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1.
Graft copolymers of poly(methyl methacrylate) and polyamide-6 (PMMA-g–PA6) were investigated via in situ anionic polymerization
of ε-caprolactam, using PMMA precursors with N-carbamated caprolactam pendants (PMMA–CCL) as macroactivators and sodium caprolactamate
as catalyst. Three grades of PMMA–CCLs obtained by free radical copolymerization were used for synthesizing the PMMA-g–PA6
copolymers with different PMMA content. The resulting graft copolymer was characterized by Fourier-transform infrared spectroscopy
and selective extraction. Scanning electron microscopy is used to clarify the phase morphology of obtained polymer by fracture
surface. The thermal property, crystallinity and dimensional stability of graft copolymer were studied using differential
scanning calorimetry, X-ray diffraction and water absorption measurement. The results show the Tg of graft copolymer is higher than that of neat PA6, but the onset and peak points of graft copolymer melting point are shifted
to lower temperature. The percentage crystallinity and water absorption of PMMA-g–PA6 copolymer decrease with increasing PMMA
content, but the crystal structure of PA6 is scarcely affected by the presence of PMMA. Graft copolymers have improved dimensional
stabilities relative to neat PA6. Upon the incorporation of 19.9 wt% PMMA into PA6, the water absorption of PMMA-g–PA6 copolymer
has been reduced from 4.8 for neat PA6 to 2.1%. 相似文献
2.
Summary The rheological behavior of the cholesteric side-chain copolysiloxane whose two kinds of mesogenic groups consist of cholesteryl
units and biphenyl benzoate units was investigated for three different compositions: 31:69, 35:65, 37:63 (in mol%). On the
frequency dependence diagram of G′ for the copolymers at various temperatures, G′ decreases with decreasing frequency. The
slope of G′ in a higher frequency region at lower temperatures (110°–130°C) is similar to that in the flow region of amorphous
polymer melts. However, the slope of G′ in a lower frequency region at higher temperatures (140°–160°C) is relatively small,
and the G′ curves in this region can not be superposed on to a single master curve. This deviation seems to be due to change
in stability of the domain structure of the cholesteric phase. Furthermore, on the temperature dependence curve of G′, G′
showed a maximum near T
c1
. This maximum of G′ curve seems to be caused by molecular organization of a blue phase. 相似文献
3.
Information is presented on fusion-cast materials that have been developed in recent years on the basis of the systems Cr2O2–Al2O3–ZrO2–SiO2, Cr2O3–MgO–SiO2, and Cr2O3–MgO–Al2O3. Such materials have good service properties in mineral melts at high temperatures. It is shown that fusion-cast chromium-bearing
refractories KhPL-85 and KhMG are as corrosion-resistant as chromium-oxide-based ceramic refractories in melts of alkali-free
borosilicate glass E and basalt fibers. 相似文献
4.
This work aims to clarify the effect of nanoparticle self-agglomeration structure on the morphology of polymer blends. The morphology development of polystyrene (PS)/polyamide (PA6) blends with titanium dioxide (TiO2) nanoparticles preferentially localized in the PA6 domains was investigated by means of electron microscopy observation, viscoelastic analysis and selective extraction tests. It was shown that the preferential dispersion of TiO2 leads to a significant reduction of the PA6 continuity in the PS/PA6 blend. The size of the PA6 domain increases gradually with further increasing the nanoparticle loading whereas the co-continuity of the PS/PA6/TiO2 mixture is destroyed by isothermal post-treatments. These experimental results are completely different from those in carbon black, nanoclay or nano-silica-filled immiscible polymer blends. To elucidate the progression to the uneven morphology change, the dynamic process of microfibril break-up and droplet coalescence in the molten PS/PA6/TiO2 mixture was traced in real-time through optical microscopy. It was confirmed that the self-agglomerating pattern of the nanoparticle in the polymer melts plays a key role in directing the morphology evolution of the immiscible polymer blend: unlike the self-agglomeration of carbon black to form three-dimensionally continuous network structure, the TiO2 nanoparticles tend to form separate clusters in the PA6 phase. This prevents PA6 droplets from fusing together to form a continuous network during the coalescence and producing larger PA6 domains at higher TiO2 loads. 相似文献
5.
