Advanced Materials Research Vols. 550-553

Abstract: In the paper, the four core technologies "low cost and efficient decomposition," "APT property control", "fuzzy exchange and super desorption," "liquid、gas efficient closed-circuit" in Zhangyuan Tungsten Co.,Ltd in the past 20 years are elaborated in all aspects，and the research of wolframite and scheelite closed-circuit smelting process and zero emission technology are also introduced

Abstract: Biodiesel, as an alternative auto fuel for conventional fossil fuel, has drawn wide attention in recent years. In this research, a two-step process for biodiesel production using waste cooking oil as feedstock was studied in a pilot plant with a treatment capacity of 3 ton/d. The results show that: the process exihibited a good conversion ratio and the biodiesel displayed suitable physical-chemical properties in comparison with diesel fuel, such as flash point of 137°C, viscosity of 4.49 mm2/s, acid value of 0.44 mg KOH/g etc. The quality of biodiesel meets the agreement with the European specification defined by EN 14214. Afterwards, the mixture of biodiesel and diesel were test in the engine with a ratio of 50/50（v/v）, 20/80（v/v）, and 0/100（v/v）. It indicates the mixed fuel has a reasonable fuel consumption rates without diesel engine modification, when the biodiesel blended with 0# diesel as fuel. The present results demonstrated that the industrial scale plant would achieve promising objective with waste cooking oils and animal fats as raw material. Also, this biodiesel-based diesel fuel could be applied in Tianjin local public transportation system that improves its sustainable development.

Abstract: We herein report the cyclo-dehydration of 1,4-butanediol (BD) assisted with additives to form tetrahydrofuran (THF) in near-critical water (NCW).Three additives including Fe2(SO4)3,ZnSO4 and NaHSO4 were screened. Effects of various experimental parameters such as temperature (260-340°C), time (60-180min), reactant/water ratio (r/w, 1:10-1:40) and pressure (15-25MPa) on the yield of THF were examined. Without the presence of additives, the results showed that increasing temperature favored the cyclo-dehydration of BD to form THF. The maximum yield (52.61 wt. %) was obtained at temperature of 340°C and time of 180 min. With the presence of additives, at temperature range of 260~300°C and time range of 60~130min, all the additives selected can promote the cyclo-dehydration of BD to yield THF. However, with further increasing temperature and time, the additives would suppress the formation of THF. The catalytic activity toward the production of THF in the order of Fe2(SO4)3> ZnSO4> NaHSO4. The maximum yield of THF assisted with Fe2(SO4)3 could reach as high as 59.85 wt. % at 320°C, 120 min. Large reactant/water ratio would not benefit the yield of THF because of the dilution of additive. Increasing the pressure will slightly increase the yield of THF. Base on experimental results, a possible reaction mechanism and pathway of dehydration of BD was proposed in NCW.

Abstract: The azeotropic mixture ethyl acetate-ethanol (EA-EtOH) enables effective separation by extractive distillation. The effectiveness of an extractive distillation process depends on the solvent selection, so the single and mixed solvent for separating ethyl acetate-ethanol by extractive distillation were examined. The results showed that the volatility of the ethyl acetate relative to ethanol increased with an increase of the ratio of any given solvent. The selectivity of the mixed solvent is superior to the single solvent. The measured data were correlated well using modified UNIFAC model. Simultaneously, the influence of temperature on solvent selectivity was proposed by using the Clausius-Mosotti equation.

Abstract: This research is concerned with the experimental study of the wall temperature behavior of salt powders in the spray-drying process under various inlet temperatures. The results are presented and discussed in terms of the temperature profiles within two sections of the drying chamber that consists of cylindrical and conical sections. Firstly, the temperature profiles of cylindrical section have shown that the behavior from the steps of spraying air, water, and solution before has lead to a steady state process. Finally, the wall temperature distribution at each elevation has shown a statistically significant difference. In our future work, the wall temperature behavior will be compared with the wall deposition flux in order to determine a prediction equation that can be applied to manage the deposition problem in the spray-drying process stage.

