改性LDH及石墨烯片协同阻燃环氧树脂性能的研究

Study on Properties of Epoxy Resin Synergistic Flame Retarded with Modified LDH and GNS

采用十二烷基苯磺酸钠(DBS)对层状双金属氢氧化物(LDH)进行改性,将改性LDH(OLDH)与石墨烯片(GNS)复配后对环氧树脂(EP)进行协同阻燃。通过X射线衍射(XRD)、傅里叶红外光谱(FTIR)分析对OLDH进行结构表征,利用热重分析仪(TGA)、锥形量热仪(CCT)、扫描电子显微镜(SEM)等对EP/OLDH-GNS复合材料的热稳定性、阻燃性能、残炭微观结构进行分析。结果表明:改性前后的LDH层间距(d)分别为0.78和1.32 nm,说明DBS进入LDH层间进行离子交换。EP/OLDH-GNS复合材料在700℃时的残炭率明显高于纯EP,说明OLDH与GNS的加入有利于环氧固化物形成致密炭层。CCT及残炭SEM分析显示,随着OLDH、GNS添加量的增加,复合材料的最大热释放速率逐渐降低,所形成的炭层能够阻隔氧气和热量的传递,起到延缓材料燃烧的作用;OLDH、GNS具有明显的协效阻燃作用。

The layered double hydroxide (LDH) was modified with sodium dodecylbenzene sulfonate (DBS), then the modified LDH (OLDH) and graphene sheets (GNS) were combined, and served as flame retardant in epoxy resin (EP). The structure of OLDH was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The thermal stability, flame retardant properties and microstructure of carbon residue of EP/OLDH-GNS composites were observed using thermogravimetric analysis (TGA), cone calorimeter (CCT) and scanning electron microscopy (SEM). The results show that, the LDH layer spacing (d) before and after modification are 0.78 and 1.32 nm, respectively. It indicates that DBS has entered the LDH layer for ion exchange. The carbon residue rate of the EP/OLDH-GNS composite at 700℃ is significantly higher than that of pure EP. OLDH and GNS is beneficial to the formation of a dense carbon layer of the cured EP product. The test results of CCT and carbon residue show that, the maximum heat release rate of flame retardant epoxy composite decreased gradually with the increasing amount of OLDH and GNS. The carbon layer can block oxygen and heat, and delay the combustion of EP. Moreover, the synergistic effect of flame retardant is obvious.