A hyperbranched azo polyurethane was synthesized by one-step polymerization of an A2 type monomer diphenylmethane-4,4′-diisocyanate and a B3 type monomer 4-(N,N′-bis(2-hydroxyethyl))amino-2′-hydroxyethoxyl-4′-nitro-azobenzene. The azo polymer was characterized by
1H nuclear magnetic resonance (NMR), ultraviolet-visible (UV-Vis) spectrum and thermal analysis. The λmax of the polymer in dimethylformamide (DMF) solution is 488 nm. The number average molecular weight (Mn) determined by GPC is 9,300 with a polydispersion index 1.9. The glass transition temperature (T
g) of the polymer is 131°C observed from DSC thermogram. The results show that the azo polyurethane has been successfully synthesized
through this scheme. Surface-relief-gratings (SRGs) were fabricated on the polymer film after being irradiated by interference
pattern of Ar+ laser beams for 1,000 s. The surface modulation depth and the grating space period measured by AMF are 67 and 770 nm, respectively.
__________
Translated from Acta Polymerica Sinica, 2007, 1: 21–25 [译自: 高分子学报] 相似文献
6.
Ke Ye Mi Lin Zhang Ye Chen Wei Han Yong De Yan Shu Quan Wei Li Jun Chen 《Journal of Applied Electrochemistry》2010,40(7):1387-1393
This study presents a novel electrochemical study on the codeposition of Mg, Li, and Mn on a molybdenum electrode in LiCl–KCl–MgCl2–MnCl2 melts at 893 K to form different phases Mg–Li–Mn alloys. Transient electrochemical techniques such as cyclic voltammetry,
chronopotentiometry, and chronoamperometry have been used in order to investigate the codeposition behavior of Mg, Li, and
Mn ions. The results obtained show that the potential of Li metal deposition, after the addition of MgCl2 and MnCl2, is more positive than the one of Li metal deposition before the addition. The codeposition of Mg, Li, and Mn occurs at current
densities lower than −1.43 A cm−2 in LiCl–KCl–MgCl2 (8 wt%) melts containing 2 wt% MnCl2. The onset potential for the codeposition of Mg, Li, and Mn is −2.100 V. α, α + β, and β phases Mg–Li–Mn alloys with different
lithium and manganese contents were obtained via galvanostatic electrolysis from LiCl–KCl melts with different concentrations
of MgCl2 and MnCl2. The microstructures of typical α and β phases of Mg–Li–Mn alloys were characterized by X-ray diffraction (XRD), optical
microscopy (OM), and scanning electron microscopy (SEM). The analysis of energy dispersive spectrometry (EDS) and EPMA area
analysis showed that the elements of Mg and Mn distribute homogeneously in the Mg–Li–Mn alloys. The results of inductively
coupled plasma analysis determined that the chemical compositions of Mg–Li–Mn alloys correspond with the phase structures
of XRD patterns, and lithium and manganese contents of Mg–Li–Mn alloys depend on the concentrations of MgCl2 and MnCl2. 相似文献
7.
A. V. Drogun 《Fibre Chemistry》2002,34(2):111-114
The method of combined evaluation of the quality of mixing and the quality of a polymer blend allows predicting the character of the change in the disperse structure of the blend when the extrusion process parameters change. The spinnability criterion, which is the ratio of the parameters of the extruder deformation field — ratio of shear strains (average and minimum, determined in the section @zeta;3), prespinneret, and spinneret drawing, allows explaining the change in the spinnability of PA6.6—PET polymer blend melts when the process parameters change from unified positions. 相似文献
8.
