Wang Zhenhua, Feng Weili, Ban Jiachen, Yang Zheng, Fang Xiaomin, Ding Tao, Liu Baoying, Zhao Junwei
College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, China.
Institute of Science and Technology, Minsheng College, Henan University, Kaifeng 475004, China.
Polymers (Basel). 2023 Feb 10;15(4):893. doi: 10.3390/polym15040893.
Natural-fiber-reinforced polypropylene (PP) composites with a series of advantages including light weight, chemical durability, renewable resources, low in cost, etc., are being widely used in many fields such as the automotive industry, packaging, and construction. However, the flammability of plant fiber and the PP matrix restricts the application range, security, and use of these composites. Therefore, it is of great significance to study the flame retardants of such composites. In this paper, sisal-fiber-reinforced polypropylene (PP/SF) flame-retardant composites were prepared using the two-step melt blending method. The flame retardant used was an intumescent flame retardant (IFR) composed of silane-coated ammonium polyphosphate (Si-APP) and pentaerythritol (PER). The influence of different blending processes on the flammability and mechanical properties of the composites was analyzed. The findings suggested that PP/SF flame-retardant composites prepared via different blending processes showed different flame-retardant properties. The (PP/SF)/IFR composite prepared by PP/SF secondary blending with IFR showed excellent flame-retardant performance, with a limited oxygen index of about 28.3% and passing the UL-94 V-0 rating (3.2 mm) in the vertical combustion test. Compared with the (PP/IFR) /SF composite prepared by a matrix primarily blended with IFR and then secondly blended with SF, the peak heat release rate (pk HRR) and total heat release (THR) of the (PP/SF)/IFR composite decreased by 11.3% and 13.7%, respectively. In contrast, the tensile strength of the (PP/SF)/IFR system was 5.3% lower than that of the (PP/IFR)/SF system; however, the overall mechanical (tensile, flexural, and notched impact) properties of the composites prepared using three different mixing processes were similar.
天然纤维增强聚丙烯（PP）复合材料具有一系列优点，包括重量轻、化学耐久性好、资源可再生、成本低等，正广泛应用于汽车工业、包装和建筑等许多领域。然而，植物纤维和PP基体的易燃性限制了这些复合材料的应用范围、安全性和使用。因此，研究此类复合材料的阻燃剂具有重要意义。本文采用两步熔融共混法制备了剑麻纤维增强聚丙烯（PP/SF）阻燃复合材料。所使用的阻燃剂是一种由硅烷包覆的聚磷酸铵（Si-APP）和季戊四醇（PER）组成的膨胀型阻燃剂（IFR）。分析了不同共混工艺对复合材料燃烧性能和力学性能的影响。研究结果表明，通过不同共混工艺制备的PP/SF阻燃复合材料表现出不同的阻燃性能。通过PP/SF与IFR二次共混制备的（PP/SF）/IFR复合材料表现出优异的阻燃性能，极限氧指数约为28.3%，在垂直燃烧试验中通过了UL-94 V-0等级（3.2 mm）。与先将基体与IFR主要共混然后再与SF二次共混制备的（PP/IFR）/SF复合材料相比，（PP/SF）/IFR复合材料的热释放速率峰值（pk HRR）和总热释放量（THR）分别降低了11.3%和13.7%。相比之下，（PP/SF）/IFR体系的拉伸强度比（PP/IFR）/SF体系低5.3%；然而，使用三种不同混合工艺制备的复合材料的整体力学性能（拉伸、弯曲和缺口冲击）相似。
