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首页> 外文会议>SPE(Society of Plastics Engineers) International Polyolefins Conference 2007 vol.1 >Nitroxyls for Control of Free Radical Crosslinking of Polyolefins During Reactive Extrusion and Vulcanization
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Nitroxyls for Control of Free Radical Crosslinking of Polyolefins During Reactive Extrusion and Vulcanization

机译：硝基酚用于反应性挤出和硫化过程中聚烯烃自由基交联的控制

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摘要

Polyolefin cross-linking via free radical chemistry is commonly practiced to improve properties such as high temperature resistance, toughness and chemical resistance. Cross-linking of polyolefins by free radical initiation using organic peroxides generally follows a two-step approach. In a first step, the cross-linkable compound is melted and extruded in a thermoplastic fashion for a short time at temperatures low enough to prevent substantial peroxide decomposition. Then, once shaped into the desired form, the product is heated to higher temperatures to accelerate decomposition of the peroxide and complete the cross-linking step. One key challenge facing the processor is premature decomposition of peroxide during extrusion causing undesirable defects. This work focuses on the use of a certain class of scorch inhibitors to enable control of free radical chemistry. In the bulk of this paper, we present results on the use of both a mono-functional and a bi-functional nitroxyl for cure control in cross-linking of polymers such as low density polyethylene (LDPE) and ethylene-propylene-diene monomer (EPDM). We also present some findings on the use of a bi-functional nitroxyl to mitigate the chain scission that is dominant during the high temperature processing of polypropylene in the presence of organic peroxide, by coupling of polymer chains.
机译：通常通过自由基化学进行聚烯烃交联以改善诸如耐高温性，韧性和耐化学性的性能。使用有机过氧化物通过自由基引发进行的聚烯烃交联通常遵循两步法。第一步，将可交联化合物在足够低的温度下熔融并以热塑性方式短时间挤出，以防止过氧化物大量分解。然后，一旦成形为所需的形式，就将产物加热至更高的温度以加速过氧化物的分解并完成交联步骤。加工者面临的一个关键挑战是挤出过程中过氧化物的过早分解会导致不良的缺陷。这项工作的重点是使用某种防焦剂来控制自由基的化学作用。在本文的大部分内容中，我们介绍了使用单官能和双官能硝酰基用于控制交联聚合物（例如低密度聚乙烯（LDPE）和乙烯-丙烯-二烯单体（ EPDM）。我们还提出了一些关于使用双官能硝酰基通过聚合物链的偶联来减轻聚丙烯在有机过氧化物存在下的高温加工过程中占主导地位的断链的发现。

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