Cationic microgel emulsion with a high solid content by a multistep addition method in inverse microemulsion polymerization

The multistep addition of a monomer and initiator was developed to successfully synthesize cationic polyacrylamide microgels with solid contents (SCs) greater than 35% and cationic monomer concentrations of 0–40 mol % by inverse microemulsion polymerization. Two feed methods, three‐step nonuniform addition and five‐step uniform addition, were implemented to obtain microgel emulsions with 37% SC. The former addition method was designed according to the solubilization limit of the microemulsion before step polymerization, and that of the latter was a constant based on the remaining surfactant weight in the reactor. The product properties in the intermediate processes of these two methods were compared by dynamic light scattering and viscosity measurement. The results show that the products here were translucent microemulsions instead of milky ones when they were synthesized by a semicontinuous polymerization. Also, the particle sizes of these two methods were almost the same; this indicated that the oscillation phenomenon in continuous polymerization at a high SC was avoided. With the former feed method, the risk and operation cost in the synthesis process could be cut down greatly. Moreover, the viscosity of the cationic microgel emulsion conformed to the Krieger–Dougherty equation with a greater value of intrinsic viscosity than that of a hard‐sphere system because of an electroviscous effect. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40585.     

Perfluorosulfonated ionomers membranes: Melt‐processing and characterization for ion exchange applications

Perflurosulfonated ionomers membranes with different ionic‐exchange capacity were successfully fabricated via melt‐extruding and casting of their –SO₂F precursors. A systematical investigation of the thermal stability, crystallinity, and rheological properties of the precursors was performed to secure their optimized processing conditions. The tensile properties of acid‐form membranes are found to increase with base‐hydrolysis time, where a tensile strength of 38.2 MPa is readily obtained after 24 h's base‐hydrolysis. The content of –SO₂F or –SO₃H containing side‐chains plays an important role in the thermal stability, rheological, and mechanical properties of the precursor or the acid‐form membranes. The strong ionic interactions, attributed to the –SO₃H groups, lead to decreased crystallinity and tensile strength for different IEC membranes. The acid‐form membranes exhibit good proton conductivity and low methanol crossover in comparison with reference Nafion membrane. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39944.     

Densification and mechanical properties of boron carbide with micro-hole array by micro-powder injection molding

For the purpose of obtaining fully dense B₄C with micro hole array of high quality and precision, synthesis of B₄C powders were carried out by micro powder injection molding. Five kinds of additive systems were used and their influences on mechanical properties were investigated. The relative density, Vickers hardness, bending strength, and fracture toughness of the B₄C ceramics with BS10AY additive sintered at 2000 °C for 2 h could reach 97.56%, 3580.4 HV, 355.3 MPa and 5.87 MPa m^1/2, respectively. The temperature was generally 100–200 °C lower than reported temperatures which was attributed to the additives. The improvement in mechanical properties was attributed to grain refinement. A mixture of intragranular and transgranular fractures occurred due to the fine microstructures and the additive systems in the B₄C ceramics after sintering. Micro-hole array with the diameter of 450 μm and the length-diameter ratio of more than 8 were obtained. The inhomogeneous filling of feedstock from the substrate to the thin wall between two adjacent micro holes caused the inhomogeneous shrinkage of the substrate and micro holes.     

色酚AS偶氮颜料（二）

色酚AS类颜料是由2-羟基-3-萘酰胺化合物作为偶合组分与取代基芳胺重氮盐偶合制得的偶氮颜料,主要给出红色谱,颜料分子中因含有甲酰氮基（-CONH-）具有良好的耐溶剂性能.文中介绍色酚AS偶氮颜料的发展历史、化学性质及生产、性能、应用,并介绍了目前市场上的二组商用色酚AS偶氮颜料,色酚AS偶氮颜料中红1 12、146以及170在传统工业领域的红色谱中具有相当的市场份额.     

Analysis of Fluorine Coating in Rubber ＆ Plastic Mold Surface

The article briefly introduced the influence factors of polymer product mold failure; noted that the effect of surface protecting of the mold was better than improving the surface hardness. Pointed out the release agents had a few shortcomings like single function so could not meet the development of modern industry after the release agent usage analysis. Analyzed three fluorine coatings which had obvious advantages： solvent-based, water-based and powder type. Its release mechanism was named as self- layering technology; fluorine coating not only enabled mold to have a smooth release at a complex surface, but itself had a good corrosion resistance, so the environmental protection composite coating is the future trend of industrial surface protection.