【作者】 瞿保钧；

【Author】 Qu Baojun Structure Research Lab,USTC,Hefei 230026

【机构】 中国科技大学结构成分分析开放实验室；

【摘要】 用溶液高分辨¹³C NMR谱首次研究了由二苯甲酮（BP）光引发低密度聚乙烯模型化合物直链烷烃n—C₂₄H₅₀交联所产生的H型交联点的结构特征。现已检测和鉴定了光交联样品中与H型交联点相联系的—CH,α—CH₂和β—CH₂上碳的共振谱线,如图1所示。其化学位移数据与H型交联点模型化合物、γ—辐射交联正烷烃和聚乙烯得到的结果符合得很好（见表1）。在40.83ppm处出现的一个新峰可指认为H型交联点的次甲碳,其相应的31.57和28.37ppm处的另外两个新峰分别指认为相邻的α—CH₂和β—CH₂上碳的共振.本工作中的定量研究表明:在真空和熔融态条件下紫外光照3～5分钟的样品中H型交联点的数目据估计为8.5～11.0/10000C。更多还原

【Abstract】 H-type cross-links produced by photoinitiated cross-linking of n-C₂₄H₅₀as a model compound of polyethylene in the presence of benzophenone as photoinitiator have been studied for the first time by solution-state ¹³C NMR spectroscopy.Resonance lines assigned to the CH,α-CH₂,andβ-CH₂ carbons associated with H-type cross-links have been observed and identified for the photocross-linked samples,as shown in Fig.1.The data of chemical shifas are good agreement with those from model compound¹ andγ-irradiation cross-linking of n-paraffins^2-5and polyethylene^6,7,as listed in Table 1. A new resonance line at 40.83 ppm is attributed to methine carbons in H-links.The other two new resonances at 31.57 ppm and 28.37 ppm are assigned toα-CH₂ andβ-CH₂,respectively.The quantitative studies in this work show that the number of H-links is estimated to be 8.5-11.0 per 10000 carbon atoms for samples UV-irradiated in vacuum in the melt for 3-5 min.更多还原