Effect of mixed size particles reinforcing on the thermal and dynamic mechanical properties of Al2O3/PPS composites

Thermal and dynamic mechanical properties of polyphenylene sulfide (PPS) composites that were reinforced with different sized alumina (Al₂O₃) particles were studied. These composites were manufactured with two different sizes of Al₂O₃ particles 1 and 63 µm, using microcompounding and injection molding. Monosized Al₂O₃ particles reinforced up to 25 wt% loading content and mixed size Al₂O₃ particles reinforced at 15 wt% loading content as following particle weight proportions: 75% × 63 μm + 25% × 1 μm, 50% × 63 μm + 50% × 1 μm, 25% × 63 μm + 75% × 1 μm. Particle distribution investigations were performed by microcomputerized tomography (micro‐CT). Thermal properties were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) methods and also dynamic mechanical properties were investigated by dynamic mechanical thermal analysis (DMTA) method. The results showed that mixed size Al₂O₃ particle reinforced composites showed a great enhancement in dynamic mechanical properties without significant change in thermal properties. It was concluded that mixed size particles showed a great synergy to give better results compared with monosized particle reinforced composites. POLYM. COMPOS., 37:3219–3227, 2016. © 2015 Society of Plastics Engineers     

Investigation of human exposure to triclocarban after showering and preliminary evaluation of its biological effects

The antibacterial soap additive triclocarban (TCC) is widely used in personal care products. TCC has a high environmental persistence. We developed and validated a sensitive online solid-phase extraction-LC-MS/MS method to rapidly analyze TCC and its major metabolites in urine and other biological samples to assess human exposure. We measured human urine concentrations 0-72 h after showering with a commercial bar soap containing 0.6% TCC. The major route of renal elimination was excretion as N-glucuronides. The absorption was estimated at 0.6% of the 70±15 mg of TCC in the soap used. The TCC-N-glucuronide urine concentration varied widely among the subjects, and continuous daily use of the soap led to steady state levels of excretion. In order to assess potential biological effects arising from this exposure, we screened TCC for the inhibition of human enzymes in vitro. We demonstrate that TCC is a potent inhibitor of the enzyme soluble epoxide hydrolase (sEH), whereas TCC's major metabolites lack strong inhibitory activity. Topical administration of TCC at similar levels to rats in a preliminary in vivo study, however, failed to alter plasma biomarkers of sEH activity. Overall the analytical strategy described here revealed that use of TCC soap causes exposure levels that warrant further evaluation.     

Inkjet printing of conjugated polymer precursors on paper substrates for colorimetric sensing and flexible electrothermochromic display

Inkjet-printable aqueous suspensions of conjugated polymer precursors are developed for fabrication of patterned color images on paper substrates. Printing of a diacetylene (DA)-surfactant composite ink on unmodified paper and photopaper, as well as on a banknote, enables generation of latent images that are transformed to blue-colored polydiacetylene (PDA) structures by UV irradiation. Both irreversible and reversible thermochromism with the PDA printed images are demonstrated and applied to flexible and disposable sensors and to displays.     

Analyzing the stability of a failing rock slope for suggesting suitable mitigation measure: a case study from the Theng rockslide,Sikkim Himalayas,India

At km 87.20 near Theng on the North Sikkim Highway, India, severe rock falls and slides in recent years rendered 180 m stretch of this important road corridor in the Sikkim Himalayas risky and vulnerable to the commuters. The rockslide at Theng has, thus, been studied in detail at 24 discrete locations using the ground-based topographic, lithologic and structural data with an objective to evaluate the mechanisms of rock sliding for suggesting the most effective mitigation measure. In this study, large scale geological mapping and site-specific kinematic analyses in different spatial domains corroborated that within this 180 m stretch, despite having a competent lithology (quartzo feldspathic gneiss and quartzites), the possibility of both plane and wedge failures are high because of gentler and unfavourably oriented planar discontinuities with respect to the available steep topography. The rock slope failure analysis both at discrete locations and in a distributed manner in a Geographic Information System further revealed that unfavourable geometric disposition of discontinuities at Theng rendered multiple modes of failure at critical locations, which is also corroborated by a very low Slope Mass Rating value (4.0) determined in this area, thus, making it difficult to suggest any cost-effective surface protection measure. However, analysis suggests slope dressing or re-excavation to contain future rock sliding in such cases, but the same appears to be difficult to implement on the ground because of unfavourable kinematic conditions of the vulnerable rock discontinuities. Accordingly, after evaluating the site conditions in detail, a short road tunnel with its probable tunnel rockmass conditions is proposed to bypass this active rock sliding stretch.     

