PET降解及绿色改性的研究

发布时间：2018-07-08 20:45

  本文选题：聚对苯二甲酸乙二醇酯 + 降解　； 参考：《湖北工业大学》2017年硕士论文

【摘要】：聚对苯二甲酸乙二醇酯(PET)具有优异的力学性能、耐摩擦性能、热稳定性能以及尺寸稳定性能等,在传统的纺织纤维、薄膜以及聚酯瓶等方面有着广泛的应用。但由于PET使用范围广,生产以及消费中产生的废弃PET也逐年增加,而PET本身热稳定性良好,自然状态下完全降解需要数十年,故而造成了极为严重的环境污染问题以及资源浪费问题。PET分子结构与市场上的苯乙烯-丙烯酸丁酯树脂(简称碳粉树脂)有许多的共同之处。本文以废弃的PET瓶片为原料,根据苯丙树脂的相关性能要求,对其进行改性研究。文中先使用醋酸锌-丙三醇对PET进行降解以降低其分子量,再分别采用聚对苯二甲酸丁二醇酯与之进行酯交换反应以破坏其分子链规整性,使用PMMA与之进行酯交换反应以在其分子链上进行接枝,最后通过乌氏粘度计、旋转流变仪、差示扫描量热仪、X射线衍射仪以及热失重分析仪等仪器对其分子量、酯交换反应情况、结晶性能以及热稳定性能进行了表征。实验表明:(1)丙三醇的加入使PET分子链上出现三元环醚结构,当丙三醇含量为2%时,PET瓶片测得的的分子量下降到5022,其熔体粘度有所下降,偏光显微镜下的结晶亮点变得细小而稀疏,XRD测得的晶粒尺寸显著下降,结晶速率降低,DSC下测得的结晶度下降到21.48%,热分解温度从406.6 ℃下降到393.5 ℃。(2)通过反应性流变测试可以明显看出,PBT与PET熔融共混后,样品的熔体粘度先增加,反应15min后逐渐稳定。当PBT含量为10%时,样品的熔体粘度最高,结晶速率明显下降,DSC测得的结晶度下降到12.42%,偏光显微镜下的图片亮点极为稀少,XRD测得的晶粒尺寸变化不明显,热分解温度下降到390.1 ℃。(3)使用旋转流变仪能够明显的观察到PMMA与PET酯交换反应后,样品的熔体粘度逐渐增大,可见PMMA通过酯交换反应接枝到PET中去。当PMMA含量为10%时,样品在偏光显微镜下的结晶形貌已经极为稀疏,晶粒尺寸变化不明显,结晶速率显著下降,测得的结晶度为14.18%,热分解温度下降到385.34 ℃。
[Abstract]:Poly (ethylene terephthalate) (PET) has been widely used in traditional textile fibers, films and polyester bottles for its excellent mechanical properties, friction resistance, thermal stability and dimensional stability. However, due to the wide use of PET, the waste PET produced in production and consumption has increased year by year, and the thermal stability of PET itself is good, and it takes decades to completely degrade PET in natural state. The molecular structure of PET has much in common with the styrene-butyl acrylate resin in the market. In this paper, the waste PET bottle was used as raw material, and the modification of the resin was studied according to the properties of styrene-acrylic resin. In this paper, PET was degraded by zinc acetate and glycerol in order to reduce its molecular weight, and then polybutylene terephthalate was used for transesterification to destroy its molecular chain regularity. PMMA was used for transesterification to graft onto its molecular chain, and its molecular weight was finally obtained by means of the Wurtzian viscometer, the rotary rheometer, the differential scanning calorimeter (DSC), the X-ray diffractometer and the thermogravimetric analyzer. The transesterification, crystallization and thermal stability were characterized. The experimental results show that: (1) the structure of ternary cycloether appears in PET molecular chain with the addition of glycerol, and the molecular weight of PET bottle decreases to 5022 when the content of glycerin is 2, and the melt viscosity decreases. The crystalline bright spots under the polarizing microscope become small and the grain size measured by the sparse X-ray diffraction (XRD) decreases significantly. The crystallization rate decreased to 21.48% and the thermal decomposition temperature decreased from 406.6 鈩，

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