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101.
Sadia Ameen Vazid Ali M. Zulfequar M. Mazharul Haq Mushahid Husain 《Central European Journal of Chemistry》2006,4(4):565-577
The temperature dependence of direct current (dc) conductivity was studied for various samples of polyaniline-polyvinylchloride
(PANI-PVC) blended films. Polyaniline was doped with different concentrations of sulfamic acid in aqueous tetrahydrofuran
(THF) and the blended films were prepared by varying the amount of doped PANI relative to a fixed amount of PVC. The dc conductivity
of PANI-PVC blended films was measured to determine the effect of sulfamic acid (dopant) in the temperature range (300–400K).
The mechanism of conduction is explained by a two-phase model. In order to evaluate the effect of the dopant, conductivity-derived
parameters such as the pre-exponential factor (σ
o) and the activation energy (ΔE) were calculated. The structural changes of polyaniline-PVC blended films were characterized
by FTIR spectroscopy that explores information about the suitability of the dopant in the chemical doping process. 相似文献
102.
The glass-transition temperature and non-isothermal crystallization of poly(trimethylene terephthalate)/poly(ethylene 2,6-naphthalate) (PTT/PEN) blends were investigated by using differential scanning calorimeter (DSC). The results suggested that the binary blends showed different crystallization and melting behaviors due to their different component of PTT and PEN. All of the samples exhibited a single glass-transition temperature, indicating that the component PTT and PEN were miscible in amorphous phase. The value of Tg predicted well by Gordon-Taylor equation decreased gradually with increasing of PTT content. The commonly used Avrami equation modified by Jeziorny, Ozawa theory and the method developed by Mo were used, respectively, to fit the primary stage of non-isothermal crystallization. The kinetic parameters suggested that the PTT content improved the crystallization of PEN in the binary blend. The crystallization growth dimension, crystallization rate and the degree of crystallinity of the blends were increased with the increasing content of PTT. The effective activation energy calculated by the advanced iso-conversional method developed by Vyazovkin also concluded that the value of Ea depended not only on the system but also on temperature, that is, the binary blend with more PTT component had higher crystallization ability and the crystallization ability is increased with increasing temperature. The kinetic parameters U* and Kg were also determined, respectively, by the Hoffman-Lauritzen theory. 相似文献
103.
Emerson Lourenço 《Polymer Degradation and Stability》2006,91(12):2968-2978
The influence of photochemical aging of in situ polymerized PS/AES blends on their mechanical properties has been studied. The PS/AES blends were subjected to photochemical aging for 168 h and 720 h. Tensile properties and Izod impact resistance of aged and non-aged samples were evaluated. The mechanical properties of the PS/AES blends are influenced by the polymerization temperature and blend composition and represent a balance between the toughness of EPDM and the stiffness of SAN in the PS matrix. Even though the impact resistance and strain at break of HIPS are higher than those of the PS/AES blends, after the aging period all PS/AES blends showed higher strain at break than HIPS. PS/AES blends present higher photochemical stability than HIPS. 相似文献
104.
Crystallization, melting and structure of three different commercial types of isotactic polypropylene (iPP) grafted by maleic
anhydride (PP-g-MAH) with different maleic anhydride content (AC) and their β-nucleated versions were studied by X-ray diffractometry
(WAXS), differential scanning calorimetry (DSC), polarised light microscopy (PLM) and scanning electron microscopy (SEM).
The presence of maleic anhydride units disturbs the chain regularity, hereby decreases the crystallization tendency of iPP
in general and the β-crystallisation ability in particular. β-modification of iPP (β-iPP) forms only in β-nucleated PP-g-MAH
polymers studied if the anhydride content is not larger than 0.5 mass%. The influence of AC of PP-g-MAH on the feature the
spherulitic structure is demonstrated by PLM and SEM micrographs. The β-nucleated iPP/PP-g-MAH blends containing 10 mass%
PP-g-MAH crystallise predominantly in β-form independently of AC of the latter. The β-nuceated blends of iPP and PP-g-MAH
with lowest AC crystallise in β-form in whole concentration range. The interaction parameter between iPP and PP-g-MAH polymers
calculated by Nishi-Wang equation indicate limited interaction between the components. 相似文献
105.
