Dissolution of Ethylenediamine Pretreated Pulp with High Lignin Content in LiCl/DMSO without Milling

Abstract

Various hardwood and softwood chemical pulps, including those with relatively high lignin content (up to ca. 10.5%), were completely dissolved without milling in lithium chloride/dimethyl sulfoxide (LiCl/DMSO) after a pretreatment with ethylenediamine (EDA). Because milling of the sample is not required, degradation of the cell wall components caused by milling does not take place. After the EDA pretreatment, the crystallinity of the pulps remained as high as the original pulps, although the crystal structure changed. This is the first time that transparent solutions of underivatized pulps with high lignin content were obtained in a simple organic solvent system. Interestingly, even in the case of coarse wood meal (40–80 mesh) about 70% could be dissolved after repeating the dissolving procedure two times. The formation of a pulp–EDA or wood–EDA complex seems to be critical for the dissolution in LiCl/DMSO. The nuclear magnetic resonance (NMR) spectrum of the EDA treated pulp solution had good resolution even though the degree of polymerization (DP) of the cellulose in the pulp is very high.     

Application of DMEU/SiO2 gel solution in the antiwrinkle finishing of cotton fabrics

In this experiment, cotton fabrics were treated by padding, drying, and curing with an antiwrinkle finishing reagent, dimethylolethylene urea (DMEU), in combination with different concentrations of tetraethoxysilane (TEOS) and isopropanol (IPA) at various volumes. The treated fabrics were studied to determine the effects of adding TEOS and IPA. They were also analyzed using Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) methods to examine the binding between SiO₂ and DMEU. The results showed that hydrogen bonds formed between SiO₂ and DMEU. TEOS was found to improve the antiwrinkle properties, tensile strength retention, and yellowing of the treated fabrics, although their softness was slightly reduced. The solvent IPA was shown to decrease the tensile strength of treated fabrics, although it improved their antiwrinkle properties. We observed only one stage of pyrolysis in untreated cotton fabrics, whereas the treated fabrics showed two stages. In addition, the fabrics treated with TEOS showed improved heat resistance. Our findings demonstrated that cotton fabrics showed excellent antiwrinkle properties and high tensile strength, when treated with a finishing solution composed of DMEU, 3% TEOS, IPA and water, followed by predrying and curing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4136–4143, 2006     

PAN/DMSO溶液的挤出对初生纤维结构的影响

应用扫描电子显微镜(SEM)和X射线衍射仪(XRD)研究了在一定的凝固条件下,挤出剪切速率(.γ)对聚丙烯腈(PAN)初生纤维聚集态及形态结构的影响规律。结果表明:随着.γ的增加,初生纤维的结晶度增大,晶粒尺寸减小;初生纤维的表面上产生了沿着轴向分布的沟槽,.γ越高,沟槽越深,初生纤维的截面结构变得不均匀,出现了一些大孔和皮芯结构;随着.γ的增加;初生纤维中的二甲基亚砜(DMSO)残留量增加。控制.γ在11 721~14 651 s-1,PAN/DMSO溶液流动性能好,可获得表面沟槽均匀、缺陷少、晶粒尺寸小且结晶度高的结构致密的PAN初生纤维。     

几种光谱方法(FTIR、FT-Raman,NMR)在橡胶分析中的应用

综述了傅里叶变换红外光谱 ,傅里叶变换拉曼光谱以及核磁共振波谱在橡胶结构的定性、定量分析中的应用     

High Fraction of Penta‐Coordinated Aluminum and Gallium in Lanthanum–Aluminum–Gallium Borates

This study is focused on structural changes induced by increasing treatment temperature of sol‐gel–derived La₂O₃?Al₂O₃?Ga₂O₃?5B₂O₃ system. The structure of samples heated for 30 min up to 900°C was investigated by X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and magic‐angle spinning nuclear magnetic resonance (MAS‐NMR) analysis of ²⁷Al, ¹¹B, and ⁷¹Ga nuclei. The vitreous structure is preserved inclusively after 800°C treatment, and starting with 850°C the only crystalline phase evidenced in XRD patterns is of LaAl_2.03B₄O_10.54 type, of La(Al,Ga)_2.03B₄O_10.54 composition. The FTIR results point out the presence of BO₃, AlO₄, and AlO₆, and starting with 800°C treatment also of BO₄ and AlO₅ structural units, but more detailed information related to boron, aluminum, and gallium environments is obtained from the analysis of MAS‐NMR data. These data evidenced in both amorphous xerogels and in crystallized samples a high fraction of penta‐coordinated aluminum and gallium.     

