Structure-direct assembly of hexagonal pencil-like ZnO group whiskers

Hexagonal ZnO group whiskers synthesized from Zn(NH₃)₄²⁺ precursor at 145°C in a structure-directing template solvent (2.5% v/v alcohol) show strong photoluminescence at 409 and 420 nm. FE-SEM and TEM observation reveals that the ZnO group whiskers consist of uniform pencil-like whiskers with the diameter of around 1.5 μm and the length of up to 6 μm.     

Nanocomposite materials from latex and cellulose whiskers

Composite materials were processed by casting a mixture of aqueous suspensions of latex and microfibrils. These microfibrils, or whiskers, are extracted from a sea animal and are monocrystals of cellulose, with an aspect ratio around 100 and an average diameter of 20 nm. It has been found that the mechanical properties (shear modulus) are increased by more than two orders of magnitude in the rubbery state of the polymeric matrix, when the whisker content was 6% (w/w). This very large effect is discussed on the basis of different types of mechanical models and it is concluded that these whiskers form a rigid network, probably linked by hydrogen bonds. The formation of this network is assumed to be governed by a percolation mechanism.     

四针状氧化锌晶须的制备及其吸波性能的研究

随着雷达探测、卫星通信、航天航空和电子对抗等高科技的发展，特别是近年来抗电磁波干扰、隐形技术、微波暗室等研究领域的兴起．对电磁波吸波材料的研究日益受到人们的重视。随着现代电子工业和信息产业的高速发展．产生电磁波的电子产品（诸如计算机、电视机、手机、微波炉及电磁炉等）的数量急剧增加，     

钛酸钾晶须界面性质研究

通过乳液聚合的方法对钛酸钾晶须进行表面改性,获得了表面包裹聚甲基丙烯酸甲酯的钛酸钾晶须. FT-IR、SEM、EDS的表征表明,钛酸钾晶须的表面包裹了聚甲基丙烯酸甲酯膜,形成了以钛酸钾晶须为核,聚甲基丙烯酸甲酯为壳的复合粒子.研究表明,改性后的晶须表面能降低,在有机溶液中的界面张力大大降低,与聚甲基丙烯酸甲酯的界面性质相似,说明改性后的晶须基本被聚甲基丙烯酸甲酯完全包裹,因此晶须由亲水性变为疏水性,在有机溶液中的分散性显著提高.     

Mechanically Adaptive and Shape‐Memory Behaviour of Chitosan‐Modified Cellulose Whisker/Elastomer Composites in Different pH Environments

Biomimetic polymer composites with water‐active mechanically adaptive and shape‐memory behaviour in different pH environments are synthesised by using chitosan‐modified cellulose whiskers (CS‐CWs) as the stimulus‐responsive phase and thermoplastic polyurethane (TPU) as the resilient matrix. The effect of surface modification on the mechanically adaptive behaviour of CS‐CW/TPU composites is investigated by using three representative solutions with various pH values. The results show that surface modification significantly enhances the modulus contrast under wet and dry conditions with the acidic solution as the stimulus, while maintaining the high modulus contrast with the basic solution as the stimulus. CS‐CW/TPU composites also exhibit excellent shape‐memory effects in all three solutions that are comparable to those pristine CW/TPU composites. Furthermore, activation of force generation in the stretched CS‐CW/TPU composites by water absorption/desorption was observed.     

Synthesis and characterization of strontium chloroborate whiskers

Single crystalline strontium chloroborate (Sr₂B₅O₉Cl) whiskers with uniform diameter have been synthesized by a facile route based on the calcination of precursor. The precursor was prepared by the sedimentation reaction between SrCl₂ and Na₂B₄O₇ aqueous solution. The products were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectrum (FT‐IR). An optimal synthesis temperature for preparing Sr₂B₅O₉Cl whiskers was obtained, and the possible formation process was also presented.     

氮化铝晶须的形态与生长条件的关系

实验以氮化铝粉料为原料,在高纯氮气气氛下用物理气相法在密闭式和半开式钨坩锅内高温生长出氮化铝晶须;并对氮化铝晶须的结晶形态与生长条件的关系进行了分析和探讨。     

Stimuli‐responsive polymer nanocomposites based on styrene‐butadiene rubber and bacterial cellulose whiskers

Water‐induced mechanically adaptive rubber nanocomposites were prepared by mixing bacterial cellulose whiskers (BCWs) suspension with styrene‐butadiene rubber (SBR) latex, followed by evaporation method. The structure, morphology, dynamic mechanical properties, water stimuli‐responsive behavior, and biodegradability of SBR/BCWs nanocomposite films were investigated. The results showed that the hydrophilic whiskers had a significant reinforcement effect on the storage modulus of SBR matrix, which originated from the formation of a rigid three‐dimensional filler network within matrix by strong hydrogen bonding between whiskers. The SBR/BCWs nanocomposites showed pronounced water stimuli‐responsive behavior compared with neat SBR. The storage modulus of SBR/BCWs nanocomposite could be decreased by 99.2% after equilibrium water swelling. This remarkable water‐triggered modulus change is attributed to the disentanglement of BCWs network via competitive hydrogen bonding with water.     

碳酸钙晶须合成过程中可溶性磷酸盐的作用机理研究

以可溶性磷酸盐为控制剂,一步碳化法制备了文石相碳酸钙晶须。借助于XRD和FTIR,分析了可溶性磷酸盐在碳酸钙晶须合成过程中的作用机理。研究结果表明：通入CO₂进行碳化反应前,可溶性磷酸盐与Ca(OH)₂反应生成了热力学上最稳定的磷酸钙化合物——羟基磷灰石;在通入CO₂初期,[CO₃^2-(OH)]进入到羟基磷灰石的晶格,部分替代[PO₄^3-],生成碳酸羟基磷灰石,然后以此为结晶中心诱导文石相的异相成核,Ca²⁺、CO₃^2-不断叠加,进而生长为碳酸钙晶须。     

New waterborne epoxy coatings based on cellulose nanofillers

New nanocomposites based on a waterborne epoxy emulsion and a suspension of cellulose crystallites were prepared by film casting in order to obtain coatings displaying both flexibility and stiffness. Tunicin cellulose whiskers are attractive reinforcing fillers due to their high aspect ratio, large interface area, and, significant mechanical properties). Typical processing problems for this type of composite are related to high viscosity values of filled polymers in the in the molten state, the incompatibility between hydrophobic matrices and hydrophilic cellulose and the formation of hydrogen bonds between cellulose of this type of natural fibres in an epoxy matrix. The aim of this work is to solve some of the problems above mentioned by selecting the nature of the components used for coating synthesis film processing. The dynamic mechanical properties display an important improvement of the composite modulus in the rubbery state of the matrix at low concentrations of fillers, which can not be expected other cellulose based fibers.