文章摘要
天然橡胶的老化机理
Aging Mechanism of Natural Rubber
  
DOI:10.16865/j.cnki.1000-7555.2018.05.013
中文关键词: 天然橡胶  紫外光老化  自然老化  老化机理
英文关键词: natural rubber  UV irradiation aging  natural aging  aging mechanism
基金项目:
作者单位
丁 玲, 李志辉, 杨 慧, 王相鹏, 梁梨花, 钟建永, 邹友思 厦门大学 材料学院福建 厦门 361005 
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中文摘要:
      采用人工紫外光老化和自然老化2种方法对天然橡胶(NR)进行老化研究,利用傅里叶变换红外光谱、核磁共振波谱及紫外-可见光吸收光谱测试法对老化产物进行表征,探究了NR的老化机理。结果表明,天然橡胶抗紫外光老化能力较差,在紫外光下照射3 h,其分子结构即发生明显改变,而在自然老化的条件下,天然橡胶经过30 d结构才发生变化。天然橡胶的老化机理:双键α-H最先被活化,随后发生氧化生成醛酮等氧化产物,同时双键被加成,烯氢含量减少;老化过程中,氧化降解与交联反应同时存在,老化前期以降解为主,后期产生交联。以核磁谱图为依据对烯氢的氧化百分比进行定量分析,建立了本实验条件下2种老化方程,并得出了自然老化时间与人工紫外光老化时间的关系,天然橡胶经紫外光老化7 d约相当于自然老化下3个月的老化效果。
英文摘要:
      The aging research of natural rubber(NR) was studied by UV irradiation aging and natural aging methods. The aging mechanism was studied by FT-IR, 1H-NMR, and UV-vis absorption spectroscopy. The results show that the ability of resistance to UV irradiation aging of NR is poor. 3 h after the irradiation of UV, the molecular structure changes sharply. 30 d after natural aging, the molecular structure of NR begins to change. The aging mechanism of NR was established∶α-H of double bond is activated first because of the low bond energy, then generated aldehyde ketone, and the addition reaction of the double bond occurs at the same time, the content of the hydrogen on the double bond reduces. Oxidative degradation and crosslinking reaction exist at the same time, oxidative degradation is dominant at the initial ageing stage, and crosslinking reaction is dominant at the final ageing stage.Quantitative analysis for oxidation percentage of the hydrogen on the double bond was based on the analysis of 1H-NMR, the ageing equation was established under this experimental conditions, so did the relationship between the time of natural aging and UV aging. The aging degree of NR during 36 h UV irradiation aging is the equal to that during 3 months natural aging.
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