Yong De Yan Mi Lin Zhang Yun Xue Wei Han Dian Xue Cao Li Yi He 《Journal of Applied Electrochemistry》2009,39(3):455-461
This work presents a novel electrochemical study on the codeposition of Mg, Li and Al on a molybdenum electrode in LiCl–KCl–MgCl2–AlCl3 melts at 943 K to form Mg–Li–Al alloys. Cyclic voltammograms (CVs) showed that the underpotential deposition (UPD) of magnesium
on pre-deposited aluminum leads to the formation of a liquid Mg–Al solution, and the succeeding underpotential deposition
of lithium on pre-deposited Mg–Al leads to the formation of a liquid Mg–Li–Al solution. Chronopotentiometric measurements
indicated that the codeposition of Mg, Li and Al occurs at current densities lower than −0.47 A cm−2 in LiCl–KCl–MgCl2 (0.525 mol kg−1) melts containing 0.075 mol kg−1 AlCl3. Chronoamperograms demonstrated that the onset potential for the codeposition of Mg, Li and Al is −2.100 V, and the codeposition
of Mg, Li and Al is formed when the applied potentials are more negative than −2.100 V. The diffusion coefficient of aluminum
ions in the melts was determined by different electrochemical techniques. X-ray diffraction and inductively coupled plasma
analysis indicated that α, α + β and β Mg–Li–Al alloys with different lithium and aluminum contents were obtained via potentiostatic
and galvanostatic electrolysis. 相似文献
9.
V. N. Odnoralova V. K. Shchel'tsyn N. P. Ermolova V. N. Kiya-Oglu V. A. Platonov G. A. Budnitskii 《Fibre Chemistry》1998,30(6):392-397
A method was developed for synthesis of poly-p-phenylenebenzobisthiazole (PPBT) from 2,5-diamino-1,4-dimercaptobenzene diphosphate
(DADMB) and terephthalic acid (TPA) in a solution of polyphosphoric acid (PPA) with a 12–15 wt. % concentration of PPBT with
a molecular weight of 34,000–38,600 ([η] = 24.5–28.8 dl/g). It was shown that a high concentration of P2O5 in PPA, which should be 85.5–86.5 wt. % at the end of the reaction, is one of the basic conditions for obtaining a high-molecular-weight
polymer from DADMB diphosphate and TPA. The synthesized liquid-crystalline polymers with a high molecular weight and concentration
of 14–15 wt. % in PPA solution were used in the form of polycondensation solutions for spinning high-modulus PPBT fibres.
Translated fromKhimicheskie Volokna, No. 6, pp. 35–39, November–December, 1998.
We would like to thank L. P. Mil'kova for participating in the x-ray diffraction studies and discussing the results. 相似文献
10.
S. R. Egorova G. E. Bekmukhamedov A. A. Lamberov R. R. Gil’mullin Kh. Kh. Gil’manov 《Catalysis in Industry》2011,3(1):87-95
This publication continues a series of our reports on the optimization of preparation conditions for obtaining a thermally
stable support for the alkane dehydrogenation catalyst. The phase composition effect on the stability, particle size distribution,
structure, texture, and mechanical properties of supports heated to 1100°C is reported. Microspherical alumina supports obtained
by successive thermal and hydrothermal treatments of gibbsite are compared to commercial supports obtained by the thermochemical
activation (TCA) of gibbsite. The dimensions of the support granules decrease upon heating because of shrinkage, which is
governed by the phase composition of the granules and by the packing of their constituent boehmite and alumina crystallites.
Three temperature intervals can be distinguished in the shrinkage of the granules. In region I (<600°C), there is intensive
shrinkage via the diffusion glide of crystallites, the mechanical strength of the granules remaining invariable. In region
II (600–900°C), the polymorphic transformations of alumina accompanied by sintering via surface diffusion do not affect the
dimensions and strength of the granules. In region III (>900–1000°C), shrinkage takes place via coalescent sintering. For
commercial manufacturing of microspherical alkane dehydrogenation catalysts and for ensuring their stability at 550–900°C,
it is recommended to use alumina supports containing the minimum possible amount of χ-Al2O3. As the single-phase boehmite support obtained by our technology is heated to 1100°C, its granules shrink by no more than
14.4% and show an attrition resistance of 89% or above. The support based on the gibbsite TCA products, which contains 14–23
wt % χ-Al2O3, is characterized by 3–5% greater granule shrinkage and 6–12% lower mechanical strength. 相似文献
11.
