Liang Lu, Dong Jianjun, Yue Dongmei
AECC Beijing Institute of Aeronautical Material 100095 Beijing China.
Beijing University of Chemical Technology 100029 Beijing China
RSC Adv. 2019 Oct 9;9(55):32130-32136. doi: 10.1039/c9ra03656c. eCollection 2019 Oct 7.
Epoxide nitrile butadiene rubber (ENBR) was prepared epoxidation from nitrile butadiene rubber (NBR) with acetic acid and hydrogen peroxide. ENBR had been selectively hydrogenated in the presence of a homogeneous Wilkinson catalyst. The hydrogenated epoxide nitrile butadiene rubber (EHNBR) and ENBR were characterized by infra-red and proton nuclear magnetic resonance. No change was noted in the epoxy content of the polymer after the reaction. The catalyst is highly selective in reducing carbon-carbon double bonds in the presence of epoxy groups. DSC analysis reveals the of ENBR varied linearly with molar epoxide content and the value increased by 0.82 °C per mol%. It also found that the introduction of epoxy groups can effectively reduce the extent of crystallization by impairing the regularity of the molecular chain, but crystalline structure was difficult to completely eliminate. Therefore, anhydrides were selected as ring-opening reagents to react with epoxy groups in EHNBR. The products, branched EHNBR, were characterized by infra-red and proton nuclear magnetic resonance. The conversion rate of the epoxide group was calculated by H NMR. The glass transition temperature of EHNBR--heptyl group was -34.1 °C, and its DSC curve demonstrated no crystal structure. The coefficient of cold resistance under compression of EHNBR grafted propyl ester was 0.36, which represented a superior low-temperature performance. Furthermore, residual epoxy groups and ester groups extremely enhanced the oil resistance of HNBR.
通过丁腈橡胶（NBR）与乙酸和过氧化氢进行环氧化反应制备环氧化丁腈橡胶（ENBR）。在均相威尔金森催化剂存在下，ENBR已被选择性氢化。对氢化环氧化丁腈橡胶（EHNBR）和ENBR进行了红外和质子核磁共振表征。反应后聚合物的环氧含量未观察到变化。该催化剂在环氧基团存在下对还原碳 - 碳双键具有高度选择性。差示扫描量热法（DSC）分析表明，ENBR的[此处原文缺失相关内容]随环氧摩尔含量呈线性变化，且[此处原文缺失相关内容]值每摩尔百分比增加0.82℃。还发现环氧基团的引入可通过破坏分子链的规整性有效降低结晶程度，但结晶结构难以完全消除。因此，选择酸酐作为开环试剂与EHNBR中的环氧基团反应。产物支化EHNBR通过红外和质子核磁共振进行表征。通过氢核磁共振计算环氧基团的转化率。EHNBR - 庚基的玻璃化转变温度为 - 34.1℃，其DSC曲线表明无晶体结构。接枝丙酯的EHNBR的压缩耐寒系数为0.36，这代表了优异的低温性能。此外，残留的环氧基团和酯基极大地提高了氢化丁腈橡胶（HNBR）的耐油性。
