纳米复合材料的制造及其在纺织品上的应用

纳米复合材料是一种在三维空间中至少有一维处于纳米尺度范围(<100nm)的材料。在聚合物基体中适当加入纳米粒子,可显著提高其性能。通过这种方法获得的材料就可称作为某种纳米填料的高分子复合材料。通过控制加入复合材料中的纳米粒子的结构,就可以得到具有新的物理机械性能和未填充材料所不具备的特性的材料,如阻燃性、加速生物降解性等。     

Ca(OH)2对低掺量水泥土的强度影响

用低掺量水泥加固3种不同的土进行室内试验研究,测试了不同Ca(OH)2掺量及不同龄期下3种水泥土的无侧限抗压强度。分析了随Ca(OH)2掺量的增加,不同龄期的3种水泥土无侧限抗压强度变化规律及原因。试验结果表明:水泥红粘土强度随Ca(OH)2掺量的增加提高最为明显,粉质粘土次之,砂土最弱。分析原因是由于土体的细度对水泥土强度影响较大。土体越细,土体中粘土矿物越多,Ca(OH)2掺量的增加促进了更多的离子交换作用和火山灰作用的发生,从而提高了水泥土强度。试验所用的3种土中红粘土最细,所以水泥红粘土强度随Ca(OH)2掺量的增加提高最为明显。     

川西坳陷新场气田沙二段气藏储层物性与渗流特征

为了分析新场气田沙二段气藏不同砂组之间产能差异较大的原因,本文利用物性分析和气水两相渗流实验,对覆压渗透率和气水两相渗流特征进行了评价和研究。结果表明,常规岩心物性证实主力层和难采层砂组渗透率平均值基本接近,但在覆压条件下,主力层和难采层渗透率差异明显;黏土矿物含量越高且产状越复杂,喉道越细小,喉道闭合越大,渗透率降低幅度越大,应力敏感性越强。难采层气相相对渗透率最大值低,临界含水饱和度高,水相上升快且相对渗透率最大值比主力层高。在开发过程中,难采层气井见水早,产水量比主力层大,井底积液、水锁伤害比主力层严重。     

Shear strength and failure mechanism of needle-punched geosynthetic clay liner

The internal shear strength of a geosynthetic clay liner (GCL) within composite liner systems is crucial for the stability of landfills and should be carefully considered in the design. To explore the shear strength and failure mechanism of the extensively used needle-punched GCL, a series of displacement-controlled direct shear tests with five normal stress levels (250–1000 kPa) and eight displacement rates (1–200 mm/min) were conducted. The shear stress to horizontal displacement relationships exhibit well-defined peak shear strengths and significant post-peak strength reductions. The monitoring results of the thickness change indicate that the degree of volumetric contraction is related to the reorientation of fibers and dissipation of pore water pressure. Furthermore, the peak and residual shear strengths both depend on the displacement rate because of the rate-dependent tensile stiffness of needle-punched fibers and shear strength of the soil/geosynthetic interface. Through additional tests and lateral comparison, it was discovered that the shear behavior of sodium bentonite, degree of hydration, and pore water pressures all affect the shear mechanisms of the NP GCL. In particular, the failure mode transfers from fiber pullout to fiber rupture with the increase in water content as the hydrated bentonite particles facilitate the stretching of needle-punched fibers.     

Percolated Network Structure Formation and Rheological Properties in Nylon 6/Clay Nanocomposites

To understand the effect of the percolated clay network structure formed by the exfoliated clay layers in nanocomposites, the clay network structure in nylon‐6‐based nanocomposites is characterized using TEM and FFT analyses. A MMT volume fraction between 0.013 and 0.014 is the percolation threshold for strong network formation. The volume spanning MMT network leads to a very high flow activation energy as compared with that of neat nylon 6, resulting in the pseudo‐solid like response under molten state in N6CNs. A canonical NVT‐MD simulation was conducted in the system made up by nylon 6 molecules/Si(OH)₄ molecules. The formation of the strong interfacial interaction between nylon 6 molecules and Si(OH)₄ molecules induced by OH groups is suggested.

