Fabrication of self-ordered nanoporous alumina with 500–750 nm interpore distances using hard anodization in phosphoric/oxalic acid mixtures

A hard anodization (HA) technique is employed using different mixtures of phosphoric/oxalic acid for fast fabrication of alumina nanopore arrays in voltages higher than 200 V. The mixtures enable to avoid the breakdown of porous anodic alumina (PAA) in the high voltages. It is revealed for the first time that continuously tunable pore intervals (D_int) from 500 to 750 nm can be controlled by varying the concentrations of oxalic acid at anodization voltages (U_anod) from 230 to 360 V, far beyond the U_anod in the single electrolyte of phosphoric acid or oxalic acid. The ratios of interpore distance, pore diameter and barrier layer thickness to anodization voltage are in the range of conventional HA process for each acid mixture. In this approach, the PAA film growth rate is 26 µm/h, being 7 times larger than that in typical mild anodization.     

Dithiocarbamate as an efficient intermediate for the synthesis of 2-(alkylthio)thiazol-4(5H)-ones

An effective approach for the synthesis of 2-(alkylthio)thiazol-4(5H)-ones from alkyl dithiocarbamates and chloroacetyl chloride in the presence of NaHCO₃ has been developed. Good to excellent yields of products, simple reaction conditions and general applicability are the most important advantages of this protocol.     

Preparation and characterization of PPRC/EPDM thermoplastic vulcanizates: A comparative study

Thermoplastic vulcanizates (TPVs) of polypropylene random copolymer (PPRC) with ethylene–propylene diene monomer rubber (EPDM) were prepared through in situ and ex situ compatibilization techniques. Silanized silica as nanofiller was incorporated in the ex situ compatibilized TPVs. Mechanical properties were measured for different formulated TPVs with increasing loading of EPDM from 10 to 30 phr. A comparative data is generated to discuss the effect of two compatibilization techniques and addition of silica filler in the TPVs. The degradation studies were also carried out to check the stability of the blends under harsh ultraviolet environment. The in situ compatibilized TPVs provided better overall mechanical properties. Moreover, it is worth mentioning that the properties of ex situ compatiblized TPVs were enhanced by incorporation of silanized silica filler. Silanized silica filler helped in reducing the die swell significantly. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46726.     

Preparation of Electrospun Electroactive Nanofibers of Four Arm Star-Shaped Poly(ε-Caprolactone)-b-Poly(2-Hydroxyethyl Methacrylate) and Its Blends with Polyaniline

A combination of ring-opening polymerization and atom-transfer radical polymerization was used to synthesize a four-arm star-shaped poly(ε-caprolactone)-b-poly(2-hydroxyethyl methacrylate). The structure of obtained copolymer was determined by Fourier transform infrared, ¹H and ¹³C NMR spectroscopies. The uniform electroactive nanofibers consisting blend of four-arm star-shaped poly(ε-caprolactone)-b-poly(2-hydroxyethyl methacrylate) copolymer and polyaniline were produced using electrospinning technique. The electroactivity of prepared nanofibers was investigated using cyclic voltammetry measurement. The morphologies of electrospun nanofibers produced from four-arm star-shaped poly(ε-caprolactone)-b-poly(2-hydroxyethyl methacrylate) and their blends with polyaniline were investigated by the scanning electron microscopy. The presence of polyaniline resulted in significant decrease of sticking fibers.     

