Embrittlement induced by oxidation in polyethylene: Role of initial bimodality

IF 6.3 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability Pub Date : 2024-10-17 DOI:10.1016/j.polymdegradstab.2024.111025

R. Laot , P.-Y. Le Gac , M. Le Gall , M. Broudin , C. Ovalle , L. Laiarinandrasana

引用次数: 0

Abstract

High density polyethylene films (200 µm) with an initial bimodal chain length distribution were aged in ovens at 60 °C, 70 °C, and 80 °C. Oxidation effects were characterized at the macromolecular scale to measure the chain length distribution, the amount of crystalline phase, the type of crystallites, and the thickness of the amorphous layer. Additionally, mechanical properties were measured using tensile tests. Regardless of the aging temperature, the same behavior was observed: bimodal chain length distribution became unimodal, the crystallinity ratio increased, the amorphous layer thickness decreased, and the polyethylene became brittle. The embrittlement of the polymer is discussed, and two criteria are proposed: a critical molar mass and a critical amorphous layer thickness. The latter appears to be independent of the initial chain length distribution of the polyethylene.

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聚乙烯氧化引起的脆化：初始双模性的作用

初始链长分布为双峰的高密度聚乙烯薄膜（200 微米）在 60 ℃、70 ℃ 和 80 ℃ 的烘箱中老化。通过测量链长分布、结晶相的数量、结晶体的类型和无定形层的厚度，对氧化效应进行了大分子表征。此外，还使用拉伸试验测量了机械性能。无论老化温度如何，都观察到了相同的行为：双峰链长分布变为单峰，结晶度比率增加，无定形层厚度减少，聚乙烯变脆。对聚合物的脆性进行了讨论，并提出了两个标准：临界摩尔质量和临界无定形层厚度。后者似乎与聚乙烯的初始链长分布无关。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Polymer Degradation and Stability 化学-高分子科学

CiteScore

10.10

自引率

10.20%

发文量

325

审稿时长

23 days

期刊介绍： Polymer Degradation and Stability deals with the degradation reactions and their control which are a major preoccupation of practitioners of the many and diverse aspects of modern polymer technology. Deteriorative reactions occur during processing, when polymers are subjected to heat, oxygen and mechanical stress, and during the useful life of the materials when oxygen and sunlight are the most important degradative agencies. In more specialised applications, degradation may be induced by high energy radiation, ozone, atmospheric pollutants, mechanical stress, biological action, hydrolysis and many other influences. The mechanisms of these reactions and stabilisation processes must be understood if the technology and application of polymers are to continue to advance. The reporting of investigations of this kind is therefore a major function of this journal. However there are also new developments in polymer technology in which degradation processes find positive applications. For example, photodegradable plastics are now available, the recycling of polymeric products will become increasingly important, degradation and combustion studies are involved in the definition of the fire hazards which are associated with polymeric materials and the microelectronics industry is vitally dependent upon polymer degradation in the manufacture of its circuitry. Polymer properties may also be improved by processes like curing and grafting, the chemistry of which can be closely related to that which causes physical deterioration in other circumstances.