桩端存在软弱夹层的后注浆工程应用

分析了桩端后注浆提高桩基承载能力的工作原理,并利用后注浆技术成功处理了桩端存在软弱夹层中的工程实例,认为采用桩端后注浆技术能够较大幅度的提高单桩承载能力,但其提高程度还需要通过现场试验确定.     

Effect of intercalant content of mica on the various properties for the charged nanocomposite poly(N‐isopropyl acrylamide) hydrogels

In this study, we intend to adjust the charge properties of the poly(N‐isopropylacrylamide) [Poly(NIPAAm)] gel by using anionic clay and cationic monomer. Hence, two series of nanocomposite hydrogels bearing different charges were designed from NIPAAm, intercalated mica (IM) (NIM‐series) and NIPAAm, IM, trimethyl (acrylamido propyl) ammonium iodide (TMAAI) (NTIM‐series), respectively. The mica was first intercalated with different contents of intercalant, trimethyl (acrylamido propyl) ammonium chloride (TMAACl), based on the cationic exchange capacity (CEC) of mica. The effect of the CEC value of IM and IM content on the charge property, swelling behaviors, mechanical properties, and drug‐release behaviors of the present gels were investigated. Results showed that the negative charges for NIM series gels decrease with increase in CEC values of the IM (from ?11 to ?6 mV), the positive charges for NTIM series gels also decrease with increase in CEC values of the IM (from +36 to +18 mV). The swelling behaviors and mechanical properties for the NTIM gels were significantly enhanced by IM content and CEC values of the IM. The microstructures, morphologies, and drug‐release behaviors in these two series gels are also investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2277–2287, 2007     

Preparation and properties of polypropylene filled with organo‐montmorillonite nanocomposites

Organo‐Montmorillonite (Org‐MMT)/maleic anhydride grafted polypropylene (PP‐g‐MAH)/polypropylene nanocomposites have been prepared by melt blending with twin‐screw extruder. The mechanical properties of the nanocomposites and the dispersion of Org‐MMT intercalated by the macromolecular chain were investigated by transmission electron microscopy and mechanical tests. The crystal properties of the nanocomposites have been tested by a differential scanning calorimeter. The thermal properties of the nanocomposites were investigated by thermo gravimetric analysis. The results show that not only the impact property but also the tensile property and the bending modulus of the system have been increased evidently by the added Org‐MMT. The Org‐MMT has been dispersed in the matrix in the nanometer scale. With the addition of the Org‐MMT, the melting point and the crystalling point of the nanocomposites increased; the total velocity of crystallization of the nanocomposites also increased. Thermal stability of the nanocomposites is increased by the filled Org‐MMT. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2875–2880, 2006     

浇铸尼龙的纳米复合抗静电改性研究

以膨胀石墨所固有的导电性能和蓬松多孔的层状结构为基础,借鉴插层复合方法,通过浇铸尼龙6(MCPA6)与石墨片层之间的纳米复合,提高MCPA6的导电性能,达到抗静电的要求。通过导电性能测试及XRD、OM和SEM分析,研究了浇铸尼龙6/膨胀石墨抗静电复合材料的纳米结构及导电机理。结果表明:当膨胀石墨质量分数为1.0％时,体积电阻率已下降到1.99×10~8Ω·cm,实现了抗静电目标。     

硬脂酸根插层水滑石的合成及应用

采用离子交换法制备了硬脂酸根插层水滑石,运用红外光谱对其进行了表征。通过Haake流变仪、颜色测定仪研究了硬脂酸根插层水滑石与钙/锌热稳定剂并用时的热稳定性,重点考察了水滑石的结构对PVC稳定性能的影响。结果表明,硬脂酸根插层水滑石与钙皂/锌皂复配显著改善了PVC热老化过程中的初期着色性。     

Preparation of polyethylene‐octene elastomer/clay nanocomposite and microcellular foam processed in supercritical carbon dioxide