Summary: The effect of poly(ε‐caprolactone) (PCL) molecular weight on the orientation of crystalline PCL in miscible poly(ε‐caprolactone)/poly(vinyl chloride) (PCL/PVC) blends, melt crystallized under strain, has been studied by a combination of wide angle X‐ray diffraction (WAXD) and small angle X‐ray scattering (SAXS) studies. An unusual crystal orientation with the b‐axis parallel to the stretching direction was observed in miscible PCL/PVC blends with PCL of high molecular weight (>21 000). SAXS showed the presence of nanosize confined PCL in the PCL/PVC blends, which could be preserved at temperatures higher than the Tm of PCL but lower than the Tg of PVC. A mechanism based on the confinement of PCL crystal growth was proposed, which can explain the formation of b‐axis orientation in PCL/PVC blends crystallized under strain.
106.
Petronela Drambei Yumiko Nakano Yuezhen Bin Tsumuko Okuno Masaru Matsuo 《Macromolecular Symposia》2006,242(1):146-156
Uniplaner orientation of a particular crystal plane along the surface of a film was investigated for poly (vinyl alcohol) (PVA) film prepared by a coagulation bath with concentrated aqueous solution containing 100 ∼ 300g of Na2SO4 against 1 ℓ of water. The orientation distribution functions of the three crystallographic principal axes of the dried films were obtained by the X-ray diffraction technique. The same treatment was carried out for the films prepared by stretching biaxially of the fresh gel and then by drying the resultant fresh gel. The very high preferential orientation of the crystal chain axes and amorphous chain segments could be realized by the biaxially elongation. Accordingly, the techniques were applied to the biaxially stretching of chitosan and PVA blend films with high Young's modulus. The planer orientation of the chain axes of chitosan and PVA crystallites could be confirmed. The morphology of the film surface was estimated by measurements of contact angle and electron spectroscopy for chemical analysis. The results suggested that the admixture of chitosan decreases wet ability of the specimen and this tendency was slightly enhanced by the biaxially elongation. 相似文献
107.
108.
Sung‐Young Park Hee‐Young Park Hwa‐Soo Lee Sang‐Wook Park Chang‐Sik Ha Dae‐Won Park 《Journal of polymer science. Part A, Polymer chemistry》2001,39(9):1472-1480
This study was related to the investigation of the chemical fixation of carbon dioxide to a copolymer bearing epoxide and the application of the cyclic carbonate group containing copolymer‐to‐polymer blends. In the synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] [poly(DOMA‐co‐EA)] from poly(glycidyl methacrylate‐co‐ethyl acrylate) [poly(GMA‐co‐EA)] and CO2, quaternary ammonium salts showed good catalytic activity. The films of poly(DOMA‐co‐EA) with poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) blends were cast from N,N′‐dimethylformamide solution. The miscibility of the blends of poly(DOMA‐co‐EA) with PMMA or PVC have been investigated both by DSC and visual inspection of the blends. The optical clarity test and DSC analysis showed that poly(DOMA‐co‐EA) containing blends were miscible over the whole composition range. The miscibility behaviors were discussed in terms of Fourier transform infrared spectra and interaction parameters based on the binary interaction model. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1472–1480, 2001 相似文献
109.
Loon‐Seng Tan Sharon R. Simko Shih Jung Bai Richard A. Vaia Barney E. Taylor Marlene D. Houtz Max D. Alexander Robert J. Spry 《Journal of Polymer Science.Polymer Physics》2001,39(20):2539-2548
As an alternative method for processing polyaniline (PANI) from its conducting (protonated) state, vacuum casting of PANI from a methanesulfonic acid (MSA) solution provided films with electrical conductivity values of about 130–150 S/cm. In addition, we similarly prepared blended films of PANI · MSA and poly(p‐phenylene benzobisthiazole) (PBZT). This process eliminated the need for a subsequent protonation step and had the additional advantage that the conjugated PBZT may provide alternative conducting pathways. Conductivity values of the composite films ranged from 100 pS/cm to 124 S/cm, and the films displayed critical concentration behavior with a PANI threshold concentration of 2.75% and a critical exponent of 4. Transmission electron micrographs displayed phase‐separated regions with PANI forming a continuous network at high concentrations. Thermogravimetric analysis results demonstrated the thermal and thermooxidative stability advantage of the blends due to the PBZT component. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2539–2548, 2001 相似文献
110.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(6):527-544
ABSTRACT Melt blending of poly(ethylene naphthalate) (PEN) and bisphenol A polycarbonate (PC) was performed without the addition of catalyst in a batch mixer at 290°C at various compositions. All the blends prepared exhibited a biphasic character and had very good mechanical properties, in some cases, even better than those of the respective pure constituents. This behavior was attributed to a copolymer formation in the mesophase, which effectively compatibilizes the system. The formation of a PEN/PC block copolymer was considered to be due to transesterification reactions between PEN and PC and was verified by extraction experiments and examination of the soluble and insoluble fractions by various spectroscopic techniques. 相似文献