Netkueakul Woranan, Fischer Beatrice, Walder Christian, Nüesch Frank, Rees Marcel, Jovic Milijana, Gaan Sabyasachi, Jacob Peter, Wang Jing
Institute of Environmental Engineering, ETH Zurich (Swiss Federal Institute of Technology Zurich), 8093 Zurich, Switzerland.
Laboratory for Advanced Analytical Technologies, Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
Polymers (Basel). 2020 Oct 14;12(10):2349. doi: 10.3390/polym12102349.
The effects of combining 0.1-5 wt % graphene nanoplatelet (GNP) and 3-30 wt % phosphorous flame retardant, 9,10- dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as fillers in epoxy polymer on the mechanical, flame retardancy, and electrical properties of the epoxy nanocomposites was investigated. GNP was homogeneously dispersed into the epoxy matrix using a solvent-free three-roll milling process, while DOPO was incorporated into the epoxy resin by mechanical stirring at elevated temperature. The incorporation of DOPO reduced the crosslinking density of the epoxy resin. When using polyetheramine as a hardener, the structural rigidity effect of DOPO overshadowed the crosslinking effect and governed the flexural moduli of epoxy/DOPO resins. The flexural moduli of the nanocomposites were improved by adding GNP up to 5 wt % and DOPO up to 30 wt %, whereas the flexural strengths deteriorated when the GNP and DOPO loading were higher than 1 wt % and 10 wt %, respectively. Limited by the adverse effects on mechanical property, the loading combinations of GNP and DOPO within the range of 0-1 wt % and 0-10 wt %, respectively, in epoxy resin were further studied. Flame retardancy index (FRI), which depended on three parameters obtained from cone calorimetry, was considered to evaluate the flame retardancy of the epoxy composites. DOPO showed better performance than GNP as the flame retardant additive, while combining DOPO and GNP could further improve FRI to some extent. With the combination of 0.5 wt % GNP and 10 wt % DOPO, improvement in both mechanical properties and flame retardant efficiency of the nanocomposite was observed. Such a combination did not affect the electrical conductivity of the nanocomposites since the percolation threshold was at 1.6 wt % GNP. Our results enhance the understanding of the structure-property relationship of additive-filled epoxy resin composites and serve as a property constraining guidance for the composite manufacturing.
研究了在环氧聚合物中添加0.1 - 5 wt%的石墨烯纳米片（GNP）和3 - 30 wt%的磷系阻燃剂9,10 - 二氢 - 9 - 氧杂 - 10 - 磷杂菲 - 10 - 氧化物（DOPO）作为填料对环氧纳米复合材料的机械性能、阻燃性能和电学性能的影响。采用无溶剂三辊研磨工艺将GNP均匀分散到环氧基体中，而DOPO则通过在高温下机械搅拌加入到环氧树脂中。DOPO的加入降低了环氧树脂的交联密度。当使用聚醚胺作为固化剂时，DOPO的结构刚性效应掩盖了交联效应，并决定了环氧/DOPO树脂的弯曲模量。添加高达5 wt%的GNP和30 wt%的DOPO可提高纳米复合材料的弯曲模量，而当GNP和DOPO的含量分别高于1 wt%和10 wt%时，弯曲强度会下降。受对机械性能不利影响的限制，进一步研究了环氧树脂中GNP和DOPO分别在0 - 1 wt%和0 - 10 wt%范围内的负载组合。基于锥形量热法获得的三个参数的阻燃指数（FRI）被用来评估环氧复合材料的阻燃性能。作为阻燃添加剂，DOPO表现出比GNP更好的性能，而将DOPO和GNP结合使用可以在一定程度上进一步提高FRI。当组合使用0.5 wt%的GNP和10 wt%的DOPO时，观察到纳米复合材料的机械性能和阻燃效率均有所提高。由于渗流阈值为1.6 wt%的GNP，这种组合不会影响纳米复合材料的电导率。我们的研究结果增进了对添加剂填充环氧树脂复合材料结构 - 性能关系的理解，并为复合材料制造提供了性能约束指导。
