摘 要

聚合物都会发生老化现象。尽管高密度聚乙烯（HDPE）具有明显的优势，应用非常广泛，从理论上来说不易发生老化，但由于它组成较复杂，有多种影响它老化的因素，其中包括因为合成而带来的溶剂、引发剂和催化剂等小分子物质。因此选择加入抗氧剂和紫外光吸收剂来改善HDPE的耐紫外光性能。

本文采用傅里叶变换红外光谱（FTIR）、差示扫描量热法（DSC）、力学性能测试，热分析测试（TG）等测试手段,研究了抗氧剂和紫外光吸收剂对HDPE的结构以及耐老化性能上的影响，并且进行在相同温度下添加不同复配比例的抗氧剂和不同复配比例的外光吸收剂的HDPE的性能的对比，综合评价了加入抗氧剂和紫外光吸收剂对HDPE的性能影响，除此之外还讨论了在哪种复配体系下对HDPE的耐紫外光性能有更好的影响，将从理论上对其机理进行讨论分析。

通过FTIR可以看出，老化时间的增加明显促进了HDPE分子链的氧化反应，HDPE的官能化速度明显加快。可以明显看出在老化400h之后加入紫外光吸收剂的HDPE的红外光谱图变化最小，而加入抗氧剂后的HDPE在不同光照时间下出现了明显不同的谱带。通过DSC可以看出，对比纯HDPE，加入抗氧剂和紫外光吸收剂的样品峰值明显向高温方向移动，可以明显的地看出起始熔融温度和终止熔融温度升高，熔融峰也变宽了，但结晶度有微小的降低。通过TG可以看出所有的样品的热分解只有一个失重阶段，并且都可以完全分解挥发，没有残留物。加入抗氧剂和紫外光吸收剂的样品的热分解温度大约在400 ^oC，而纯的HDPE的热分解温度在425 ^oC附近，说明纯HDPE的热稳定性要高于加入抗氧剂和紫外光吸收剂的HDPE。通过力学性能图可以看出加入抗氧剂或是紫外光吸收剂对HDPE的拉伸强度和断裂伸长率都有一定程度的提高，但加入紫外光吸收剂的HDPE的拉伸强度和断裂伸长率要明显高于加入抗氧剂的HDPE和纯HDPE。

关键词：HDPE 老化 抗氧剂 紫外光吸收剂

Effects of Antioxidants and Ultraviolet Absorbers on the UV Resistance of HDPE

Abstract

High-Density Polyethylene（HDPE）is a kind of polymer with excellent performance. Compared with low-density polyethylene, its composition is more complex, and there are many factors that affect its aging. Among them, there are residual small-molecule substances such as solvents, initiators, and catalysts that are produced by the synthesis, which will affect its oxidation and cause oxidation. More complicated. Therefore, the research on the oxidation and UV-resistance of HDPE is of positive significance.

In this paper, FTIR, DSC, mechanical property test, and TG were used to study the aging structure of HDPE by antioxidants and UV absorbers. The effect of the processing stability and the impact on the aging resistance, and the performance performance of the HDPE with different compounding ratios of antioxidants and different compounding ratios of external light absorbers at specific temperatures were compared to comprehensively evaluate the addition of antioxidants. The effect of UV absorbers and UV absorbers on the performance of HDPE, and discussed in which compound system has a better impact on the UV-resistant properties of HDPE, will theoretically discuss its mechanism.

It can be seen from the FTIR that the increase of aging time significantly promotes the oxidation reaction of the HDPE molecular chain, and the functionalization speed of HDPE is significantly accelerated. It can be clearly seen that the infrared spectrum of HDPE added with UV absorber after 400 h aging has the smallest change, while the HDPE with antioxidant has significantly different bands under different illumination time. It can be seen from DSC that, compared with pure HDPE, the peaks of the samples added with antioxidants and UV absorbers move significantly towards the high temperature. It can be clearly seen that the initial melting temperature and the termination melting temperature increase, and the melting point also increases. However, there is a slight decrease in crystallinity. It can be seen from the TG that the thermal decomposition of all samples has only one weight loss stage, and all can be completely decomposed and volatilized without residue. The thermal decomposition temperature of the samples with antioxidants and UV absorbers was about 400 ^oC, while the thermal decomposition temperature of pure HDPE was around 425 ^oC, indicating that the thermal stability of pure HDPE is higher than that of antioxidants and ultraviolet light. From the mechanical properties, it can be seen that the addition of antioxidant or UV absorber has a certain degree of increase in the tensile strength and elongation at break of HDPE, but the tensile strength and breaking elongation of HDPE added with UV absorber The growth rate is significantly higher than HDPE and HDPE with antioxidants added.

Keywords：HDPE；Aging；Antioxidants；UV absorber

目 录

摘 要 I

Abstract II

第一章 前言 1

1.1 课题背景 1

1.2 本课题工作 1

第二章 文献综述 2

2.1 HDPE的光氧化机理 2

2.2 抗氧剂 2

2.2.1 抗氧剂的抗氧作用和机理 3

2.2.2 抗氧剂之间的相互作用 3

2.3 紫外光吸收剂 3

2.4 本论文使用的抗氧剂和紫外光吸收剂 3

2.5 国内外进展 4

第三章 实验部分 5

3.1 实验原料 5

3.2 实验仪器与设备 5

3.3 实验配方 5

3.4 样品制备 6

3.5 测试与表征 6

3.5.1 傅里叶红外光谱测定 6

3.5.2 差示扫描量热仪测定 6

3.5.3 热重测定 7

3.5.4 力学性能测定 7

第四章 结果与讨论 8

4.1 傅里叶变换红外光谱分析 8

4.2 差示扫描量热法分析 9

4.1 热重分析 10

4.2 力学性能分析 11

第五章 结论 13

参考文献 14

致谢 16

第一章 前言

1.1 课题背景

高密度聚乙烯（HDPE）为无毒、无味的白色粉末或颗粒，它的应用十分广泛，可以用来制成各种各样的容器、工业配件等。几乎所有聚合物都会产生老化现象，聚乙烯也不例外。老化^[1]基本可以分成两种情况，一种是物理老化，另一种是化学老化。化学老化是指材料在其合成加工或者应用当中接触到了热、氧、光从而导致材料发生不良的变化，它会导致材料的颜色发黄，材质变差，材料变脆，最后使材料丧失了价值，无法使用。如果发生的是物理老化，那老化现象是可逆的，但如果发生的是化学老化，那老化现象是不可逆的。其实，老化现象的产生主要就是由聚合物中的一些自由基和氢过氧化物引起的，例如不饱和双键、支链、羰基、末端羟基等，在光、氧等外界环境因素的影响下，聚合物得到进一步的老化。在紫外光的照射下，聚乙烯材料会发生光氧化作用，产生自由基链式反应，分子结构产生变化，链段中发生交联或者降解情况，加快老化的进行。因为在平常工业生产中会对HDPE进行加工合成，会引入一些容易发生氧化反应杂质，这样HDPE在平常实际应用当中还是会发生光氧化作用而老化，所以选择加入光稳定剂和抗氧剂来阻断链式反应的继续进行，以此来提高HDPE的耐紫外光性能。

1.2本课题工作