A new version of the STRUCTON-1.2 computer program (2009) has been presented. The program combines the algorithm for calculating
real distributions of Q
n
structons in binary silicate melts (with allowance made for their disproportionation) and the statistical simulation of molecular-mass
distributions of polymerized ions at different temperatures. This model has been used to perform test calculations for two
melts in the Na2O-SiO2 system (Na6Si2O7, Na6Si3O9). The results of the calculations have made it possible to trace variations in the set and concentrations of chain and ring
silicon-oxygen complexes with a decrease in the temperature in the order: stochastic molecular-mass → distribution molecular-mass
distribution at T = 2000 K → molecular-mass distribution at the liquidus temperature. The main result of these calculations is that the dominant
species of silicon-oxygen anions at the liquidus temperatures (in contrast to the stochastic distributions) exactly correspond
to the stoichiometry of the initial melts: the Si2O76− chain anions and (Si
n
O3n
)3n− ring complexes are dominant in the Na6Si2O7 and Na6Si3O9 melts, respectively. It has been established that, with a decrease in the temperature, the average size of polymer complexes
varies weakly in the Na6Si2O7 melt but increases by a factor of approximately 1.5 in the metasilicate system. 相似文献
12.
N. I. Zalomov V. N. Boronenkov M. Zinigrad S. M. Shanchurov 《Glass Physics and Chemistry》2007,33(5):455-458
Water vapor dissolution in the slag melt model introduced in the paper is based on polymer theory. Calculated data on water
dissolution in CaF2-CaO-SiO2 system melts are presented and compared with the experimental data. The results can be used for mathematical modeling of
physicochemical processes of submerging arc welding and special electro-metallurgy.
This paper was presented at the Topical Meeting of the European Ceramic Society “Structural Chemistry of Partially Ordered
Systems, Nanoparticles, and Nanocomposites,” St. Petersburg, Russia, June 27–29, 2006.
The text was submitted by the authors in English. 相似文献
13.
?smet Kaya 《Journal of Inorganic and Organometallic Polymers and Materials》2010,20(2):369-379
Oxidative polycondensation reaction conditions of [(2-mercaptophenyl)iminomethyl]-2-naphthol (2-MPIM-2N) were studied using
oxidants such as air and NaOCl in an aqueous alkaline medium between 40 °C and 90 °C. The structure of poly-[(2-mercaptophenyl)iminomethyl]-2-naphthol
(P-2-MPIM-2N) was characterized by 1H- 13C NMR, FT-IR, and UV–Vis spectroscopy, size exclusion chromatography (SEC), and elemental analysis. At optimum reaction conditions,
the yield of P-2-MPIM-2N was found to be 78 and 82% for air and NaOCl oxidants, respectively. From SEC measurements, the number-average
molecular weight (M
n
), weight-average molecular weight (M
w
) and polydispersity index (PDI) of P-2-MPIM-2N are 2900, 3500 g mol−1 and 1.207; 2200, 2500 g mol−1 and 1.136, for air and NaOCl oxidants, respectively. Polymer–metal complexes were synthesized by the reaction of P-2-MPIM-2N
with Co2+, Cu2+, Zn2+, Pb2+ and Cd2+ ions. The highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and electrochemical
band gaps (E¢g E^{\prime}_{g} ) of 2-MPIM-2N and P-2-MPIM-2N were −5.97, −2.66 and 3.31 eV and −5.82, −2.68 and 3.14 eV, respectively. The conductivity
of polymer and polymer–metal complexes were determined in the solid state. Conductivity measurements of doped and undoped
Schiff base polymer and polymer–metal complexes were carried out at room temperature and atmospheric pressure by the four-point
probe technique using an electrometer. The conductivities of the polymer and polymer–metal complexes increased when iodine
was used as doping agent. 相似文献
14.
