反应性树脂体系化学增黏和物理减黏机制的分离

采用等温差示扫描量热(DSC)法,研究了CTD-128环氧树脂与GA-327(DDM改性芳胺)的固化度-时间变化关系;采用AR2000EX型旋转流变仪,测试了上述体系的等温黏度-时间关系.比较等温条件下的固化度-时间关系和黏度-时间关系,建立了等温条件下的黏度-固化度的等时对应关系,结果表明在纯化学增黏机制影响下,树脂体系的黏度随固化度增加先缓慢增加,当固化度增大到一定程度后黏度快速增加.将等温条件下的黏度-固化度关系进行变换,得到恒定固化度下的黏度-温度关系,揭示了在物理减黏机制影响下,树脂体系黏度随温度的增加而降低,并且黏度降低幅度随固化度的增加而增大.两种黏度影响机制分离的实现,为反应性树脂体系实时黏度的准确预测提供了技术支持.     

Controlling Novichoks after Salisbury: revising the Chemical Weapons Convention schedules

ABSTRACT

Novichok agents are a class of nerve agents developed by the Soviet Union during the Cold War. In light of the use of a Novichok agent in Salisbury in March 2018, two sets of proposals to amend Schedule 1 of the 1993 Chemical Weapons Convention (CWC) have been put forth, one jointly by the United States, Canada, and the Netherlands, and the other by Russia. Both sets of proposals will be discussed and voted upon at the next Conference of States Parties of the Organisation for the Prohibition of Chemical Weapons (OPCW) in November 2019. If either set of proposals is approved, it will be the first time that the list of chemicals subject to verification under the CWC will have been modified. This viewpoint will discuss these proposals, and argue that, if adopted, the joint proposal and the portions of the Russian proposal upon which consensus can be reached would significantly strengthen the CWC by considerably expanding the coverage of its Schedule 1 and bringing Novichok agents firmly within the CWC’s verification system. We also argue that, since the OPCW Technical Secretariat did not deem the fifth group of chemicals proposed by Russia to meet the criteria for inclusion in Schedule 1, Russia should withdraw this part of its proposal from consideration. The proposals have also served an important purpose in clarifying the identity of the chemical agent used in the Salisbury incident, squarely placing it within one of the two families of Novichok agents described by the Russian chemical-weapons scientist and whistleblower Vil Mirzayanov. If either proposal is approved in November, it will be important to conduct a thorough assessment of key precursors for the synthesis of Novichok agents and assess the need to amend CWC schedules and national and multinational export-control lists accordingly.     

Chemical-weapon use in Syria: atrocities,attribution, and accountability

ABSTRACT

International efforts to hold the government of President Bashar al-Assad accountable for the use of chemical weapons in the Syrian Civil War have entered a new phase. For the first time, the Organisation for the Prohibition of Chemical Weapons (OPCW), the international organization responsible for implementing the 1993 Chemical Weapons Convention, has been empowered to identify the perpetrators of chemical attacks in Syria. The Investigation and Identification Team (IIT), which was formed to conduct the OPCW’s new attribution mission, has announced its intention to investigate and identify the perpetrators of nine chemical attacks in Syria, including the April 7, 2018, attack in Douma. This article reviews recent efforts to attribute chemical attacks in Syria, describes what we know about the nine incidents to be investigated, summarizes what is known about the Syrian government officials, military commanders, and chemical-warfare scientists suspected of being responsible for these attacks, discusses what to expect during the next phase of the attribution process, and offers insights into how the international community can move beyond attribution to accountability. Accountability is necessary to provide justice for victims and to prevent future incidents by demonstrating that perpetrators of chemical attacks will be identified and punished.