处理琥珀和树脂的ESR行为及13C NMR表征

ESR Behavior and 13C NMR Representation of Treated Amber and Resin

  • 摘要: 近期市场上出现的琥珀究竟是处理琥珀还是处理柯巴树脂或处理现代树脂?就这一疑惑问题,采用IR,ESR,13C NMR测试方法,重点对这类处理品中碳官能团的变异特征和13C NMR化学位移及共振谱峰进行了剖析。研究结果初步证实,天然树脂中稳定自由基的自旋浓度与芳香化程度密切相关,并受控于所处的地质年代、石化期后的物理化学环境;后期的熔结作用、聚合与酯化作用以及外来填充物的不等量掺入是造成处理琥珀和处理柯巴树脂或处理树脂中稳定自由基自旋浓度和芳香化程度变异的主要缘由。人工聚合、酯化或熔结处理易导致天然树脂中不稳定的T-CH2碳官能团和脂甲基碳官能团及脂肪族连氧碳官能团断键,与之对应的13C NMR共振谱峰是判断处理琥珀或处理树脂的重要依据。羰基碳官能团与脂甲基碳官能团的相对含量随着地质年代的递增而衰减直至消失,它对天然树脂相对年龄的判别及鉴定具有重要的标型意义。

     

    Abstract: In recentjewelry market,the identification of ambers turns into a puzzle because itis difficult to differentiate among treated ambers,treated copal resins and treated resins. IR, ESR and 13C NMR testing methods are employed to the study on treated ambers(heat-treated or pressed) and treated resins. This study is focused on the analysis of the differentiation charater and 13C NMR and the resonance spectral peak for the carbon functional groups.The results show that the spinning concentration of the stable free radical in the natural resin is closely associated with the aromatic concentration,and at the same time is controlled by the geological period when it occurred,and the physiochemical environment which it existed in the post-petrification period. The clinkering in the late period,the polymerization and esterification and the unequal incorporation of foreign filling materials are the major causes of the changes in the spinning concentration of stable free radical and in the aromatic contents. The research results prove tentatively that the artificial polymerization,esterification or clinkering treatments may resulteasily in the faultbonds forthe unstable T-CH2 carbon functional group, adeps-methyl carbon functional group and aliphatic adaptor-oxygen carbon functional group. The corresponding 13C NMR resonance peaks are the major basis for the differentiation between treated amber and treated resin.This study also shows thatthe relative contents of car-bonyl carbon functional group and adeps- methyl carbon functional group decrease with geological age increasing until they totally disappear,which may serve as the representative significance for the identification of the relative age of the natural resin.

     

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