Sorption of water vapor by chemically modified polyamide fibre

Conclusions Sorption and desorption isotherms of water vapor by chemically modified PCA fibre have been analyzed.It has been shown that the modified PCA fibre absorbs water vapor like cotton fibre over a wide range of variation in relative humidity.The elevated sorptive capacity as compared with Kapron fibre is explained by an increase in the number of active hydrophilic functional groups and volume of sorbing pores.Translated from Khimicheskie Volokna, No. 1, pp. 20–21, January–February, 1984.     

Morphology and rheological properties of blends of chemically modified thermoplastic starch and polycaprolactone

Polycaprolactone (PCL) was blended in a twin‐screw extruder with chemically modified thermoplastic starch (CMPS) to provide biobased and biodegradable resin composition. Reacting starch with maleic anhydride (MA) in the presence of a plasticizer and a free radical initiator provided the CMPS. The starch modification improved interfacial adhesion and processability in blending with other thermoplastic polyesters. The rheological, mechanical, thermal, and morphological properties of the blends were examined. Differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) studies revealed that the PCL/CMPS blends are thermodynamically immiscible. However, they formed compatible blends due to the reaction of the carboxyl groups on starch backbone with hydroxyl groups of the PCL chain ends. The tensile strength and elongation decreased with increasing CMPS content, whereas the modulus increased. Dynamic viscoelastic measurements showed that the flow behavior of PCL was that of Newtonian fluid within the tested frequencies, whereas the CMPS exhibited strong shear thinning characteristics. The flow behavior of the blends varied with the CMPS content. The complex viscosity, storage, and loss moduli of the blends containing more than 40% of CMPS were higher than those of pure CMPS and PCL. In addition, the properties of CMPS to those of chemically unmodified thermoplastic starch (TPS) were compared. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

复合吸附剂MWCNT/MgCl2的水蒸气吸附性能

通过研磨将多壁碳纳米管分别与质量分数为30%、40%和50%的无水氯化镁复合,制备了3种不同配比的复合吸附剂MWCNT/MgCl₂。采用数字化扫描电子显微镜（SEM）观察复合吸附剂表面材质的结构样貌,通过Hot Disk热常数分析仪测得复合吸附剂的热导率,使用恒温恒湿箱选取具有代表性的温湿度,测试复合吸附剂在不同工况下的水蒸气吸附性能,并采用准二级动力学模型对25℃、50% RH工况下的实验数据进行拟合,应用Autosorb-IQ全自动气体分析仪测试了三种样品在25℃下的等温吸湿曲线。实验结果表明,相同温湿度工况下,随着氯化镁含量增加,复合吸附剂的吸附量提高,25℃、50% RH下氯化镁含量为30%、40%和50%的复合吸附剂M1、M2和M3的吸附量分别为0.62、0.79和0.94 g/g;恒定湿度为50% RH,温度变化为15~35℃时,复合吸附剂吸附量受温度和饱和水蒸气分压力的双重影响,表现为先增加后减小;温度固定为25℃,相对湿度从50% RH增加到80% RH时,复合吸附剂吸附量均大大提升;复合吸附剂在35℃、25% RH中高温、低湿条件下仍表现出较好的吸附能力;在相对压力P/P₀为0.3时,M1、M2和M3的吸附量分别为0.24、0.25和0.30 g/g,随着吸附压力的增加,复合吸附剂的吸附量也不断提升,最大吸附量分别达到3.54、3.75和4.42 g/g。复合吸附剂MWCNT/MgCl₂的制备研究,为吸附剂的性能研究提供了基础,对太阳能吸附式空气取水的研究具有潜在意义。     

The adsorption and absorption of water vapor by polyethylene terephthalate

An experimental technique for the simultaneous determination of the amount of gas or vapor absorbed and adsorbed by a film of material is given. For Mylar film at 40°C it was found that the amount of water at an activity of 0.9 that was adsorbed was about 1 × 10^?7 g/cm². Assuming that a water molecule is cubical in shape and 3.26 Å on an edge and the surface is geometrically flat, this amounts to several layers of water molecules on the surface for any thickness.     

