摘要
使用热重分析法(TGA)研究了空气状态下过氧化物预硫化天然胶乳(PPVL)制备的医用胶乳胶管试样的热氧降解反应过程及其反应动力学。TG-DTG曲线显示,试样氧化降解过程为二步反应,DTG曲线相应出现明显主降解峰和次降解峰,它们失重1%时的温度(TO)、降解峰温度(Tp)、终止温度(Tf)均随升温速率(β)的增加而向高温方向偏移,降解速率也随之增大。在第1步降解反应前,试样出现明显的氧化增重现象,增重峰的温度随β的增加而升高,而增重率随β的增大而减少;试样β为5℃/min的增重峰温度187.9℃,增重率1.33%。第1步反应的最大热氧降解率(CP1)、最终热氧降解率(Cf1),反应活化能(E)随着β的增加而增加;表观活化能E0=107.5kJ/mol;不同β的降解反应级数(n)均是1.7,不受β的影响。第2步反应的CP2和Cf基本上不受β的影响;n随β的大小而不同,但二者无相关关系;E随β的增加而增加,E0=154.0kJ/mol。第1步反应和第2步反应的频率因子(A)均随β的增加而几乎呈几何级数增加。第1步反应最大相关系数r均在0.999以上,第2步反应的r均在0.982以上。各升温速率试样在600℃降解率为99.2%￣99.5%不等。
Thermo-oxidative degradation reaction and its kinetics of the medical rubber latex tube samples prepared from PPVL （peroxide prevulcanized natural rubber latex） in air atmosphere with the temperature rising rates （β） at 5℃/min, 10 ℃/min, 15 ℃/min, 20 ℃/min, 25 ℃/min and 30 ℃/min were studied by the thermog ravimetric analysis （TGA） method. The results of TG-DTG curves showed that the oxidative degradation of the samples was a two-stage reaction. The temperature at 1% weight loss T0.01, the degradation peak temperature Tp and the final temperature Tf were shifted towards the high temperature side with an in crease in.β, and the degradation rate was increased at the same time. The samples displayed obviously an oxidative weight gain before the first stage of degradation reaction, and the temperature of the weight gain peak rose with β, but the weight gain rate decreased; the peak temperature of weight gain was 187.9 ℃ and the weight gain rate 1.33 % when the temperature rising rate .8 of the test samples was 5 ℃/min. At the first stage the maximum rate of thermo-oxidative degradation （Cp）, the final rate of thermo- oxidative degradation（Cf） and the activation energy of reaction（E） were also increased with β; the apparent activation energy Eo was 107.5 kJ/mol; the degradation reaction order （n） of different β was 1.7 but not influenced by β. The Cr2 and Cf at the second stage were not affected by β virtually; n varied with different β, but had no correlation between each other; E increased with β with Eo=154.0 kJ/mol. The frequency factor （A） at the first and second reaction stages increased almost geometrically as .8 increased. The maximum correlation coefficients r at the first and second stages of reaction were above 0.999 and 0.982 respectively. The samples under various temperature rising rates had a degradation rate of between 99.2 % and 99.5 % at 600 ℃.
出处
《热带作物学报》
CSCD
2005年第1期20-24,共5页
Chinese Journal of Tropical Crops
基金
国家自然科学基金资助项目(50063002)
中国热带农业科学院科技基金重点项目
关键词
医用胶乳制品
PPVL
TGA
氧化增重
热氧降解
动力学
medical rubber latex product PPVL TGA oxidative weight gain thermo-oxidative degradation kinetics
作者简介
陈美男，1949年生，大学本科，研究员。研究方向：天然橡胶性能与加工工艺。发表论文约50篇。E-mail：chgdzjcm@yalaoo.com.cn。