1 M LiPF6 dissolved in oligo(ethylene glycol) dimethyl ether with a molecular weight, 500 g mol−1 (OEGDME500, 1 M LiPF6), was investigated as an electrolyte in experimental Al–Li/LiFePO4 cells. More than 60 cycles were achieved using this electrolyte in a Li-ion cell with an Al–Li alloy as an anode sandwiched
between two Li
x
FePO4 electrodes (cathodes). Charging efficiencies of 96–100% and energy efficiencies of 86–89% were maintained during 60 cycles
at low current densities. A theoretical investigation revealed that the specific energy can be increased up to 15% if conventional
LiC6 anodes are replaced by Al–Li alloy electrodes. The specific energy and the energy density were calculated as a function of
the active mass per electrode surface (charge density). The results reveal that for a charge density of 4 mAh cm−2 about 160 mWh g−1 can be reached with Al–Li/LiFePO4 batteries. Power limiting diffusion processes are discussed, and the power capability of Al–Li/LiFePO4 cells was experimentally evaluated using conventional electrolytes. 相似文献
15.
Synthesis of poly(ethyl vinyl ethers) containing two dipolar electronic systems and their properties
Summary
5-Nitro-2-(2′-vinyloxyethoxy)benzylidenemalononitrile (2a), methyl 5-nitro-2-(2′-vinyloxyethoxy)benzylidenecyanoacetate (2b), 3-nitro-4-(2′-vinyloxyethoxy)benzylidenemalononitrile (4a), and methyl 3-nitro-4-(2′-vinyloxyethoxy)benzylidenecyanoacetate (4b) were prepared by the condensation of 5-nitro-2-(2′-vinyloxyethoxy)benzaldehyde (1) and 3-nitro-4-(2′-vinyloxyethoxy)benzaldehyde (3) with malononitrile or methyl cyanoacetate, respectively. Vinyl ether monomers 2a-b and 4a-b were polymerized with boron trifluoride etherate as a cationic initiator to yield poly(vinyl ethers) 5-6 having nitrooxybenzylidenemalononitrile and nitrooxycyanocinnamate, which is effective chromophore for second-order nonlinear
optical applications. Polymers 5-6 were soluble in common organic solvents such as acetone and DMSO. T
g
values of the resulting polymer were in the range of 70–81°C. Electrooptic coefficient (r33) of the poled polymer films were in the range of 19–27 pm/V, which was improved by introducing of nitro group. Polymers 5–6 showed a thermal stability up to 300°C in TGA thermograms, which is acceptable for NLO device applications.
Received: 24 November 1998/Revised version: 19 January 1999/Accepted: 29 January 1999 相似文献
16.
Adriane S. Gruber Gisèle Boiteux Roberto F. de Souza Michèle O. de Souza 《Polymer Bulletin》2002,47(6):529-537
Summary
Phenylacetylene (PhA) is polymerized by the dicationic nickel complex Ni(MeCN)6(BF4)2 associated with AlEt2Cl as co-catalyst. The production of 200g of polymer per gram of nickel per hour represents a typical activity of this system.
Under our experimental conditions, the polymer displays an exclusive trans structure. The molecular weight distribution of the polymer is polymodal (5000 g.mol−1 and 200 g.mol−1). The highest average molecular weight fraction (5000 g. mol−1) represents the highest published value for polyphenylacetylene (PPA) where a nickel catalyst is employed. The electrical
conductivities vary between 10−7 and 10−16 S.cm−1, and are characteristic of a semi-conductor polymer. Equivalent values are cited in the literature only in the case of doped
PPA. Experimental observations enabled us to propose a mechanism for the formation of the active species through the reaction
of Ni(MeCN)6(BF4)2 with AlEt2Cl.
Received: 13 September 2001/Revised version: 10 January 2002/ Accepted: 11 January 2002 相似文献
17.
