Synthesis of cerium-based flame retardant containing phosphorus and its impact on the flammability of polylactic acid

The synthesis and characterization of [Ce2(PPPA)4(OH)2]·4H2O, wherein PPPA denotes 3-(hydroxy(phenyl)phosphoryl)propanoate, were conducted. Its potential as a flame-retardant additive for poly(L-lactic acid) (PLA) in conjunction with ammonium polyphosphate (APP) was investigated. Remarkably, with just incorporation of the 1 % Ce-complex and 4 % APP, the resulting PLA composite (PLA-8) meets the V-0 standard, exhibiting an impressive limiting oxygen index (LOI) of 29.4 %. Moreover, the introduction of the Ce-complex leads to a significant extension of ignition time (TTI), a significant 24.1 % decrease in total heat release (THR) compared to pure PLA, and a notable increase in residual carbon rate from 0.3 % to 3.51 %. Although PLA-8 exhibits a minor decline of 8.7 % in tensile strength and 3.4 % in elongation at break, respectively, compared to pure PLA, there is a substantial improvement of 32.2 % in Young's modulus and 29.9 % in impact resistance. These results emphasise the potential of cerium-based phosphorus-containing flame retardants, with cerium playing a key role in enhancing the flammability characteristics of PLA. This study contributes to the development of sustainable and fire-resistant materials in polymer chemistry.

Recent remediation strategies for flame retardancy via nanoparticles

This review article delves into the application of nanoparticles (NPs) in fire prevention, aiming to elucidate their specific contribution within the broader context of various fire prevention methods. While acknowledging established approaches such as fire safety principles, fire suppression systems, fire alarm systems, and the use of fire-retardant chemicals and safety equipment, this review focuses on the distinctive properties of NPs. The findings underscore the remarkable potential of NPs in controlling and mitigating fire propagation within both architectural structures and vehicles. Specifically, the primary emphasis lies in the impact of NPs on reducing oxygen levels, as assessed through the limiting oxygen index , a subject explored by various researchers. Furthermore, this review delves into the examination of combustion reduction rates facilitated by NPs, utilizing assessments of ignition time, heat release rate (HRR), and flammability tests (UL-94) on plastic materials. Beyond these aspects, the review evaluates the multifaceted role of NPs in achieving weight reduction and establishing fire-retardant properties. Additionally, it discusses the reduction of smoke, a significant contributor to environmental pollution and health risks. Among the nanoparticles investigated in this study, SiO2, MgAl, and nano hydrotalcite have demonstrated the best results in weight reduction, smoke reduction, and HRR, respectively. Meanwhile, Al2O3 has been identified as one of the least effective treated nanoparticles. Collectively, these findings significantly contribute to improving safety measures and reducing fire risks across a range of industries.

Design and Synthesis of PET-Based Copolyesters with Flame-Retardant and Antidripping Performance

Poly(ethylene terephthalate) (PET) is a fiber-forming polymer with the largest output and widest usage. Its flame retardation is well-achieved via a mechanism of promoting the melt dripping while ignited. However, the melt dripping leads to secondary damage and an immediate empyrosis during fire. How to address the contradiction between the flame retardation and the melt-dripping behavior of PET via an inherent flame-retardant approach becomes a real challenge. This feature article highlights the design and synthesis of novel PET-based copolyesters with flame-retardant and antidripping performance. Three approaches are used to design these copolyesters: "ionic aggregation," "smart self-cross-linking," and "rearrangement at high temperatures." Some new conceptions are proposed accordingly. The synthesis, structure characterization, and properties of those copolyesters are discussed together with the ongoing challenges and limitations at this frontier.

Thermolysis parameter and kinetic research in copolyamide 66 containing 2-carboxyethyl phenyl phosphinic acid

Polyamide 66 (PA66) containing phosphorus with flame-retardant property (FR-PA66) was synthesized with adipic acid hexamethylene salt and 2-carboxyethyl phenyl phosphinic acid as raw materials. The thermal degradation kinetics of FR-PA66 and PA66 were measured using a thermogravimetric analyzer, and the data obtained were analyzed with Flynn–Wall–Ozawa and Coast–Redfern methods. The results show that the activation energy ( Ea) of PA66 fabricated under different conditions will be different, while the mechanism functions of thermal decomposition remain the same. Comparing the limit Ea value of PA66 with FR-PA66 at different stages of thermolysis, FR-PA66 keeps the initial thermolysis Ea almost unchanged, reduces the middle thermolysis Ea to 139.1 kJ mol−1, and increases the last thermolysis Ea to 454 kJ mol−1, that is 223 kJ mol−1 higher than that of PA66 with 231 kJ mol−1. This result may be explained by the first cleavage of P–C bond and the formation of the carbonized protective layer. In addition, the most probable kinetic mechanism functions ( F( α)) of thermolysis of FR-PA66 in three different stages were when the rate of decomposition ( α) is lower than 0.4, F( α) = −ln(1 − α); when α is between 0.4 and 0.65, F( α) = [−ln(1 − α)]; and when α is beyond 0.65, F( α) = [−ln(1 − α)].