聚苯氧基磷酸联苯二酚酯/聚磷酸铵膨胀阻燃剂对环氧树脂阻燃性能影响研究

以聚苯氧基磷酸联苯二酚酯(PBPP)与聚磷酸铵(APP)组成复合阻燃剂,对环氧树脂(EP)进行阻燃改性.通过氧指数(LOI)、垂直燃烧(UL-94)、热失重(TGA)、锥形量热(CONE)和扫描电镜(SEM)等方法研究改性环氧树脂的阻燃性能和阻燃机理.结果表明,PBPP/APP体系对EP具有较好的阻燃性能,阻燃剂添加量为10%时能使环氧树脂的氧指数提高到29.6%,垂直燃烧等级达到UL94 V-0级,残炭量大大增加;平均热释放速率下降45.7%,热释放速率峰值下降51.0%,有效燃烧热平均值下降21.1%;TGA、CONE、SEM等综合分析显示了PBPP/APP改性后的环氧树脂比纯环氧树脂具有更高的热稳定性,燃烧后能够形成连续、致密、封闭、坚硬的焦化炭层,在聚合物表面产生有效覆盖、隔绝了氧气,改善了环氧树脂的燃烧性能.

Influence of Poly(biphenyl phenoxy phosphate)/APP on Flame Retardancy of Epoxy Resin

A novel and efficient flame retardant additive poly(biphenyl phenoxy phosphate) (PBPP) was prepared by reaction of biphenol with dichloro phenoxyphosphate.The structure of PBPP was confirmed by Fourier transform infrared spectroscopy (FTIR).Thermogravimetric analysis (TGA) result demonstrated that the initial decomposition temperature of PBPP was 253 ℃,with a char residue of 51.41 wt％ at 700 ℃.PBPP blended with ammonium polyphosphate (APP) at the ratio of 1 ∶ 2 was incorporated into epoxy resins and cured by m-phenylenediamine (m-PDA) to form a flame retardant thermoset (FR-EP).The effect of intumescent flame retardant (IFR) composed of PBPP and APP on epoxy resin was investigated by limiting oxygen index (LOI),vertical burning (UL-94),TGA,cone calorimetry (CONE) and scanning electron microscope (SEM).Comparing epoxy resin retardant common used with 30 wt％ of APP,this PBPP based flame retardant with PBPP amount of 10 wt％ showed similar retardant effect as the classical one.At this low addition amount of PBPP,this PBPP/APP modified FR-EP past UL-94 V0 grade and gave 29.6％ as the LOI value at the same time.TGA test results revealed that the incorporation of PBPP/APP into epoxy resins stimulated the degradation of thermosets at initial degradation stage and charring formation.The char yield of the FR-EP thermosets increased from 15.02 wt％ to 22.17 wt％ at 700 ℃C.According to the cone test,heat release rate (HRR),total heat release (THR) and total smoke release (TSR) were all decreased dramatically in the FR-EP.The cone test showed that the av-HRR,pk-HRR,and av-EHC of the FR-EP were lowered by 45.7％,51.0％ and 21.1％,respectively,in comparison with those of the pure EP.The char residue of the new FR-EP was about 80 times of that observed in the pure EP.Moreover,PBPP/APP promoted the epoxy resins thermosets forming more homogeneous and compact char layer during combustion as seen by SEM.Char layer prevented the inner matrix from further decomposition and combustion,which enhanced by consequence the flame retardancy of the FR-EP thermosets.The tensile strength of EP was also affect by loading of the flame retardant with a decrease at lower loading and an increased at higher loading.