The Study On Preparation Of Low Temperature Expandable Graphite

The expandable graphite is inorganic materials with great capabilities.At present,the flame-retarded material is trend to a low smoke,low toxicity or non-toxic,non-halogenated.As halogen-free flame retardants,expandable graphite has been widespread concerned.Expandable graphite had a special layer compounds to oxidation,intercalation processing,because the graphite intercalation compounds has the characteristics.Under high temperature,expandable graphite volume can be inflated several hundred times,and have an excellent expansion of the anti-oxidation.The expanded graphite can be used as expansion of fire retardant.Expanded graphite in the field of application of fire retardant, flame-retardant industry will undoubtedly bring a new dynamic.It is to develop new products,improve product performance flame-retardant an effective way to strengthen surface modification and strengthen expandable graphite in the field of fire-retardant materials in various applications.In this thesis,the expanded graphite was prepared by filtrating insert and using different methods.The main research work and experimentation results are as follows:First,low temperature expansible graphite were prepared by a chemical method from natural graphite,using chlorate acid and acetic acid mixing as intercalation agent and potassium permanganate as oxidant.The conditions of preparing expandable expansible graphite were optimized and factors affecting expansion volume were obtained.There was natural graphite:concentrated nitric acid:potassium permanganate:potassium chlorate: acetic acid=1:0.6:0.05:0.2:0.5(quality)at room temperature,and the reaction time was 50 min.Then the productions carried though decoloring,washing,decompressing filtration and drying.The largest expansion volume was 245mL/g at 600℃.Second,a study has been made on preparation of low temperature expandable graphite by mixture of nitric acid and sulfuric acid intervenes.First,put into the mixture of sulfuric acid and nitric acid,and then add the oxidant,churning up sufficiently.Low temperature expandable graphite was prepared after washing and drying.The results show that the best materiel ratio is graphite:potassium permanganate:mixed acid=1:0.11:3 at the room temperature.The expansion volume of product is 180mL/g at 300℃,400mL/g at 600℃.Third,a study has been made on preparation of low temperature expandable graphite with the method of secondary intervening.First,the imbricate graphite was put into 70% sulfuric acid and potassium permanganate,churning up sufficiently.The Graphite intercalation compounds were prepared after washing,and drying.Then,Low temperature expandable graphite was prepared by nitric acid,formic acid,acetic acid secondary intervening.The results show that the best materiel ratio is graphite:potassium permanganate:70%sulfuric acid=1:0.1:3(quality):nitric acid:formic acid:acetic acid=4:2:3(volume)at the room temperature.The expansion volume of product is 280mL/g at 300℃,450mL/g at 600℃.