Preparation of oil-modified polycaprolactone and its further modification with benzoxazine for coating purposes

Sunflower oil-modified polyester (SOMPE) was prepared via the ring opening polymerization of ?-caprolactone (CL) using partial glycerides (PGs) and stannous octoate (SO) as the initiator and catalyst, respectively. In addition to being the initiator, PGs participate in the drying process of the film sample for coating purposes. The structure of the sample was characterized by FT-IR and ¹H NMR. The film of SOMPE cannot reach a fully dried state as a result of its less oil moiety content. By increasing the oil fraction, the chain length of polycaprolactone (PCL) decreased by changing the [monomer]/[initiator] mol ratio and shortening the reaction time. Even with these precautions, the molecular weight of SOMPE could not be reduced below 5000 g/mol, and this caused the film to become soft. Therefore, hydroxy-functional benzoxazine monomer (HFB-a) was prepared and used in a further modification of SOMPE. HFB-a was chemically combined with SOMPE via the urethane linkage formed from the reaction of 2,4-toluene diisocyanate, yielding SOMPE-HFB-a. Because the SOMPE-HFB-a sample also had a soft film, additional HFB-a was used to prepare the SOMPE-HFB-a/HFB-a blend. The cured blend prepared with SOMPE-HFB-a and HFB-a in a weight ratio of 1/8, [SOMPE-HFB-a/HFB-a:1/8], had good film properties. The cured film was examined by FT-IR and DSC following the curing process. After our modifications were applied, PCL and polybenzoxazine lost their softness and brittleness, respectively, and a binder with good film properties was formed.     

Physical and Mechanical Properties of Iron Powder Filled Polystyrene Composites

This article reports on an experimental study of the physical and mechanical properties of Polystyrene (PS) and Fe-PS polymer composites containing 5, 10, and 15 vol.% of Fe powder. After mixing Fe powder and PS in a twin-screw extruder, an injection-molding machine was used to prepare unfilled PS and Fe-PS polymer composite samples. After that, the material properties were experimentally determined for each sample. The investigated material properties included the modulus of elasticity, yield and tensile strength, % elongation, Izod impact strength (notched), hardness (Shore D), melt flow index (MFI), heat deflection temperature (HDT), Vicat softening point, and glass transition temperature (T _g ). The results indicated that, compared to the unfilled PS, an addition of Fe into PS decreases the yield and tensile strength, % elongation, and Izod impact strength. Furthermore, it was determined that the Fe particles increase the modulus of elasticity, hardness, MFI, Vicat softening point, and HDT values.     

可溶性丝蛋白的制备及性能研究

采用氯化钙溶解废弃蚕丝制备可溶性丝蛋白,考察了透析时间与溶解废丝量对蛋白质质量分数、钙离子含量及表面性能的影响。实验结果表明:透析时间对蛋白质质量分数变化影响较小,钙离子含量在6～18 h有较快的变化,18 h后变化变缓,而钙离子含量随废丝量增加而增加。乳化性在透析时间24 h时最好,几乎达到100%;起泡性随透析时间变化较小,起泡性在200%左右,而泡沫稳定性在12 h最高为87%,随后略有降低;随废丝量的增加其乳化性增加,溶解废丝量15 g时,乳化稳定性最高为89%,起泡性和泡沫稳定性随废丝量增加而增加,起泡性最高达到224%,泡沫稳定性可达到85%。     

Filler Wetting in Miscible ESBR/SSBR Blends and Its Effect on Mechanical Properties

The selective wetting behavior of silica in emulsion styrene butadiene rubber (ESBR)/solution styrene butadiene rubber (SSBR) blends is characterized by the wetting concept, which is further developed for filled blends based on miscible rubbers. It is found that not only the chemical rubber–filler affinity but also the topology of the filler surface significantly influences the selective filler wetting in rubber blends. The nanopore structure of the silica surface has been recognized as the main reason for the difference in the wetting behavior of the branched ESBR molecules and linear SSBR molecules. However, the effect of nanopore structure becomes more significant in the presence of silane. It is discussed that the adsorption of silane on silica surface constricts the nanopore to some extent that hinders effectively the space filling of the nanopores by the branched ESBR molecules but not by the linear SSBR molecules. As a result, in silanized ESBR/SSBR blends the dominant wetting of silica surface by the tightly bonded layer of SSBR molecules causes a low‐energy dissipation in the rubber–filler interphase. That imparts the low rolling resistance to the blends similar to that of a silica‐filled SSBR compound, while the ESBR‐rich matrix warrants the good tensile behavior, i.e., good abrasion and wear resistance of the blends.

