Di Maro Mattia, Faga Maria Giulia, Pedraza Riccardo, Malucelli Giulio, Bartoli Mattia, Gomez d'Ayala Giovanna, Duraccio Donatella
Institute of Sciences and Technologies for Sustainable Energy and Mobility, National Council of Research, Strada delle Cacce 73, 10135 Torino, Italy.
Department of Applied Science and Technology, Politecnico di Torino, Viale Teresa Michel 5, 15121 Alessandria, Italy.
Polymers (Basel). 2023 Mar 12;15(6):1411. doi: 10.3390/polym15061411.
In this work, the combination of biochar produced through a pyrolytic process of hemp hurd with commercial humic acid as a potential biomass-based flame-retardant system for ethylene vinyl acetate copolymer is thoroughly investigated. To this aim, ethylene vinyl acetate composites containing hemp-derived biochar at two different concentrations (i.e., 20 and 40 wt.%) and 10 wt.% of humic acid were prepared. The presence of increasing biochar loadings in ethylene vinyl acetate accounted for an increasing thermal and thermo-oxidative stability of the copolymer; conversely, the acidic character of humic acid anticipated the degradation of the copolymer matrix, even in the presence of the biochar. Further, as assessed by forced-combustion tests, the incorporation of humic acid only in ethylene vinyl acetate slightly decreased both peaks of heat release rate (pkHRR) and total heat release (THR, by 16% and 5%, respectively), with no effect on the burning time. At variance, for the composites containing biochar, a strong decrease in pkHRR and THR values was observed, approaching -69 and -29%, respectively, in the presence of the highest filler loading, notwithstanding, for this latter, a significant increase in the burning time (by about 50 s). Finally, the presence of humic acid significantly lowered the Young's modulus, unlike biochar, for which the stiffness remarkably increased from 57 MPa (unfilled ethylene vinyl acetate) to 155 Mpa (for the composite containing 40 wt.% of the filler).
在本研究中，对通过大麻秸秆热解过程产生的生物炭与商业腐殖酸的组合作为乙烯-醋酸乙烯酯共聚物潜在的生物质基阻燃体系进行了深入研究。为此，制备了含有两种不同浓度（即20重量%和40重量%）大麻衍生生物炭以及10重量%腐殖酸的乙烯-醋酸乙烯酯复合材料。乙烯-醋酸乙烯酯中生物炭负载量的增加导致共聚物的热稳定性和热氧化稳定性提高；相反，即使存在生物炭，腐殖酸的酸性也会促使共聚物基体降解。此外，通过强制燃烧试验评估，仅在乙烯-醋酸乙烯酯中加入腐殖酸会使热释放速率峰值（pkHRR）和总热释放量（THR）略有降低（分别降低16%和5%），对燃烧时间没有影响。相比之下，对于含有生物炭的复合材料，观察到pkHRR和THR值大幅下降，在填料负载量最高时分别接近-69%和-29%，尽管如此，后者的燃烧时间显著增加（约增加50秒）。最后，与生物炭不同，腐殖酸的存在显著降低了杨氏模量，对于生物炭，其刚度从57兆帕（未填充的乙烯-醋酸乙烯酯）显著增加到155兆帕（对于含有40重量%填料的复合材料）。
