Xuefan Yang , Xiaochen Dong , Mengna Liu , Haoqi Xing , Jichun Liu , Haibo Chang , Tong Lin
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引用次数: 0
Abstract
The most conspicuous problem regarding fire retardation of ethylene vinyl acetate (EVA) copolymer is that the flame-retardant efficiency of traditional fire retardants is very low. How to achieve high-efficient flame retardation has long been a big challenge. Herein, polyurea-modified microencapsulated expandable graphite (MEG) was synthesized through in-situ polymerization, and it was found that the proper combination of MEG and polyphosphoric acid (PPA) exhibits an unexpectedly high flame-retardant efficiency to EVA. The incorporation of just 5 wt% MEG/PPA enables EVA to achieve V-0 rating in UL-94 flammability test, increases its limiting oxygen index from 19.3 % to 25.7 %, and reduces its peak heat release rate by 72 % during combustion. The EVA/MEG/PPA composite, containing 5 wt% MEG/PPA, not only demonstrates improved fire retardancy, smoke suppression, and processability compared to virgin EVA, but also maintains good electrical insulation, water resistance, and mechanical properties. The high fire-retardant efficiency is ascribed to the larger expansion volume of MEG and the formation of high-quality intumescent char, which shield the polymer from burning. This work renders a simple and cheap approach for development of high-efficient flame-retarded EVA with good processability and mechanical property simultaneously.
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.