29Si MAS-NMR Study of the Short-Range Order in Lithium Borosilicate Glasses

²⁹Si MAS-NMR measurements have been made on a series of lithium borosilicate glasses of general composition R Li₂O.B₂O₃· K SiO₂. At low alkali contents ( R < 1), the ²⁹Si resonance envelope is broadened and indicates a distribution of Si sites. As R increases above 1, the FWHM of the ²⁹Si resonance narrows considerably to that representative of a single chemical site. Simultaneously, the average chemical shift of the resonance shifts upfield in agreement with the trends found in the binary lithium silicate glass system. Using the chemical shifts for the individual Q species in the binary system it was found that very good agreement between the chemical shifts of the binary glasses and the ternary glasses examined here could be achieved if a model of proportional sharing of the added oxygen (from lithia) between silicate and borate units was used. In contrast to the ¹¹B NMR studies of these same glasses, the ²⁹Si NMR data are quantitatively best-fit if it is assumed that the proportional sharing of the oxygen from the added lithia begins at R = 0. Models of sharing developed from the ¹¹B NMR studies of these glasses, where proportional sharing above a certain fixed (independent of K ) or variable (dependent on K ) minimum R ₀, have been reexamined and were quantitatively shown through residual analysis to give consistently poorer fits to our data. At present the reasons for the discrepancy between the two sets of NMR data are unknown.     

烯丙基氯含量及其对氯化聚氯乙烯热稳定性能的影响

选取了3种具有相近相对分子质量及其分布的氯化聚氯乙烯（CPVC）树脂,通过固态核磁（13C-NMR）对CPVC树脂的序列结构进行了表征,并对CPVC树脂中烯丙基氯的生成机理进行了分析,在此基础上建立了计算烯丙基氯含量的方法。运用Brabender流变仪研究了3种CPVC树脂的热稳定性。结果表明,相对分子质量及其分布相近的3种CPVC树脂,随着烯丙基氯含量的降低,树脂的热稳定性能越来越好。     

Functionalized poly(ether ether ketone): Improved mechanical property and acellular bioactivity

Poly(ether ether ketone), PEEK, was functionalized by addition of pendant functional groups, that is, acetyl, carboxylic, acyl chloride, amide, and amine groups in the benzene ring of polymer backbone without substituting the parent (ether or ketonic) functional groups of polymer to improve the mechanical and surface adhesivity with acellular inorganic biomaterials. The functional groups of virgin PEEK and functionalized PEEK were identified by Fourier transform infrared spectroscopy and ¹³C nuclear magnetic resonance. The crystallinity was studied by X‐ray diffraction and further supported by differential scanning calorimetry (DSC) analysis. Similarly, the change in glass transition temperature was confirmed by the DSC and dynamic mechanical analysis (DMA). The improved mechanical property was also evaluated by DMA. The excellent surface adhesivity and bioactivity were revealed by acellular in vitro test using simulated body fluid. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

In Situ 27Al NMR Studies of Cement Hydration: The Effect of Lithium-Containing Setting Accelerators

Hydration of calcium aluminate cements is known to cause phase transformations during which the coordination number of aluminum by oxygen changes from 4 to 6. Systematic ²⁷Al magic angle spinning and wide-line nuclear magnetic resonance (NMR) experiments at 78.3 MHz with detailed attention to the quantitative aspects of quadrupolar NMR spectroscopy show that the fraction of Al(6) is a monotonic function of the water/solid (w/s) ratio and does not depend on the type and concentration of setting accelerators. In situ ²⁷Al wide-line NMR measurements during the hydration process can provide good estimates of the induction period and the rate of the phase conversion. Using this approach, lithium carbonate at a concentration of 0.5 wt% of the mixing solution has been shown to eliminate the induction period but to leave the rate of the phase conversion essentially unchanged.     

Structural Changes of Porous Silicon Surface with Thermal Annealing Studied by 29Si Nuclear Magnetic Resonance Spectroscopy and Fourier Transform Infrared Spectroscopy

²9Si nuclear magnetic resonance (NMR) spectra and infrared spectra were measured for as-prepared and annealed porous silicon (PS) samples to characterize the change of PS structure. Annealing changed the infrared spectra remarkably: after 4-h annealing, the signals due to SiH₂ disappeared and the intensity of the signals due to SiH decreased. On the other hand, the ²9Si NMR spectra with magic-angle spinning (MAS) were not much affected by the annealing. The linewidth of spectra without MAS, however, increased with annealing time with the peak location unchanged. Annealing caused hydrogen on the PS surface to be desorbed, especially in the case of SiH₂ species, and (SiH)₂ dimer structure was produced during the annealing.     

