Study On Preparation And Modification Of Crystal Type Ⅴ Ammonium Polyphosphate Flame Retardant

With the continuous development of polymer materials in recent years,flame retardant products are also being updated.Traditional halogenated flame retardants release a large amount of toxic and harmful gases during the combustion process,which is harmful to human health and has carcinogenic and teratogenic effects on the human body.The call for"de halogenation"of flame retardants is becoming increasingly fierce.Ammonium polyphosphate（APP）,as a phosphorus based flame retardant,does not produce harmful products during its flame retardant process.Due to its excellent flame retardancy,and more importantly,its non-toxic and environmentally friendly properties,it has become a hot topic in the research of flame retardants.There are six crystal forms of APP,among which Crystal II and Crystal V APP are high degree of polymerization materials commonly used as flame retardants.Currently,most of the materials used are APP-II,and there are not many applications of APP-V.However,the polymerization degree and decomposition temperature of APP-V are higher than those of APP-II,which has high flame retardant application value.Due to its hydrophilic structural characteristics,APP lacks sufficient dispersion when added to polymer materials,and the added materials have certain conditions during use,which can easily reduce flame retardancy in wet environment.This study investigated the preparation and performance analysis of crystal type V-APP flame retardant,and characterized the crystal form of the product using XRD diffraction patterns.The preparation method of crystal type Ⅴ-APP flame retardant is using melamine（MEL）as a condensation agent,paired with a system of diammonium hydrogen phosphate（DAP）and phosphorus pentoxide.The optimal experimental conditions for preparing APP Ⅴ are explored by exploring the ingredient ratio of the three materials during the preparation process,the polymerization temperature during the reaction process,the ripening temperature and time of the materials,and the effect of ammonia flow rate during the reaction on the crystal form and basic properties of APP V.The best performance APP-Ⅴflame retardant was modified by coupling agent,vinyl trimethoxysilane（A-171）was selected as the coupling agent,and the basic performance of the modified APP-Ⅴflame retardant was measured.Using XRD,XPS,SEM,FTIR,TG-DTG and other characterization methods to compare the modified self-made APP flame retardants with commercially available APP flame retardants,and discuss the effect of modification on the performance of APP-V.The APP-V flame retardant before and after modification and the commercial APP flame retardant were respectively combined with DPER and MEL to form an expansion system flame retardant.The differences in flame retardant effects of the three were studied through flame retardant EPDM rubber.Draw the following conclusion.（1）The APP-Ⅴ product produced by the phosphorus pentoxide system meets the requirements of the Chinese chemical industry standard"H/GT2770-2020 Industrial Ammonium Polyphosphate".The optimal experimental conditions are:DAP,P₂O₅,and MEL are mixed in a molar ratio of 1:1.1:0.2,the ammonia flow rate is adjusted to 1.0L/min,the polymerization reaction temperature is selected as 320℃,the curing temperature is selected as 260℃,and the curing time is 3.0 hours.（2）The self-made APP-Ⅴ product was modified with coupling agent,and through testing and characterization,the modified APP-V product not only had better solubility and other properties than commercial APP products,but also the microscopic crystal structure and thermal stability of the product were better than commercial APP products to varying degrees.（3）The flame retardancy of the three products was measured using vertical combustion testing method,and they all belong to the flame retardancy level of V-1.In terms of the duration of flame combustion during the combustion process of a single sample,the modified self-made APP-V is better than the self-made APP-V and better than the commercial APP.The modified self-made APP-V flame retardant can be better applied to polymer.