Flame Retardance plus Mechanical Reinforcement: Phosphorus-Containing LCP toward in situ Composites
The flame retardation of polymeric materials has received more and more attentions recently due to the increased fire disasters caused by ignition of polymers. The existing traditional flame retardants, especially small molecular flame retardants exhibit practical drawbacks such as their migration problems, deterioration of polymer performance, and potential persistence, bio-accumulation and toxicity (PBT), et al. Therefore, the scientists and producers have recognized use of polymeric flame retardants over small molecule flame retardants. It is a challenging work how to design and synthesize polymeric flame retardants that can overcome the aforementioned drawbacks of existing flame retardants, especially address the issue that by addition of flame retardants, the flame retardation of polymers always accompanies the deterioration of their mechanical properties almost without expectation.
Recently, our group successfully developed for the first time a method for addressing the aforementioned issue, that is, designed and synthesized a kind of phosphorus-containing thermotropic liquid crystalline polymer (TLCP), which was used as a flame retardant for conventional thermoplastic polymers. In addition to the increase in the flame retardance of the polymers, the tensile properties of the polymers were also enhanced due to the in situ microfibrillation of TLCP in the polymer matrix during the processing.
However, challenges still remain in the research of the in situ composites with both flame retardance and reinforcement. Developing more effective and economic flame-retardant monomer, synthesizing TLCP with lower liquid crystalline phase transition temperature and wide temperature range of liquid crystalline phase, and solving the factors influencing the fibrillation of TLCP in the matrix are the key points of this field.
Nevertheless, the exploration of the novel method for flame retardation of polymers with improved mechanical properties can be seen as a class of efficient flame-retardant method, and hence provides a powerful basis for the construction of flame-retardant technologies and potential industrial applications.
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