Papers by Keyword: Copolymer

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Authors: Hong Ru Wang, Xiao Bo Zhang, Xiao Zhou Su
Abstract: A polyamic acid suitable for either pretanning or retanning wet-blue in leather industry has been synthesized by polycondensing pyromellitic dianhydride with diaminodiphenyl ether. Its performances for improving physical properties of crust leather, reinforcing absorption and fixation of chromium were investigated by applying it in a reduced chromium offer system. The results show that the extension and tearing strength, especially thickness of crust leather can be significantly improved by the polyamic acid, and residual chromium in spent tanning bath could be reduced to below 40 mgCr+3/l by pretanning with the polyamic acid. The chromium released from wet-blue during fatliquoring can be reduced by 85.7%, and kept at a much lower limit of 6 mg/l by the polyamic acid. A much fuller crust leather with shrink temperature of over 95°C can be obtained with 3% of normal chrome powder by pretannig or retanning with the polyamic acid. Therefore, this polyamic acid has the good potential for industrial application in ecological leather.
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Authors: Yi Jie Tao, Zhao Yang Zhang, Hai Feng Cheng, Wen Wei Zheng
Abstract: An electrochromic copolymer based on pyrrole and 3,4-ethylenedioxythiophene (EDOT) are electrodeposited on ITO electrode in aqueous micellar solution. The copolymer show blue grey in neutral state (-0.8V) and light blue in oxidized state(0.8V). The λmax of the copolymer in neutral state is 530nm and the onset energy for π-π* transition (Eg) is calculated to be 1.68eV by the onset wavelength. And successive cycle voltammagrams indicate that the incorporation of EDOT units into the Ppy improves the electrochemical stability of the copolymer films, which retains 89% of electroactivity after 500 cycles, the copolymer could be as a promising candidate material for electrochromic devices.
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Authors: Jia Guo Yu, Jimmy C. Yu
Abstract: Calcium carbonate particles with different morphologies were fabricated by the precipitation reaction of sodium carbonate with calcium chloride in the absence and presence of the copolymer poly(styrene-alt-maleic acid) (PSMA) at 80oC, respectively. The as-prepared products were characterizedwith SEM, XRD, Infrared and BET surface areas. The results showed that the pH of solution and the concentration of PSMA and CaCO3 significantly influenced the morphologies of CaCO3 particles. Various crystal morphologies of calcium carbonate, such as plates, rhombohedras, rods, ellipsoids, dumbbells, peanuts, spheres etc., could be obtained depending on the experimental conditions.
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Authors: Guo Ping Zeng, Chun Bo Yue, Ya Qing Weng, Ming Yu Wang, Heng Feng Li
Abstract: A series of vinylidenefluoride (VDF) and chlorotrifluoroethylene (CTFE) copolymers were prepared by radical copolymerization, the chain elements structures of the copolymers were gain with the elemental analysis, and the crystal regions with X-ray diffraction spectrum. The effect of chain elements structure on the crystallinity and dynamic mechanical properties was discussed with the DMA analysis. The result shows: the increasing of the CTFE content decreases the chain elements structure of VDF-VDF, the random distribution of VDF-CTFE structure has a great effect on the crystallization properties and the dynamic mechanical properties. The increasing of CTFE content improves the storage modulus and the damping of copolymers in the amorphous copolymers, while the distribution of chain segments’ length gets narrower.
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Authors: Li Guo, Yong Guo Zhang, Shi Zhao Yang
Abstract: The influence of the solvent temperature and the solvent quality on the chain conformation and the aggregation of semiconducting block copolymers is described in this paper. In selective solvents for the polystyrene block, aggregation is detected by means of optical spectroscopy. The author thinks that the research is useful for the development of material engineering.
