Shao Mingqiang, Shi Yiran, Liu Jiangtao, Xue Baoxia, Niu Mei
College of Textile Engineering, Taiyuan University of Technology, Taiyuan 030024, China.
Polymers (Basel). 2023 Jun 23;15(13):2791. doi: 10.3390/polym15132791.
Improving the residual char of polypropylene (PP) is difficult due to the preferential complete combustion. Here, we designed a combination catalyst that not only provides physical barrier effects, but also dramatically promotes catalytic charring activity. We successfully synthesized WS monolayer sheets decorated with isolated Ni atoms that bond covalently to sulfur vacancies on the basal planes via thiourea. Subsequently, PP blends composed of 8 wt.% Ni-decorated WS, NiO, and activated carbon (AC) were obtained (Ni-WS-AC-PP). Combining the physical barrier effects of WS monolayer sheets with the excellent catalytic carbonization ability of the Ni-WS-AC combination catalyst, the PP blends showed a remarkable improvement in flame retardancy, with the yield of residual char reaching as high as 41.6 wt.%. According to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations, it was revealed that the microstructure of residual char contained a large number of carbon nanotubes. The production of a large amount of residual char not only reduced the release of pyrolytic products, but also formed a thermal shield preventing oxygen and heat transport. Compared to pure PP, the peak heat release rate (pHRR) and total heat release rate (THR) of Ni-WS-AC-PP were reduced by 46.32% and 26.03%, respectively. Furthermore, benefiting from the highly dispersed WS, the tensile strength and Young's modulus of Ni-WS-AC-PP showed similar values to pure PP, without sacrificing the toughness.
由于聚丙烯（PP）优先完全燃烧，提高其残炭率具有挑战性。在此，我们设计了一种复合催化剂，它不仅能提供物理阻隔效应，还能显著促进催化成炭活性。我们成功合成了由孤立镍原子修饰的WS单层片，这些镍原子通过硫脲与基面的硫空位共价键合。随后，制备了由8 wt.%的镍修饰WS、NiO和活性炭（AC）组成的PP共混物（Ni-WS-AC-PP）。将WS单层片的物理阻隔效应与Ni-WS-AC复合催化剂优异的催化碳化能力相结合，PP共混物的阻燃性能有了显著提高，残炭产率高达41.6 wt.%。根据扫描电子显微镜（SEM）和透射电子显微镜（TEM）观察，发现残炭的微观结构包含大量碳纳米管。大量残炭的产生不仅减少了热解产物的释放，还形成了一个阻止氧气和热量传输的隔热层。与纯PP相比，Ni-WS-AC-PP的峰值热释放速率（pHRR）和总热释放速率（THR）分别降低了46.32%和26.03%。此外，受益于高度分散的WS，Ni-WS-AC-PP的拉伸强度和杨氏模量与纯PP相似，且不牺牲韧性。
