The issue of fire hazard safety with regard to materials is of great concern. Polybutylene terephthalate/butylene terephthalate (PBAT) is the most extensively researched and utilized biodegradable material. However, the absence of flame-retardant chain segments in its molecular structure poses a significant environmental safety hazard. Our team utilizes the reversibility of the polymerization reaction of PBT (polybutylene terephthalate) materials and a chemical recycling process to degrade PBT into BHBT (butylene terephthalate), a raw material for the preparation of PBAT. At the same time, together with the halogen-free and environmentally friendly flame-retardant CEPPA (3-hydroxyphenylphosphinyl-propanoic acid) and BHAT (butylene glycol adipate), we design and produce an environmentally friendly and highly efficient halogen-free flame-retardant PBAT copolyester (PBATcept). The closed-loop recycling of nonbiodegradable PBT materials into small-molecule oligomers (BHBT) and oligomers into PBATcept was realized. The successful introduction of CEPPA into the PBAT chain segment was demonstrated to result in a reduction in the crystalline properties of PBATcept and an improvement in transparency and flame retardancy. The introduction of 5.0 mol % CEPPA resulted in a tensile strength of 10.93 ± 0.97 MPa and an elongation at break of 830.40 ± 48.25% for PBATcept5.0. Furthermore, the LOI value is 32.0%, and the UL-94 rating is V-0. CEPPA exerts synergistic flame-retardant effects of gas-phase flame retardancy and condensed-phase flame retardancy in PBATcept. During combustion, CEPPA undergoes preferential decomposition, generating nonflammable gases (H₂O and CO₂) to impede combustion and dilute the concentration of flammable gases. Concurrently, it forms a dense carbon layer on the surface of the polymer, which mitigates the safety hazards associated with PBAT due to fire. Furthermore, the preferential hydrolysis of the flame retardant enhances the biodegradation performance of PBATcept. The relative biodegradation rate can reach 33.92% after 30 days when the addition amount of CEPPA is 10.0 mol %.

中文翻译：

---

PBT化学醇解和闭环回收制备具有阻燃和可降解功能的PBAT共聚酯


与材料相关的火灾危险安全问题非常令人担忧。聚对苯二甲酸丁二醇酯/对苯二甲酸丁二醇酯 （PBAT） 是研究和利用最广泛的可生物降解材料。然而，其分子结构中缺乏阻燃链段构成了严重的环境安全隐患。我们的团队利用 PBT（聚对苯二甲酸丁二醇酯）材料聚合反应的可逆性和化学回收过程将 PBT 降解成 BHBT（对苯二甲酸丁二醇酯），这是制备 PBAT 的原料。同时，与无卤环保阻燃CEPPA（3-羟基苯基膦基丙酸）和BHAT（己二醇丁二醇酯）一起，我们设计生产了一种环保高效的无卤阻燃PBAT共聚酯（PBATcept）。实现了将不可生物降解的 PBT 材料回收为小分子低聚物 （BHBT） 和低聚物为 PBATcept 的闭环回收。事实证明，将 CEPPA 成功引入 PBAT 链段可降低 PBATcept 的结晶性能，并改善透明度和阻燃性。引入 5.0 mol % CEPPA 导致 PBATcept5.0 的拉伸强度为 10.93 ± 0.97 MPa，断裂伸长率为 830.40 ± 48.25%。此外，LOI 值为 32.0%，UL-94 等级为 V-0。CEPPA 在 PBATcept 中发挥气相阻燃和凝聚相阻燃的协同阻燃作用。在燃烧过程中，CEPPA 发生优先分解，产生不易燃气体（H₂O 和 CO₂）以阻碍燃烧并稀释易燃气体的浓度。 同时，它在聚合物表面形成致密的碳层，从而减轻了火灾引起的与 PBAT 相关的安全隐患。此外，阻燃剂的优先水解增强了 PBATcept 的生物降解性能。当 CEPPA 添加量为 10.0 mol % 时，30 天后相对生物降解率可达 33.92%。