Salimi A.,Iran Polymer And Petrochemical Institute
International Journal of Adhesion and Adhesives | Year: 2012
The incorporation of oxidized PP wax OPPW additive into polypropylene resulted to the improved surface adhesion. Atomic force microscopy (AFM) was employed to show either the surface topography or the changes in adhesion force measurements between the probe tip and sample surface. The results of surface characterization tests revealed lower surface roughness and higher adhesion force for higher OPPW content in the blends. The lower surface roughness may be attributed to higher melt flow ability of OPPW and hence better mold filling during sample fabrication. The improvement of surface adhesion was in favor for wetting behavior of solid surface using three test liquids of distilled water, diiodomethane and formamide. The thermodynamic work of adhesion W a was calculated from surface free energy components using geometric mean model of OwensWendtRabel and Kaelble (OWRK approach) and also from the theory of van OssGoodChaudhary (VOGC approach). The adhesion force measurements in AFM were also employed to derive the W a using JohnsonKendalRoberts (JKR approximation). The results indicate that the increase in W a was mainly due to polar part in OWRK approach and the acidbase part in VOGC approach. However, the results of work of adhesion in JKR approximation does not in general scale linearly with the respective OPPW content for the sample series, may be due to varying in near-surface modulus. The adhesion promoting effect of OPPW in the blends seems to work mainly via increasing surface acidbase interactions, better surface wettability and to some extent by plastic deformation mechanisms during debonding. © 2011 Elsevier Ltd. All rights reserved.
Jahani Y.,Iran Polymer And Petrochemical Institute
Polymers for Advanced Technologies | Year: 2011
The effect of filler types of mica and talc on the oscillatory shear rheological properties, mechanical performance, and morphology of the chemically coupled polypropylene composites is studied in this work. The Maleic Anhydride grafted Polypropylene (MAPP) was used as an adhesion promoter for coupling mineral particles with the polypropylene matrix. The samples were prepared by a co-rotating, L/D=40, 25mm twin screw extruder. The tensile tests carried out on the injection molded samples showed a reinforcing effect of talc up to 20wt% on the Polypropylene (PP). The tensile strength of PP-mica composites showed a slight decrease at all percentages of mica. The effect of chemical coupling by using MAPP on the tensile strength was more pronounced in increasing the tensile strength for PP-mica than PP-talc composites. The complex viscosity curve of pure PP and the composites, showed a Newtonian plateau (η0) up to 30wt% at low frequency terminal zone. By increasing the filler content to 40 and 50wt%, the complex viscosity at very low shear rates sharply increased and showed yield behavior that can be due to the formation of filler particles networks in the melt. At the optimum amount of coupling agent, a minimum in cross over frequency curve against MAPP content is observed. The optimum amount of coupling agent for PP-talc composites is about 1.5%, and about 3% for PP-mica formulations. The analysis of viscosity behavior at power-law high region, revealed the more shear thinning effect of mica than talc on the PP matrix resin. © 2009 John Wiley & Sons, Ltd.
Serendipitous stereoselective synthesis of brand-new fluorescent dyes: (1Z)-3-(alkylimino)-1-[(chromone-3-yl)methylene]-1,3-dihydro-9H-furo[3,4-b] chromen-9-one-type fluorophores with blue fluorescence emission properties
Teimouri M.B.,Iran Polymer And Petrochemical Institute
Tetrahedron | Year: 2011
The reactions of 3-formylchromones with alkyl isocyanides in dry dichloromethane at room temperature lead to new types of organic fluorophores (1Z)-3-(alkylimino)-1-[(chromone-3-yl)methylene]-1,3-dihydro-9H-furo[3,4-b] chromen-9-one, which exhibited strong blue emission in solution. The reactions involve a [4+1] cycloaddition followed by an activated electrophilic aromatic substitution at the furan ring and dehydration sequence. © 2011 Elsevier Ltd. All rights reserved.
Zeynali M.E.,Iran Polymer And Petrochemical Institute
Journal of Petroleum Science and Engineering | Year: 2012
One of the problems during drilling operation is wellbore instability. Many parameters affect the wellbore stability. Some of these parameters are related to the properties of drilling mud and its interaction with the formation and some of them are related to the mechanical properties of the formation and the magnitude and distribution of the forces around the wellbore. Generally the wellbore instability is calssified as mechanical, physico-chemical or both. This paper is an attempt to investigate the mechanical and physico-chemical aspects of wellbore stability during drilling operations. . © 2011 Elsevier B.V.
Jahani Y.,Iran Polymer And Petrochemical Institute
Journal of Vinyl and Additive Technology | Year: 2010
The oscillatory shear rheological properties, mechanical performance, shrinkage, and morphology of polypropylene (PP)-talc composites chemically coupled by maleic-anhydride-grafted polypropylene (MAPP) were studied. The samples were prepared in a co-rotating L/D = 40, 25 mm twin-screw extruder. Tensile tests carried out on injection-molded samples showed a reinforcing effect of talc up to 20 wt% on PP. Upon using MAPP, the mechanical performance of PP-30% talc showed a maximum of about 10% increase in tensile strength at 1.5 wt% of MAPP. A Newtonian plateau (g0) at the terminal zone was observed for the complex viscosity curve of pure PP and PP-talc composites plotted against frequency up to 30 wt%. Upon increasing the talc content to 40 and 50 wt%, the complex viscosity at very low shear rates sharply increased and showed yield behavior that might be due to the formation of a network of filler agglomerates in the melt. Analysis of viscosity behavior in the power-law region revealed that the flow behavior index-n-decreased from 0.45 for 10 wt% of talc down to about 0.4 for 40 wt% of talc. Upon increasing the talc content to 50 wt%, n decreased to a value even lower than that of the neat PP resin. The frequency of the crossover point represents molecular mobility and relaxation-time behavior. The crossover frequency of the composites was nearly constant up to 30 wt% of talc and decreased at higher filler loadings. The optimum amount of coupling agent could be correlated with the minimum point in crossover frequency and crossover modulus. The shrinkage behavior of the composites with and without MAPP resin was studied and correlated with the rheological properties. © 2009 Society of Plastics Engineers.