Browsing by Author "Zhao, Junhuan"
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Item Bio-based flame retardants to polymers: A review.(Advanced Industrial and Engineering Polymer Research, 2022) Wang, Meiting; Yin, Guang-Zhong; Yang, Yuan; Fu, Wanlu; Díaz Palencia, José Luis; Zhao, Junhuan; Wang, Na; Jiang, Yan; De-Yi, WangDue to environmental concerns, some of the conventional halogenated flame retardants have been banned. In this context, both the industrial and academics have made efforts to develop more eco-friendly and sustainable flame retardant materials. Among new flame retardants, bio-based groups have attracted plenty of attention. In this review, varied types of bio-based flame retardants are systematically described, including the structural characteristics, flame retardant behaviors, and an overview of flame retardant mechanism. Recent research progress on various bio-based materials such as flame retardants (e.g., chitosan, lignin, phytic acid, polydopamine, Tannic acid, β-cyclodextrin, etc.) applied to different polymers are adequately summarized. Finally, the opportunities and challenges for the future development of bio-based flame retardants are briefly outlooked.Item Recent Advances in Flame Retardant and Mechanical Properties of Polylactic Acid: A Review.(Advanced Materials, 2023) Yang, Xiao-Mei; Qiu, Shuang; Yusuf, Abdulmalik; Sun, Jun; Zhai, Zhongjie; Zhao, Junhuan; Yin, Guang-ZhongThe large-scale application of ecofriendly polymeric materials has become a key focus of scientific research with the trend toward sustainable development. Mechanical properties and fire safety are two critical considerations of biopolymers for large-scale applications. Polylactic acid (PLA) is a flammable, melt-drop carrying, and strong but brittle polymer. Hence, it is essential to achieve both flame retardancy and mechanical enhancement to improve safety and broaden its application. This study reviews the recent research on the flame retardant functionalization and mechanical reinforcement of PLA. It classifies PLA according to the type of the flame retardant strategy employed, such as surface-modified fibers, modified nano/micro fillers, small-molecule and macromolecular flame retardants, flame retardants with fibers or polymers, and chain extension or crosslinking with other flame retardants. The functionalization strategies and main parameters of the modified PLA systems are summarized and analyzed. This study summarizes the latest advances in the fields of flame retardancy and mechanical reinforcement of PLA.Item Surface Modification of Ammonium Polyphosphate for Enhancing Flame-Retardant Properties of Thermoplastic Polyurethane.(Materials, 2022) Wang, Zhiwen; Jiang, Yan; Yang, Xiaomei; Zhao, Junhuan; Fu, Wanlu; Wang, Na; De-Yi, WangCurrently, the development of efficient and environmentally friendly flame-retardant thermoplastic polyurethane (TPU) composite materials has caused extensive research. Ammonium polyphosphate (APP) is used as a general intumescent flame retardant to improve the flame retardancy of TPU. In this paper, we developed a functionalized APP flame retardant (APP-Cu@PDA). Adding only 5 wt% of APP-Cu@PDA into TPU can significantly improve the flame-retardant’s performance of the composite material, reflected by a high LOI value of 28% with a UL-94 test of V-0 rating. Compared with pure TPU, the peak heat release rate, total heat release, peak smoke release rate, and total smoke release were reduced by 82%, 25%, 50%, and 29%, respectively. The improvements on the flame-retardant properties of the TPU/5%APP-Cu@PDA composites were due to the following explanations: Cu2+-chelated PDA has a certain catalytic effect on the carbonization process, which can promote the formation of complete carbon layers and hinder the transfer of heat and oxygen. In addition, after adding 5% APP-Cu@PDA, the tensile strength and elongation at the break of TPU composites did not decrease significantly. In summary, we developed a new flame-retardant APP-Cu@PDA, which has better flame-retardant properties than many reported TPU composites, and its preparation process is simple and environmentally friendly. This process can be applied to the industrial production of flame retardants in the future.