Flocculation of coal suspension with mono/dual polymer systems and contribution of Ca(II)/Mg(II) ions

In the experimental study carried out on mono-flocculation, anionic and especially non-ionic polymers strongly flocculated the coal suspension than cationic polymer. The dual-flocculation of the coal suspension with cationic and anionic polymer combination was also studied and the high performances of flocculation were also reached with dual-polymer approach. Furthermore, dual-polymer system required lower concentrations for the successful flocculation of coal particles. On the other hand, the pre-destabilization of the coal suspension with calcium and magnesium ions at particular pH and concentrations highly improved the flocculation of fine coal particles with these polymers.     

基于电沉积导电高分子改性硫电极的Li-S电池

采用电化学法,在硫电极表面沉积一层聚(3,4–乙烯二氧噻吩)薄膜,并研究了相关锂–硫(Li-S)电池的电化学性能。结果表明,这种简单的电化学方法容易实现在整个硫电极表面制备一层致密、均匀、厚度可控的导电高分子薄膜,并且显著提高Li-S电池的循环稳定性。其中,薄膜电沉积500次时,其改性硫电极的初始放电比容量为955 mAh／g,在放电电流密度为900 mA／g时,800次充放电循环后比容量为590 mAh／g,即每个循环的容量损失率仅为0.047%。     

高分子链结构对聚酰胺酰亚胺溶液流变行为的影响

以高分子主链分别含3个和10个亚甲基结构的脂肪族–芳香族聚酰胺酰亚胺(PAI)为模型聚合物,采用旋转流变仪研究了高分子链结构对PAI溶液流变行为的影响。研究结果表明,含10个亚甲基结构的PAI在较宽的剪切速率范围内表观黏度变化不大,但含3个亚甲基结构的PAI溶液在一定的剪切速率区间发生了剪切增稠现象,并且随着温度的升高,剪切增稠现象逐渐减弱,同时剪切增稠所对应的剪切速率向高剪切速率方向移动。     

压裂用疏水缔合聚合物溶液性质及减阻性能研究

摘要：以一种功能性疏水单体与丙烯酰胺（AM）、丙烯酸（AA）和2-丙烯酰胺-2-甲基丙磺酸（AMPS）为原料,合成了一种疏水缔合聚合物HAWP-18。采用流变仪考察了疏水缔合聚合物HAWP-18的耐剪切性能、黏弹性及触变性,结果表明,HAWP-18属于假塑性流体,临界缔合浓度为2.31g/L,表现出较强的耐剪切性能;黏弹性测试表明,HAWP-18是典型的黏弹性结构流体,具有较宽的线性黏弹区,该体系的储能模量G''大于损耗模量G'',并且黏度越大,弹性特征越强;采用稳态剪切测试研究了不同质量浓度HAWP-18的剪切应力与剪切速率的关系,HAWP-18具有触变性,并且触变性随质量浓度增大而增强;使用自制摩阻测试仪测定了不同质量浓度HAWP-1的减阻性能,结果表明,HAWP-18减阻率随质量浓度的增加先上升后降低。HAWP-18的耐剪切性及其良好的黏弹性、触变性和减阻性能为其应用于压裂液提供了实验支撑。     

Attributes of Polymer and Silica Nanoparticle Composites: A Review

In this article, polymer microspheres and silica nanoparticles have been discussed as important filler in polymer composites. Their synthesis methods, properties, and application were particularly stressed. Silica is usually used as nucleating agent, surface enhancement mediator, and as templates and cores. Among polymer/silica composites, various categories including polyaniline, polypyrrole, polystyrene, epoxy, rubber, and acrylate polymer were discussed in detail. It was observed that silica nanoparticles enhanced mechanical strength and overall performance of composites. Furthermore, composites having carbon nanotube along with silica particles possess high electrical and mechanical performance. These composites are important in nanoelectronic devices, nanomedicines, and defense-related applications.     

