Papers by Author: Li Qun Zhang

Abstract: Carbon nanotubes/alumina (CNTs/Al₂O₃) nanocomposites were prepared by the poly (dopamine) assisted chemical liquid phase deposition (CLPD). The poly (dopamine) layers were firstly coated on the CNTs surface uniformly by the self-oxidative polymerization of dopamine in mild aqueous solution and then the Al₂O₃ nanoparticles formed on the poly (dopamine) coated CNTs surface by the CLPD. The hydrophilic poly (dopamine) layers on the CNTs surface can improve the dispersion of CNTs in aqueous solution. Moreover, it can be used as a key linker between the CNTs and Al₂O₃ because of the nitrogen-containing group in poly (dopamine) could coordinate with Al³⁺ ions. The as-prepared poly (dopamine) coated CNTs and CNTs/Al₂O₃ nanohybrids were characterized by X-ray photoelectron spectroscopy (XPS), X-radial diffractometer (XRD) and high resolution transmission electron microscopy (HRTEM). These results showed that the poly (dopamine) layers were coated on the surface of CNTs uniformly, and the Al₂O₃ nanoparticles embellished with the poly (dopamine) coated CNTs surface. Compared with pristine NR composites, the thermal conductivity of the as-prepared NR/CNTs@Al₂O₃ composites increased 17%.

Abstract: The new comb-copolymers [polyacetylene–MPEG (polyethylene glycol monomethyl ether)] were synthesized with (nbd)Rh⁺[η⁶-C₆H₅B^- (C₆H₅)₃] as catalyst. The copolymers with moderate molecular weights (Mn) (13000-170000) and yields (31.6-47.3%) exhibited higher optical activities compared with chiral monomer, which accorded with the “Chiral Amplification” effect. The optical activity of the copolymers gradually decreased as the amount of MPEG increased. The maximum amounts of MPEG for successful copolymerization and optical activity of copolymers were 40%, 30%, 20%(mol%) as the Mn of MPEG was 350, 750,1900, respectively. The optical activity of copolymers could change at external environmental stimulation, e.g., decreased as methanol content increased.

Abstract: A melt blending process was employed to prepare nano-composites based on thermoplastic polyurethane (TPU) and multi-walled carbon nanotubes (MWNT). The content of MWNT filled in TPU was increased till 40phr (parts per hundreds of rubber). Scanning electron microscope (SEM) and transmission electron microscope (TEM) showed that the unmodified MWNT were dispersed uniformly in the TPU matrix beyond expectation. Dynamic mechanical thermal analysis (DMTA) test demonstrated that the nano-composites possessed greatly increased modulus, and the flowing temperature moved to higher temperature with increasing MWNT content. Moreover, the nano-composites exhibited improved wear resistance, evidently increased thermal conductivity, and prominently raised electrical conductivity that might mean the TPU/MWNT nano-composites have potential application as multi-functional materials.

Abstract: Since rubber was applied in people’s normal life, researchers have started to exploit the rubber reinforcing techniques and the relative mechanism. Developing high-effective, simple and economical reinforcing methods and fillers are the emphasis of rubber industry, technology and science. In this paper a rubber ideal filler (IF) is shown. This IF is a kind of composite with core-shell structure which was synthesized by seeded emulsion polymerization. It used styrene (St), polybutadiene oligomer (PBD) as monomers and divinyl benzene (DVB) as cross-linking agent. The effect of the amount of cross-linking agent, concentration of emulsifier and initiator on the stability of the emulsion was studied. The morphology of the latex particles with core-shell structure was characterized by high resolution SEM (ESEM) and DSC (Tg). The results showed that cross-linking polymeric particles exhibited strong reinforcing effect on styrene-butadiene rubber (SBR).

Abstract: The reinforcing mechanism of novel aramid pulp (AP) short fibre in CR matrix has been discussed in this paper, and it has been shown that the reinforcing effects of AP depend mainly on the dispersing uniformity and openness of those ultra-fine short fibres of AP in CR matrix.By proper pretreating method, the dispersing uniformity and openness of ultra-fine AP short fibres with high specific area can be improved markedly, so the large reinforcing potential can bring into play adequately.

Abstract: Hydrogenation of neoprene (CR) latex was carried out by utilization of diimide with boric acid as a catalyst. Various hydrogenation conditions were studied and the hydrogenation degree could reach 48.1%. The most effective ratio of hydrogen peroxide/hydrazine hydrate was 0.8. The hydrogenation degree increased with increasing the temperature, the amount of boric acid and hydrazine hydrate. However, it decreased as prolonging the reaction time. The gel content was also investigated. Microstructure of hydrogenated neoprene (HCR) was characterized by IR and 1HNMR.