Mechanical and chemical properties of metakaolin-based geopolymer exposed to elevated temperature

A method is presented to fabricate metakaolin-based geopolymers that are structurally and mechanically stable up to 600°C. The chemical environment of the geopolymers is characterized using thermogravimetric analysis and Fourier-transform infrared spectroscopy. Residual free water turned into steam and caused damage to the geopolymer when exposed to elevated temperatures. The curing temperature was increased from 80 to 120°C to remove water during the curing process. A correlation was drawn between the amount of Si-O-Al linkage formed and the position of fingerprint peaks in infrared spectra, providing a tool to evaluate the level of geopolymerization. Flexural and tensile properties of geopolymers fabricated using the optimized method were measured for no heat treatment and for exposure to elevated temperatures of 200, 400, and 600°C. The flexural strength was measured to be 10.80 ± 2.99 MPa at room temperature, 10.36 ± 0.64 MPa at 400°C, and 8.04 ± 1.60 MPa at 600°C. The flexural modulus is reported to be 13.09 ± 3.40 GPa at room temperature and 11.03 ± 0.53 GPa at 600°C. The flexural toughness decreased with increasing temperature. The tensile properties of the geopolymer were measured with direct tensile tests paired with an extensometer. The tensile strength decreased from 4.16 ± 2.08 MPa at room temperature to 3.13 ± 0.97 MPa at 400°C, and 2.75 ± 0.86 MPa at 600°C. The Young's modulus decreased from 45.38 ± 30.30 GPa at room temperature to 26.88 ± 6.65 GPa at 600°C. Both flexural and tensile tests have shown that the metakaolin-based geopolymers cured at 120°C is mechanically stable at temperatures up to 600°C.     

In Situ NMR Study of Dislocation Jump Distance During Creep of Pure Sodium Chloride Single Crystals

Nuclear magnetic resonance pulse techniques were used in situ during creep of single crystals of NaCl to evaluate the contribution of mobile dislocations to spin relaxation. ²³Na spin-lattice relaxation rates were measured in the rotating frame ( T _1p) during compression creep of single crystals of NaCl along the [110] direction at 473 K at an applied stress of 20 MPa. The relaxation rates were evaluated from the spin-echo height following π/2, locking, and 64° pulse sequence. We describe here the experimental setup and methodology in evaluating the dislocation jump distance from NMR-creep experiments. The height of the free induction decay decreased as soon as the load was applied followed by a gradual increase until the steady state was reached, at which point a saturation value was observed corresponding to the constant steady-state creep rate. The mean jump distance of the mobile dislocations, evaluated from the ratio of the signal heights without deformation and during creep, decreased with time/strain, reaching a constant value during the steady-state creep regime. The results are compared with the dislocation-dislocation spacing, subgrain size, as well as the jump distance predicted from creep models.     

可剥蓝胶的成分分析

采用各种分离、测试手段剖析可剥蓝胶的成分及含量。首先借助红外光谱(FT-IR)法确定其基体树脂为氯醋树脂,再通过核磁氢谱(1H-NMR)法确定其固化体系和基体树脂的成分,随后用凝胶渗透色谱(GPC)法验证了基体树脂和固化体系的成分及含量;此外,利用X射线荧光光谱法确定了润滑体系和颜填料体系的成分及含量;最后通过热失重分析(TGA)法将各成分的含量进一步细化。结果表明:该可剥蓝胶中各成分及含量(以质量分数计)分别为氯醋树脂60%~65%、环氧树脂(EP)10%~12%、甲阶酚醛树脂8%~10%、邻苯二甲酸酯8%~10%、硬脂酸钡1%~2%、磷酸三苯酯1%~3%、碳酸钙1%~2%、二氧化硅1%~2%和酞菁蓝0.5%~1%;还原试验证明各种分析结果有效可靠。     

29Si MASNMR Spin-Lattice Relaxation Study of α-, β-, and Amorphous Silicon Nitride

The spin-lattice relaxation times, T ₁, in α-, β-, and amorphous Si₃N₄ have been obtained for the first time, using a multiple-pulse saturation recovery method. The saturation recovery of the ²⁹Si magnetization follows exponential behavior under magic-angle spinning conditions, within the limits of experimental error. A rather wide dispersion of T ₁ values is observed for the phases of Si₃N₄: 284 ± 29 min (–46.686 ppm) and 260 ± 23 min (–48.812 ppm) for the α-phase, 36 ± 4 min for the β-phase, and 11 ± 1 min for the amorphous phase, assuming an exponential recovery. The values obtained for the exponent in the power-law fitting are 0.599(9) (–46.686 ppm) and 0.61(1) (–48.812 ppm) for the α-phase, 0.52(2) for the β-phase, and 0.53(3) for the amorphous phase.     

