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Crosslinked Materials (crosslinked + material)
Selected AbstractsPolyethersulfone-epoxy terminated materials as thermosetting resins for microelectronic devicesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2009Emilio Scamporrino Abstract A totally aromatic polyether/sulfone resin (PES-E) was synthesized and tested as an insulating glue in the construction of a Chip-on-Chip (CoC) device. PES-E, essentially constituted of open-chain macromolecules of low molecular mass (Mn of about 3000 Da) with hydroxy and/or epoxy end-groups, has a glass transition temperature of about 150 °C and is subject to crosslinking at temperatures higher than 320 °C. A CoC device was assembled using a five-step process by interposing a layer of PES-E between two chips. After curing, SEM cross section images showed a homogeneous crosslinked resin layer well stuck (flick and shear tests) to both chips. The chemical structure of the chains and the hydroxy/epoxy end-groups ratio were optimized to obtain a crosslinked material with good adhesion and sufficient flexibility to avoid cracking during assembly and use. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5682,5689, 2009 [source] Photoinitiated polymerization in bicontinuous microemulsions: Fluorescence monitoringJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2006C. Peinado Abstract The photopolymerization of bicontinuous microemulsions was simultaneously monitored with differential scanning calorimetry and fluorescence. The kinetics and mechanism of the reaction were studied throughout the entire photopolymerization reaction. The role played by the surfactant in the kinetics and morphology was studied. The nature of the surfactant changed the autoacceleration process and final conversion. The behavior was explained as a result of the differences in the interfacial properties. Anionic cetyltrimethylammonium bromide (CTAB) gave rise to a more flexible interfacial film than anionic sodium dodecyl sulfate (SDS), resulting in competition between the intramolecular and intermolecular reactions in the former systems. As cyclization did not contribute to the increase in the degree of crosslinking, SDS photopolymerization gave solids with a more rigid microstructure. Fluorescence methodology was applied to monitor bicontinuous microemulsion polymerization and to reveal the microstructure and morphology development during photopolymerization. The microemulsion composition was designed to prepare nanoporous, crosslinked materials. Even though the nanostructure of the precursor microemulsions was not retained because of phase separation during polymerization, mesoporous solids were obtained. Their morphologies depended on the nature of the surfactant, and membranes with open cells were successfully prepared with CTAB, whereas more complex morphologies resulted with SDS. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5291,5303, 2006 [source] Synthesis of Reactive Polymeric Dyes as Textile AuxiliariesMACROMOLECULAR MATERIALS & ENGINEERING, Issue 9 2003Angelina Altomare Abstract New polymeric materials containing amino-substituted azobenzene chromophores and reactive functional groups and characterized by some hydrophilicity were prepared with the aim of investigating alternative textile dyeing routes. The indicated materials were obtained either by copolymerization of suitable monomers or by modification of preformed polymers. In both cases commercial 4-amino-2,,3-dimethylazobenzene (FG) was used as chromogenic compound. According to the first synthetic strategy, the methacrylamido derivative of FG was copolymerized by free radical initiation with different monomers, such as methyl methacrylate, glycidyl methacrylate, N - tert -butylacrylamide, methacrylic acid, N -vinyl-2-pyrrolidinone, and vinyl acetate. Reaction of FG with preformed polymers containing epoxy groups generally afforded crosslinked materials. On the other hand, low FG loading extents were recorded by amidation of polymers containing carboxylic groups. Indeed, almost quantitative conversions were obtained only in the reaction of FG with anhydride containing polymers. The chemical structure, molecular weight properties, and the physical-chemical characteristics of all synthesized polymeric dyes were thoroughly investigated. Some very preliminary dyeing tests of different cloth types with the prepared polymeric dyes were also performed. UV absorption spectrum of poly(FGMAA) and poly(FGMAA- co -MMA) in chloroform at 25,°C (FGMAA,=,4-methacrylamido-2,,3-dimethylazobenzene). [source] Direct Synthesis of PVA- g -PDMS in MicrosuspensionMACROMOLECULAR RAPID COMMUNICATIONS, Issue 5 2008Emmanuel Pouget Abstract The synthesis of P(VA- co -VAc)- graft -PDMS copolymers has been achieved in microsuspension by direct reaction between an epoxy-terminated PDMS and some pendant alcohol groups in P(VA- co -VAc). In this synthesis, the copolymer is used both as dispersant and reactant. The hydrophilic/hydrophobic character of the final material can be varied at will by incorporating various contents of epoxy-functionalized PDMS through optimized reaction conditions. The final composition was determined by TGA and 1H NMR. Products prepared from monofunctional PDMS were easily redispersed in water whereas a film of crosslinked materials, arising from difunctional PDMS, showed the best waterproofing as shown by contact angle analysis. [source] A new crosslinked protein fiber from gliadin and the effect of crosslinking parameters on its mechanical properties and water stabilityPOLYMER INTERNATIONAL, Issue 10 2008Ying Li Abstract BACKGROUND: Although several cereal proteins have been used to develop fibers and films, it has not been possible to obtain protein materials with good mechanical properties and water stability, even after crosslinking. Previously, high concentrations of glutaraldehyde were used to improve the mechanical properties of protein fibers but the effect of crosslinking conditions on the properties of the crosslinked materials has not been studied in detail. RESULTS: Low concentrations of glutaraldehyde can be used to improve the mechanical properties and water stability of gliadin fibers. Quantitative relationships that can predict the breaking tenacity of the fibers at various crosslinking conditions are developed. Glutaraldehyde crosslinking is more resistant to hydrolysis in neutral pH than under acidic conditions in terms of increasing and retaining the breaking tenacity. The crosslinked fibers show improved resistance to hydrolysis over poly(lactic acid) fibers in aqueous dispersions at pH = 4 and 7 at 50 and 90 °C, respectively. CONCLUSIONS: This study shows that low concentrations of glutaraldehyde can impart excellent mechanical properties to gliadin fibers. The quantitative relationships developed can be used to select the crosslinking conditions such low glutaraldehyde concentration and high temperature or vice versa to obtain the desired improvement in mechanical properties or water stability. Copyright © 2008 Society of Chemical Industry [source] | ||||||||||