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11.
Jiang Ming 《高等学校化学研究》1990,6(4):378-385
For a variety of multicomponent polymers including simple blends, block copolymers, IPNs, lonomer blends, homopolymer/block copolymer blends and composites composed of Inorganic particles and polymer matrix, the current situation and trend of introducing specific Interactions and its effect on the misclbility and properties of the systems have been reviewed with emphasis on the recent results obtained in the author' s laboratory. 相似文献
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Wen‐Yi Chen Ko Shan Ho Tar‐Hwa Hsieh Feng‐Chih Chang Yen‐Zen Wang 《Macromolecular rapid communications》2006,27(6):452-457
Summary: This investigation presents a simultaneous and convenient approach to produce a high‐performance polyimide with a low dielectric constant by introducing the octa‐acrylated polyhedral oligomeric silsesquioxane (methacrylated‐POSS) into a polyimide matrix to form polyimide semi‐interpenetrating polymer network (semi‐IPN) nanocomposites. The differential scanning calorimetry (DSC) and Fourier‐transform infrared (FT‐IR) results indicate that the self‐curing of methacrylated‐POSS and the imidization of polyamic acid (PAA) occurs simultaneously. The morphology of a semi‐IPN structure of polyimide/POSS‐PI/POSS nanocomposites with POSS nanoparticles embedded inside the matrix is elucidated. The POSS particles are uniform and are aggregated to a size of approximately 50–60 nm inside the polyimide matrix. The interconnected POSS particles are observed at high POSS content. The structure is highly cross‐linked, so the PI/POSS nanocomposites have an enhanced glass transition temperature. The high porosity of the PI/POSS nanocomposites markedly reduces the dielectric constant of PI because of the nanometer‐scale porous structure of POSS.
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Shoubing Chen Qihua Wang Tingmei Wang 《Journal of Macromolecular Science: Physics》2014,53(2):243-253
A series of castor oil-based polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer network (IPN) composites modified by two kinds of hydroxy-terminated liquid nitrile rubber (HTLN) was prepared. A systematic investigation of the tribological properties of the two kinds of HTLN-modified PU/EP IPN composites was carried out through a pin-on-disk arrangement under dry sliding conditions. Experimental results revealed that the incorporation of HTLN can improve the friction and wear properties of PU/EP IPN significantly. Both the friction coefficient and wear loss decreased with increasing content of HTLN. The worn surfaces of the samples were analyzed using scanning electron microscope and a three-dimensional (3D) noncontact surface-mapping profiler; the results showed that the worn surfaces of the PU/EP IPN composites became smooth when the HTLN was added. The mechanisms for the improvement of tribological properties are discussed. 相似文献
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Recent DC conductivity measurements on iodine-doped full and psuedo IPNs of poly (carbonate-urethane) (PCU) and natural rubber (NR) reveal that these materials possess a modest conductivity. Both such full and pseudo IPNs (with linear NR chains) are single-phased materials if the NR is of sufficiently high molecular weight derived from Brazilian Manihot glaziovii. On iodine doping the electrical conductivity rises eight orders of magnitude of both the full IPN (to ca. 10?5S cm?1) and the pseudo IPN (to ca. 10?4 S cm?1). A simple theory based on the assumption that conduction occurs essentially along the linear NR chains, composing a percolation cluster, in the iodine-doped pseudo IPNs of PCU and NR accounts for the observed electrical conductivity dependence on temperature, iodine molality, and weight fraction of NR. As temperature decreases the DC conductivity falls and the material becomes essentially an insulator. At sufficiently low temperature (ca. 115 K) this trend reverses and the DC conductivity rises by two orders of magnitude with further decreasing temperature up to that of liquid helium. © 1994 John Wiley & Sons, Inc. 相似文献
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In this study, a novel blend of polyurethane and diglycidyl 1,2-cyclohexanedicarboxylate epoxy was prepared and reinforced with various content of functional nanodiamond (0.1–5 wt%). According to morphological analysis, diglycidyl 1,2-cyclohexanedicarboxylate/polyurethane/nanodiamond nanocomposite revealed beaded-twine network structure due to entrapment of nanodiamond aggregates into epoxy/polyurethane interpenetrating networks. Exclusive self-assembled nanodiamond-tethered interpenetrating network was due to physical inter-linking of nanodiamond with blend components. There was a 47% rise in tensile strength and an 80% increase in Young’s modulus of diglycidyl 1,2-cyclohexanedicarboxylate/polyurethane/nanodiamond 5 nanocomposite relative to neat polymer. The original shape of diglycidyl 1,2-cyclohexanedicarboxylate/polyurethane/nanodiamond 5 was 95% recovered using heat-induced shape-memory effect. 相似文献
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Grafted semi‐interpenetrating polymer networks (IPNs) were prepared from polyurethane (PU) prepolymers with polyester soft segments and hard segments containing carboxylic functional groups as well as polymethacrylate (PM) prepolymers with tertiary amine functional groups. The dependence of morphological and mechanical properties on the concentration of functional groups was studied. The enhanced miscibility of PU and PM prepolymers was observed at concentrations of functional groups of 0.25 mmol/g of polymer and above. Despite the improved miscibility, the PM prepolymers showed a tendency toward phase separation. Because the observed glass‐transition temperature shifts of PU prepolymers indicated substantial miscibility, we ascribed this phenomenon to the presence of methyl methacrylate rich sequences in the PM prepolymer. The observed changes in mechanical properties by increasing the content of functional groups were typical for ionomers. Young's modulus increased as a result of physical interactions between functional groups. A significant drop in tensile strength was observed in IPN samples with phase‐separated PU and PM prepolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 115–123, 2002 相似文献
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The polyethylene glycol (PEG) based polyurethane (PU) and its semi interpenetrating polymer networks (SIPNs) with polystyrene (PS) were prepared. The FTIR, physico-mechanical properties like density, tensile strength, percentage elongation at break and surface hardness of the IPNs were measured. Wide angle X-ray studies (WAXS) were made to know the microcrystalline parameters such as crystal size (〈N〉), lattice disorder (g), surface (Ds) and volume (Dv) weighted crystal size of SIPNs. The different asymmetric column length distribution functions were employed using Exponential, Lognormal and Reinhold methods and the results are compared. 相似文献
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Mohamad‐Ali Tehfe Frdric Dumur Neus Vil Bernadette Graff Cdric R. Mayer Jean Pierre Fouassier Didier Gigmes Jacques Laleve 《Macromolecular rapid communications》2013,34(13):1104-1109
For polymer synthesis upon visible light, actual photoinitiator operates in a restricted part of the spectrum. As a consequence, several photoinitiators are necessary to harvest all of the emitted visible photons. Herein, 2,7‐di‐tert‐butyldimethyldihydropyrene is used for the first time as a multicolor photoinitiator for the cationic polymerization of epoxides. Upon addition of diphenyliodonium hexafluorophosphate and optionally N‐vinylcarbazole, the originality of this approach is to allow efficient monomer conversions under various excitation light sources in the 360–650 nm wavelength range: halogen lamps, and light‐emitting and laser diodes. The synthesis of an interpenetrated polymer network from an epoxide/acrylate blend using a red light at 635 nm is also feasible. The formed polymer material exhibits a photochromic character.