聚磷酸铵的疏水改性及聚丙烯阻燃性能

Hydrophobic Modification of Ammonium Polyphosphate and Its Application in Flame Retardant Polypropylene Composites

首先以γ-氨丙基三乙氧基硅烷(KH550)对聚磷酸铵(APP)进行表面化学修饰,然后用水解后的正硅酸四乙酯在其表面引发原位聚合,最后用十七氟癸基三乙氧基硅烷(氟硅烷)进行外表面修饰,制备了疏水聚磷酸铵(M-APP).M-APP的静态接触角为134°,表明M-APP具有很好的疏水性.通过傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)对M-APP的结构及表面元素进行分析,结果表明,M-APP即为目标产物.将M-APP与三嗪成炭发泡剂(CFA)以质量比4∶1复配制备改性膨胀型阻燃剂(M-APP/CFA),并添加到聚丙烯(PP)中,制备阻燃PP(PP/M-APP/CFA).通过极限氧指数(LOI)和垂直燃烧(UL-94)研究了其阻燃性能,用热重分析(TGA)研究了材料的热降解行为,通过耐水测试研究了耐水性能,通过拉伸、弯曲和冲击强度研究了材料的力学性能,通过扫描电子显微镜(SEM)研究了改性膨胀型阻燃剂与聚合物的相容性.结果表明,当m IFR的添加量为23%时,PP/M-APP/CFA通过UL-94 V-0级,LOI值达到30.8%,且经过耐水测试后,依然能通过UL-94 V-0级,PP/M-APP/CFA的失重率仅为0.92%.在相同实验条件下,由APP制备的PP/M-APP/CFA材料在耐水测试后UL-94测试无级别,失重率达2.45%,表明APP的表面疏水改性大大提高了PP/M-APP/CFA材料的耐水性能.M-APP/CFA的加入提高了材料的热稳定性及成炭性能,燃烧时形成的膨胀炭层能很好地保护内部材料的降解和燃烧,从而提高了材料的阻燃性能.APP的改性提高了M-APP/CFA与PP的相容性,从而提高了材料的力学性能.

Ammonium polyphosphate （APP） surface was modified with （3-aminopropyl）triethoxysilane （ KH550）, then microencapsulated by silicone in situ polymerization of tetraethyl orthosilicate （ TEOS）, finally surface-modified with （heptadecafluoro-1,1,2,2-tetradeeyl） trimethoxysilane to prepare the hydrophobic APP （M-APP）. The structure and surface elemental composition of M-APP were characterized by Fourier transform infrared spectroscopy （FI＇IR） and X-ray photoelectron spectroscopy （XPS）, and the results indicated that M-APP was the target product. The wettability of the modified APP was measured by water contact angle（CA） test and the CA reached 134°, which demonstrate the modified APP possessed obviously hydrophobic proper- ty. The modified APP mixed with triazine char foaming agent（CFA） with the mass ratio of4：1 to prepare in- tumescent flame retardant（IFR） and afterwards IFR was incorporated into polypropylene （PP） to prepare flame retardant PP composites. The flame retardancy and thermal degradation behavior of PP composites were evaluated by limiting oxygen index （ LOI）, vertical burning （UL-94） and thermal gravimetrie analysis （TGA） tests. The water resistant property of the flame retarded PP materials were evaluated by water resistant test, and the mechanical properties were measured by the tensile, flexural and impact strength test, the compatibili- ty between the flame retardant and polymer was investigated by scanning electron microscopy （SEM）. The re- sults indicated that the modified APP/CFA/PP composite reached UL-94 V-0 flammability rating when the loading amount of IFR was 23%, the PP composite after water resistance test still successfully passed UL-94 V-O rating and the mass loss was only 0. 92%. Under the same experimental conditions, the APP/CFA/PP composite after water resistance test was no rating in vertical burning test and the mass loss was 2.45%. It can be deduced that hydrophobie modification of APP can greatly improve the water resistance of the flame retardant PP material. The TGA results indicated that the incorporation of IFR into PP matrix improved the thermal stability and char-forming ability of PP composite, the formed intumescent char layer during combus- tion protect the underlying matrix from further combustion and degradation, consequently enhanced the flame retardaney of PP materials. The results of SEM and mechanical test revealed that the modification of APP im- proved the compatibility between the flame retardant and PP matrix, which mechanical properties of the flame retarded PP composites.