Matta Samuele, Bartoli Mattia, Frache Alberto, Malucelli Giulio
Department of Applied Science and Technology and Local INSTM Unit, Politecnico di Torino, Viale Teresa Michel 5, 15121 Alessandria, Italy.
Department of Applied Science and Technology and Local INSTM Unit, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino, Italy.
Polymers (Basel). 2021 Apr 13;13(8):1256. doi: 10.3390/polym13081256.
In this work, three biochars, deriving from soft wood, oil seed rape, and rice husk and differing as far as the ash content is considered (2.3, 23.4, and 47.8 wt.%, respectively), were compounded in an ethylene vinyl acetate copolymer (vinyl acetate content: 19 wt.%), using a co-rotating twin-screw extruder; three loadings for each biochar were selected, namely 15, 20, and 40 wt.%. The thermal and mechanical properties were thoroughly investigated, as well as the flame retardance of the resulting compounds. In particular, biochar, irrespective of the type, slowed down the crystallization of the copolymer: this effect increased with increasing the filler loading. Besides, despite a very limited effect in flammability tests, the incorporation of biochar at increasing loadings turned out to enhance the forced-combustion behavior of the compounds, as revealed by the remarkable decrease of peak of heat release rate and of total heat release, notwithstanding a significant increase of the residues at the end of the tests. Finally, increasing the biochar loadings promoted an increase of the stiffness of the resulting compounds, as well as a decrease of their ductility with respect to unfilled ethylene vinyl acetate (EVA), without impacting too much on the overall mechanical behavior of the copolymer. The obtained results seem to indicate that biochar may represent a possible low environmental impact alternative to the already used flame retardants for EVA, providing a good compromise between enhanced fire resistance and acceptable mechanical properties.
在本研究中，采用同向旋转双螺杆挤出机，将源自软木、油菜籽和稻壳且灰分含量不同（分别为2.3%、23.4%和47.8%重量百分比）的三种生物炭与乙烯-醋酸乙烯酯共聚物（醋酸乙烯酯含量：19%重量百分比）进行共混；每种生物炭选择了三种添加量，即15%、20%和40%重量百分比。对所得复合材料的热性能、力学性能以及阻燃性能进行了全面研究。具体而言，无论生物炭类型如何，均会减缓共聚物的结晶：这种效果随着填料添加量的增加而增强。此外，尽管在燃烧试验中的效果非常有限，但随着生物炭添加量的增加，复合材料的强迫燃烧行为得到改善，热释放速率峰值和总热释放量显著降低，尽管试验结束时残余物显著增加。最后，增加生物炭添加量会提高所得复合材料的刚度，并降低其相对于未填充乙烯-醋酸乙烯酯（EVA）的延展性，同时对共聚物的整体力学性能影响不大。所得结果似乎表明，生物炭可能是一种对EVA已使用的阻燃剂而言环境影响较低的替代品，在提高耐火性和可接受的力学性能之间取得了良好的平衡。
