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Situ Polymerization Method (situ + polymerization_method)
Selected AbstractsEnhanced Optical Properties and Opaline Self-Assembly of PPV Encapsulated in Mesoporous Silica SpheresADVANCED FUNCTIONAL MATERIALS, Issue 23 2009Timothy L. Kelly Abstract A new poly(p -phenylenevinylene) (PPV) composite material has been developed by the incorporation of insoluble PPV polymer chains in the pores of monodisperse mesoporous silica spheres through an ion-exchange and in situ polymerization method. The polymer distribution within the resultant colloidal particles is characterized by electron microscopy, energy dispersive X-ray microanalysis, powder X-ray diffraction, and nitrogen adsorption. It was found that the polymer was selectively incorporated into the mesopores of the silica host and was well distributed throughout the body of the particles. This confinement of the polymer influences the optical properties of the composite; these were examined by UV,vis and fluorescence spectroscopy and time-correlated single-photon counting. The results show a material that exhibits an extremely high fluorescence quantum yield (approaching 85%), and an improved resistance to oxidative photobleaching compared to PPV. These enhanced optical properties are further complemented by the overall processability of the colloidal material. In marked contrast to the insolubility of PPV, the material can be processed as a stable colloidal dispersion, and the individual composite spheres can be self-assembled into opaline films using the vertical deposition method. The bandgap of the opal can be engineered to overlap with the emission band of the polymer, which has significant ramifications for lasing. [source] Monitoring ultrathin film photopolymerization of tetra-alkylepoxyporphyrin by UV-Vis spectroscopyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2009Kalle Lintinen Abstract Cationic photopolymerization is a convenient in situ polymerization method for organic thin film preparation. In this work, the polymerization mechanisms is applied for highly viscous cross-linking monomers, using tetra-alkylepoxyporphyrin (TAEP) as a case study. By comparing the UV-Vis spectra of the polymerized sample before and after the unreacted monomers have been dissolved, it is possible to estimate the polymerization yield. An IR spectrum of a reference thick film confirms full polymerization. Scanning fluorescence lifetime microscopy and AFM show the uniformity of the polymer. It was shown that photopolymerization is highly dependent on the substrate nature and requires at best case a 10 min illumination at 90 °C. Thermal polymerization of the same sample requires 10 min heating at 150 °C in dark. It was also shown that TAEP works as a self-sensitizer for cationic photopolymerization. The proposed method is a mild and versatile technique for in situ preparation of thin polymeric films directly from chromophore monomers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6095,6103, 2009 [source] The unidirectional glass fiber reinforced furfuryl alcohol for pultrusion.POLYMER COMPOSITES, Issue 6 2008The development of unidirectional glass fiber reinforced furfuryl alcohol (FA) composites has been conducted using an in situ polymerization method. The FA prepolymer synthesized in this study was prepared from blends of FA monomer and catalyst (p -toluene sulfonic acid). The process feasibility, and kinetic analysis of the unidirectional glass fiber reinforced FA composites by pultrusion has been investigated. From the investigations of the long pot life of FA prepolymer, the high reactivity of FA and FA/glass fiber, and excellent fiber wet-out of FA resin and glass fiber, it was found that the FA resin showed excellent process feasibility for pultrusion. A kinetic autocatalytic model, d,/dt = A exp(,E/RT),m(1,,)n, was proposed to describe the curing behavior of FA/glass fiber composites. Kinetic parameters for the model were obtained from dynamic differential scanning calorimetry scans using a multiple regression technique. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] Polystyrene,organoclay nanocomposites prepared by melt intercalation, in situ, and masterbatch methodsPOLYMER COMPOSITES, Issue 3 2006Ulku Yilmazer In this study, polystyrene (PS)/montmorillonite nanocomposites were prepared by melt intercalation, in situ polymerization, and masterbatch methods. In the masterbatch method, as the first step, a high clay content composite of PS,organoclay (masterbatch) was prepared by in situ polymerization, and then the prepared masterbatch was diluted to desired compositions with commercial PS in a twin-screw extruder. The structure and mechanical properties of the nanocomposites were examined. X-ray diffraction (XRD) analysis showed that the d -spacing of the in situ formed nanocomposites increased from 32.9 Å for the organoclay powder to 36.3 and 36.8 Å respectively in nanocomposites containing 0.73 and 1.6 wt% organoclay, indicating intercalation. However, the d -spacing of the other prepared materials remained nearly unchanged when compared with pure organoclay powder. Thus, at these low clay contents, in situ formed nanocomposites showed the best improvement in mechanical properties including tensile, impact strength, and Young's modulus. In situ polymerization method did not prove to be efficient at high clay loadings in terms of intercalation and mechanical properties. At high clay loadings, the effects of the three methods in promoting mechanical properties were not significantly different from each other. POLYM. COMPOS., 27:249,255, 2006. © 2006 Society of Plastics Engineers [source] Study on flame retardance of co-microencapsulated ammonium polyphosphate and dipentaerythritol in polypropylenePOLYMER ENGINEERING & SCIENCE, Issue 12 2008Zhengzhou Wang Co-microencapsulated ammonium polyphosphate and dipentaerythritol [M(A&D)] was prepared using a melamine-formaldehyde (MF) resin by in situ polymerization method, and characterized by XPS. The co-microencapsulation of ammonium polyphosphate and dipentaerythritol (DPER) leads to a great improvement in water solubility of the additives. The flame retardant effect of M(A&D) in polypropylene (PP) is evaluated using limiting oxygen index (LOI) and UL 94 test, and the water resistance of the PP/M(A&D) composites is also studied. The flame retardant properties and water resistance of the PP/M(A&D) composites are much better than the ones of the PP/APP/DPER composites. Moreover, the thermal stability of the PP/M(A&D) composites is improved compared with the PP/APP/DPER composites. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Synthesis of effective poly(4-vinylpyridine) nanocomposites: in situ polymerization from edges/surfaces and interlayer galleries of clayPOLYMER INTERNATIONAL, Issue 2 2006Sinan Abstract Poly(4-vinylpyridine) (P4VP) nanocomposites have been prepared by using an in situ polymerization method in the presence of organically modified montmorillonite (MMT) clays with a quarternary salt of cocoamine containing a vinyl group, as well as trimethoxy vinyl silane. The nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The desired exfoliated nanocomposite structure was achieved when the MMT modification was conducted in the presence of both modifiers, whereas individual modifications all resulted in intercalated structures. This resultant exfoliated nanocomposite was found to have better thermal stability and dynamic mechanical performance when compared to the other nanocomposites, even with 2 % clay loading. Copyright © 2005 Society of Chemical Industry [source] | ||||||||||