     

阳离子聚合物粘土稳定剂的合成及性能研究

以二甲胺、环氧氯丙烷为原料,通过缩合聚合反应,合成了阳离子有机聚合物粘土稳定剂。考察了原料配比、反应温度、反应时间对防膨率的影响。结果表明,最佳合成工艺条件为:环氧氯丙烷与二甲胺的摩尔配比为1∶1.2,反应时间5 h,反应温度60℃。粘土稳定剂用量2.0%时,防膨率为87.5%;与KCl或NH4Cl以1∶1复配,用量为4%时,防膨率分别为94.9%,93.2%。粘土稳定剂用量2.0%时,第1次和第2次岩屑回收率分别为82.16%,79.49%;2%聚合物+1%KCl+1%NH4Cl三元复配,第1次和第2次回收率分别为89.66%,86.41%。     

白土精制工艺优化研究及工业应用

文章对两种白土精制工艺进行了阐述,确定了"先加热后加白土"工艺精制的最佳温度;在实验室针对减二、减三分别采用两种工艺进行白土精制试验,结果表明,无论采用"先加热后加白土"新工艺或原工艺,白土精制油的理化性能都满足要求。本文还进行了工业装置试生产。     

Biobased nanocomposites from clay modified blend of epoxidized soybean oil and cyanate ester resin

Novel bio-based nanocomposites were prepared by blending surface modified natural clay with epoxidized soybean oil (ESO) and cyanate ester resin (CE). A convenient method was employed to modify the attapulgite (ATT) clay by adsorbing the poly(ethylene glycol) diglycidyl ether (PEGDE) onto the clay surface, which was confirmed by the appearance of a new peak of infrared spectroscopy due to hydrogen bonding and chelation. Thermogravimetic analysis (TGA) showed that the amount of PEGDE adsorbed on ATT was influenced by PEGDE concentration in acetone solution. Scanning electron microscope (SEM) and transmission electron microscope (TEM) results showed that nanoscaled ATT dispersed well in the blend of epoxidized soybean oil (ESO) before and after curing. The thermal-physical and mechanical properties were evaluated by dynamic mechanical analysis (DMA), TGA and tensile mechanical test. The nanocomposites showed higher glass transition temperature and modulus, and the tensile strength of the nanocomposites was reinforced as compared to that of ESO/CE blends.     

The Crystallinity Behavior of Polyethylene/Clay Nanocomposites Under the Influence of Water-Assisted Melt Blending

High-density polyethylene (HDPE)/clay nanocomposites were prepared via water-assisted and conventional melt blending. The influence of exfoliated/intercalated domains on crystallinity of nanocomposites was then investigated. X-ray diffraction and electron microscopy evidenced for enhanced intercalation and partial exfoliation of clay platelets pursuing rheological measurements. The methane permeability of water-injected nanocomposites was lower compared to melt-blended specimens implying the influence of intercalated domains. A theoretical/experimental analysis was performed to roughly determine the lamellar thickness distribution of the crystalline regions. Contribution of clay platelets to crystallization mechanisms was indicative of clay impact as heterogeneous nucleating agent, whereas mechanical properties were dependent on interface situation.     

Removal of cadmium in leachate from waste alumina beads using electrochemical technology

US Air Force uses alumina beads (aluminum oxide) as a blast media in routine maintenance operations. These spent alumina beads fail to pass the TCLP test for their cadmium contents. A chemical process consisting of leaching and electrochemical methods is investigated for the feasibility of treating the alumina beads. Dilute nitric acid was found the most effective solution for cadmium leaching. Electrochemical reduction was able to reduce cadmium content in the leachate from 180 mg/L to 15 mg/L. With consumable aluminum electrodes, electrochemical coagulation reduced the cadmium concentration to less than 1 mg/L. Electroflotation was effective for metal sludge, ferric, aluminum, and ferrous hydroxide separations with the assistance of commercial surfactants.