Papers by Keyword: Copolymer

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.

Abstract: In order to select effective carbon black (CB) and matrix resin for fabricating semi-conductive shielding materials of XLPE insulated high voltage cable, the crosslinkable composites were prepared by melt blending different types of CB with three types of copolymer resin, and the crosslinking samples were compressed. The electrical conductivity, mechanical properties, thermal elongation properties and rheological properties of the crosslinkable semi-conductive composites were measured. The research results indicated that compared to EVA-based and EEA1-based composites, the EEA2-based composites have the lowest volume resistivity and the best rheological properties, and the CB content has less effect on their mechanical properties. The properties of the composites with CB1 were superior to that of the composites with CB2. The composites prepared with CB1 and EEA2 present the best overall properties. These composites are expected to be used in the manufacture of semi-conductive shielding layer for high voltage cable.

Abstract: The paper describes synthesis and evaluation of polymeric additives for improving the flow properties of lubricating oils. The polymer (AAV) was prepared by the free-radical initiated polymerization of methacryl esters (A₁₄) with acrylamide and vinyl acetate. A₁₄ and AAV were characterized by infrared spectroscopy (IR). Three lubricating oils were selected as the test oil samples and the effect of solidification point depressant (ΔSP) with different mass fractions and other physicochemical characteristics of the samples with and without AAV added were investigated. In order to analyze the effect of AAV on the viscosity of lubricating oils, viscosity-temperature curves were plotted. The results showed that AAV not only had a good effect on dropping solidifying point for Yanshan lubricating oils, but also had a good effect on dropping viscosity; what’s more, other physicochemical characteristics of lubricating oil have little changes before and after AAV added.

Abstract: A series of copolymers modified with oxidized starch containing maleic anhydride (MA), styrene sulfonic sodium (SSS) and oxidized starch (OS) were synthesized by the free-radical polymerization. The polymerization is initiated by ammonium persulfate. The effects of content of monomer and initiator, reaction time, reaction temperature on dispersion ability for Fe₂O₃ were investigated by single factor experiment. The dispersion ability for Fe₂O₃ measured through UV spectroscopy was studied. The experimental results show that the copolymer has good dispersion ability for Fe₂O₃ when the mass proportion of monomers is OS:SSS:MA = 1:3:1, the mass fraction of initiator in total monomers is 10 %, reaction time is 5 h, and the reaction temperature is 70 ^oC. The morphology of the copolymer was observed by scanning electron microscope (SEM). The experimental results indicate that the prepared copolymer modified with oxidized starch could be used in the corrosion inhibitor of high temperature water.

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.

Abstract: In this study, we study morphological transitions of diblock copolymer subjected to an applied external electric field by means of external potential dynamics simulation. With this method, the lamellar and the cylindrical phase aligned along the electric field directions are presented, and the kinetic pathways of lamellae are investigated.

Abstract: The poling and local piezoresponse mechanism has been investigated in ferroelectric polymers. Isotropic 94/6 composition vinylidenefluoride and tetraflouroethylene copolymer films is formed from acetone at room temperature by slow evaporation of solvent. The copolymer crystallization results in metastability (nonequilibre) form at high overcooling temperatures. IR spectroscopy shows occurrence of isomers with conformation TGTG^-, T₃GT₃G^- and (TT)_n. The local piezoresponse shows that ferroelectric domains include crystals areas as well as nonordered phase. After annealing by heating to 150 oC was found conformation changes in polymer chain: T₃GT₃G^- TGTG^- and T₃GT₃G^- (TT)_n. It is show that the regular conformation chains length rising after annealing. Polarization value decreasing kinetic was investigated by piezoresponse force microscopy method.

Abstract: Abstract:The blood substitutes refer to the substitutes of red blood cell with the ability to carry oxygen. This paper adopts open-loop coordination polymerization and gets amphiphilic triblock copolymer of mPEG-PAGE-PDLLA with the hydrophilic end-mPEG segment, and hydrophobic end-PLA segment. And it can be automatically assembled into vesicles in the water. The hemoglobin nanoparticles can be obtained by combining with Vesicle-coated hemoglobin, which are independently blended with oxygen and biodegradable. Meanwhile the paper makes an analysis of various physical and chemical properties to hemoglobin nanoparticles.

Abstract: A series of novel copolymers [p (AOBHA-co-NPMA)] containing 2-Allyloxy-N-benzylidene hexadecylamine (AOBHA) as film formation material and β-naphtayl methacrylate (NPMA) as photosensitive group were synthesized by free-radical polymerization. The copolymers could form stable condensed monolayer at air/water interface and be transformed onto solid substrates. Positive-tone patterns with the resolution of 0.75 μm of the copolymers Langmuir-Blodgett (LB) films with 35 layers were fabricated by deep UV irradiation, followed by developing with acetone. The etched gold patterns with resolution of 0.75 μm were also obtained, showing that the copolymer has enough resistance to wet etching suitable for fabricating photomask. The mechanism of photolysis was also investigated by UV and GPC, in which showed that the scission of main and side chain of p (AOBHA-co-NPMA) LB films occurred at the same time.

Abstract: Copolymer (aniline-co-pyrrole)/TiO₂ composites with different TiO₂ contents were prepared by chemical oxidative polymerization method. The crystal structure and morphology evolution of composites were characterized by XRD and SEM. Using Tafel polarization plots and temporal OCP to study the anti-corrosion properties of Pani/py/TiO₂+EP coatings in 3.5% NaCl solution at the same time. It has been found that the anti-corrosion abilities of the composite are strongest when the TiO₂ content accounts for 30%, which shows better abilities of metal protection than Pani and Pani/py.