Study On Halogen-free Flame Retardant Ethylene-Vinyl Acetate Copolymer By Microencapsulated Palygorskite

Polymers has been widely used in modern industries,but one of major drawbacks of polymers is its poor fire performance.With the more and more application of polymers,the requirements foused on its safety was also become higher and higher.A series of colorful and innovative products made from polymers have come into our families,at the same time,it is necessary to ensure that these products are not only attractive,but also have high fire safe factors.The EU has proposesed to limit the use of brominated biphenyl oxide flame retardants due to the high toxicity and potential carcinogenic formation of brominated furan and dioxin in the combustion process.Therefore,the development of flame retardant materials needs to comply with strict safety regulations.A major method for the recreasing of the combustibility of the polymers is the use of retardant.Because it can not only decrease the combustibility,but also can depress the formstion of smoke and toxic gases after polymers was ignited.The preparation of effective flame retardant materials to reduce or avoid the fire threats has become an urgent problem which should to be further studied.Many flame retardants are hydrophilic,they have poor compatibility with the matrix of the polymer,and sometimes thay are toxic and corrossive.These shortcomings lead to a decrease in the performance of polymer composites,not only in flame retardant properties,but also in other application performance.Considering the above problems,several methods such as ultrafine processing,coupling agent modification,and microcapsule surface modification with a hydrophobic polymer has been employed.In recent years,it was reported that microcapsule technologies has been applied as a very effective method in the preparation of flame retardants.As a layered silicate mineral,palygorskite(PGS)is very abundant reserved in our country as well as in Gansu province.Due to its big specfic surface area,high absorbility,good rheology,ideal colloidal performance and good heat resistance,PGS has been widely applied in the research of flame retardant.But its flame retardance is poor when PGS is solely used as a flame retardant.Therefore,it becomes an important task to improve the flame retardancy and compatibility of PGS for manychemists.In this paper,microcapsule technologies were used to modify PGS to improve its flame retardancy.The main contents and conclusions are as follows:1.A novel organic-inorganic hybrid flame retardant of PGS@B-N was prepared via the microcapsulational decoration of palygorskiteby boric acid(B)and dodecylamine(N),and was incorporated with EVA(EVA = ethylene-vinyl acetate copolymer)to improve its flame retardancy.The structure and morphology of PGS@B-N were characterized by the scanning electron microscopy(SEM).The flame retardancy and the application performance of EVA/PGS@B-N/EG(EG =expandable graphite)composites were studied through the mechanical property test,the thermogravimetric analysis(TGA),the limiting oxygen index(LOI),the vertical burning test(UL-94),and the cone calorimeter test(CCT).It was found that the PGS@B-N particles have good dispersion in the composite owing to their good interaction with EVA resin,which can effectively improve the thermal stability and the flame retardancy of the composite.2.A novel organic-inorganic hybrid flame retardant of PGS@P-N was prepared via the microcapsulational decoration of PGS by phosphoric acid(P)and dodecylamine(N),and was incorporated with EVA to improve its flame retardancy.It showed that the PGS@P-N particles appeared good dispersion in the EVA/PGS@P-N/EG composites owing to their good interaction with EVA resin,and therefore,can effectively improve the thermal stability and the flame retardancy of the composite simultaneously.3.The Organic palygorskite hybrid material of OPGS was prepared via the microcapsulational decoration of PGS by o-phthalic anhydride and octadecylamine,and was incorporated with EVA to improve its flame retardance.The results shoued that the OPGS particles were well dispersed in the EVA/APP/PER/OPGS composites owing to their good interaction with EVA resin,and the the thermal stability as well as the flame retardancy was effectively improve.