophobicity and thermal stability. The potassium permanganate treated CTPF composite's maximum tensile strength of 128 MPa, flexural strength of 119 MPa, impact strength of 9.9 J/cm², hardness value of 99 HRRW and thermal stability up to 193°C make them appropriate for lightweight mobility and structural applications.     

Carbon black–polybenzoxazine nanocomposites for high K dielectric applications

This work involves the development of surface functionalized carbon black (FCB) reinforced polybenzoxazine (PBZ) nanocomposites, using a benzoxazine monomer and varying weight percentages of functionalized carbon black (0.5, 1.0, and 1.5 wt%) through ring opening polymerization via thermal cure. Data from the morphological studies indicate that the nanosized FCB particles are homogeneously distributed in the polybenzoxazine matrix. The incorporation of FCB improves the dielectric constant, electrical conductivity, and reduction in resistivity of the resulting FCB–PBZ nanocomposites when compared to neat PBZ. A significant improvement observed in glass transition temperature and thermal stability of resulting FCB–PBZ nanocomposites, when compared to neat PBZ. POLYM. COMPOS., 35:2121–2128, 2014. © 2014 Society of Plastics Engineers     

The effects of alternating current electrocoagulation on dye removal from aqueous solutions

The main goal of this study is to investigate the effects of alternating current (AC) on dye removal from aqueous solutions by electrocoagulation (EC). An EC system with parallel-connected aluminium electrodes was operated in batch mode. Two different aqueous dye solutions were used: one was obtained from Dianix Yellow CC (DY) and the other was obtained using Procion Yellow (PY). The experiments employing direct current (DC) were carried out using a DC power supply. The AC experiments were conducted using rectangular wave, which is produced with an adjustable time relay connected to the output of DC power supply. This current is called alternating pulse current (APC) in order to refer AC system in this study. Total organic carbon (TOC) and dye removal efficiencies were measured to assess treatment efficiency. Operating cost was calculated for both power supply systems and alternating pulse current was found superior to direct current for the treatment of reactive and disperse dyes used in this study.     

Corrosion inhibition of mild steel by benzotriazole derivatives in acidic medium

Benzotriazole derivatives, namely, N-[1-(benzotriazolo-1-yl)alkyl] aryl amine (BTMA), N-[1-(benzotriazolo-1-yl)aryl] aryl amine (BTBA), and 1-hydroxy methyl benzotriazole (HBTA), were synthesized and their inhibition behaviour on mild steel in 0.5 M H₂SO₄ at room temperature was investigated by various techniques. Preliminary screening of the inhibition efficiency (IE) was carried out using weight-loss measurements. Potentiodynamic polarization and AC impedance studies were used to investigate the inhibitor mechanism. Benzotriazole derivatives were found to act as mixed type inhibitors. Among the compounds studied, HBTA exhibited the best performance giving more than 95% IE in H₂SO₄ solutions. The passive film characterization was done using FTIR spectrum.     

Water-soluble polymers. I. Synthesis of N-succinimido (N) thiocarbonyl acrylamide and its polymerization: Grafting of this monomer and acrylamide onto poly(vinyl alcohol)

A new monomer, N-succinimido (N) thiocarbonyl acrylamide is formed when succinic anhydride, thiourea, and acryloyl chloride are condensed in mole proportions at low temperatures. The monomer is polymerized and graft copolymerized onto poly(vinyl alcohol) using a potassium bromate-thiourea redox system. Acrylamide is also similarly grafted to poly(vinyl alcohol) using the same initiator system. Grafting efficiencies of the monomers are determined from the elemental analyses data of the graft copolymers. Thermal behavior of the polymers are derived from the DSC thermograms of the polymers. © 1993 John Wiley & Sons, Inc.     

Effects of Modified Atmosphere Packaging with Various Carbon Dioxide Composition on Biogenic Amines Formation in Indian Mackerel (Rastrelliger kanagurta) stored at 5 ± 1°C

The profile of major biogenic amines was investigated in Indian mackerel packed in modified atmosphere for up to 12 days at 5 ± 1°C. Beheaded and gutted Indian mackerel was packed under different carbon dioxide compositions to study the effects on biogenic amines formation. The treatments were control air (C), vacuum packaging (VP), 30% CO₂/65% N₂/5% O₂ (M30C), 60% CO₂/35% N₂/5% O₂ (M60C), 80% CO₂/15% N₂/5% O₂ (M80C) and 100% CO₂ (M100C). Each amine responded differently to different CO₂ levels. After 12 days of storage, concentrations of histamine were reduced by 6.4%, 8.5%, 70.3%, 78.8% and 90.2% in fish packed under VP, M30C, M60C, M80C and M100C, respectively as compared with control air. Changes in putrescine and cadaverine showed a similar pattern. Gas mix of M30C and VP stimulated the formation of tyramine reaching 203 and 172 ppm, respectively. Higher composition of CO₂ had a significant inhibitory effect on tyramine concentration (p < 0.05). There were parallel increases of putrescine and spermidine in C, VP and M30C. No significant effect of CO₂ was observed on spermine (p > 0.05). After 9 days of storage, more than 300 ppm of histamine was detected in mackerel packed in VP and M30C; therefore, these atmospheres pose a histamine intoxication risk. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis,structural and optical characterization of ZrO2 core–ZnO@SiO2 shell nanoparticles prepared using co-precipitation method for opto-electronic applications

Nanocrystalline Zirconia (ZrO₂) and Zinc oxide (ZnO) as well as Silica (SiO₂) coated ZrO₂ core–shell structures were synthesized by both Co-precipitation and seeded polymerization technique. The phase analysis and the core–shell structure formation were confirmed by X-ray diffraction (XRD), FESEM and high resolution transmission electron microscopy (HRTEM) analysis. The existence of SiO₂ on ZrO₂@ZnO was characterized by FT-IR measurement. UV–Vis study reveals coating of ZnO over Zirconia shows red shift in the absorption spectra. Photoluminescence studies show the non-monotonous variation in luminescence behavior of these core–shell nanoparticles. This investigation explains that the interfacial effect between the core (ZrO₂) and the shell materials (ZnO and SiO₂) can be exploited to tune the optical properties of the material. This implies that we can envisage the core–shell materials as potential candidates for optical–electronic devices.     

Characterization of products evolved from supercritical water gasification of xylose (principal sugar in hemicellulose)

The catalyst decomposition of xylose (the principal sugar in hemicellulose) was examined in supercritical water for temperature from 400 to 600°C. Experiments were performed in the absence and presence of three main types of catalysts [alkali catalysts (K₂CO₃ and KOH) and metal impregnated activated carbons (Ni/AC) and (Ru/AC)] with a reaction time of 1h. Gasification yield reaches maximum values by using K₂CO₃ and KOH at the highest temperature of 600°C. The highest H₂ yield and the highest CH₄ yield were obtained by using Ru/AC and Ni/AC, respectively. Acetic acid and 5-methyl furfural were determined as the main aqueous products and reached maximum value by using Ru/AC.     

Mean grain size determination in marbles by ultrasonic first backwall echo height measurements

In ultrasonic grain size determination several techniques are in use. In this paper, the Ultrasonic Relative Attenuation (URA) method has been used to estimate the mean grain size of marble samples. Also, mean grain size versus first backwall echo height graphs have been plotted to see the direct relation between these two parameters. The results show less than 10% difference compared with values obtained in an optic microscope. In a comparison, mean grain size values of marbles determined by ultrasonic velocity methods are given.