【作者】 李小建；

【导师】 朱新生；

【作者基本信息】 苏州大学 ， 材料学， 2006， 硕士

【摘要】 本文主要目的是通过添加氧化剂和成炭剂促进膨胀阻燃低密度聚乙烯成炭,改善体系阻燃性能。以氧指数和水平燃烧法作为考察阻燃性能的手段,主要研究了氧化剂（NH₄）₂SO₄和成炭剂煤、沥青对膨胀阻燃低密度聚乙烯阻燃性能的影响,结合热分析方法,对膨胀阻燃低密度聚乙烯体系热降解过程的化学反应机理、成炭机理等进行探讨。通过扫描电镜观察膨胀炭层的形态和结构,对炭层形态与阻燃效率之间的关系进行了探讨。经过以上一系列的研究得到以下主要结论:（1）添加剂对低密度聚乙烯膨胀阻燃体系有促进作用,其中EVA可增强膨胀型阻燃体系和LDPE间的相容性,提高共混物的断裂伸长率,促进体系成炭。硫酸铵对膨胀阻燃低密度聚乙烯氧化炭化作用明显,其添加量在10～15phr时炭化效果显著。SiO₂含量较低（小于2phr时）可提高共混体系的断裂强度和冲击强度,并有利于硫酸铵-膨胀阻燃低密度聚乙烯系统协同作用。（2）煤单独作为阻燃剂阻燃低密度聚乙烯时,随煤含量的增加,LOI逐渐上升;煤与聚乙烯之间逐步形成了两相具有连续结构聚合物体系。扫描电镜显示,含50phr煤LDPE燃烧时能形成多孔膨胀型炭层。50phr煤阻燃低密度聚乙烯阻燃效果相当于加入传统膨胀剂IFR30phr的效果。（3）在正交实验中,硫酸铵明显恶化复合体系的断裂强度,而煤粉与沥青用量对阻燃低密度聚乙烯的断裂强度无明显影响。方差结果表明,添加剂对体系阻燃性能影响为硫酸铵> SiO₂>蒙脱土>煤。试验中,40phr硫酸铵,30phr煤,1.5phr SiO₂,1.5phr蒙脱土添加到膨胀阻燃聚乙烯时样品的LOI可达30.4。（4）本文所加添加剂对聚乙烯电性能影响不大,基本都能满足行业要求。更多还原

【Abstract】 The main purpose of this thesis was aimed to strengthen char formation of intumescent flame retarded low density polyethylenes by adding oxidant and charring agent in order to improve the flame retardancy properties of LDPE blends. The flame retarded properties of intumescent flame retarded LDPE blends in the presence of oxidant （（NH₄）₂SO₄） and the charring agents （coal and asphalt） were studied with the limited oxygen index and the horizontal burning methods. The flame retardant, thermal and thermo-oxidative degradation mechanisms of flame retarded LDPE were investigated with thermal analysis techniques （DSC and TG）. The relationship between the char layer morphology and the retardant efficiency was discussed based on the observation with scanning electron microscopy （SEM）.The main important findings are as follows:（1） All additives improved properties of intumescent flame retarded LDPE blends to various extents, EVA enhanced the elongation at break and char formation. 2phr SiO₂ improved tensile strength at break, elongation at break and the impact strength of notched specimens. （NH₄）₂SO₄ oxidatively strengthened char formation, SiO₂ synergistically enlarged flame retardation with ammonium sulfate. 10-15 phr of （NH₄）₂SO₄ and 2 phr of SiO₂, together with 30 phr of intumescent flame retardant （IFR）, could maximize the flame retardance of LDPE.（2） The values of limited oxygen index of flame retarded LDPE were increased and the bi-continuous interlocked phases were gradually formed with the increase of更多还原