Modeling of coal swelling induced by water vapor adsorption

Gas adsorption-induced coal swelling is a well-know phenomenon. Coal swelling or shrinkage by adsorption or desorption of water vapor has not been well understood but has significant implications on gas drainage process for underground coal mining and for primary and enhanced coalbed methane production. Decreased matrix moisture content leads to coal shrinkage and thus the change of cleat porosity and permeability under reservoir conditions. Unlike gas adsorption in coal which usually forms a single layer of adsorbed molecules, water vapor adsorption in the coal micropores forms multilayer of adsorbed molecules. In this work, a model has been developed to describe the coal swelling strain with respect to the amount of moisture intake by the coal matrix. The model extended an energy balance approach for gas adsorption-induced coal swelling to water vapor adsorption-induced coal swelling, assuming that only the first layer of adsorbed molecules of the multilayer adsorption changes the surface energy, which thus causes coal to swell. The model is applied to describe the experimental swelling strain data measured on an Australian coal. The results show good agreement between the model and the experimental data.     

Correlation of water vapor adsorption behavior of wood with surface thermodynamic properties

To improve the overall performance of wood–plastic composites, appropriate technologies are needed to control moisture sorption and to improve the interaction of wood fiber with selected hydrophobic matrices. The objective of this study was to determine the surface thermodynamic characteristics of a wood fiber and to correlate those characteristics with the fiber's water vapor adsorption behavior. The surface thermodynamic properties, determined by inverse gas chromatography at infinite dilution or near zero surface coverage, were the dispersive component of the surface energy, surface acid‐base free energy and enthalpy of desorption of acid‐base probes, and surface acid‐base acceptor and donor parameters (K_A and K_D). Water vapor adsorption was expressed in terms of the percentage of weight gain (ΔW%) resulting from water vapor adsorption on the wood particles, calculated relative to their initial weight after preconditioning in a vacuum dessicator at room temperature. The results showed a strong correlation between ΔW% and K_A, and between ΔW% and surface acid‐base free energy of water desorption (ΔH^AB_water), calculated from experimental K_A and K_D and values in the literature for acceptor and donor values of water. These results suggest that for substrates such as wood, whose surface Lewis acid‐base properties are characterized by a relatively stronger tendency to accept electrons, the key to controlling water vapor adsorption is to manipulate the magnitude of ΔH^AB_water, primarily via K_A, and to a lesser extent via K_D. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 399–407, 1999     

Pore structure and graphitic surface nature of ordered mesoporous carbons probed by low-pressure nitrogen adsorption

Ordered mesoporous carbons (OMCs) were produced by pyrolysis of sucrose adsorbed in two different silica matrices (MCM-48 and SBA-15), followed by dissolution of the matrix in hydrofluoric acid. Subsequently, some of these OMCs were heat-treated at temperatures of up to 1600 °C. The OMC pore structure was studied by low-pressure nitrogen adsorption. Information on the graphitic order of the surface of the mesopore walls was also obtained from the nitrogen adsorption data. These results were correlated to the order of the graphene layers at the outer surface, which was studied by X-ray photoelectron spectroscopy (XPS).

The OMCs were predominantly mesoporous, but they also contained micropores. For OMCs produced in an SBA-15 matrix, the micropore volume decreased upon heating. After heating to 1600 °C, nearly all micropores had disappeared. Furthermore, upon heating the width of the mesopores increased from 35 to 50 Å. All these changes can be explained by a shrinking of the OMC framework upon heating. A different behavior was found for OMCs derived from MCM-48. Upon heating these materials at increasingly high temperatures, the width of the mesopores first decreased, and for temperatures above 1100 °C it increased again. For all OMCs studied the graphitic order of the mesopores and the order of the graphene layers at the outer surface increased upon heating. For a given temperature, the graphitic surface order of OMCs derived from SBA-15 and MCM-48 was similar.     

载镁鸡蛋壳的制备及其对水体中磷酸盐的吸附特性

采用氯化镁溶液对鸡蛋壳进行改性,制得了载镁鸡蛋壳(MgES)并应用于水中磷酸盐的去除.采用XRF、SEM、FTIR和XRD等对材料进行表征.通过静态吸附实验分析MgES对水体中磷酸盐的去除性能.结果表明,Langmuir模型能够较好地拟合吸附等温线,25℃时最大吸附量为112.1560 mg/g;MgES对磷酸盐的吸附是自发的吸热过程;吸附动力学遵循准二级动力学模型;酸性条件有利于其吸附进程;MgES具有较好的再生性能,经5次再生使用后对磷酸盐的去除率仍达61.22％.     

