Synthesis of superabsorbent resin by ultraviolet photopolymerization

Synthesis of superabsorbent resin (SAR) was achieved by a new method, that of direct UV photopolymerization, and in particular the synthesis of a SAR of acrylic acid–potassium acrylate copolymer by UV photopolymerization was investigated. Influences of ratio (mol) of acrylate monomer to acrylic acid monomer, photoinitiators, crosslinking agents, and exposure time of UV light on the water‐absorbent properties were investigated. The results showed that the water absorbency (Q) of SAR based on Irgacure 1700 or Irgacure 1800 was 545–530 mL/g, but under the same conditions Q was 450 mL/g for the SAR based on Irgacure 651. N,N′‐Methylene bisacrylamide, hydroethyl acrylate, and glycerol were used as crosslinking agents, of which N,N′‐methylene bisacrylamide was the most effective. It crosslinked the molecular chains through attending the copolymerization with acrylic acid (AA) and potassium acrylate. When the exposure time was 5 min, the value of Q was 1368 mL/g (the content of N,N′‐methylene bisacrylamide was 100 ppm). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1618–1624, 2004     

氟化铵溶解含氟硅渣制备氟硅酸铵的实验研究

以氟化铵溶液和含氟硅渣为原料,通过化学溶解的方式,制备氟硅酸铵产品。考察了反应温度、反应时间、氟化铵溶液浓度和物料配比（氟化铵与二氧化硅的物质的量比）等不同工艺条件对氟硅酸铵收率、二氧化硅转化率的影响。实验结果表明：反应温度为93 ℃、反应时间为60 min、氟化铵溶液质量分数为20%~30%、物料配比为6∶1.1、反应体系搅拌速度为200~300 r/min时,氟硅酸铵的收率和氟化铵的转化率可控制在90%以上。     

静电除尘器在磷石膏制硫酸联产水泥工程中的应用

阐述了磷石膏烘干脱水后,粉状半水石膏的收集、磷石膏煅烧窑气净化除尘均应选择静电除尘器的必要性。根据电除尘器处理介质(烘干尾气与水泥窑气)的特性及操作条件,介绍了设计选型要考虑防爆、结露等问题,并提出相应改进措施。     

架空在“云”端的网络体系结构

随着近年来云技术的飞速发展,常规的数据网络在扩展性、带宽、规模、成本等方面都明显处于劣势地位,已经无法适应未来的发展需求。在这种情况下,云端网络技术在节约运算成本、提升公司运行效率方面有很好的效果。受到了企业的青睐。基于此本文对架空在“云”端的网络体系结构进行探讨。     

Random arithmetic formulas can be reconstructed efficiently

Informally stated, we present here a randomized algorithm that given black-box access to the polynomial f computed by an unknown/hidden arithmetic formula ? reconstructs, on the average, an equivalent or smaller formula \({\hat{\phi}}\) in time polynomial in the size of its output \({\hat{\phi}}\) . Specifically, we consider arithmetic formulas wherein the underlying tree is a complete binary tree, the leaf nodes are labeled by affine forms (i.e., degree one polynomials) over the input variables and where the internal nodes consist of alternating layers of addition and multiplication gates. We call these alternating normal form (ANF) formulas. If a polynomial f can be computed by an arithmetic formula μ of size s, it can also be computed by an ANF formula ?, possibly of slightly larger size s ^O(1). Our algorithm gets as input black-box access to the output polynomial f (i.e., for any point x in the domain, it can query the black box and obtain f(x) in one step) of a random ANF formula ? of size s (wherein the coefficients of the affine forms in the leaf nodes of ? are chosen independently and uniformly at random from a large enough subset of the underlying field). With high probability (over the choice of coefficients in the leaf nodes), the algorithm efficiently (i.e., in time s ^O(1)) computes an ANF formula \({\hat{\phi}}\) of size s computing f. This then is the strongest model of arithmetic computation for which a reconstruction algorithm is presently known, albeit efficient in a distributional sense rather than in the worst case.     

利用仿真软件优化电磁场与电磁波教学

针对电磁场与电磁波课程理论公式复杂、相关概念模型抽象的特点,结合长期积累的教学经验,利用软件仿真将电磁场定理模型、分布特性可视化,简化推导计算过程,优化课程结构、节省课时的同时提高了教学效果。     

Microcellular foaming of PE/PP blends

Three different polyethylene/polypropylene (PE/PP) blends were microcellular foamed and their crystallinities and melt strengths were investigated. The relationship between crystallinity, melt strength, and cellular structure was studied. Experimental results showed that the three blends had similar variation patterns in respect of crystallinity, melt strength, and cellular structure, and these variation patterns were correlative for each blend. For all blends, the melt strength and PP melting point initially heightened and then lowered, the PP crystallinity first decreased, and then increased as the PE content increased. At PE content of 30%, the melt strength and PP melting point were highest and the PP crystallinity was least. The blend with lower PP crystallinity and higher melt strength had better cellular structure and broader microcellular foaming temperature range. So, three blends had best cellular structure at PE content of 30%. Furthermore, when compared with PE/homopolymer (hPP) blend, the PE/copolymer PP (cPP) blend had higher melt strength, better cellular structure, and wider microcellular foaming temperature range, so it was more suited to be microcellular foamed. Whereas LDPE/cPP blend had the broadest microcellular foaming temperature range because of its highest melt strength within three blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4149–4159, 2007     

甲烷磺酸电镀Sn-Pb合金添加剂研究

介绍了国内外磺酸型Sn-Pb合金电镀添加剂近十年的研究历程现况并根据各组分的化学结构及其在电镀中所体现出的性质将添加剂分为Sn^2 离子稳定剂、光亮剂及分散剂三类。最后列出了新研制的甲烷磺酸Sn-Pb合金电镀添加剂的主要性能及具体工艺配方。     

增韧聚丙烯三元共混体阻燃性能的研究

研究了多种阻燃剂，包括Ｓｂ２Ｏ３、Ａｌ（ＯＨ）３、ＣＰＣ、ＤＢＤＰＯ对聚丙烯／高密度聚乙烯／乙丙橡胶（ＰＰ／ＨＤＰＥ／ＥＰＲ）三元共混体—增韧聚丙烯—阻燃性能的影响；阻燃剂间的协同作用；并探讨了阻燃机理。结果表明：１、ＡＬ（ＯＨ）３的重量含量超过４０％时，阻燃效果显著；２、三种阻燃剂（Ｓｂ２Ｏ３、ＤＢＤＰＯ、ＣＰＥ）并用，阻燃效果明显提高，含卤化合物（ＤＢＤＰＯ与ＣＰＥ）是Ｓｂ２Ｏ３重量的四倍时，阻燃性能最佳；３、Ｓｂ２Ｏ３与ＤＢＤＰＯ并用时，当Ｂｒ／Ｓｂ的摩尔比为３∶１时阻燃效果最好     

Phase field simulation of the 180°domain-switching process in PbTiO_3 single crystal under an antiparallel electric field

The process of 180°domain switching in PbTiO_3 single crystal under an antiparallel electric field was investigated by the three-dimensional phase field simulation,especially the effect of electric field on the type and duration of domain switching.It is found that the polarization reversal of domains takes place under an antiparallel electric field in PbTiO_3 single crystal.The results of the phase field simulation indicate that there is only 90°domain switching under a weak electric field.With the rise...