抗氧化因子功能化石墨烯的构筑及其对天然橡胶的抗氧化性能与机理研究

It is a critical issue for the antioxidation of polymer materials and their products that effectively solving the physical loss and environment pollution of low molecular weight antioxidant due to the volatilization, migration or extraction during processing, storage and long term service of polymer. This project aim to synthesize a compound with hindered phenol, hydroxyl (or amino) and thioether groups, namely antioxidant factor (AF), through thiol–acrylate Michael addition reaction between the functional thiol with hydroxyl (or amino) and the compound with hindered phenol and acrylate. Furthermore, the AF will be intergrated with graphene oxide (GO) through either an esterification or ring opening reaction, and the graphene which is functionalized with thioether and hindered phenol groups (AF-GO) will be obatined. In this study, the synthesis conditions of the AF, GO and AF-GO will be optimized systematically. The thermo-oxidative aging resistance, extraction and migration resistances of the AF-GO for natural rubber (NR) will be detailedly investigated. Moreover, the relationship between the surface chemical structure of AF-GO and the antioxidative and reinforcing effect will be established. Additionly, the mechanisms of dispersibility and antioxidation of the AF-GO will be revealed. Through this study, the new method and theory for the mutil-function additive with highly antioxidative and reinforcing properies will be developed.

如何有效解决小分子抗氧剂在聚合物材料加工、贮存及使用过程中因挥发、迁移或抽提而造成的物理损失及环境污染，是当前高分子材料及其制品抗氧化亟待解决的重要科学问题。本项目拟以双酚单丙烯酸酯类化合物和含醇羟基（或氨基）功能硫醇为原料，通过巯基-丙烯酸酯Michael加成反应合成含有醇羟基（或氨基）和硫醚基团的受阻酚作为抗氧化因子（AF）。进而利用其与氧化石墨烯（GO）表面的羧基或环氧基团通过酯化或开环反应对GO表面进行共价键改性，得到表面具有硫醚和受阻酚基团的抗氧化因子功能化石墨烯（AF-GO）。优化AF、GO和AF-GO的制备条件；探讨AF-GO对天然橡胶（NR）的抗热氧老化作用及其耐迁移、耐抽提性能；构建AF-GO表面化学结构与其抗氧化性能及补强效能的构效关系；揭示AF-GO在NR中的分散及其抑制NR老化的作用机理。为兼具高抗氧化和补强效能的多功能助剂的构筑及应用提供新方法和理论支撑。

如何有效解决小分子抗氧剂在聚合物材料加工、贮存及使用过程中因挥发、迁移或抽提而造成的物理损失及环境污染，是当前高分子材料及其制品抗氧化亟待解决的重要科学问题。本课题采用改良的Hummers法制备氧化石墨烯，通过对其接枝抗氧化基团和巯基化并应用于抗氧化领域，不仅丰富了氧化石墨烯的功能化方法，而且进一步拓展了其应用领域。课题的主要研究内容和结果包括以下几个方面：.(1) 以IPDI为桥接剂，制备出受阻酚-氨基甲酸酯功能化氧化石墨烯HPUGO，小分子抗氧剂DBHMP相对接枝率达到18.34%。采用胶乳共混、絮凝干燥、开炼的工艺方法制备NR/HPUGO纳米复合硫化胶，结果表明HPUGO在NR基体中分散均匀。与未加抗氧剂的硫化胶相比，当HPTGO添加量为2phr时，NR硫化胶的初始失重温度和最大失重速率温度分别由338.8 oC 和372.9 oC提高至372.8 oC 和394.5oC，老化96 h后断裂伸长率保持率和拉伸强度保持率分别由0.25和0.37增加至0.51和0.57，表明NR/HPTGO复合硫化胶具有优良的热稳定性和抗热氧老化性能。这主要归因于HPTGO对氧气的有效阻隔以及受阻酚基团和氨基甲酸酯之间的协效作用。. (2) 以KH590对GO改性，制得含巯基的氧化石墨烯(mGO)，然后与含不饱和双键的GM在三乙胺的催化作用下发生巯烯加成反应，制备出受阻酚-硫醚键功能化氧化石墨烯HPTGO。采用胶乳共混、絮凝干燥、开炼的方法制备NR/HPTGO纳米复合硫化胶，结果表明HPTGO较好地分散在NR基体中。热重分析和加速热氧老化结果表明HPTGO能显著提高天然橡胶在空气中的热稳定性和抗热氧老化性能。通过分析认为，与HPUGO相比，HPTGO有着更好的抗热氧老化效果，这主要是因为HPTGO不仅存在阻隔氧气渗透以及受阻酚基团和硫醚键之间的协效作用，且在相对宽松的反应条件下具有更高的相对接枝率。