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图2是废弃汽车塑料保险杠颗粒在加热速率为10、15、20 K/min，温度范围为30～850 ℃内的TG和DTG曲线。由图可知，材料的分解分为两个阶段，分别发生在300~500 ℃和600~750 ℃。当温度低于200 ℃时，基本不发生热解反应。10 K/min的升温速率时，汽车PP保险杠在348～504 ℃温度范围内存在一个明显的失重峰，有64.34%的挥发分在该阶段析出；在605～740℃温度范围内存在一个较为缓和的失重峰，有12.05%的样品失重量，残余重量为23.61%；两失重阶段的失重峰值温度分别为428 ℃和702 ℃。随升温速率的提高，原料的起始失重温度和最快失重温度都有不同程度的升高，起始失重温度对应的失重量亦有明显的增加。随着升温速率的加快，DTG峰明显增大，表明提高升温速率，能显著提高原料的热解速率；而不同升温速率下的TG曲线基本没有变化，说明热解温度对热解进程具有决定性影响，升温速率的提高不能改变某一温度区间内的热解反应进程。 聚丙烯中存在的大量叔碳原子，使其热稳定性较差；聚丙烯的热分解均在较窄的温度范围内一步完成而且几乎无残余物[3]。苟进胜等[4]研究表明：在10 K/min的升温速率下，PP塑料的最大热解速率出现在480.2 ℃，热解温度区间为444～493 ℃；吴靖[5]研究表明：EPDM（三元乙丙橡胶）的热解温度区间为280～520 ℃。本实验中，废弃汽车塑料保险杠在10 K/min的升温速率热解时，第一阶段的失重温度范围为348～504 ℃，但由于原料是一种复杂的混合物，使得热解温度区间变宽。第一阶段主要为PP和EPDM的热分解，第二阶段的热解可能是无机填料的高温分解。以上均与中国保险杠专用料主要采用PP/EPDM共混改性[6]相一致。 软件翻译无效哦，谢谢大家。 |
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xinyi8853(金币+20,VIP+0): 11-24 08:13
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Figure 2 is the curves that a rubbish car plastic bumpers particles in the heating rate of 10,15,20 K / min, temperature range of 30 ~ 850 ℃ within the TG and DTG . From the figure we can see that decomposition of the material is divided into two phases, respectively, occurred in the 300 ~ 500 ℃ and 600 ~ 750 ℃. When the temperature is below 200 ℃, the basic pyrolysis reaction does not occur. at the 10 K / min heating rate, the car PP bumper at 348 ~ 504 ℃ temperature range of will express in obvious weight loss peaks, there are 64.34% of the volatile matter precipitates at this stage; in the 605 ~ 740 ℃ temperature range there will be a the a relatively moderate weight loss peak, there are 12. 05% of the sample weight loss and residual weight of 23.61%; the two weight loss weight loss phase of the peak temperatures were seprately 428 ℃ and 702 ℃. With the increase of heating rate, initial weight loss temperature of raw materials and the fastest weight loss temperatures will have different varying degrees .The initial weight loss temperature of the corresponding weight loss will also increase significantly. As the heating rate of speed up, DTG peak increased significantly, indicating increased heating rate, can significantly improve the rate of thermal decomposition of raw materials; while under different heating rates unchanged TG curve shows that the pyrolysis temperature has a decisive influence on pyrolysis process ,increase heating rate can not be change the thermal decomposition reaction of the process within a certain temperature range . There exists a large number of tertiary carbon atoms in the Polypropylene which make poor thermal stability; thermal decomposition of polypropylene are in a narrow temperature range in one step and almost no residue . Gou Jin-sheng et al [4] studies have shown that: with the 10 K / min heating rate, PP plastic 'pyrolysis rate of the largest at the 480. 2 ℃, the pyrolysis temperature range between 444 ~ 493 ℃; Wu Jing, [5] studies have shown that: EPDM (ethylene propylene diene rubber) the pyrolysis temperature'range is at 280 ~ 520 ℃. In this study, the scrap automotive plastic bumpers at 10 K / min heating rate pyrolysis, the first phase of the weight loss temperature range at 348 ~ 504 ℃, but with a complex mixture of raw materials which make the pyrolysis temperature range change widely. The first stage of mainly the thermal decomposition of PP and EPDM, the second phase of the pyrolysis may be high-temperature decomposition of inorganic fillers. Special Material of the above which is related to China bumper majorly adopt PP / EPDM blends modified [6] |
2楼2009-11-17 20:24:06