Polyethylene‐octene elastomer (POE)/organoclay nanocomposite was prepared by melt mixing of the POE with an organoclay (Cloisite 20A) in an internal mixer, using poly[ethylene‐co‐(methyl acrylate)‐co‐(glycidyl methacrylate)] copolymer (E‐MG‐GMA) as a compatibilizer. X‐ray diffraction and transmission electron microscopy analysis revealed that an intercalated nanocomposite was formed and the silicate layers of the clay were uniformly dispersed at a nanometre scale in the POE matrix. The nanocomposite exhibited greatly enhanced tensile and dynamic mechanical properties compared with the POE/clay composite without the compatibilizer. The POE/E‐MA‐GMA/clay nanocomposite was used to produce foams by a batch process in an autoclave, with supercritical carbon dioxide as a foaming agent. The nanocomposite produced a microcellular foam with average cell size as small as 3.4 µm and cell density as high as 2 × 10¹¹ cells cm^?3. Copyright © 2005 Society of Chemical Industry     

Influence of the structure of the onium iodide salts on the properties of modified montmorillonite

Dialkyl imidazoline, alkyl pyridine and alkyl quinoline containing salts have been synthesized and used as new surfactants for cationic exchange of layered silicates, such as montmorillonite (MMT) in order to evaluate their role in the formation of intercalated MMT clays. The new salts have been characterized by FTIR, ¹H, ¹³C‐NMR spectra. These compounds have been intercalated into the layers of MMT via a solution dispersion technique and the extent of the interlayer space expansion was confirmed by using wide angle X‐ray diffraction and FTIR spectra. Thermogravimetry analysis shows that these salts can be used in place of ammonium salts to produce organophilic clays with higher thermal stability than commercial alkyl ammonium‐treated MMT. Moreover, the results also show that the imidazolium‐modified clays have a greater thermal stability compared to the quinolinium and the pyridinium‐modified clay. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

可聚合性季铵盐—膨润土嵌入复合物的制备

本文合成了三种含有可聚合基团的季铵盐，用它们膨润土夹层中的阳离子进行离子交换，制得可聚合性季铵盐－膨润土嵌入复合物。这些嵌入复合物在苯乙烯中具有很好的防沉降性，表观密度比膨润土小，而白度比膨润土有较显著的提高。     

插层有机纳米蒙脱土改性骨胶胶粘剂的制备与性能研究

用十六烷基三甲基溴化铵和十二烷基三甲基溴化铵对蒙脱土(MMT)进行有机化处理,得到有机纳米MMT;将骨胶插层到有机纳米MMT中,再经环氧氯丙烷(ECH)交联改性,得到插层有机纳米MMT改性骨胶胶粘剂。通过单因素试验探讨了各种工艺因素对胶粘剂黏度的影响。结果表明:制备插层有机纳米MMT改性骨胶胶粘剂的最佳工艺条件为酸解温度60℃,接枝共聚温度50℃,m(ECH)≈0.5 g,接枝共聚时间90 min,m(MMT)=0.35 g;在此工艺条件下制取的骨胶胶粘剂,其适用期增至60 d,凝固点降至-4℃,克服了传统骨胶储存期短、常温呈固态以及使用时要现用现熬等缺点,具有良好的应用前景。     

Preparation of polystyrene–clay nanocomposites via dispersion polymerization using oligomeric styrene‐montmorillonite as stabilizer

This study describes the preparation of polystyrene–clay nanocomposite (PS‐nanocomposite) colloidal particles via free‐radical polymerization in dispersion. Montmorillonite clay (MMT) was pre‐modified using different concentrations of cationic styrene oligomeric (‘PS‐cationic’), and the subsequent modified PS‐MMT was used as stabilizer in the dispersion polymerization of styrene. The main objective of this study was to use the clay platelets as fillers to improve the thermal and mechanical properties of the final PS‐nanocomposites and as steric stabilizers in dispersion polymerization after modification with PS‐cationic. The correlation between the degree of clay modification and the morphology of the colloidal PS particles was investigated. The clay platelets were found to be encapsulated inside PS latex only when the clay surface was rendered highly hydrophobic, and stable polymer latex was obtained. The morphology of PS‐nanocomposite material (after film formation) was found to range from partially exfoliated to intercalated structure depending on the percentage of PS‐MMT loading. The impact of the modified clay loading on the monomer conversion, the polymer molecular weight, the thermal stability and the thermomechanical properties of the final PS‐nanocomposites was determined. Copyright © 2012 Society of Chemical Industry