过氧化物预硫化医用天然胶乳制品热空气老化过程的超微结构与热氧降解的研究

Thermooxidative degradation and ultrastructure of medical product made from peroxide prevulcanized natural rubber latex in the process of ageing

本文使用过氧化物预硫化天然胶乳(PPVL)制备医用天然胶乳胶管,并采用热重分析法(TGA)和扫描电镜(SEM)研究胶管试样的热氧降解机理和超微结构的变化。热重法/微分热重法(TG-DTG)曲线表明,试样的氧化降解过程为两步反应,并在产生轻微降解后,出现明显的吸氧增重过程。增重率随升温速率β的增加而减少;β为5℃/min的增重峰温度187.9℃,增重率达1.33%。第一步反应和第二步反应的频率因子A和活化能E均随β的增加而增大。SEM研究显示,试样经过100℃×22h空气老化后的超微结构受破坏程度比较轻微,试样经过70℃×166h空气老化后超微结构受破坏程度比较严重。

This paper deals with the study of the thermooxidative degradation reaction mechanism and ultrastructure of the medical natural rubber latex tubes prepared with peroxide prevulcanized natural rubber latex （PPVL） by the thermogravimetric analysis （TGA） and SEM. The thermogravimetry / differential thermal gravity （TG-DTG） curves showed that the oxidative degradation reaction of the sample was a two-stage reaction and an oxygen-absorption mass-gain process occurred after slight mass loss. The mass-gain rate decreased with the increment of the temperature rising rate （β） . The mass-gain peak temperature was 187.9 ℃ and the mass-gain rate was 1.33% when β was 5℃/min. Both the frequency factor （ A ） and the activation energy of reaction （E） in the first and the second reaction stage increased with the increment of β. The test results of SEM showed that uhrastructure of the sample after ageing with 70℃ × 166h was much poorer than that of the sample after ageing with 100℃ × 22h.