Chemical interactions between polyamide 66 and phosphorus flame retardants

IF 6.3 2区化学 Q1 POLYMER SCIENCE

Polymer Degradation and Stability Pub Date : 2025-05-22 DOI:10.1016/j.polymdegradstab.2025.111435

Zixuan Zheng , John Lou Yao , Qiang Yao

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引用次数: 0

Abstract

To elucidate chemistry taking place during thermal degradation of polyamide 66 in the presence of phosphorus flame retardants and understand how commonly used phosphorus flame retardants achieve their flame retardancy, PA66 and a series of model compounds which include N,N'-dibutylhexanediamide, 1-butylazepane-2,7-dione and 1,8-diazacyclotetradecane-2,7‑dione have been subjected to thermal treatments together with melamine polyphosphate, aluminum diethylphosphinate or their combination respectively. Analyses of degradation products indicate that aluminum diethylphosphinate accelerates a cyclization reaction but does not change degradation mechanisms of polyamide 66 and its model compounds while melamine polyphosphate significantly shifts their degradation pathways to dehydration via a modified Hofmann elimination reaction which produces adiponitrile and water. Adiponitrile intumesces strongly when heated with polyphosphoric acid. Water hydrolyzes amides to amines, accompanied by the formation of amino-6-oxohexanoic acid which cyclizes to cyclopentanone. Water and amines together convert aluminum diethylphosphinate to diethylphosphinic acid. On the basis of the identification and transformation of reactive species, modes of flame retardant action of the combination of aluminum diethylphosphinate and melamine polyphosphate for PA66 have been proposed.

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聚酰胺66与磷系阻燃剂的化学相互作用

为了阐明在磷系阻燃剂存在下聚酰胺66热降解过程中发生的化学反应，并了解常用的磷系阻燃剂是如何实现其阻燃性的，我们将PA66和一系列模型化合物（包括N，N'-二丁基己二胺、1-丁氮杂烷-2,7-二酮和1,8-二氮杂环四环-2,7-二酮）与聚磷酸三聚氰胺一起进行了热处理。二乙基膦酸铝或它们的组合。降解产物分析表明，磷酸二乙酯铝加速了环化反应，但不改变聚酰胺66及其模型化合物的降解机制，而聚磷酸三聚氰胺通过改进的霍夫曼消除反应将其降解途径显著转向脱水，产生己二腈和水。己二腈在与多磷酸加热时发生强烈的膨胀。水将酰胺水解成胺，同时生成氨基-6-氧己酸，该氨基-6-氧己酸环戊酮。水和胺一起将二乙基磷酸铝转化为二乙基磷酸。在对反应物质进行鉴定和转化的基础上，提出了磷酸二乙基铝与聚磷酸三聚氰胺复合对PA66的阻燃作用模式。

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.