基于微胶囊化聚磷酸铵和微胶囊化膨胀石墨的阻燃硬质聚氨酯泡沫复合材料的制备及性能

Preparation and properties of flame retardant rigid polyurethane foam composites based on microencapsulated ammonium polyphosphate and microencapsulated expanded graphite

采用原位聚合法,以聚氨酯为壳材,制备微胶囊化聚磷酸铵(PUAPP)和微胶囊化膨胀石墨(PUEG)。采用XPS、FTIR、TG和SEM分别对PUAPP和PUEG进行表征,结果表明,聚氨酯有效包覆在聚磷酸铵和膨胀石墨表面,成功制备了PUAPP和PUEG。在此基础上,采用一步法全水发泡工艺将PUAPP和PUEG引入到聚氨酯硬泡(RPUF)中,制备出一系列阻燃RPUF复合材料。采用极限氧指数(LOI)、垂直燃烧(UL-94)、TG、万能试验机、导热及密度测试研究了PUAPP/RPUF、PUEG/RPUF及PUAPP-PUEG/RPUF复合材料的阻燃性能、力学性能、保温性能及热稳定性。研究表明,微胶囊化阻燃剂的加入可以提高RPUF复合材料的高温稳定性,PUEG/RPUF、PUAPP/RPUF和PUAPP-PUEG/RPUF复合材料在700℃的残炭率从1.2wt%分别提高至6.9wt%、11.2wt%和10.7wt%。阻燃测试表明,PUAPP和PUEG可以有效提高RPUF复合材料的阻燃性能,当加入10.4wt%PUAPP时,PUAPP/RPUF复合材料的LOI提高到22.3vol%,UL-94等级为V-0级;当加入10.4wt%PUEG时,PUEG/RPUF复合材料的LOI达到25.3vol%,UL-94等级为V-0级;PUAPP-PUEG/RPUF复合材料的LOI达到24.3vol%,UL-94等级为V-0级。SEM和拉曼测试表明,PUAPP和PUEG可以提高RPUF复合材料的炭渣石墨化程度,使炭渣的致密性更强。

Microencapsulated ammonium polyphosphate(PUAPP) and microencapsulated expanded graphite(PUEG) were prepared by in situ polymerization with polyurethane as shell material. XPS, FTIR, TG and SEM were used to characterize PUAPP and PUEG. The results show that polyurethane is effectively coated on the surface of ammonium polyphosphate and expanded graphite, and PUAPP and PUEG are successfully fabricated. On this basis,a series of flame-retardant rigid polyurethane foam(RPUF) composites were prepared with PUAPP and PUEG loading by one-step water-blown method. The flame retardancy, mechanical properties, thermal insulation and thermal stability of PUAPP/RPUF, PUAPP/RPUF and PUAPP-PUEG/RPUF composites were investigated by limiting oxygen index(LOI), underwriters laboratories vertical burning test(UL-94), TG, universal testing machine, heat conduction and density test. The results show that the thermal stability at high temperature of RPUF composites can be improved by the addition of PUAPP and PUEG. The charresidues of PUAPP/RPUF, PUAPP/RPUF and PUAPPPUEG/RPUF at 700℃ are increased from 1.2 wt% to 6.9 wt%, 11.2 wt% and 10.7 wt%, respectively. Flame retardant tests show that the microencapsulated flame retardant can effectively improve flame retardancy of RPUF composites. When 10.4 wt% PUAPP is added, the LOI of the PUAPP/RPUF composite is increased to 22.3 vol% with V-0 rating in UL-94 test;when 10.4 wt% PUEG is added, the LOI of the PUAPP/RPUF composite is increased to 25.3 vol% with UL-94 V-0 rating;PUAPP-PUEG/RPUF composite presents LOI of 24.3 vol% with UL-94 V-0 rating. SEM and Raman tests indicate that PUAPP and PUEG can increase graphitization degree of char residues for RPUF composites with enhanced compactness of the char residues.