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Ultra-high molecular weight polypropylene (UHMWPP), with a molecular weight of more than 106 g/mol, is expected to have superior properties, such as high mechanical strength, high thermal properties, high chemical resistance and outstanding tribological properties. However, UHMWPP has a very poor processability due to its high melt viscosity. Therefore, we aimed to improve processability of UHMWPP by blending it with a low molecular weight polypropylene (LMWPP). We attempted to improve the interfacial miscibility and intermolecular entanglement of the UHMWPP/LMWPP system by using a kneader machine. The addition of LMWPP tended to change the mechanical, thermal, and rheological properties of the blend system. [ABSTRACT FROM AUTHOR]

The Al(OH)3/acrylic copolymer latexes were synthesized through the emulsion polymerization of acrylic monomers, butyl acrylate and 2-ethylhexyl acrylate in the presence of surface-functionalized Al(OH)3 filler particles. The polymerization was stabilized by polyoxyethylene (50) nonyl phenyl ether (NP-1050, nonionic surfactant) and ammonium (POE) alkyl aryl ether sulfate (EU-S133D, anionic surfactant) to produce stable composite latexes. The improved compatibility of Al(OH)3 surface with acrylic monomers was achieved by the modification with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS). Transmission electron microscopy showed that nano-sized Al(OH)3 particles were slightly agglomerated in the copolymer latex. When pristine Al(OH)3 was used as a filler or γ-MPS-modified Al(OH)3 particles were added above 30 wt% with respect to monomers, unstable latexes were obtained, which were partially precipitated out on standing for prolonged time. The flame retardation effect was not apparent with the incorporation of Al(OH)3 in the latexes by 30 wt% as shown by LOI test. [ABSTRACT FROM AUTHOR]

Organic-inorganic composites composed of electrically conducting poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotube (PEDOT/MWNT) were prepared by in-situ oxidative polymerization of ethylenedioxythiophene (EDOT) in the presence of MWNTs in supercritical carbon dioxide. Prior to the polymerization, MWNTs were surface modified with 3-(trimethoxysilyl) propyl methacrylate in order to improve the dispersibility in CO2. This approach provides a facile way to develop solvent free composites with nanostructures and uniformity. The resulting composites were analyzed by FT-IR, transmission electron microscopy, field emission scanning electron microscopy, thermogravimetric analysis, X-ray diffraction and UV-visible spectroscopy. In addition, the effect of the ratio of the MWNT to PEDOT on the polymerization was investigated. [ABSTRACT FROM AUTHOR]

On the basis of the stereocomplex formation between poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), the stereocomplexation-induced surface properties of enantimeric polylactide blends were inverstigated by electron spectrometer for chemical analysis (ESCA) and contact angle measurements as a function of a degree of complexation. The complexation of blends was controlled by using the stereochemical polylactides (stPLAs) with percent D repeat unit contents (optical purity) of 100, 98, 95, 90, and 85%. The PLLA-b-poly(dimethyl siloxane) (PDMS)-b-PLLA triblock copolymer, instead of PLLA was used as a surface probe material because of the high surface segregation of PDMS blocks. From ESCA measurements, the surface segregation of PDMS of PLLA-b-PDMS-b-PLLA/stPLA blends with ≤10% optical impurity was rapidly decreased with a degree of complexation. However, the uncomplexed blends >10% optical impurity showed that the surface segregation of PDMS was nearly that of PLLA-b-PDMS-b-PLLA. Similar behaviors were observed in the contact angle measurements. These results indicate that 10% optical impurity is a critical value at which the complex formation and the surface properties of the PLLA-b-PDMS-b-PLLA/stPLA blends can be controlled. [ABSTRACT FROM AUTHOR]

Three series of waterborne polyurethane (WBPU)/carbon nanotube (CNT) nanocomposites were prepared, and their morphology and properties with various 2,2-dimethylol propionic acid (DMPA) and CNT contents were investigated. The CNTs were homogeneously dispersed up to the optimum content in WBPU/CNT nanocomposite films. The degree of homogeneous CNT dispersion increased with increasing DMPA content in WBPU/CNT nanocomposite films. The optimum CNT content showed maximum tensile strength, Young's modulus and adhesive strength of WBPU/CNT nanocomposite film. The optimum CNT contents for WBPU/CNT nanocomposite samples containing 3.61, 5.16 and 5.86 wt% DMPA were about 0.50, 1.00 and 1.50 wt%, respectively. The WBPU/CNT nanocomposite adhesive showed higher adhesive strength at moderately high temperatures (40/60/80/100°C) compared to conventional WBPU. The highest adhesive strength at moderately high temperatures was found with 5.86 wt% DMPA and 1.5 wt% CNT content. [ABSTRACT FROM AUTHOR]