Preparation,morphology, and properties of silane‐modified MWCNT/epoxy composites

Both epoxy resin and acid‐modified multiwall carbon nanotube (MWCNT) were treated with 3‐isocyanatopropyltriethoxysilane (IPTES). Scanning electron microscopy (SEM) and transmission electronic microscope (TEM) images of the MWCNT/epoxy composites have been investigated. Tensile strength of cured silane‐modified MWCNT (1.0 wt %)/epoxy composites increased 41% comparing to the neat epoxy. Young's modulus of cured silane‐modified MWCNT (0.8 wt %)/epoxy composites increased 52%. Flexural strength of cured silane‐modified MWCNT (1.0 wt %)/epoxy composites increased 145% comparing to neat epoxy. Flexural modulus of cured silane‐modified MWCNT (0.8 wt %)/epoxy composites increased 31%. Surface and volume electrical resistance of MWCNT/epoxy composites were decreased with IPTES‐MWCNT content by 2 orders and 6 orders of magnitude, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

化学改性铝污泥强化Cu~(2+)的吸附

以净水厂铝污泥(AlS)为主要原料,依次经过铁盐浸渍和壳聚糖(CS)包覆,制得复合吸附剂AlS-Fe-CS,研究其对Cu⁽²⁺⁾的吸附。结果表明,化学改性后,铁(氢)氧化物和CS复合在铝污泥上;最优吸附pH为5.5,吸附平衡时间为20 h,对Cu(2+)的吸附。结果表明,化学改性后,铁(氢)氧化物和CS复合在铝污泥上;最优吸附pH为5.5,吸附平衡时间为20 h,对Cu⁽²⁺⁾的最大吸附量为72.36 mg/g,相比纯AlS性能提高了约1倍,且温度升高有利于吸附反应的进行;吸附过程符合拟二级动力学和Freundlich吸附等温线。     

化学改性铝污泥强化Cu~(2+)的吸附

以净水厂铝污泥(AlS)为主要原料,依次经过铁盐浸渍和壳聚糖(CS)包覆,制得复合吸附剂AlS-Fe-CS,研究其对Cu~(2+)的吸附。结果表明,化学改性后,铁(氢)氧化物和CS复合在铝污泥上;最优吸附pH为5.5,吸附平衡时间为20 h,对Cu~(2+)的最大吸附量为72.36 mg/g,相比纯AlS性能提高了约1倍,且温度升高有利于吸附反应的进行;吸附过程符合拟二级动力学和Freundlich吸附等温线。     

Preparation of silica glass doped with nitrogen by modified chemical vapor deposition

A thermodynamic analysis of the doping of silica glass with nitrogen by the chemical vapor deposition methods has been carried out. The fundamental differences are revealed between the plasma chemical vapor deposition and modified chemical vapor deposition methods. The basic parameters of nitrogen introduction into silica glass are determined by thermodynamic calculations. It is found that the main factor that ensures doping of silica glass with nitrogen by the modified chemical vapor deposition is an extremely low partial oxygen pressure in the reaction zone. The results of theoretical analysis are used in practice for nitrogenizing silica glass by modified chemical vapor deposition. The increment in the refractive index is equal to 0.0015.     

Preparation of silica glass doped with nitrogen by modified chemical vapor deposition

A thermodynamic analysis of the doping of silica glass with nitrogen by the chemical vapor deposition methods has been carried out. The fundamental differences are revealed between the plasma chemical vapor deposition and modified chemical vapor deposition methods. The basic parameters of nitrogen introduction into silica glass are determined by thermodynamic calculations. It is found that the main factor that ensures doping of silica glass with nitrogen by the modified chemical vapor deposition is an extremely low partial oxygen pressure in the reaction zone. The results of theoretical analysis are used in practice for nitrogenizing silica glass by modified chemical vapor deposition. The increment in the refractive index is equal to 0.0015.     

