废旧轮胎热解行为的TG/DTA研究

运用热重/差热联用仪（TG/DTA）研究了4种废旧轮胎样品及3种橡胶原料（天然橡胶、丁苯橡胶、顺丁橡胶）的热解行为,通过TG/DTA数据计算了各个降解阶段的热解动力学参数（表观活化能和指前因子）,并确定了轮胎中的橡胶类型（天然胶和合成胶）,得到其基本组成（有机助剂、橡胶、炭黑和无机助剂）的含量,为进行废旧轮胎的转化利用提供基础数据。结果表明:橡胶原料、轮胎样品的热解过程均可划分为两个一级反应阶段,其中轮胎样品的第1段热解活化能比第2段的小,随着反应温度的升高及转化深度的增大,热解对温度的依赖程度增大;废轮胎样品中可热解部分为64％～66％,炭黑为30％～33％,灰分为3％～6％;升温速率可明显地改变轮胎样品的热解历程,但对热解产物的收率影响甚微;天然橡胶的热解失重和合成橡胶的解聚使废旧轮胎的热解表现为一放热过程。

PYROLYSIS OF TIRES AND TIRE COMPONENTS BY TG/DTA ANALYZER

Four different used tire samples were pyrolysed in a TG/DTA analyzer under N2. The tire samples showed two distinct weight losses in TG/DTG profiles, representing decomposition at a lower and a higher temperature. The major rubber ingredients of the tires, natural rubber (NR), styrene -butadiene rubber (SBR) and polybutadiene rubber (BR), were pyrolysed separately under the same conditions. NR decomposed mainly at a lower temperature, SBR and BR at a higher temperature. In addition, different heating rates affected the shape of DTG curves in tire samples pyrolysis. It was found that tires and rubber ingredients pyrolysis can be described by 1st order kinetics. The kinetic parameters (pre - exponential factor and apparent activation energy) were determined in Arrhenius plots with two linear regions. Also, tire samples composition was obtained by using TGA, in general, 6% - 9% volatile matters, 55% - 60% rubber, 30% - 33% carbon black, and 3% - 6% ash. The DTA results showed that the pyrolysis of tires is an exothermic process which may result from synthetic rubber depolymerization and natural rubber pyrolysis weight loss.