有机硅改性松香基环氧树脂的制备及阻燃性能

制备了聚甲基苯基硅氧烷（PMPS）改性松香基乙二醇二缩水甘油醚AR-EGDE。红外光谱(IR)、核磁共振（¹³C NMR）和环氧值测试结果表明有机硅成功接枝至环氧树脂。同时，将PMPS与AR-EGDE充分混合得到物理改性树脂。通过力学性能和极限氧指数测试探讨了改性方法对改性树脂力学及阻燃性能的影响：化学改性优于物理改性及未改性的AR-EGDE。热失重、炭层分析表明，PMPS改性的树脂在受热和燃烧过程中，都能形成含硅炭层，该炭层可延缓内部材料热分解,同时阻止可燃裂解气体的释放和熔滴发生,从而提高材料的耐热和阻燃性能。物理改性松香基环氧，燃烧时无法形成有效富硅炭层覆盖于底部材料，从而使其阻燃性劣于化学改性。

Preparation and flame retardancy of siloxane modified epoxy resins based on acrylic acid rosin

Silicone modified epoxy resins is prepared via polycondensation of polymethylphenylsilicone DC-3074(PMPS) and epoxy resin from acrylic acid rosin(AR-EGDE).The chemical structure of the produced resins was determined by FTIR,13C NMR and epoxy content testing.At the same time,physical modified resin is obtained by mixture of PMPS and AR-EGDE.Mechanical properties and limiting oxygen index(LOI) value of the cured epoxy resins were studied.The results indicated that the method of modification played an important role in the properties of cured resins.The cured system of chemically modified resin had better properties.The tensile strength of the system was slightly lower than the unmodified resin AR-EGDE,at the same time its breaking elongations increased rapidly.The LOI value of the system increased from 21.6%(unmodified) and 25.3%(physically modified) to 30.2%.The thermogravimetric analysis(TGA) result showed that the thermal stabilities of the modified resins were better than those of unmodified resin.Because PMPS segment could absorb more thermal energy and dissipate thermal energy through its flexible siloxane structure,the onset decomposition temperatures(T-5%) for modified resins were higher than that of unmodified resin.The solid residue at 700℃ of the modified resins were 14.9% for chemically modified and 16.2% for physically modified,more than that of the unmodified resin.The chemical structure of char for the resin at the end of LOI test was analyzed by Fourier transform infrared spectroscopy.Based on the above results,the flame retardant mechanism was discussed.At an elevated temperature or upon burning,the silicone-containing group immigrated to the surface of material rapidly and formed a stable carbon-silicon residue.The carbon-silicon residue could act as thermal insulation which inhibited the degradation of the underlying material and improved the flame retardancy of the material.The physically modified resin could not form efficient carbon-silicon residue during burning,so its LOI value was lower than that of the chemically modified resin.