Suitable Processability Research Articles

Progress in flexible energy storage and conversion systems, with a focus on cable-type lithium-ion batteries

The unending demand for portable, flexible, and even wearable electronic devices that have an aesthetic appeal and unique functionality stimulates the development of advanced power sources that have excellent electrochemical performance and, more importantly, shape versatility. The challenges in the fabrication of next-generation flexible power sources mainly arise from their limited form factors, which prevent their facile integration into differently shaped electronic devices, and from the lack of reliable electrochemical materials that exhibit optimized attributes and suitable processability. This review describes the technological innovations and challenges associated with flexible energy storage and conversion systems such as lithium-ion batteries and supercapacitors, along with an overview of the progress in flexible proton exchange membrane fuel cells (PEMFCs) and solar cells. In particular, recently highlighted cable-type flexible batteries with extreme omni-directional flexibility are comprehensively discussed.

Thermal Properties and Electrical Conductivity of Graft Copolymers from Polystyrene and Polyvinyl Propionate with Polyaniline

AbstractA synthesized graft copolymer from polystyrene (PS) and polyvinyl propionate (PVPr) with polyaniline (PANi) with suitable electrical properties, thermal resistance, solubility and processability was optimized. Samples were prepared in the form of smooth and thin films. Four-point probe method was adapted to examine electrical DC conductivity. It was found that the electrical conductivity and thermal stability of copolymers were increased, but their processability and solubility decreased when PANi increased. Thermal stability of copolymers was investigated by Differential Scanning Calorimetry (DSC) and Thermal Gravimetrical Analysis (TGA). The prepared copolymers were much more thermally stable, soluble, flexible and ability to form a film than polyaniline, polystyrene and polyvinyl propionate. An irreversible exothermic transition was observed by DSC, which is believed to be an indication of cross-linking. Percentage of grafted PANi electrical conductivities of PS-g-PANi and PVPr-g-PANi have been examined and produced conductivities, 3.3 × 10−2 and 4.6 × 10−2 S/cm respectively.

Preparation and electrical characterization of poly(vinyl amine) hydrogels, crosslinked with Cu(II) ions, and evaluation of their potentiality as water sensor material

AbstractA method to prepare water sensitive composites employing crosslinked poly(vinyl amine) (PVAm) and Cu(II) ions as reticulation agent is disclosed in this work. This article presents in detail, the reticulation reaction and its pH dependence, as well as its electrical, rheological, and thermal properties of the PVAm‐Cu(II) composites obtained. The complex bonds formed between the Cu(II) ions and the amine groups of PVAm produce an interesting network of crosslinked structures that generate a microporous morphology when the material is extruded. This characteristic favors fast absorption of water when it is wetted, and a concomitant decrease in its apparent resistivity in a very short period of time. Furthermore, they present an excellent thermal stability and suitable processability. These characteristics make them interesting candidates to design ultra fast water sensors. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Halogen Free Flame Retardant Agents for Polypropylene in Wire Coating Process

Abstractthe processing behaviour and physical properties of polypropylene/flame retardant blends were investigated in order to evaluate their use in the wire‐coating process. In particular, the need of flame retardancy, suitable melt processability and good mechanical properties of blends was taken into account. Three types of halogen free flame retardants were chosen and were melt blended to the polypropylene matrix. Blends properties were analysed by rheological, mechanical, and thermal characterization including flame retardancy tests. The wire coating process was also performed by a laboratory wire coating apparatus. The results demonstrated that some of the blends are suitable for the purpose of flame retardancy of electrical household wires as an alternative to PVC.

Binary and Ternary mLLDPE Blends: Tailoring Their Properties Using Complex Viscosity Measurements