A series of waterborne polyurethane (WBPU) adhesives were prepared with various ratios of polyol, poly(tetramethylene oxide glycol) (PTMG), and chain extender, ethylene diamine (EDA), at a fixed content of diisocyanate, 4,4-dicyclohexylmethane diisocyanate (H12MDI) and hydrophilic agent, 2,2-dimethylol propionic acid (DMPA). WBPU adhesives were characterized by IR and 1H-NMR spectroscopies, X-ray diffraction (XRD) and gel permeation chromatography (GPC). It was found that the extent of hydrogen bonds between hard–hard segment (i.e., hydrogen bonds between the NH and carbonyl groups) increased with increasing chain extender content (decreasing polyol content). Moreover, the disordered hydrogen bond of carbonyl group (hydrogen bond of urethane groups in the interfacial region) increased with increasing chain extender content (decreasing polyol content). The cyclic urea and allophanate group, which are attributed to the side reaction and cross-linking reaction, respectively, were found above a molar ratio 0.17 of chain extender to diisocyanate. The adhesive strength was maximum with 0.95 wt% and 63.10 wt% chain extender and soft segment (PTMG), respectively (H2 sample) at room temperature for the WBPU adhesive. However, with increasing application temperature the adhesive strength decreased for all samples. [ABSTRACT FROM AUTHOR]

This study investigated the stereocomplex-induced surface structure of enantiomeric poly(lactide) (PLA) blend films by differential scanning calorimeter, electron spectrometer for chemical analysis, and contact angle measurements. The design of the blend systems is based on principles of surface segregation of a modified component with a low surface energy, fluorocarbons (F), as an end group. The two blend systems, uncomplexed (F-l-PLA/l-PLA) and complexed (F-l-PLA/d-PLA), showed quite different surface structures: the surface segregation of fluorocarbon groups in the (F-l-PLA/l-PLA) blend film was observed while the surface structure of the (F-l-PLA/d-PLA) blend film was similar to its bulk one. This indicates that the interchain interaction to form stereocomplexes between l- and d-PLA is strong enough to overcome the driving force of fluorocarbon groups toward the surface. [ABSTRACT FROM AUTHOR]

In this work, we discuss the relative efficiency of the organic electroluminescent devices (OELDs) utilizing various fluorine-containing polyimides in hole transporting layer (HTL) in terms of the structure of the polyimides (PI) by molecular dynamics estimation. Materials for polyimides investigated in this study are; 1,2,4,5-benzentetracarboxylic dianhydride (PMDA), 4,4′-(hexafluoroisopropylidene) diphtalic anhydride (6FDA), 4,4′-oxydianiline (ODA), and 4,4′-(hexafluoroisopropylidene) dianiline (6FDAm). The devices used in this study consist of two organic layers, i.e. ITO-coated glass/TPD-dispersed polyimide/Alq3/Al devices. It was found that the EL efficiency of the OELDs is significantly affected by the molecular structure of polyimides as well as the contents of fluorine atoms in the PI. Molecular dynamics calculation proved that PMDA-6FDAm PI exhibits largest steric hindrance among the four PIs used in this work, due to the largest torsion of benzene rings. [ABSTRACT FROM AUTHOR]

The purpose of this work is to preliminarily investigate the surface structure of poly(methacrylate)/poly(styrene-co-acrylonitrile)(SAN) blend thin films cast from tetrahydrofuran solution by contact angle measurements. The main questions investigated in this work are: (1) relation between the composition of the surface and the bulk, (2) the extent of surface enrichment of the lower surface free energy component, (3) the change of the surface composition corresponding to the change in the degree of mixing in the bulk, and (4) the effect of alkyl group on the surface structure. [ABSTRACT FROM AUTHOR]

The miscibility in binary polymer systems in 2-dimensional state at the air/water interface was investigated by the relationship between the mean molecular area at a constant surface pressure and the mole fraction of one component in the binary mixtures of poly(methyl methacrylate)(PMMA) and poly(vinyl acetate)(PVAc). Compatibilization of the immiscible PMMA/PVAc blend at the air/water interface was achieved by introducing carboxyl acid to either of the two component polymers. [ABSTRACT FROM AUTHOR]

In order to control the rate of corrosion, plasma gas discharge was applied to modify the surface of a polymer coated-steel sheet to be hydrophobic. Since the corrosion resistance of steel is strongly related to water permeation, the surface hydrophobicity of materials was introduced by CF 3 H plasma exposure. The corrosion property before and after the plasma treatment was investigated in a slat spray tester of 3.5% NaCl fog at 35°C. The results showed that the CF 3 H plasma-induced polymer exhibited significant retardation of corrosion. [ABSTRACT FROM AUTHOR]