Polyethylene/Polycaprolactone Nanocomposite Films for Food Packaging Modified with Magnetite and Casein: Oxygen Barrier,Mechanical, and Thermal Properties

Polyethylene (PE) was modified and prepared as double-layer polyethylene/polycaprolactone (PE/PCL) film. Magnetite and casein were added to the PCL-coating film to improve barrier properties and prevent destruction of basic structure of primary polymer PE. Significant improvements were observed with regards to mechanical (tensile strength, elongation at break) and thermal properties, while barrier (O₂ permeability) properties were slightly improved. Overall migration values into acetic acid were lower (from 1 to 4.6 mg/dm²) than the upper limit set by the legislation. Specific migration of iron in PE/PCL-Fe samples is also below (µg/L) specific migration limit value set by the legislation (mg/kg).     

Technical Relevance of Polymer/Cement/Carbon Nanotube Composite: Opportunities and Challenges

The polymer/cement/carbon nanotube composites are known for piezoelectric properties in intelligent structures. Polymers are also used to fulfill deficiencies in carbon nanotube/cement mortars. High-impact polystyrene has replaced sand to enhanced properties like energy consumption, waste disposal, and environmental pollution. Spray-applied fire-resistive material in engineered cementitious composite may overcome drawbacks of conventional brittle composite. Carbon nanotube is used as nanofillers in ordinary Portland cement due to superior mechanical properties. Cementitious polymer/carbon nanotube composite has potential to determine heat-dependent and self-sensing capacity of composites. Smart properties of composites are measured using conductivity measurement. Polymers are also used for making better carbon nanotube dispersion.     

聚合物/定向石墨烯复合材料研究进展

综述了近几年国内外关于石墨烯在聚合物基体中定向排列的方法及其研究进展,包括层层自组装、抽滤诱导自组装、挥发诱导自组装和外加场诱导自组装等。介绍了石墨烯的定向排列对聚合物复合材料力学、导电、导热等性能的影响。此外,对聚合物/定向石墨烯复合材料的未来发展方向进行了展望。     

超支化聚合物在天然植物纤维复合材料中的应用研究

介绍了超支化聚合物在天然植物纤维表面改性中的研究情况,包括端羧基超支化聚酯和端氨基超支化聚酰胺胺。总结了超支化聚合物改性在树脂/植物纤维复合材料中的应用研究进展,并重点对改性后复合材料的力学性能进行了详细阐述。     

Poly(methyl methacrylate)‐grafted cellulose nanocrystals: One‐step synthesis,nanocomposite preparation,and characterization

Cellulose nanocrystals (CNCs) are ideal reinforcing agents for polymer nanocomposites because they are lightweight and nano‐sized with a large aspect ratio and high elastic modulus. To overcome the poor compatibility of hydrophilic CNCs in non‐polar composite matrices, we grafted poly(methyl methacrylate) (PMMA) from the surface of CNCs using an aqueous, one‐pot, free radical polymerization method with ceric ammonium nitrate as the initiator. The hybrid nanoparticles were characterized by CP/MAS NMR, X‐ray photoelectron spectroscopy, infrared spectroscopy, contact angle, thermogravimetric analysis, X‐ray diffraction, and atomic force microscopy. Spectroscopy demonstrates that 0.11 g/g (11 wt %) PMMA is grafted from the CNC surface, giving PMMA‐g‐CNCs, which are similar in size and crystallinity to unmodified CNCs but have an onset of thermal degradation 45 °C lower. Nanocomposites were prepared by compounding unmodified CNCs and PMMA‐g‐CNCs (0.0025–0.02 g/g (0.25–2 wt %) loading) with PMMA using melt mixing and wet ball milling. CNCs improved the performance of melt‐mixed nanocomposites at 0.02 g/g (2 wt %) loading compared to the PMMA control, while lower loadings of CNCs and all loadings of PMMA‐g‐CNCs did not. The difference in Young's modulus between unmodified CNC and polymer‐grafted CNC composites was generally insignificant. Overall, ball‐milled composites had inferior mechanical and rheological properties compared to melt‐mixed composites. Scanning electron microscopy showed aggregation in the samples with CNCs, but more pronounced aggregation with PMMA‐g‐CNCs. Despite improving interfacial compatibility between the nanoparticles and the matrix, the effect of PMMA‐g‐CNC aggregation and decreased thermal stability dominated the composite performance.