Preparation and identification of a soluble copolymer from pyrrole and o-toluidine

A series of copolymers were prepared by chemically oxidative polymerization of pyrrole (PY) and ortho-toluidine (OT) in HCl aqueous medium. The yield, intrinsic viscosity, and solubility of the copolymers were studied by changing the monomer molar ratio. The resulting PY/OT copolymers were identified by FTIR, ¹H–NMR, DSC, and WAXD techniques. The experimental results showed that the oxidative polymerization of pyrrole and o-toluidine is exothermic and the resulting polymers exhibit an enhanced solubility in most organic solvents compared with that of pyrrole homopolymer. The polymer obtained is a real and amorphous copolymer containing pyrrole and o-toluidine units. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 510–518, 2001     

Dielectric properties evaluation of NiFe2O4/MWCNTs nanohybrid for microwave applications prepared via novel one step synthesis

NiFe₂O₄/MWCNTs nanohybrids were synthesized via novel one step ultrasonication assisted method using ortho-xylene as a dispersive medium with varying MWCNTs concentration (0.0%, 1.0%, 1.5%, 2.0% and 2.5%). The nanohybrids were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and Impedance Analyzer techniques. XRD indexed patterns confirmed the formation of NiFe₂O₄/MWCNTs nanohybrid. The SEM images showed the decoration of nickel ferrite nanoparticles on MWCNTs. The FTIR results show two absorption bands. The Cole-Cole plots of impedance show the resistance was only due to the grain boundary contribution. The dielectric properties were found to be increasing with increasing MWCNTs concentration. For 2.5% MWCNTs concentration, dielectric constant and loss 1.06×10⁵, 1.99×10⁶ were achieved as compared to pure nickel ferrite 6.17×10³, 3.87×10⁴, respectively. Such increase in the dielectric properties renders its application at high frequency     

Extraordinary swelling behavior of poly(AMPS) organogel in solvent/DMSO binary mixed media

The present article deals with super‐swelling behavior of crosslinked homopolymer of 2‐acrylamido‐2‐methylpropane sulfonic acid, poly(AMPS), in binary mixtures of dimethyl sulfoxide (DMSO) and various polar solvents including water, mono‐, and polyhydric alcohols, and amide solvents such as N‐methyl pyrrolidone. Extraordinary phase transition sequences including a new unusual swelling phenomenon, referred to as “overentrant” swelling, was observed for this polymeric organogel in the solvent/DMSO mixtures. The swelling behaviors were preliminarily explained based on the major interactions involved in the solvation process and dielectric constant of the swelling media. It was established that the “overentrant” region of the swelling profiles was progressed with the increase of dielectric constant of the mixed solvent media. The overentrant region was disappeared with partial replacement of AMPS units with acrylic acid. This was taken as an additional practical evidence for a major role of the sulfonic acid as the main interactive group involved in the solvation process. The unusual phase transitions were also explained via a semiquantitative approach based on the Gutmann's acceptor number and donor number values to emphasis on the key effect of dissociation degree of the sulfonic acid group (as a function of the solvent type and composition) on the swelling behaviors. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Separation and Structural Characterization of Lignin from Hybrid Poplar Based on Complete Dissolution in DMSO/LiCl

In this paper, the physicochemical properties and structural features of six lignin preparations separated with a total dissolution of ball-milled wood in dimethyl sulfoxide and lithium chloride (DMSO/LiCl) followed by extraction with ethanol/water were investigated. These isolated lignin fractions were characterized using wet chemical analysis, FT-IR, and ¹H and¹³C-NMR techniques. Experimental results showed that separated lignin preparations were relatively free of associated polysaccharides. These lignin fractions were classified as guaiacyl-syringyl lignin type: mainly composed of guaiacyl units with noticeable amounts of syringyl units and fewer p-hydroxyphenyl units. The molar ratio of non-condensed guaiacyl units to syringyl units (G/S) decreased as the ratio of LiCl to poplar weight increased. The results also showed that these lignin preparations consisted mainly of β-O-4 ether bonds combined with small quantities of β-β′ and β-5 carbon-carbon linkages. Furthermore, considerable amounts of esterified p-hydroxybenzoic acids and minor amounts of esterified p-coumaric acid were also detected in these lignin fractions.