     

Highly sensitive electrochemical sensor based on zirconium oxide-decorated gold nanoflakes nanocomposite 2,4-dichlorophenol detection

Journal of Applied Electrochemistry - In this study, a sensitive and selective electrochemical sensor based on a zirconia oxide-decorated gold nanoflake nanocomposite-modified glassy carbon...     

Optimization of some parameters of stirred mill for ultra-fine grinding of refractory Au/Ag ores

In this study, optimization of some parameters of stirred mill on ultra-fine grinding of refractory Au/Ag ores was performed. A three-level Box-Behnken design combining a response surface methodology (RSM) with quadratic programming (QP) was employed for modelling and optimization of some operating parameters in ultra-fine grinding. Grinding tests were carried out in a laboratory scale pin-type vertical stirred mill. The relationship between the response, i.e. d₈₀ size, and four grinding parameters, i.e. ball diameter, grinding time, ball charge ratio and stirrer revolution was presented as empirical model equations. Analysis of variance showed a high coefficient of determination value (R² = 0.9698), thus ensuring a satisfactory of the second-order regression model with the experimental data.The model equations were then optimized using the quadratic programming method to minimize for d₈₀ size within the experimental range studied. The optimum conditions were found to be 1.61 mm for ball diameter, 11.50 min for grinding time, 80% for ball charge ratio and 745 rpm for stirrer revolution for this grinding process.In order to verify the improvement of grinding performance using the optimal level of control factors three verification experiments were conducted, and the results for d₈₀ was 3.37 μm, which were smaller than those obtained in the initial tests.     

Electrical and rheological percolation in poly(vinylidene fluoride)/multi‐walled carbon nanotube nanocomposites

Nanocomposites of poly(vinylidene fluoride) (PVDF) and multi‐walled carbon nanotubes (MWCNTs) were prepared through melt blending in a batch mixer (torque rheometer equipped with a mixing chamber). The morphology, rheological behavior and electrical conductivity were investigated through transmission electron microscopy, dynamic oscillatory rheometry and the two‐probe method. The nanocomposite with 0.5 wt% MWCNT content presented a uniform dispersion through the PVDF matrix, whereas that with 1 wt% started to present a percolated network. For the nanocomposites with 2 and 5 wt% MWCNTs the formation of this nanotube network was clearly evident. The electrical percolation threshold at room temperature found for this system was about 1.2 wt% MWCNTs. The rheological percolation threshold fitted from viscosity was about 1 wt%, while the threshold fitted from storage modulus was 0.9 wt%. Thus fewer nanotubes are needed to approach the rheological percolation threshold than the electrical percolation threshold. Copyright © 2010 Society of Chemical Industry     

电位滴定法快速测定洗衣粉中的聚磷酸盐含量

用强酸分解洗衣粉中的聚磷酸盐，以电位滴定法间接测定其中的聚磷酸盐含量。该法简便，快速，结果可靠。     

The adsorption behavior of cesium on poly(N-isopropylacrylamide/itaconic acid) copolymeric hydrogels

In this study, N-isopropylacrylamide/itaconic acid (NIPAAm/IA) hydrogels prepared by irradiating with γ radiation were used in experiments on cesium ion adsorption. The cesium ion adsorption capacity of the hydrogels was investigated as a function of Cs⁺ concentration, pH and temperature. The adsorption behavior of cesium was evaluated by using the radiotracer method. The adsorption isotherm models were applied to the experimental data, and it was seen that Freundlich isotherm explained the adsorption better than Langmuir isotherm. Two simplified kinetic models including pseudo-first-order and pseudo-second-order equation were selected to follow the adsorption processes. The Cs⁺ adsorption could be best described by the pseudo-first-order equation. The thermodynamic parameters including ΔG°, ΔH° and ΔS° for adsorption processes of Cs⁺ on the hydrogel were also calculated, and the negative ΔH° and ΔG° confirmed that the adsorption process was exothermic and spontaneous.