Abstract: The absorbencies of poly(acrylic acid-co-acrylamide) (PAAM) are measured for the ion strengths of the salt solutions using the self-made PAAM by inverse suspension polymerization. The effects of various salt solutions on the swelling properties were studied systemically, and the relationship between the absorbency (Q) of PAAM and the concentrations of different salt solutions(c) could be expressed as Q=kcⁿ. The absorbencies of PAAM decrease obviously with the ion strengths (less than 0.03mol/kg) and had no great change when the ion strengths were higher than 0.03mol/kg for the same solution systems. The absorbency decreased with an increase in charge of the metal cation. The absorbencies of the PAAM in the sodium solutions with different anion decreased with an increase of the ion strengths. However, the absorbencies increased with the increase in charge of the anionic group and were in order PO₄^3->CO₃^2->Cl^-.

Abstract: Compared with in the conventional scales, the rheological properties of polymer melts have changed in the micro-scales. Based on the principle of capillary flow and modified with the method of Bagley or zero die micro-die, the rheological characteristics of polypropylene (PP) were investigated using the HAAKE capillary rheometer under the micro-die and conventional die. The results show that: the viscosity of polymer melt modified with the method of bagley or zero die micro-die in the different L/D ratio of micro-die is the same and the shear viscosity of PP decreases with the increase of shear rate; Compared with the viscosity in the conventional scales, the measured viscosity of PP in the micro-scales was reduced by 46% in 0.25mm diameter die, 44% in the 0.20mm diameter die and 88% in the 0.15mm diameter die at the same shear rate; a layer of fixed polymer melt was found in the inwall of the micro-die through the calculation of wall slip rate.

Abstract: In this work, a flame retardant system consisting of P-N intumescent flame retardant (IFR), melamine phosphate, ammonium polyphosphate (APP) and polytetrafluoroethylene (PTFE) was applied to polypropylene (PP). The IFR/APP/PTFE flame-retardant system showed significant synergistic effect, and the PP/IFR/APP/PTFE can reach a LOI value of 30.1% and UL-94 V-0 with only 24wt% flame-retardant (APP: 6wt%, IFR: 17.5wt%, PTFE: 0.5wt%). By using FTIR, SEM and XPS, the burning process of flame-retardant PP and the components of residual char were analyzed, and the flame retardant mechanism of PP/APP/IFR/PTFE system was studied.

Abstract: Keywords: Polyethersulfone MMMs, Zeolite 4A, Silane Coupling Agent, Gas separation Abstract.Mixed Matrix Membranes (MMMs) is one of the alternative ways to increase the performance of plain polymeric membrane. In this study, the performance of MMMs using treated zeolite and the ones using untreated zeolite were compared to see the effect of the coupling agent towards the separation of O2 and N2. The polymer solution contains Polyethersulfone (PES) as the polymer, N-Methyl Pyrrolidone (NMP) as the solvent and distilled water (H2O) as the non-solvent. For the MMMs using treated zeolite, the zeolite was first treated using Aminopropyl-Trimethoxysilane (APTMOS), a silane coupling agent before inserted into the polymer solution. For both types of MMMs, the zeolite concentration between 5 to 20 wt % were applied. The dry/wet phase inversion methods were used to produce the asymmetric flat sheet membrane. The prepared membranes were coated with silicone and N-Hexane in order to decrease the surface defect of the membrane. The best performance had found for membranes using treated zeolite where the selectivity was 3.3 for 15 % zeolite concentration at 3 bar operating pressure compare to the untreated zeolite . As a conclusion, it believe that surface modification of zeolite plays an important role to the incompatibility of zeolite and polymer to the formation of large free voids and it affected the overall selectivity and permeability.

Abstract: Dynamic rheological results of 17 commercial and noncommercial metallocene-catalyzed polyethylenes, such as shear thinning index(SHI), modulus of crossover point of store modulus and loss modulus (G_co) and flow activation energy(Ea), are presented. The effects of molecular weight distribution(MWD), and degree of short chain branching (SCB) determined by gel permeation chromatography (GPC) and FTIR, were analyzed. Plots of SHI versus MWD revealed the influence of branching level on the shear thinning behavior of polyethylenes. G_co was observed scaling with MWD for metallocene-catalyzed polyethylenes and the correlation between them was generated by MWD=193378*G_co . Correlation between flow activation energy measured by dynamic temperature sweep at low frequency and short chain branch ^-0.9038was also established for metallocene polyethylenes as SCB=7*10^-8*Ea^6.024. Thus, an alternative single rheological method, based on the effect of molecular structural parameters on dynamic rheological behaviors, was proposed to evaluate the polydispersity and short chain branching of metallocene-catalyzed polyethylene.