聚氨酯软质泡沫吸油性能的研究

以聚醚多元醇(PP0330)和甲苯二异氰酸酯(TDI)等为原料,合成了一种结构良好的聚氨酯软质泡沫,研究了该泡沫的最大吸油量、保油率、吸油速率和缓释性能.结果表明,该泡沫可吸收柴油14.11 g/g、汽油26.41 g/g、甲苯39.01 g/g、四氯化碳43.47 g/g,且保油率达到90％以上.该泡沫材料对油品的缓...     

聚氨酯多孔膜的结构和透湿性能研究

研究了湿法涂层技术制备聚氨酯(PU)多孔膜的工艺条件以及致孔剂含量对多孔膜微孔结构和透湿性能的影响。致孔剂的加入可以增大多孔膜的孔径。多孔膜的表面(与水的接触面)孔径为10μm～20／μm，而底面(与基材的接触面)孔径为60／μm～100／μm。断面结构显示，多孔膜的内部疏松多孔，孔与孔之间相互连通。进一步探讨了溶液的成膜过程和多孔膜的透湿机理。     

聚氨酯软质泡沫的制备及其泡孔结构和吸油性能的研究

采用全水发泡工艺,通过对配方的调节,研制了一种具有一定耐压强度和较好吸油性能的聚氨酯软质泡沫塑料。研究了催化剂配比及用量、泡沫稳定剂用量、粗MDI指数对聚氨酯软质泡沫吸油性能的影响。采用聚醚(N-220),当催化剂辛酸亚锡的质量份为0.20、催化剂A33的质量份为0.55、泡沫稳定剂有机硅油的质量份为1.0、粗MDI指数0.85左右、发泡剂去离子水的质量份为4～8时,所制备的聚氨酯泡沫泡孔结构和吸油效果较好。     

Structure and swelling of poly(acrylic acid) hydrogels: effect of pH, ionic strength, and dilution on the crosslinked polymer structure

The network formation of crosslinked polymer hydrogels made via a free radical polymerization mechanism is significantly influenced by the polymerization conditions. In particular, the crosslinked structure of ionic networks like poly(acrylic acid) copolymers is affected by the monomer concentration, the pH, and ionic strength during the polymerization. In this work experimental data as well as theoretical analysis are used to investigate how these factors control the degree of crosslinking and primary cyclization during the network formation of multifunctional monomers. It was found that the amount of water present during the polymerization increases primary cyclization rates, and this change affects the subsequent swelling behavior of the acrylic acid hydrogel. The effects of ionic strength and pH on the network structure are interrelated. An increase in the pH decreases the degree of primary cyclization while an increase in the ionic strength increases cyclization. To investigate further the effect of pH, a cationic polymer was formed that contained a monovinyl amine monomer and a novel diamine crosslinking agent synthesized in our laboratory. The combined effect of the ionizing backbone chain and crosslinking agent cause the degree of primary cyclization in this material to be extremely sensitive to the pH during polymerization. This result confirms the significant role of pH on the network formation in ionic materials.     

Processing Parameters on the Extraction of Olive Pomace Oil and Its Bioactive Compounds: A Kinetic and Thermodynamic Study

The effect of temperature (40–60 °C), solid/liquid ratio (1/4–1/12 g mL^?1), and agitation speed (AS) (100–800 rpm) on the extraction yield of olive pomace oil and on the recovery of its unsaponifiable matter (USM) during extraction were studied. Two kinetic models were tested to correlate the experimental data; the first proposed by So and Macdonald and the second by Sulaiman et al. The two models adequately describe the extraction process of both oil and USM. Higher extraction temperatures, solid to liquid ratios, and AS led to increased oil yield and favored USM in the extracted oil, and also increased the calculated mass transfer coefficients of the extraction. Changes in enthalpy and entropy were found to be positive while change in free energy was negative, indicating that the process was endothermic, irreversible, and spontaneous. Under equilibrium conditions, the oil yield was increased by a factor of approximately 1.096 and 1.054 for the model of So and Macdonald and Sulaiman et al., respectively, for every 10 °C rise in temperature.     

Study on the kinetics of hazardous pollutants adsorption and desorption by biomass: Mechanistic considerations

The kinetics of biosorption and desorption of lindane, diazinon and 2-chlorobiphenyl by inactive activated sludge and Rhizopus arrhizus biomass was studied. The effects of solution initial concentration, temperature and type of biomass on the observed biosorption and desorption rates were also examined. The results of the present work show that the biosorption rates are reasonably rapid, with equilibrium attained within 4 h by activated sludge and 1 h by R. arrhizus. The observed biosorption kinetics consist of a rapid initial stage followed by a slower second stage. The observed rate of organic pollutants biosorption by activated sludge during the first stage can be described by second order kinetics. The biosorption of lindane by both biomass types is reversible and the desorption process is rapid and could be described by zero order kinetics when activated sludge is used as adsorbent. The type of biomass can have a significant effect on the observed biosorption and desorption rates.     

