Zuccarello Bernardo, Bongiorno Francesco, Militello Carmelo
Dipartimento di Ingegneria, Università degli Studi di Palermo, 90128 Palermo, Italy.
Polymers (Basel). 2022 Apr 3;14(7):1457. doi: 10.3390/polym14071457.
The increasing attention given to environmental protection, largely through specific regulations on environmental impact and the recycling of materials, has led to a considerable interest of researchers in biocomposites, materials consisting of bio-based or green polymer matrixes reinforced by natural fibers. Among the various reinforcing natural fibers, sisal fibers are particularly promising for their good mechanical properties, low specific weight and wide availability on the current market. As proven in literature by various authors, the hybridization of biocomposites by synthetical fibers or different natural fibers can lead to an interesting improvement of the mechanical properties or, in turn, of the strength against environmental agents. Consequently, this can lead to a significant enlargement of their practical applications, in particular from quite common non-structural applications (dashboards, fillings, soundproofing, etc.) towards semi-structural (panels, etc.) and structural applications (structural elements of civil construction and/or machine components). Hybridizations with natural fibers or with ecofriendly basalt fibers are the most interesting ones, since they permit the improvement of the biocomposite's performance without an appreciable increment on environmental impact, as occurs instead for synthetic fiber hybridizations that are also widely proposed in the literature. In order to further increase the mechanical performance and, above all, to reduce the aging effects on high-performance sisal-reinforced biocomposites due to environmental agents, the hybridization of such biocomposites with basalt fibers are studied with tensile, compression and delamination tests performed by varying the exposition to environmental agents. In brief, the experimental analysis has shown that hybridization can lead to further enhancements of mechanical performance (strength and stiffness) that increase with basalt volume fraction and can lead to appreciable reductions in the aging effects on mechanical performance by simple hybridization of the surface laminae. Therefore, such a hybridization can be advantageously used in all practical outdoor applications in which high-performance sisal biocomposites can be exposed to significant environmental agents (temperature, humidity, UV).
对环境保护的日益关注，主要通过关于环境影响和材料回收利用的具体法规得以体现，这引发了研究人员对生物复合材料的浓厚兴趣。生物复合材料是由生物基或绿色聚合物基体与天然纤维增强而成的材料。在各种增强天然纤维中，剑麻纤维因其良好的机械性能、低比重以及在当前市场上的广泛可得性而特别具有前景。正如众多作者在文献中所证实的，通过合成纤维或不同天然纤维对生物复合材料进行混杂，可以使机械性能，进而使抵抗环境因素的强度得到有趣的提升。因此，这能够显著扩大其实际应用范围，特别是从相当常见的非结构应用（仪表板、填充物、隔音材料等）向半结构应用（面板等）和结构应用（民用建筑结构元件和/或机器部件）拓展。与天然纤维或环保玄武岩纤维的混杂最为引人关注，因为它们能够在不显著增加环境影响的情况下提升生物复合材料的性能，而合成纤维混杂则不然，尽管文献中也广泛提出了合成纤维混杂，但会增加环境影响。为了进一步提高机械性能，尤其是减少高性能剑麻增强生物复合材料因环境因素产生的老化影响，通过改变对环境因素的暴露程度进行拉伸、压缩和分层试验，研究了此类生物复合材料与玄武岩纤维的混杂情况。简而言之，实验分析表明，混杂能够进一步提高机械性能（强度和刚度），且随着玄武岩体积分数的增加而提高，并且通过简单地对表面层进行混杂，能够显著降低对机械性能的老化影响。因此，这种混杂可有利地应用于所有高性能剑麻生物复合材料可能暴露于显著环境因素（温度、湿度、紫外线）的实际户外应用中。
