Highly efficient two-stage ring-opening of epichlorohydrin with carboxylic acid in a microreaction system

Ring-opening of epoxides with carboxylic acids has been widely used to prepare many high value intermediates in the polymer and pharmaceutical industries. Most of conventional processes proceeded in batch stirred reactors. As such they always suffer from low productivity and selectivity. Here we developed an advanced technology to perform the ring-opening reaction of epichlorohydrin with neodecanoic acid (NDA) for continuous production of 3-chloro-2-hydroxypropyl neodecanoate in a more efficient and safer way. A microreaction system where a microreactor connected to a stirred reactor was established. When the conversion of NDA rapidly reaching around 90% in a microreactor at 110°C, the reaction solution was transferred to a stirred reactor at 90°C. This two-stage operating mode can reduce the reaction time and improve the selectivity through free switching of temperature in the consecutive two reactors, thus substantially reducing the consumption of energy and materials.     

PVC糊树脂发展前景

介绍了PVC糊树脂的生产现状及生产工艺。并展望了近阶段的发展前景。指出我国PVC糊树脂产能将在2012年集中释放,高端PVC糊树脂产品需进口补充,但普通PVC糊树脂产品市场供大于求。     

高强度模拟酸雨淋滤珠江三角洲地区潮土的有机质含量变化研究

采用高强度（平均离子强下10年、20年、30年雨量）模拟酸雨淋滤珠江三角洲地区的潮土,用重铬酸钾滴定法测定淋滤后土壤的有机质含量。研究表明：高强度模拟酸雨对土壤有机质含量的影响不大。各层土有机质含量变化最大的为下降13.04%,最小的为-1.33%。     

基于网络表示学习的机会网络链路预测

针对机会网络的多维链路属性和网络结构动态变化的特点,提出基于网络表示学习的链路预测方法。设置切片时长,将机会网络转化为网络快照序列,利用多维链路属性表示每个快照内的链路状态。采用网络表示学习方法聚合邻居节点的多维链路属性,并映射为低维的属性嵌入矩阵;采用基于注意力机制改进的循环神经网络学习网络拓扑随时间动态演化的规律,提取属性嵌入矩阵之间的时序特征;在输出层建立时序特征与链路状态之间的映射关系,实现下一时刻整网的链路预测。在Infocom-05和Hyccups等数据集上的实验结果表明,与现有同类方法相比,所提方法具有更高的预测精度。     

ZMBCH -2.7型复极式离子膜电解槽运行总结

介绍ZMBCH - 2.7型复极式离子膜电解槽的基本结构和基本性能参数.通过与30 - DD350离子膜电解槽对比,说明ZMBCH - 2.7电解槽具有电流密度高、运行阴阳极压力高、内部循环、压滤机式密封的特点.给出运行初期电解槽发生的异常情况及处理措施.     

景观水体表观污染成因分析

景观水体的表观污染已经成为一个普遍面临的水环境污染问题,探寻其产生的原因具有非常重要的意义。文章在前人研究成果的基础上,从化学、物理、生态等方面对表观污染成因进行分析。目的是为了更好地维持景观水体生态平衡,控制水体污染,预防水体表观污染的发生提供参考。     

An analysis of microstructural variations in carbon black modified by oxidation or ultrasound

The microstructure and electronic structure of modified carbon black (CB) were investigated by Raman spectroscopy, transmission electron microscopy, electron energy loss spectroscopy and ultraviolet spectroscopy. The modified CB samples include oxidised CB and ultrasound-treated CB under different modification conditions. Typical parameters, such as graphene layer size, the ratio of sp²/sp³-hybridised carbon atoms, energy gap (E_g), and π–π^∗ band position, provide information on the microstructure and electronic structure, and these parameters also allow discrimination between different modified CB samples to achieve a desired structure. Oxidation conditions could be carefully chosen to prevent excessive corrosion and form an ordered structure. However, ultrasound has a reverse effect; the graphite layers of the CB samples were exfoliated, and a disordered microstructure was visible. The results indicate that increasing sp²-island size in CB samples decreases the optical gap and increases ultraviolet absorption.     

Zinc‐based catalyst for the ring‐opening polymerization of cyclic esters

A zinc‐based catalyst zinc bis[bis(trimethylsilyl)amide] was used for the polymerization of cyclic esters including L ‐lactide (L ‐LA) and 2‐methyl‐2‐carboxyl‐propylene carbonate (MBC). The polymerization of L ‐lactide in THF could be carried out successfully under mild conditions in very short time by using the zinc catalyst and alcohols as the initiators. Kinetic study in solution polymerization prooved the polymerization has high monomer conversion degree close to 100% and the molecular weight of the resulting polyester has linear increase with the increase of [M]₀ /[I] (molar ratio of monomer to initiator). Sequential polymerization of L ‐LA and MBC in THF also showed high MBC conversion of 94% with a narrow molecualr weight maintained, indicating a living nature of this polymerization. The zinc catalyst system has also been used for the L ‐LA bulk polymerization with a high monomer conversion. ¹³C NMR indicated the polymer possesses high regioregularity and the minor regioirregular component was owing to the D ‐LA in the monomer inserted into the polymer mainchain during the transesterifcation. Interaction between monomer and zinc catalyst has been found to be a key factor to sustain a homogenous solution during the initiating procedure. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

回热吸附式可逆型热泵变工况特性

余热驱动的回热吸附式可逆型热泵能有效利用工业余热并且无环境公害问题 ,在一定意义上优越于传统热泵 ,针对此类热泵的实验样机研究其性能随工作参数的变化规律可指导优化运行和进一步的优化设计 ,是产品化过程中的必要环节 .从模型和实验的角度分别定义此热泵的主要性能指标 ,基于实用三热源模型研究其变工况特性 ,即分析热源温度、供暖温度、环境温度、热容比和最终回热温差等参数对热泵性能 (供暖系数COA ,单位质量供暖功率SHP)的影响。样机实验结果表明 ,样机性能较优且与模型预测接近 ,说明回热吸附式可逆型热泵商业前景乐观。