Possible use of volcanic ash as a filler in polyphenylene sulfide composites: Thermal,mechanical, and erosive wear properties

It is a common practice to use particle materials as fillers to improve engineering properties of polymer composites and to lower the cost of final products. There is an obvious cost advantage of compounding volcanic ash (VA) in polymers, either to replace traditional fillers. This study is concerned with thermal, mechanical, and erosive properties of VA‐filled polyphenylene sulfide (PPS) composites. Composite samples containing VA particles at various concentrations (0, 2.5, 5, 10, 15, and 20 wt%) were manufactured by twin screw extruder and injection molding machine. Thermal properties were investigated by thermogravimetric and dynamic mechanical analysis methods. Erosive wear properties were investigated by performing solid particle erosion tests at 30º and 90º impingement angles. The mechanical properties such as flexural strength and modulus of uneroded samples and residual flexural strength and modulus of eroded composite samples were determined by three‐point bending tests. Results show that thermal, mechanical, and residual mechanical properties of the PPS composite were significantly improved by adding VA, although erosion resistance was decreased markedly. It was concluded that VA can be used as a reinforcement in PPS composites to improve thermal and mechanical properties and to reduce the cost of the PPS composites. POLYM. COMPOS., 35:1826–1833, 2014. © 2014 Society of Plastics Engineers     

Functionalized polyethylene on property enhancement of lubricating oil and their performance evaluation study

Methyl methacrylate (MMA) functionalized polyethylene additives for improving the properties of lubricating oil has been investigated in which poly(MMA-co-ethylene) were synthesized by using three different polymerization techniques such as miniemulsion, post polymerization and reverse atom transfer radical polymerization with 1.0 molL −1 of MMA and 20 bar of ethylene pressure. The copolymers are block in nature with the composition of 1:3 molar ratios of ethylene:MMA which is independent of polymerization techniques used. ¹H NMR analysis confirmed the successful incorporation of the copolymers in the lubricating oil. Thermogravimetric analysis reveals that the addition of poly(MMA-co-ethylene) increases thermal stability of the additive doped lubricating oil by approximately 40°C with a single stage decomposition pattern. Flash point measurements show an increasing flash point values for copolymer doped lubricating oil. From rheological study, the viscosity index of base lubricating oil has found significant increases from 102 to 129 with the addition of poly(MMA-co-ethylene) and the higher molecular weight (MW) of this copolymer provides better thickening efficiency. However, copolymer with higher MW seems to be more susceptible to mechanical degradation resulting in lower shear stability whereas copolymer with lower MW acts as a better pour point depressant.     

Nanocomposites of polymer gel electrolyte based on poly(ethylene glycol diacrylate) and Mg–Al layered double hydroxides

The present paper describes the synthesis and characterization of nanocomposite materials composed of the polymer gel electrolyte and a layered double hydroxide (LDH) inorganic filler. Mg–Al LDHs were prepared with various ratios of Mg/Al. It was observed that the layered structure of Mg–Al LDH was totally exfoliated by the PEGDA. The ionic conductivity and mechanical strength were highly improved in the nanocomposite systems. In the case of the composite films having 4.5 wt% of the Mg–Al LDH, the ionic conductivity reached 1.6 × 10^?3 S cm^?1 at room temperature. The incorporation of nanoparticles into the gel resulted in a two‐ or threefold increase in the tensile modulus. Copyright © 2004 Society of Chemical Industry