Alosime Eid M, Basfar Ahmed A
King Abdulaziz City for Science and Technology, P.O. Box 6086, Riyadh 11442, Saudi Arabia.
M.Sc. in Nuclear Engineering Program, College of Engineering, King Saud University, Riyadh P.O. Box 145111, Saudi Arabia.
Polymers (Basel). 2024 Feb 1;16(3):417. doi: 10.3390/polym16030417.
Due to high filler loading, clean, commercial, thermoplastic, flame-retardant materials are mechanically unstable when insulating wires and cables. In this study, composite formulations of linear low-density polyethylene (LLDPE)/ethylene-vinyl acetate (EVA) containing a flame retardant, such as magnesium hydroxide (MH; formula: Mg(OH)) and huntite hydromagnesite (HH; formula: MgCa(CO), Mg(CO)(OH)·3HO), were prepared. The influence of carbon nanotubes (CNTs) and carbon black (CB) on the mechanical properties and flame retardancy of LLDPE/EVA was studied. Three types of CNTs were examined for their compatibility with other materials in clean thermoplastic flame-retardant compositions. The CNTs had the following diameters: 10-15 nm, 40-60 nm, and 60-80 nm. Optimum mechanical flame retardancy and electrical properties were achieved by adding CNTs with an outer diameter of 40-60 nm and a length of fewer than 20 nm. Large-sized CNTs result in poor mechanical characteristics, while smaller-sized CNTs improve the mechanical properties of the composites. CB enhances flame retardancy but deteriorates mechanical properties, particularly elongation at break, in clean, black, thermoplastic, flame-retardant compositions. Obtaining satisfactory compositions that meet both properties, especially formulations passing the V-0 of the UL 94 test with a minimum tensile strength of 9.5 MPa and an elongation at break of 125%, is challenging. When LLDPE was partially substituted with EVA, the limiting oxygen index (LOI) increased. The amount of filler in the formulations determined how it affected flammability. This study also included a reliable method for producing clean, black, thermoplastic, flame-retardant insulating material for wire and cable without sacrificing mechanical properties.
由于填充量高，清洁的商用热塑性阻燃材料在用于电线电缆绝缘时机械性能不稳定。在本研究中，制备了含有阻燃剂（如氢氧化镁（MH；化学式：Mg(OH)₂）和水菱镁矿（HH；化学式：MgCa(CO₃)₂、Mg₅(CO₃)₄(OH)₂·3H₂O））的线性低密度聚乙烯（LLDPE）/乙烯-醋酸乙烯酯（EVA）复合配方。研究了碳纳米管（CNT）和炭黑（CB）对LLDPE/EVA机械性能和阻燃性的影响。考察了三种类型的碳纳米管与清洁热塑性阻燃组合物中其他材料的相容性。这些碳纳米管的直径分别为：10 - 15纳米、40 - 60纳米和60 - 80纳米。通过添加外径为40 - 60纳米且长度小于20纳米的碳纳米管，可实现最佳的机械阻燃性和电性能。大尺寸的碳纳米管会导致机械性能不佳，而小尺寸的碳纳米管则可改善复合材料的机械性能。在清洁的黑色热塑性阻燃组合物中，炭黑增强了阻燃性，但会降低机械性能，尤其是断裂伸长率。获得同时满足这两种性能的理想组合物，特别是通过UL 94测试的V - 0级、最小拉伸强度为9.5兆帕且断裂伸长率为125%的配方，具有挑战性。当用EVA部分替代LLDPE时，极限氧指数（LOI）增加。配方中填料的量决定了其对可燃性的影响。本研究还包括一种可靠的方法，用于生产清洁的黑色热塑性阻燃电线电缆绝缘材料，同时不牺牲机械性能。
