【作者】 杨杰；

【导师】 王军； 唐涛；

【作者基本信息】 哈尔滨工程大学 ， 工程硕士（专业学位）， 2014， 硕士

【摘要】 随着碳纤维复合材料的广泛使用,材料加工过程以及碳纤维复合材料报废之后产生大量废料。为避免将废弃的碳纤维复合材料掩埋处理,同时回收高价值的碳纤维,碳纤维回收方法不断发展。热分解法是回收碳纤维增强聚合物复合材料的一种常用方法,但是纤维表面会形成残炭,影响回收碳纤维的再应用。空气中热处理过程可以除去残炭,但同时碳纤维也会发生氧化,导致力学性能降低。为了得到表面干净并且力学性能没有严重下降的回收碳纤维,本课题研究了氧浓度对碳纤维增强4, 4’-二氨基二苯甲烷固化环氧树脂复合材料热分解的影响。首先对碳纤维增强环氧树脂复合材料的热分解动力学进行了研究。将高纯氮气和高纯氧气分别以95 : 5、90 : 10的体积比混合得到气体5 %O2、10 %O2。分别在N2、5 %O2和空气条件下以5、10、15和20℃/min的升温速率进行热重分析。动力学分析采用Kissinger法和Flynne-Wall-Ozawa (FWO)法确定热分解过程阿仑尼乌斯方程动力学参数:活化能E和指前因子A;然后采用Coats Redfern法确定碳纤维复合材料的热分解机理函数,最后通过动力学结果计算一定温度和氧浓度下碳纤维复合材料中树脂基体完全分解所需要的时间。研究结果表明,有氧条件下树脂基体热分解包含与氮气条件下相同的阶段,氧浓度改变主要影响积炭氧化过程。热分解实验在固定床反应器中进行。反应气体为5%O2、10%O2和空气。研究发现,温度是影响复合材料热分解最重要的因素,氧气浓度也需要严格控制。采用单丝拉伸测试、扫描电子显微镜、表面界面张力仪和X射线光电子能谱对回收碳纤维的性能进行了表征。随着氧浓度、反应时间和温度的增加,回收碳纤维表面的积炭逐渐减少,但其力学性能下降。5%O2气氛下回收的碳纤维力学性能明显高于10%O2和空气气氛中回收碳纤维的力学性能。反应温度为650 ℃,反应气氛为5%O2,反应时间为45分钟时,回收碳纤维的拉伸强度约为原纤维强度的83%。有氧条件下处理之后,碳纤维表面的含氧基团含量增加。另外,对热分解反应的物料衡算和树脂的分解产物也进行了分析。碳纤维复合材料在氮气和有氧条件下的热分解产物并不相同,氧气在热分解时有氧化作用。更多还原

【Abstract】 With the increasing use of CFRP, substantial waste is generating during manufacture as well as at the end of the service life of the composite. In order to reclaim the valuable carbon fiber in CFRPs and to avoid landfill of CFRPs, various recycling techniques have been developed. Pyrolysis is a common method for recycling CFRP. However, carbonized residue is preferred to form on fiber surface. Thermal processing in air could eliminate the carbonized residue but the mechanical strength of the inherent fiber tends to be damaged by oxidation.For the purpose of reclaiming clean carbon fibers without severe reduction in tensile strength,we investigated the influence of the oxygen concentration in nitrogen on the thermal decomposition of carbon fiber reinforced 4, 4’-diaminodiphenylmethane cured epoxy resin composites.A kinetic study on the thermal degradation of CFRP was presented. The gas 5%O2 was a mixture of high purity nitrogen and high purity oxygen at a volume ratio of 95 : 5. The gas 10%O2 was a mixture of high purity nitrogen and high purity oxygen at a volume ratio of 90:10. The degradation behavior was investigated by means of dynamic thermogravimetric analysis ( TG ) in 5%O2, air and inert atmosphere at heating rates from 5 to 20 ℃/min. The overall rate equation can be modeled by an Arrhenius-type equation, from which the kinetic parameters such as the activation energy and the pre-exponential factor were determined by using Kissinger method and FWO method. The probable decomposition mechanism function of CFRP was also obtained by Coats Redfern method. The information about the kinetic parameters based only on thermal degradation data has been used for a quick estimation of lifetime of CFRP at different temperatures and atmosphere. The pyrolysis pocess of CFRP in oxygen-containing gas also included the process in nitrogen. The increase of oxygen concentration accelerate the oxidation of carbonized residue.The pyrolysis experiments were conducted in a fixed bed reactor. 5%O2, 10%O2 and air were used as reactant gas. Temperature was proved to be most critical to the decomposition of CFRP. Oxygen concentration should be carefully designed. The properties of the recycled carbon fiber were characterized using single-filament tensile test, SEM and XPS. With the increase of oxygen concentration, reaction time and temperature, the mechanical properties of recovered fibers decreased and the deposited char on the fiber was removed. The recovered fibers in 5%O2 show much better mechanical properties than that of the fibers recovered in 10%O2 and air. Tensile strength of 650-5%-45 was about 83% of the strength of virgin fiber.The content of the oxygenated functional groups increased after treating in oxygen containing atmosphere. The surface energy of fibre recycled had no obvious change. The end of this paper includes the mass balance of the decomposition reaction and a detailed characterization of the decomposition products of epoxy resin. The components were identified by GC and GC/MS. The decomposition products in nitrogen were different from that in oxygen-containing gas, which indicated the oxidation of epoxy resin.更多还原