Tertiary‐amine‐free,non‐planar,sulfone‐containing,tetrafunctional epoxy and its application as a high temperature matrix

Non‐amine‐derived tetrafunctional epoxies have several advantages over the amine‐derived N,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenyl methane (TGDDM) in high temperature applications. Although two non‐amine‐derived tetrafunctional epoxies were developed in our laboratory, further improvements in toughness using less loading amount is still desirable. Thus, a tertiary‐amine‐free, non‐planar and triphenylmethane‐containing tetrafunctional epoxy (STFE) with a sulfone spacer was synthesized. When it was mixed with diglycidyl ether of bisphenol A (DGEBA) and cured with 4,4′‐diaminodiphenylsulfone (DDS), both thermal and mechanical performances outperformed TGDDM. Moreover, STFE modified system shows the highest toughness (35.7 kJ m^–2) among three amine‐free and triphenylmethane‐containing epoxies at merely 5 wt% loading. Molecular simulation and thermomechanical analysis results suggest that the improved mechanical properties could be related to the geometry of the molecule and larger free volume. Despite a marginal drop in T_g, the thermal degradation temperature is better than that of TGDDM/DDS. In addition, the moisture resistance of STFE/DGEBA/DDS is much better than that of TGDDM/DDS. Thus, STFE modified DGEBA could be a potential replacement for TGDDM in some high temperature applications. © 2020 Society of Chemical Industry     

二乙基三胺五乙酸浸取-电感耦合等离子体质谱法测定石灰性土壤中有效态铜锌铁锰

采用二乙基三胺五乙酸(DTPA)浸提石灰性土壤样品中有效态Cu、Zn、Fe、Mn后,样品溶液基体盐分较大,此时若直接采用电感耦合等离子体质谱法(ICP-MS)进行测定,极易使仪器的采样锥和截取锥发生堵塞,雾室和炬管积盐,进而影响测定准确性。据此,实验用DTPA浸提样品后,采用对样品溶液稀释10~30倍和在标准溶液系列中加入DTPA溶液进行基体匹配的方法以消除基体干扰,利用氦碰撞模式进行测定以消除多原子离子⁴⁰Ar¹⁶O对⁵⁶Fe的质谱干扰,最终实现了ICP-MS对石灰性土壤中有效态Cu、Zn、Fe、Mn的测定。对氦气流量进行了优化,并确定氦气流量为4.5mL/min。在优化的实验条件下,Cu、Zn的质量浓度为5~200ng/mL、Fe的质量浓度为100~3000ng/mL、Mn的质量浓度为30~1000ng/mL时,各元素质量浓度分别与其计数值呈线性关系,相关系数均不小于0.9998。方法检出限为0.003~0.01mg/kg。按照实验方法测定土壤有效态成分分析标准物质中的有效态Cu、Zn、Fe、Mn,测定值与认定值一致,相对标准偏差(RSD)为1.3%~3.1%。采用实验方法和标准方法HJ 804—2016(电感耦合等离子体原子发射光谱法)进行方法对照试验,二者测定值基本一致。     

土壤环境污染及监测技术现状分析

经过多年的建设发展,我国在生产、生活等各个领域都已经取得了举世瞩目的成就,尤其是在经济建设方面,取得的建设成果非常显著。在城市建设过程中取得的变化可以用日新月异来形容,但是环境污染尤其是土壤污染问题也随之产生。目前,土壤污染是环境治理难题中的重点内容。在相关技术人员实际工作中,需要运用多种不同的方法开展及时有效地监测,以此来制定正确的策略,解决土壤污染的治理问题。     

交联聚乙烯电缆绝缘老化超低频介损试验及评价规程研究

本文基于通过检测电缆超低频介损值确定电缆老化程度的基本原理,结合某地实测得到的多组数据,通过国际规程IEEE 400.2—2013进行初步判断,分析处于不同状态下的电缆介损值的变化规律及其原因,并得出该规程仅适用于没有局部劣化的电缆.此外,由于我国电缆制造材料、结构和生产工艺与国外产品存在差异,采用国际规程判断电缆老化程度有时会变得不准确.为解决此类问题,本文建立更加全面的判据体系,给出最优判断阈值的确定方法,并对该地区实测得到的数据进行拟合,得到更加准确的分级判断阈值.此方法可为建立符合我国电缆实际情况的评价规程提供参考.     

A novel method to enhance magnetic property of bioactive glass-ceramics for hyperthermia

In this study, a novel method was proposed to enhance the magnetic property of magnetic bioactive glass-ceramic (MBGC) using graphite-modified magnetite. The crystalline composition, chemical structure, in vitro bioactivity, magnetic property, heat generating ability, cytotoxicity and the hyperthermia treatment effectiveness of the synthesized material were investigated thoroughly. The results revealed that the addition of graphite could prevent the magnetite from being oxidized. The main phases of the as-prepared material were found to be Fe₃O₄, Ca_2.87Fe_0.13(SiO₃)₃ and Ca₂SiO₄ in the CaO-SiO₂-MgO-CaF₂-P₂O₅-Fe₃O₄ system. Moreover, the material was bioactive and hydroxyapatite was observed on the surface after soaking in simulated body fluid (SBF) for 10 d. Under a magnetic field of 1.6?×?10⁶ A?m^?1, the saturation magnetization of MGBC was about 10.6?A?m² Kg^?1, while that of the contrast sample was only 2.9?A?m² kg^?1. When exposed to an alternating magnetic field (252?kHz, 1.9?×?10³ A?m^?1) for about 20?s, a temperature rise of 20?°C could be observed on the sample surface. MTT assay results showed that the material had no cytotoxicity for VX2 cells. Moreover, the hyperthermia treatment experiments were carried out by exposing the block samples (Φ8?×?2?mm) and VX2 cells simultaneously to the alternating magnetic field for 20?min. Only about 30% cells survived after the treatment, and dead cells were observed around the material. Therefore, this novel material could have potential applications for clinical hyperthermia treatment.