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Since the first observation of carbon nanotubes (CNTs) in 1991, their synthesis techniques has been extensively investigated. The chemical vapor deposition (CVD) process have attracted much attention because of both their versatility and easy large scale production for CNTs . This paper is focused on a catalytic CVD-based method for synthesis of whisker multiwalled carbon nanotubes (WMWCNTs). The new type of carbon nanotube is similar to the whisker. The morphology of the WMWCNTs are very different from traditional carbon nanotubes prepared by traditional chemical vapor deposition process. The traditional CNTs were twisted and entangled with each other. These suggested that there are a lot of deficiencies on the CNTs and are difficult to disperse in matrix materials. The as-produced WMWCNTs are very straight and not entangled with each other. The line structure means that WMWCNTs are easily dispersed in matrix materials than traditional CNTs which are twined together. The crystallinity of WMWCNTs increased to 96% which was much higher than traditional CNTs after graphitization treatment at 2800°C.

Conventional and modified membrane bioreactors (MBRs) are effective increasingly used in small sized wastewater treatment plant. However, their widespread applications are hindered by their elevated energy consumption and the high costs of investment for the membrane modules. In this study, we investigated a modified an improved MBR system that utilized a cost effective woven fabric instead of nonwoven as the filter material in MBR modules. The woven fabric bioreactor (WFBR) system was operated in a continuous mode at HRT from 33 to 12h. Under the operational conditions of BOD loading rates from 0.12 to 0.28 kg BOD/kg MLSS /d, the WFBR system was able to reduce up 93.57% COD. The 38µm woven fabric performed well in solid-liquid separator, with an average suspended solids retention of 99.47% at MLSS of 4710~9951 mg/L. The WFBR system eliminated suction pumping by using a gravity head in the membrane filtration of the effluent over the entire operational period of 60 d.

Summary:Influence of amide interchange reactions of polyamide 6 (PA6) on its molecular weight distribution (MWD) was analyzed using a kinetic Monte Carlo simulation method, by which two reaction systems with different types of initial non‐equilibrium distributions, monodisperse and bimodal distribution, were investigated. The simulation results indicate that initial deviations from equilibrium MWD are rapidly relaxed to an equilibrium one, which approaches the most probable MWD proposed by Flory. The reaction time to reach the equilibrium MWD decreases with an increase in reaction temperature. The simulated polydispersity index data suggest that about 0.3 interchanges per segment are sufficient to equilibrate the non‐equilibrium systems, consistent with the results reported by Jo et al. on ester interchange reactions of poly(ethylene terephthalate) (PET).

A new model of solid‐state polymerization of nylon‐6,6 has been developed. The polymer crystalline fraction is assumed to consist of only repeat units, leaving end‐groups and condensate in the amorphous fraction. Many effects neglected by previous models are considered, such as variable crystallinity, initial moisture and starting molecular weight. This model is compared to experimental data with good agreements. Differential scanning calorimetry graphs show that the crystalline structure phase tends to be increasingly perfect during heat treatment, indicative of the premelting temperature drawing near the melting point up to 14 °C after solid‐state polycondensation with little change of melting point. Copyright © 2000 John Wiley & Sons, Ltd.

A new model of solid-state polymerization of nylon-6,6 has been developed. The polymer crystalline fraction is assumed to consist of only repeat units, leaving end-groups and condensate in the amorphous fraction. Many effects neglected by previous models are considered, such as variable crystallinity, initial moisture and starting molecular weight. This model is compared to experimental data with good agreements. Differential scanning calorimetry graphs show that the crystalline structure phase tends to be increasingly perfect during heat treatment, indicative of the premelting temperature drawing near the melting point up to 14 °C after solid-state polycondensation with little change of melting point. Copyright © 2000 John Wiley & Sons, Ltd.

A variety of 2,5‐disubstituted pyrrolidines is synthesized by radical cyclization of various N‐4‐ and N‐5‐alkenyl and alkynyl N‐benzoyloxysulfonamides.