Studies on Energetic Compounds Part 27: Kinetics and Mechanism of Thermolysis of Bis(Ethylenediamine)Metal Nitrates and Their Role in the Burning Rate of Solid Propellants

Four bis(ethylenediamine)metal(II) nitrate (BEMN) complexes, i.e. [M(EDA)₂](NO₃)₂, where M=Cu, Co, Ni and Zn, have been prepared and characterized. Thermolysis of these complexes induced by heat and drop‐weight impact has been investigated by TG‐DTG, DTA, explosion delay (D_E), explosion temperature (T_E) and impact sensitivity measurement. The kinetics of early thermolysis reaction prior to fast decomposition have been evaluated. Contracting area (CA, n=2) and contracting cube (CC, n=3) equations were found to give the best fits in isothermal TG data among all tested nine mechanism‐based kinetic models. The values of activation energy (E_a), T_E, D_E and activation energy for explosion (E*) have been found to be quite lower for the copper complex as compared to cobalt, nickel and zinc complexes. A mechanism of thermolysis has also been proposed. All these complexes were found to be insensitive towards impact of 2 kg weight up to the height of 110 cm. These complexes were used as energetic burning rate modifiers in the combustion of hydroxy‐terminated polybutadiene (HTPB)‐ammonium perchlorate (AP) composite solid propellants. A two‐fold increase in burning rate was observed with copper and cobalt complexes at low concentration (2% by wt.). The in situ freshly formed metal oxides with large number of active sites in their crystallites seem to be better additives for combustion of propellants.     

Influences of Ligand Structure and pH on the Adsorption with Hydrophobic Charge Induction Adsorbents: A Case Study of Antibody IgY

The adsorption behaviors of hydrophobic charge induction chromatography (HCIC) adsorbents with different functional ligands were investigated with immunoglobulin of egg yolk (IgY) as a model antibody. The adsorption isotherm and retention behavior in the column were studied, and the influences of the ligand structure and the pH on the adsorption were discussed. The results indicated that the pI of the target protein and pKa of HCIC ligand are the important parameter to determine the maximum adsorption pH of HCIC adsorbent, and high adsorption of IgY was found at pH 5 for all five adsorbents tested. Some differences could be found for different HCIC adsorbents, and the ligand structure influenced pH effect on the binding/elution of target protein. 2-mercapto-1-methyl-imidazole (MMI) ligand with a sulfone group showed a high adsorption capacity and strong pH-sensitivity, which would be more suitable for antibody purification. Moreover, the retention experiments indicated that IgY could be efficiently eluted from the adsorbents with 4-mercapto-ethyl-pyridine (MEP) or MMI as the ligand at acid conditions, while 2-mercapto-benzimidazole (MBI) ligand showed some difficulties on the elution. The retention study would help in defining not only the effective pH of elution for a given protein but also the elution efficiency of a given adsorbent.     

Generating Cyan Fluorescence with De Novo Tripeptides: An In Vitro Mutation Study on the Role of Single Amino Acid Residues and Their Sequence

Amino acids are natural choices as building blocks when developing biofunctional entities owing to their superior diversity and versatile physicochemical properties compared to nucleotide bases. A simple permutation of the amino acids creates a broad palette of proteins and these have been successfully engineered into useful biofunctional agents. For example, the intrinsic ultraviolet fluorescence of phenylalanine and tryptophan has been engineered to emit in the visible spectrum, which has broad applications for imaging/sensing probes, photothermal therapy agents, optogenetic switches, etc. Nature produces more colorful coats/furs, feathers/hairs, and eyes through various biochemical modifications of tyrosine-based pigmentation. However, it is challenging to modulate the fluorescence wavelength from the UV to the visible region through oligopeptides. Herein, we report an innovative approach to obtain cyan fluorescence by using de novo tripeptides containing glycine, tyrosine, and lysine, which form robust dimer structures under moderate oxidizing conditions. Through an in vitro mutation approach, we deduce that both the amino acids and their sequence play significant roles in modulating the fluorescence. We believe this work holds great promise for developing novel cell imaging and resonance energy-transfer-based fluorescent probes.