4-乙基苯酚低聚物的酶催化合成及抗氧化性能研究

摘要

4-Ethylphenol oligomer was synthesized by enzymatic polymerization and was characterized by IR, GPC and TGA analysises.Data from free radical scavenging activity tests suggest that 4-ethylphenol oligomer can efficiently quench 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2, 2-azino-di-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) cation free radical due to its good H-atom donor capacity.Thermal-oxidative resistance of PP is improved remarkably after blending with 4-ethylphenol oligomer.In contrast with virgin PP, oxidation induction temperature of PP stabilized with 4-ethylphenol oligomer (0.5%) increases to 41 ℃ and oxidation induction time increases to 11.5 min.The antioxidant capacity of 4-ethylphenol oligomer are not only higher than 4-ethylphenol monomer, but also higher than two other widely used commercial antioxidants, 2,6-di-tert-butyl-4-methylphenol (BHT) and butylated hydroxyanisol (BHA).Chemical composition of PP stabilized with 4-ethylphenol oligomer was almost unchanged after thermal aging at 120 ℃ in air atmosphere for 72 h.As a result, enzymatic polymerization of phenolic compound shows potential application prospect for synthesizing new phenolic antioxidant.%以辣根过氧化物酶为催化剂制备了4-乙基苯酚低聚物,利用红外光谱、凝胶渗透色谱、热重对其进行了表征.4-乙基苯酚低聚物具有良好的清除1,1-二苯基-2-三硝基苯肼(DPPH)自由基和2,2-联氮双(3-乙基苯并噻唑啉-6-磺酸)二铵盐(ABTS)阳离子自由基的性能.4-乙基苯酚低聚物作为添加剂与聚丙烯复合后,可明显提高聚丙烯的抗热氧性能,与聚丙烯相比,4-乙基苯酚低聚物(0.5%)/聚丙烯复合物的氧化诱导温度提高了41 ℃,氧化诱导时间提高了11.5 min,抗氧化能力不仅大大高于4-乙基苯酚单体,而且优于市售抗氧剂2,6-二叔丁基-4-甲基苯酚(BHT)和丁基羟基茴香醚(BHA).加速老化试验表明,添加4-乙基苯酚低聚物的聚丙烯在120 ℃的空气氛围中老化72 h后,其化学组成没有明显变化.因此,酚类化合物的酶催化聚合在新型抗氧剂的合成方面有潜在的应用前景.