当前位置: X-MOL 学术Eur. Polym. J. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Protected N -heterocyclic carbenes as latent organocatalysts for the low-temperature curing of anhydride-hardened epoxy resins
European Polymer Journal ( IF 5.8 ) Pub Date : 2017-10-01 , DOI: 10.1016/j.eurpolymj.2017.05.032
Hagen J. Altmann , Stefan Naumann , Michael R. Buchmeiser

Abstract Epoxy resins based on commonly used epoxy compounds, various anhydrides and CO2-protected N-heterocyclic carbenes (NHCs), which combine the favorable properties of fast curing at low reaction temperatures, pot life in the range of hours to days and full homogeneity in the form of low-viscosity liquids, are presented. These characteristics are achieved by careful tuning of the components. 1,3-Dimethylimidazolium-2-carboxylate (5u-Me-CO2) as a thermally latent organocatalyst offers facile one-step preparation and robustness towards atmospheric conditions as well as the high reactivity required once the polymerization is “switched on” by heating. A systematic screening of several epoxy compounds and 14 different anhydrides is conducted to identify the monomers that are suited best for rapid monomer consumption and thus for low curing temperatures. From these experiments, more than 15 different systems were found where a homogeneous liquid can be formed in the absence of further additives (no solvent or reactive thinner). Several of these one-component mixtures were investigated more detailed by in-situ DSC and rheology measurements. In general, the combination of aliphatic epoxides and low-melting or liquid anhydrides delivers the fastest polymerization under the mildest conditions, while maintaining a very low initial viscosity (

中文翻译:

受保护的 N-杂环卡宾作为潜在有机催化剂用于酸酐硬化环氧树脂的低温固化

摘要 基于常用环氧化合物、各种酸酐和 CO2 保护的 N-杂环卡宾 (NHC) 的环氧树脂,结合了在低反应温度下快速固化、适用期为数小时至数天和完全均匀的优点。呈现低粘度液体的形式。这些特性是通过仔细调整组件来实现的。1,3-二甲基咪唑鎓-2-羧酸盐 (5u-Me-CO2) 作为一种热潜性有机催化剂,可提供简便的一步制备和对大气条件的稳健性,以及一旦通过加热“开启”聚合所需的高反应性。对几种环氧化合物和 14 种不同的酸酐进行系统筛选,以确定最适合快速单体消耗并因此适合低固化温度的单体。从这些实验中,发现了超过 15 种不同的系统,其中可以在没有其他添加剂(无溶剂或反应性稀释剂)的情况下形成均质液体。通过原位 DSC 和流变学测量对这些单组分混合物中的几种进行了更详细的研究。一般来说,脂肪族环氧化物和低熔点或液体酸酐的组合在最温和的条件下提供最快的聚合,同时保持非常低的初始粘度(发现了超过 15 种不同的系统,其中可以在没有其他添加剂(无溶剂或反应性稀释剂)的情况下形成均质液体。通过原位 DSC 和流变学测量对这些单组分混合物中的几种进行了更详细的研究。一般来说,脂肪族环氧化物和低熔点或液体酸酐的组合在最温和的条件下提供最快的聚合,同时保持非常低的初始粘度(发现了超过 15 种不同的系统,其中可以在没有其他添加剂(无溶剂或反应性稀释剂)的情况下形成均质液体。通过原位 DSC 和流变学测量对这些单组分混合物中的几种进行了更详细的研究。一般来说,脂肪族环氧化物和低熔点或液体酸酐的组合在最温和的条件下提供最快的聚合,同时保持非常低的初始粘度(
更新日期:2017-10-01
down
wechat
bug