AbstractSummary: Metallocene‐catalysed linear low density polyethylenes (mLLDPEs) of different molecular weights are mixed with a base mLLDPE to obtain a pre‐determined grade and a suitable extrusion processability. Complex viscosity results are revealed as a very suitable tool to tailor the properties of the prepared binary and ternary blends. The investigated blends show symptoms of miscibility like time‐temperature superposition and observance of Cox‐Merz rule. This allows to evaluate the molecular weight distribution, supplying also practical data related to the polyethylene grade and ‘sharkskin’ instability. The complex viscosity curve of a model sample that would have both, a suitable grade and processability, is created; blends are prepared to match the model curve. The blend with a low molecular weight mLLDPE shows a parallel shift of the complex viscosity to lower values (molecular weight distribution is not broadened), postponing sharkskin, but changing the polymer grade. Satisfactory results are neither obtained with blends of a high molecular weight mLLDPE. Best results are obtained with ternary blends, which combine the modifications provided by low and high molecular weight mLLDPEs, approaching the complex viscosity and molecular weight distribution of the model.Complex viscosity results of PR‐207 (– —), PR‐209 (···) and PR‐210 (– –) ternary blends, as compared with those of base samples PR‐201 (symbols) and the model (line).magnified imageComplex viscosity results of PR‐207 (– —), PR‐209 (···) and PR‐210 (– –) ternary blends, as compared with those of base samples PR‐201 (symbols) and the model (line).

New Soluble n-Type Conjugated Polymers for Use as Electron Transport Materials in Light-Emitting Diodes

We report the synthesis of a series of six new soluble n-type conjugated copolymers that incorporate bis(phenylquinoline) and regioregular dialkylbithiophene in the backbone, the investigation of their electrochemical, photophysical, and electroluminescent properties, and their use as electron transport materials in light-emitting devices. Variation of the alkyl chain length of the head-to-head dialkylbithiophene linkage from butyl (C4) to dodecyl (C12) had little or no effect on the photophysical or redox properties of the new polyquinolines. However, the glass transition temperature decreased from 256 °C for the butyl derivative to 76 °C for the dodecyl derivative. A single-crystal X-ray structure of a model compound allowed quantification of the intramolecular torsion angles which explain the significant difference in optical band gap and redox properties between the head-to-tail and head-to-head polymers. The high electron affinity (2.88−2.97 eV), robust thermal stability, suitable solution processability, and weak-to-moderate intrinsic electroluminescence of the polymers make them attractive for use as electron transport materials in organic LEDs. Initial use of the polymers as the electron transport materials in bilayer poly(2-methoxy-5-(2‘-ethylhexyloxy)-1,4-phenylenevinylene) (MEH−PPV) LEDs showed substantial enhancement in device performance under ambient air conditions (1.4% external quantum efficiency, 2170 cd/m2) compared to most current electron transport polymers for LEDs.

Phosphor paste properties in ink-jet patterning of phosphors for high resolution pdp

A novel ink-jet printing method with the precision nozzle(φ = 0.2 mm and L = 1.0 mm)for fine pattening of phosphor layer in PDP was investigated. In order to optimize the rheological properties of the phosphor paste for the precision nozzle, the composition of the paste was developed by proper combinations of binder polymer, solvnet, dispersant, phosphor powder and additives. It was found that combination of hydroxypropylcellulose and poly(methylmethacrylate-co-methacrylic acid)as binder polymer and 50 wt%of phosphor powder in the paste resulted in suitable processability to the ink-jet printing with the precision nozzle and produced phosphor layers with 29 μm of thickness after sintering process.

Structural modifications and fibre processing of hydroxy-functionalised mesogenic polyazomethines

A number of semiflexible homopolyazomethines and copolyazomethines based on hydroxy-functionalised mesogenic cores have been synthesised and characterised. The reported polymers include structural modifications such as an alteration of the coaxiality, shortening of the flexible spacers or copolymerisation to attain materials with reduced melting temperatures and suitable processability. These structural alterations have been introduced by condensing different α,ω-bis-[(4-formyl-3-hydroxyphenyl)oxy]alkanes with 2-methyl-1,4-phenylenediamine and/or 4-methyl-1,3-phenylenediamine. Fibres have been melt extruded from those nematic polyazomethines with the most favourable thermal properties. As-spun and tension-annealed fibres have been investigated by thermal analysis (TGA and DSC), X-ray diffraction and SEM microscopy in an attempt to infer a relationship between microstructure and tensile properties. From the results presented here, copolymerisation incorporating flexible spacers of different lengths seems to be the best strategy to balance ease of processing and tensile properties. Some of the fibres have improved mechanical properties compared with those previously reported for this class of semiflexible polyazomethine. A nematic polyazomethine with a decamethylenic spacer has also been modified with low percentages of several metal ions [Fe(III), Zn(II), V(IV) and Ni(II)] in order to establish a comparison with previously reported Cu(II)-modified fibres.