A technique for production of nanocrystalline cellulose with a narrow size distribution

Nanocrystalline cellulose (NCC) was prepared by sulfuric acid hydrolysis of microcrystalline cellulose. A differential centrifugation technique was studied to obtain NCC whiskers with a narrow size distribution. It was shown that the volume of NCC in different fractions had an inverse relationship with relative centrifugal force (RCF). The length of NCC whiskers was also fractionized by differential RCF. The aspect ratio of NCC in different fractions had a relatively narrow range. This technique provides an easy way of producing NCC whiskers with a narrow size distribution.     

Formaldehyde‐Free Wood Adhesives from Decayed Wood

Summary: Extensive studies using mussel adhesive protein as a formaldehyde‐free, strong, and water‐resistant adhesive model revealed that a combination of a polymer with catechol moieties and a polymer with amino groups could serve as a strong and water‐resistant wood adhesive. This study demonstrated that the treatment of abundant and readily available brown‐rot‐fungus‐decayed wood with NaBH₄ followed by mixing with polyethylenimine resulted in a formaldehyde‐free, strong, and water‐resistant wood adhesive.

Lignin is demethylated by brown‐rot fungi and then reduced using NaBH₄.     

基于联邦滤波的航迹推算方法研究

由于传统的基于IMU/里程仪组合的航迹推算系统受地形起伏及其打滑影响较大,影响了探测车导航系统的精度和稳健性,为了提高探测车导航系统的定位精度和稳健性,提出了一种基于联邦滤波的IMU/里程仪组合导航方法,该方法充分利用IMU提供的信息,在原航迹推算的方法上增加一个滤波器,将IMU的比力输出作为观测量进行滤波,并建立联邦组合导航系统的数学模型实现最优融合;从而提高了探测车导航系统的定位精度;最后地下矿道实验证明该方法能有效提高移动平台导航定位结果的精度和稳健性。     

关于钻尖的变导程拟螺面磨法的研究

本文介绍了确保钻尖质量的变导程拟螺面磨法、相应的几何优化模型及其算法,由于经过实例计算和3659开刃机上的试验的验证,因而本文为磨得高质量钻尖提供了可靠依据。     

Investigation on the dissolution behavior of 2HNIW·HMX co-crystal prepared by a solvent/non-solvent method in N,N-dimethylformamide at T = (298.15–318.15) K

Journal of Thermal Analysis and Calorimetry - 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexazisowurtzitane (HNIW)·1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) co-crystal in a 2:1 molar ratio was...     

Chemical Modification of Soy Protein for Wood Adhesives

Mussel protein is a strong and water‐resistant adhesive, but is expensive and not readily available. Soy protein is inexpensive, abundant, and annually renewable, but suffers from low adhesive strengths and low water resistance of the bonded products. This study reveals that introducing a key functional group from the marine adhesive protein to soy protein converts the soy protein to a strong and water‐resistant wood adhesive.     

Modification of Soy Protein for Wood Adhesives using Mussel Protein as a Model: The Influence of a Mercapto Group

Summary: Mussel protein can serve as a strong and water‐resistant adhesive, but is expensive and not readily available. Soy protein is inexpensive, abundant, and readily available, but is a poor adhesive. Mussel protein contains a high amount of mercapto‐containing cysteine. This study revealed that increasing the free mercapto group content in soy protein could greatly increase the strength and water‐resistance of wood composites bonded with the modified soy protein.

Preparation of the modified SPIs.     

Structural characterization and high‐temperature compressive creep of PTFE‐based composites filled with inorganic nanoparticles

The PTFE‐based nanocomposites with various contents of inorganic nanoparticles (n‐AlN and n‐Si₃N₄) were prepared by cold compaction followed by free sintering. The results of scanning electron microscopy, differential scanning calorimetry, and X‐ray diffraction show that PTFE spherulite formed in the nanocomposites. When 2 wt% inorganic nanoparticles were added into the PTFE matrix, the crystallinity increased from 34.3% to 42.1% and 43.2%, respectively. Moreover, the interplanar distances for each crystal plane were enlarged and the grain sizes were smaller than that of pure PTFE. In addition, the mechanical and high‐temperature compressive creep properties were investigated. The results indicate that the introduction of inorganic nanoparticles largely increased the high‐temperature compressive creep resistance, and the maximal reduction of percentage of creep strain was up to 68%. The tensile strengths of the nanocomposites increased with increasing filler content when it was no more than 2%, and then decreased with the further increase of the filler content, whereas the elongations at break showed a reverse tendency. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and Properties of Semicrystalline Copolyimides Based on 4,4′-Diaminodiphenylether and 1,3-Bis(4-aminophenoxy) Benzene

Copolyimides were prepared from 4,4′-diaminodiphenylether (4,4′-ODA), 1,3-bis(4-aminophenoxy) benzene (TPER), and pyromellitic dianhydride (PMDA) through a three-step imidization process with different monomer compositions. The copolymerization disrupted the molecular regularity and decreased the intermolecular interaction of the polyimide chains. The X-ray diffraction (XRD) results indicated the prepared copolyimides showed the same semicrystalline character, but had various crystallinity and crystal forms. The copolymerization also changed the crystal morphologies of the polyimides. With increasing TPER ratio, the copolyimides started to form spherulites and hedrites, which then tended to grow more perfectly as the TPER ratio was further increased. The solubility of the copolyimides and their dependence on the crystallnity and the chain flexibility was investigated. These copolyimides exhibited excellent thermal and thermo-oxidative stability.