Effects of chemical surface pretreatment on tensile properties of a single glass fiber and the glass fiber reinforced epoxy composite

The aim of this article is to determine the effect of surface pretreatments, prior to the silanization, on the structure and tensile properties of the glass fibers and their epoxy composites. Commercial glass fibers were washed with acetone to remove the soluble portion of sizing, calcinated for the removal of organic matter, activated for surface silanol regeneration, and silanizated with glycidoxypropyltrimethoxysilane (GPS). Tensile test was carried out. The morphology of pretreated glass fibers and the fracture surfaces of the epoxy composites were observed with a scanning electron microscope (SEM). The results revealed that both apparent modulus and strength of a single glass fiber and the glass fiber/epoxy resin composites strongly depend on the fiber surface pretreatments. The acetone treatment did not change appreciably the composition and tensile properties of glass fibers, but there was a weak interface between fibers and matrix. In calcinated and acid activated fibers, the two competitive effects was observed: (1) degradation of the fibers themselves and (2) improved interfacial adhesion between the glass fibers and the epoxy matrix, once the samples was silanizated. The ATR‐FTIR results show that the surface content of Si OH increases as reflected by the increasing of the Si O band, resulting in an interaction between silane coupling agent and glass fiber. POLYM. COMPOS., 91–100, 2016. © 2014 Society of Plastics Engineers     

Using short‐term resource scheduling for assessing effectiveness of CCS within electricity generation subsector

A new methodology for assessing the effectiveness of carbon capture and storage (CCS) that does explicitly consider the detailed operation of the target electricity system is proposed. The electricity system simulation consists of three phases, each one using a modified version of an economic dispatch problem that seeks to maximize the producers’ and consumers’ surplus while satisfying the technical constraints of the system. The economic dispatch is formulated as a dynamic mixed‐integer nonlinear programming problem and implemented in general algebraic modelling system (GAMS). The generating unit with CCS is designed and simulated using Aspen Plus®. In the first case study, the operation of the IEEE RTS ’96 (Institute of Electrical and Electronics Engineers One‐Area Reliability Test System—1996) is simulated with greenhouse gas (GHG) regulation implemented in the form of CO₂ permits that generators need to acquire for every unit of CO₂ that it is emitted. In the second case study, CCS is added at one of the buses and the operation of the modified IEEE RTS ’96 is again simulated with and without GHG regulation. The results suggest that the detailed operation of the target electricity system should be considered in future assessments of CCS and a general procedure for undertaking this for any GHG mitigation option is proposed. Future work will use the novel methodology for assessing the effectiveness of generating units with flexible CO₂ capture. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4210–4234, 2015     

Synthesis of a Series of PEG-Based ABA Triblock Copolymers and Their Influence on Rheology of Cement Slurries

A series of water-soluble ABA triblock copolymers consisting of a polyethylene glycol central block joined to two blocks of six different homopolymers have been synthesized via simple solvent-free and ecofriendly routes and characterized by FTIR and ¹HNMR spectroscopy. Dispersing and slump-retaining abilities of the copolymers in cement slurries were evaluated by mini-slump spread method. Rheological measurements of samples with the best performance were carried out using a rate-controlled coaxial cylinder viscometer. The test results indicate that the dispersing power of the copolymers in cement pastes is strongly affected by the structure and degree of polymerization of the monomers.     

Development of Carbon Nanotube Modified Cement Paste with Microencapsulated Phase-Change Material for Structural–Functional Integrated Application

Microencapsulated phase-change materials (MPCM) can be used to develop a structural–functional integrated cement paste having high heat storage efficiency and suitable mechanical strength. However, the incorporation of MPCM has been found to degrade the mechanical properties of cement based composites. Therefore, in this research, the effect of carbon nanotubes (CNTs) on the properties of MPCM cement paste was evaluated. Test results showed that the incorporation of CNTs in MPCM cement paste accelerated the cement hydration reaction. SEM micrograph showed that CNTs were tightly attached to the cement hydration products. At the age of 28 days, the percentage increase in flexural and compressive strength with different dosage of CNTs was found to be up to 41% and 5% respectively. The optimum dosage of CNTs incorporated in MPCM cement paste was found to be 0.5 wt %. From the thermal performance test, it was found that the cement paste panels incorporated with different percentages of MPCM reduced the temperature measured at the center of the room by up to 4.6 °C. Inverse relationship was found between maximum temperature measured at the center of the room and the dosage of MPCM.