Dawn M. Jennings Sarah E. Brady Ginger V. Shultz Lev N. Zakharov David R. Tyler 《Polymer Bulletin》2012,68(9):2243-2254
The (CH3)2Si[CpMo(CO)3]2 complex (1) was synthesized and used to explore ring-opening polymerization (ROP) as a method to prepare high molecular weight polymers
containing Mo–Mo bonds along their backbones. Attempts to initiate ROP of 1 using n-BuLi or PtCl2 did not yield any polymers. The X-ray crystal structure of 1 shows that the Si center is not strained, and it is suggested that no ROP occurred because 1 is less strained than other organometallic ROP monomers, such as the silicon-bridged ferrocenophanes. Thermal ROP (TROP)
of 1 was successful and yielded a polymer (M
w = 210,000 g mol−1) containing both Mo–Mo single bonds and Mo≡Mo triple bonds. When CO(g) is passed over the polymer in the solid state, the Mo≡Mo triple bonds are converted to Mo–Mo single bonds. Attempts to increase
the yield of the TROP polymer by increasing the reaction times led to polymer decomposition. The decomposition is likely caused
by the weakness of the Mo–Mo bond, cleavage of which causes the polymer to degrade. 相似文献
18.
Active carbons with various particle sizes (38–150, 300–500 and 800–1,200 μm) were modified by ionic liquids (ILs), and organic
polymer was modified by acrylamide using a simple procedure, and these materials were applied to capture carbon dioxide (CO2). The CO2 adsorption amounts were calculated using a mass balance equation at three different temperatures (298.15, 308.15 and 318.15
K), respectively, and the influences of gas pressure, particle size and temperature on adsorption were discussed. Experimental
results showed that the CO2 adsorption capacity of ILs-modified active carbons was better than amino-modified polymer, and the smaller particle size
(38–150 μm) ILsmodified active carbons had the largest adsorption capacity at 298.15 K. Compared with previous research about
polyethyleneimine (PEI)-modified silica gel, the adsorption amount of CO2 on ILs-modified active carbons has been greatly improved with lower cost. 相似文献
19.
Yu. A. Vinogradov 《Fibre Chemistry》2006,38(1):1-6
Steady-state flow ofpolymer systems (polymer melts and solutions) in the viscoelastic state is considered the superposition
of two processes — flow of a viscous fluid and extrusion of an elastic fluid (elastic state). The dynamic elasticity is proposed
for characterizing the elastic properties of polymer systems, and the complex viscosity, which is the total value of the dynamic
elasticity and the dynamic viscosity, widely used for assessing viscous properties, is proposed for characterizing the generalized
properties, by analogy with periodic deformation.
__________
Translated from Khimicheskie Volokna, No. 1, pp. 3–6, January–February, 2006. 相似文献
20.
Víctor M. Ovando-Medina Piedad S. Pi?a-García Miguel A. Corona-Rivera Paola E. Díaz-Flores René D. Peralta Hugo Martínez-Gutiérrez Tania E. Lara-Ceniceros 《Polymer Bulletin》2012,68(9):2313-2322
Semicontinuous heterophase polymerization was used to copolymerize methyl methacrylate (MMA) with reactive surfactant HITENOL
BC10 (HBC10) at 60 °C using sodium dodecyl sulfate as pre-stabilizing agent and potassium persulfate as initiator. The mixture
of MMA and HBC10 was added at constant rate in continuous mode varying the MMA/HBC10 ratio. High-polymerization rates were
observed, decreasing as the MMA/HBC10 ratio decreased. Latexes with polymer content near 20% and polymer to surfactant (P/S)
weight ratios between 5 and 15 were obtained. Particle sizes distribution were bimodal in all cases with a tendency to be
monomodal as HBC10 concentration increased which was ascribed to enhanced particle stabilization by the presence of HBC10.
The average particle diameters at the end of polymerizations for the first and second populations were around 10 and 50 nm,
respectively. Very high average molecular weights were observed (1.4 × 106 ≤ M
w
≤ 2.1 × 106 g/mol), which decreased when HBC10 concentration increased. The corresponding polydispersity indexes (M
w
/M
n
) were in the range of 1.45–2.24. 相似文献