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Authors: S. Pomogailo, Gulzhian I. Dzhardimalieva, Anatolii D. Pomogailo
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Authors: Sri Mulijani, Erizal, Tun Tedja Irawadi, Tyas Cipta Katresna
Abstract: Realizing the growing extraordinary interest in the development of polymer hydrogels, successful attempt has been made for synthesis of copolymer hydrogels from aqueous solution of acrylamide/bacterial cellulose (AAm/BC) with irradiation processing technology using Co-60 gamma source. The study envisaged to: (i) develop a novel high strength polymer nanocomposite hydrogels containing natural BC, and (ii) investigate chemical structure, morphology, and mechanical strength properties of the formed gels. The effectiveness of AAm/BC hydrogel for wound dressing application was also tested. Structure and properties of composite were investigated using Fourier Transform Infrared spectrophotometer (FTIR), Differential Scanning Calorimetry (DSC), and Atomic force microscopy (AFM). While investigating the influence of irradiation dose and concentration of acrylamide on gel content, swelling properties and thermal stability of copolymer hydrogel,maximum gel content of prepared hydrogel was obtained at the radiation dose of 40 kGy. Swelling ratio and equilibrium water content increased with increasing irradiation dose and concentration of acrylamide in feed solution. The water absorption of hydrogel increased with increased standing time in swelling medium. It was rapid up to 24 h and got slowed down thereafter. The water absorption also increased with increasing concentration of irradiation dose in the feed solution. The water absorption of copolymer hydrogel obtained at 40 kGy irradiation dose decreased from 1800 to 1400%. This type of diffusion of prepared hydrogel was found to be a non Fickian diffusion. The thermal stability of copolymer hydrogel prepared at the irradiation dose of 40 kGy increased with increasing amount of AAm in the feed solution. The mechanical behavior of composite hydrogels at optimum irradiation dose performed value of tensile and strain at 46.3MPa and 36.6%, respectively.
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Authors: Anne-Claude Courbaron Gilbert, Nour-Eddine El Bounia, Eve Péré, Laurent Billon, Christophe Derail
Abstract: Interface between Carbon NanoTubes (CNT) and epoxy matrix is admitted to play an important role in the dispersion quality and in the mechanical stress transfer. To improve the interfacial adhesion, we propose to chemically graft molecules onto CNT surface. To achieve this chemical modification, a controlled radical polymerization, named Nitroxide Mediated Polymerization NMP, is used to synthesize a diblock copolymer based on Acrylic Acid (PAA block) and Methyl MethAcrylate (PMMA block). In the present paper, this polymerization is performed “in situ”. The PAA block presents a good affinity with the CNT which enable grafting. The PMMA miscibility with epoxy is expected to give a good adhesion - between the CNT and the matrix - and to bring a better dispersion. In order to compare the chemical modification and the physical adsorption of the copolymers onto CNT dispersion, the same block copolymer was synthesized with and without CNT. The copolymer synthesis was controlled and characterized by different methods as NMR 1H (conversion and composition), SEC (molecular weight) and TGA (grafting density). We show that the better dispersion quality and better physical properties have been obtained with grafted CNT.
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Authors: Chun Fa Ouyang, Qun Gao, Yu Tao Shi, Wen Tao Li
Abstract: The effect of liquid carboxyl terminated butadiene acrylonitrile copolymer (CTBN) on the properties of oxide graphene (OG) /epoxy resin (EP) composite has been studied. The results show that oscillations process can greatly increase the tensile strength, shear strength and hardness of the composites, for the compatibility between the EP and the OG can be greatly improved after oscillations. Infra-red analysis shows that CTBN reacts with EP to form ester group. The tensile strength of the EP decrease, and the elongation at break increase, as more and more CTBN added. The tensile strength of the OG/EP composite is 14.37 MPa, while that of CTBN/OG/EP (15/0.001/100) composite is 4.84 MPa.
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Authors: Minna Malin, Joni Korventausta, Ville Meretoja, Jukka Seppälä
Abstract: A series of ceramic-polymer scaffolds were studied for bone tissue engineering applications. These applications require bone reactivity as well as suitable scaffold properties and structure. Bioactive glass (BAG) and sol-gel derived silicas were chosen for ceramic components of the scaffolds, and crosslinked poly(ε-caprolactone/D,L-lactide) copolymers with monomer ratios 90/10 and 70/30 were used as polymer matrices. Scaffolds were prepared by photo-curing crosslinkable oligomers in the presence of the ceramic component and porosity producing salt. Scaffolds with 60-80 vol-% continuous phase macroporosity were obtained by using calcium chloride hexahydrate (CaCl2⋅6H2O), and were further tested in simulated body fluid (SBF). The ceramics remained highly reactive during scaffold preparation resulting in in vitro calcium phosphate formation.
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