Study On Surface Functionalization Of Ammonium Polyphosphate And Its Research On Flame Retardant Unsaturated Polyester

Unsaturated polyester resin(UPR)is a commercially important resin in modern plastic industry.Because of its rapid curing,excellent physical properties,ease of production,etc.,UPR has been widely used in shipbuilding,high-speed rail,automobile and other processing and production fields.However,its high flammability has significantly impeded its widespread practical application in industry.For this reason,it is imperative to develop flame retardant UPR to enable it to meet the demanding fire-retardant requirements in an industrial setting.Ammonium polyphosphate(APP),an environmentally friendly phosphorus-based flame retardant,is often used to produce flame retardant UPR.However,the insufficient fire-retardant efficiency,the poor compatibility between APP and UPR,and high required loading levels,often lead to many issues,such as poor flame retardancy durability and deteriorated physical properties.In response to these issues of APP,this thesis aims to create surface-modified APP by designing two new Schiff bases as a surface modifier,in addition to using polyamide epichlorohydrin resin,and the modified APP is then is used to produce flame retardant UPR.Firstly,a modified ammonium polyphosphate MAPP was prepared by modifying APP with a Schiff base using 1,2-bis(2-aminoethoxy)ethane and p-phenyldiformaldehyde as starting materials.The results show that UPR/MAPP has a better thermal performance than UPR/APP and generates a higher carbon residue.During the vertical combustion test,17 wt%MAPP makes the resultant UPR composite pass a UL-94 V-0.The Cone test shows that the UPR/MAPP exhibits lower total heat release(THR)and total smoke production(TSP)values.Also,the UPR/MAPP has better mechanical properties than the UPR/APP counterpart.In order to understand whether the chemical structures of different Schiff bases have an impact on the fire retardant efficiency effect of modified APP,this chapter prepares modified APP(GAPP)using 1,6-hexanediamine and p-phenylenediamine as raw materials,.The results show that the thermal properties of UPR/GAPP composite materials are further improved.The char residues of UPR/17GAPP(17wt%of GAPP)reach are 26.1wt%and 6.27wt%700℃,under nitrogen and air atmospheres,respectively,which are higher than those of UPR/17APP.In terms of flame retardancy,similarly,17 wt%of GAPP leads to a UL-94 V-0.Meanwhile,UPR/GAPP also has a lower PHRR value.In addition,the UPR/GAPP exhibits better mechanical properties compared to the UPR/APP.Since the modified APP with Schiff bases still show unsatisfactory fire retardant efficiency in UPR,in order to obtain a highly efficient modified APP,this chapter uses polyamide epichlorohydrin resin(PAE)to modify APP,and prepares a high-efficiency flame retardant,PAPP.The results indicate that PAPP has a excellent flame retardance.In UL-94 testing,the addition of only 13wt%of PAPP into UPR can result in a UL-94 V-0 grade,and the LOI value increases from 19.6%to 31.2%.The PHRR value of the UPR/13PAPP is as low as 282 KW/m~2,which decreases by 63.3%compared to pure UPR resin.In addition,Compared with the APP modified by Schiff base,the flame retardant UPR composite material of PAPP has higher mechanical properties.This thesis offers two surface-modification approaches for APP and fabricates three kinds of functionalized APP.Relative to unmodified APP,modified APP exhibits better fire retardancy in UPR,and leads to less adverse impacts on the mechanical properties of UPR.Overall,this work contributes to the creation of high-performance fire-retardant UPR via providing technical supportant and theoretical values.