Advanced Materials Research Vols. 87-88

Abstract: Synthesis of carbon nanofibers from the V-type pyrolysis flame is a new method and it has wide application prospects. It needs simple laboratory equipments and normal atmosphere pressure. The V-type pyrolysis flame experimental system is introduced, involving V-type pyrolysis flame burner, mass flux controllers, sampling substrate etc. The carbon nanofibers were characterized by scanning electron microscope and transmission electron microscope. Carbon nanofibers with less impurities and high quality can be captured when the temperature was from 800 to 880°C, austenitic stainless steel type304 was served as sampling substrate, nickel nitrate was served as catalyst precursor and sampling time was 5 minutes. The carbon nanofibers are from 100 to 200 nm in diameter and dozens microns in length. The average diameter of catalyst particles is approximately from 20 to 50 nm. The effects of temperature, sampling substrate materials, sampling time and catalyst were analyzed. The temperature determined the diameter and shape of carbon nanofibers. The austenitic stainless steel type304 substrate containing nickel is in favor of synthesis of carbon nanofibers. The number of carbon nanofibers got more and more while the diameter got thicker firstly and then had little change with the sampling time increased within 5 minutes. In addition, experimental results also indicated that carbon nanofibers had much impurity and worse morphology if the diameter of catalyst particles was above 50nm.

Abstract: Carbon nanotube is a new kind of carbon material. Synthesis of carbon nanotubes from V-type pyrolysis flame is a kind of novel technique. It needs simple laboratory equipments and normal atmosphere pressure. The V-type pyrolysis flame experimental system is introduced. Carbon source is the carbon monoxide which is carried to the middle pipe of V-type pyrolysis flame combustor. Heat source is from acetylene /air premixed flame. Pentacarbonyl iron, served as catalyst, is transported by spray- pyrolysis method into the burner. The carbon nanotubes were characterized by scanning electron microscope and transmission electron microscope. The diameter of carbon nanotubes is approximate 20nm and its length is dozens of microns. The impact of the temperature, reactant composition and catalyst was analyzed to reveal the rule of carbon nanotube growth. Carbon nanotubes with good form and less impurity can be captured when the temperature was from 800°C to 1000°C and carbon monoxide/hydrogen/helium mixed gas flow was supplied. The effective diameter of pentacarbonyl iron nanoparticles is approximate from 5nm to 20nm in the process of carbon nanotube formation. Mechanism of carbon nanotube base on the V-type pyrolysis flame method was proposed. The carbon “dissolved-proliferation-separate out” theory can be used to explain how the pentacarbonyl iron catalyses carbon monoxide to form carbon nanotubes.

Abstract: The basic and dynamic mechanical properties and thrermal conductivity of rubber composites filled with carbon nanotubes (CNTs) and various particle-sized carbon blacks (CB) were investigated. Results indicated that tear strength and modulus at a definite elongation of rubber composites filled with CNTs were enhanced compared to the conventional CB filler. However, tensile strength and elongation at break became lower. Thermal conductivity of rubber composites partly filled with CNTs is higher than those filled with CB. Rubber filled with the combination of CNTs and the bigger CB particles was beneficial to improve wet-resistant performance and roll resistance of elastomer such as tire.

Abstract: It summarized the basic principle and characteristics of the rotational molding technology. Based on the experiment of the single axis device the processing of rotational molding was studied and predigested. Especially the heat transfer during rotational molding was analysed and a detailed mathematic model was presented. The heating time of mold and the heating time of resin material was resolved. We also brought forward the solution of analysing the function of time, radius and distribution about melting process.

Abstract: Erythromycin molecularly imprinted membranes (EM-MIMs) were prepared by wet phase inversion from imprinted polymers which were prepared by MAA as functional monomer, AN as membrane monomer and EDMA as crosslinker in the presence of erythromycin as template. The influences of the proportion of EM and MAA, cross-linking use level, different initiators and use level as well as extraction time on the imprinted sites and specific separation of EM-MIMs for EM were investigated. The results show that EM-MIMs were provided with more imprinted sites and more excellent separation properties for EM when adding MAA 0.0461mol, EM 0.724mmol, AIBN and (NH4)2S2O8 each 0.12g as initiators, and the mole ratio of EDMA and MAA at 5:1. The extraction of templates was carried out by using absolute ethyl alcohol as eluant and ultrasonic oscillating for 40min.

Abstract: The shape change in microprofile extrusion was investigated using a capillary rheometer with two different die orifices:a trilobal and a elliptic orifice. The material used in extrusion was fiber-grade polypropylene. The result showed that during microprofile extrusion the shape of extrudate deviated greatly from that of the die orifice. The size of extrudate increased with the increase of the extrusion speed and temperature but decreased with the increase of the drawing speed. Furthermore, water cooling was found to be beneficial in reducing shape change. For the trilobal shape, the shape change of trilbolal leaf in the width direction was much larger than that in the length direction. For the elliptic shape, the shape change along the minor axis was larger than along the major axis.

Abstract: The Density Function Theory (DFT) method are employed to study the geometries of the polybutadiene （C4H6）n（n=3，4，5）on the base of B3LYP/6-311+G in the paper. the polybutadiene have five isomers, including Cis-1，4-polybutadiene, Trans-1, 4-polybutadiene, Isotactic1, 2-polybutadiene, Syndiotactic1，2-polybutadiene, Atactic1, 2-polybutadiene. The molecular structures of each isomer were evaluated on the basis of single point energy with zero point vibration correction. The results show that the energies of polybutadiene varied with increase of molecular weight.

Abstract: The effects of a combination of polymeric plasticizers and bis(2-etylhexyl) phthalate (DOP) and DOP on mechanical and oil resistance properties of flexible PVC/PNBR blends were investigated. The result showed that the oil resistance of PVC/PNBR blends could be improved obviously by polymeric plasticizer.

Abstract: Micro- and nano- silicone carbide particles are used as heat conductive fillers of methyl vinyl silicone rubber, and the influence of filler amount, particle size and the surface treatment of filler on the thermal conductivities and mechanical properties of silicone rubber are studied. The results show that the thermal conductivities of silicone rubber are improved, but the mechanical properties are worse with the increase of the amount of fillers. The composite filled with smaller sized silicone carbide has a better thermal conductivity than that filled with large particles in a relatively high filling fraction, and composite filled with different sized silicone carbide has different mechanical properties at the same filling amount. Treatment of fillers with coupling agent (KH-560, A-171) has active impacts on the thermal conductivity but negative impacts on mechanical properties of the filled silicone rubber.

Abstract: Electrorheological (ER) characteristics of ER fluids (ERF) containing bacterial cellulose (BC) particles in silicone oil was investigated as a function of particle water content, DC electric field strength and particle concentration. It was found that the existence of water in BC particles strongly influenced the performance of water-activated ERF based on BC particles. Around 8.8 wt% water, yield stress reached its maximum valve of 1118 Pa after which it decreased with increasing water content. At the same water content, yield stress increased linearly with increasing in either electric field strength or particle concentration. The ERF based on BC particles was introduced into the poly (dimethylsiloxane) (PDMS) gels to prepare electric field sensitive composite gel. Electric fields were applied to these composite gels using flexible electrodes. Compressions of these gels with varying PDMS/ERF ratios were confirmed by the electrode displacement. It was found that 50/50 PDMS/ERF gel exhibited the maximum displacement of 102um at 2 kV/mm electric field.