Diffusion of water and alcohol in chemically modified polyurethane

Diffusion of methanol and water in polyurethane and polyurethane chemically modified by grafting different acrylic monomers was carried out. The absorption of these two molecules was found to vary with the nature and percentage grafting of the monomers. The possible use of chemically modified polyurethanes as membranes having high selectivity towards the interaction of alcohol and water is highlighted.     

Microporosity of carbon deposits collected in the Tore Supra tokamak probed by nitrogen and carbon dioxide adsorption

Nitrogen and carbon dioxide adsorption experiments have been used to investigate the porosity of carbon deposits formed in the Tore Supra tokamak as a consequence of the erosion of the plasma-facing components. We compare BET, α_s-, and Dubinin-Raduskevich methods to distinguish between micropore volume (∼0.04 cm³ g⁻¹) and external surface (∼90 m² g⁻¹). Consistent results have been obtained for nitrogen and carbon dioxide, and the smallest pores are shown to be reversibly closed and opened under air exposure and outgassing at 600 °C, respectively, probably due to blocking of pore entrances by surface oxides. Pore size distribution is calculated using the non-local density functional theory: a novel and straightforward method is used to fit the experimental isotherms by Lorentzian distributions of pores centered in some relevant pore size regions. We thus show that the tokamak sample micropores are mainly ultra-micropores (∼75%) whose widths are centered at 0.6 nm. This latter result is in good qualitative agreement with the outgassing effect and in good quantitative agreement with what is deduced from α_s-plot.     

Hydrations and water properties in the super salt-resistive gel probed by FT-IR

The so-called “Super Salt-Resistive Gel”, i.e., poly(4-vinyl phenol) (P4VPh) hydrogel, of different water contents (H = 95-40%) was prepared by crosslinking with different amounts of ethylene glycol diglycidyl ether (EGDGE). FT-IR spectroscopy was used to investigate the hydration and hydrogen bond (HB) properties of water in the gel samples. The OH stretching band around 3300 cm⁻¹ was deconvoluted into four sub-bands. On the basis of the relative band area and the peak wave number, it was suggested that HB of water in the gel is most stabilized when the acidic proton of the phenol residue is intact, being free from the chemical crosslinking. Difference spectra for the water band obtained in the presence of salts suggested that only sulfate systems specifically affect polymer hydrations in the gel phase. The sulfate systems were also specific in the perturbation on the main chain CH₂ stretching band; namely, with increasing the salt concentration, the peak showed a significant blue shift, which means that the hydrophobic hydration is stabilized by the typical salting-out divalent anion. All the experimental results on the FT-IR spectroscopy for the P4VPh hydrogel seem to be consistent with our previous ¹H NMR data on the water T₂ (Sakai Y, Kuroki S, Satoh M. Langmuir 2008; 24:6981-7.) as well as the specific stabilization of water (HB and hydration) in the gel that has been suggested on the basis of the swelling behavior.     

浸渍法改性活性炭纤维吸附一氧化氮的研究

采用不同浓度的硝酸铁溶液在不同的处理温度和时间下,浸渍聚丙烯腈基活性炭纤维(PANACF), 用正交实验法分析影响改性PAN-ACF吸附一氧化氮转化率的主要因素。实验结果表明,浸渍液的初 始浓度是影响一氧化氮吸附转化率的主要因素。在初始浓度为0.1-0.14mol／L时,吸附转化率达到最大 值70％左右,吸附温度和吸附时间对吸附转化率影响不大。通过扫描电镜观察,铁离子不规则分布在PANACF 表面。     

Functional properties of chemically modified egg white proteins

Functional properties of egg white proteins can be altered through selected chemical reactions. Acylations with acid anhydrides have received the greatest amount of attention. Oleic acid and sodium dodecyl sulfate (SDS) have also been used to affect function of egg white proteins. The charge characteristics of acylated proteins are altered through modification of the N-terminal and epsilon-amino groups. The acid anhydride used and the extent of modification have a major effect on the ionic properties of the protein. The altered ionic properties have been shown to affect the optical properties of protein sols, heat stability, foaming, performance in angel cakes, initiation of gelation, ultimate strength and freeze-thaw stability of heat-set gels. Although exact explanations of the mechanisms for the interactions of oleic acid and SDS with egg white protein are not available, increases in charge occur and result in gels with physical properties very similar to gels made from succinylated egg protein.