基于含氮杂环结构的交联共聚酯的合成、表征及其阻燃抗熔滴行为研究

Polyesters, especially for poly (ethylene terephthalate) (PET), have been widely used in many application field more than just fibre-like materials, due to its excellent comprehensive properties. However, PET ignites and burns quickly, along with serious melt dripping during combustion; and for the developed flame-retardant PET, flame retardance is mostly achieved through melt dripping to remove heat and fire after ignition, particularly for the phosphorus-containing inherent flame retardant PET. .Facing on the contradiction between the non-flammability and non-dripping for the flame-retardant PET, in this project, based on the chemical nature to ring-opening and cross-linking at a certain temperature, and the potential tendency to char forming of the cross-linked structures, a series of main-chain or side-chain type benzoxazine-containing bi-functional co-monomers will firstly be designed and synthesized. Then the flame retardance and anti-dripping performance could be achieved simultaneously only by introducing the benzoxazine-containing co-monomers through copolymerization, despite the absence of phosphorus or any other traditional flame-retardant elements. Next, molecular regularity of the copolyesters will be controlled by using solid-state polymerization, including a two-step process: prior to the solid-state copolymerization, neat PET pre-polymer will be firstly prepared and then mixed with the benzoxazine-containing co-monomers. Consequently the inherent physical and mechanical properties will be maintained with the increase of chain regularity of the copolyesters. Positive contribution of the ring-opening and cross-linking reactions of the benzoxazine group on the flame retardance and anti-dripping performance will be systematically investigated, and the potential mechanism will be revealed. Based on the above-mentioned, relationship among "the molecular structure of the copolyester", "flame retardance and anti-dripping performance", "rheological behaviour and processability" and "physical and mechanical properties" will be established, and hence to explore an effective solution to resolve the contradiction between the non-flammability and non-dripping for the flame-retardant polyesters. .Therefore, this project has both scientific meanings and application prospects and hence to provide a scientific basis for development of environment-friendly flame-retardant polyesters with high flame retardance and anti-dripping performance, as well as excellent comprehensive physical and mechanical properties. And this project may raise a new thought to develop a new kind of flame-retardant polymer materials.

针对目前阻燃聚对苯二甲酸乙二醇酯（PET）存在的"提升阻燃效用和抑制熔滴之间的矛盾"，本项目利用苯并噁嗪官能团在一定温度下发生开环交联的化学属性，首先设计合成不同结构双官能团含苯并噁嗪共聚单体；其次在不引入磷等传统阻燃元素的前提下，仅通过共聚含苯并噁嗪单体同时实现共聚PET阻燃和抗熔滴；然后利用固相聚合控制共聚酯分子链段规整度，保持其固有性能；最后通过研究苯并噁嗪开环交联反应对共聚酯成炭耐熔滴的贡献，阐明此类智能交联共聚酯阻燃和抗熔滴的机理，建立起"共聚酯分子结构"-"阻燃与抗熔滴行为"-"流变行为与成型加工性能"-"物理机械性能"之间的构效关系，揭示不同结构共聚单体对共聚酯综合性能的影响规律，探索出解决"提升阻燃效用和抑制熔滴之间的矛盾"这一难题的有效途径，为制备综合性能优良的无卤阻燃抗熔滴聚酯材料打下理论基础，同时为开发其它阻燃材料提供一种新的思路。因此，本项目兼具科学意义和应用前景。

本项目针对聚酯无卤阻燃改性研究中存在的“提升阻燃效用和抑制熔滴之间的矛盾”这一公认的技术壁垒和科学难题，利用不同的可交联氮杂环结构在一定温度下发生开环交联的化学属性，设计合成三种不同结构双官能团可交联共聚单体，包括三氮唑、酰亚胺化降冰片烯和苯并马来酰亚胺，进而在不引入磷等传统阻燃元素的前提下，仅通过共聚含可交联氮杂环结构的单体同时实现PET共聚物的阻燃和抗熔滴性能；通过研究含可交联氮杂环结构交联反应对共聚酯成炭抗熔滴的贡献，阐明此类智能交联共聚酯阻燃和抗熔滴的机理，建立起“共聚酯分子结构”—“阻燃与抗熔滴行为”—“流变行为与成型加工性能”—“物理机械性能”之间的构效关系，揭示不同结构共聚单体对共聚酯综合性能的影响规律，对比了侧基含降冰片烯并酰亚胺环结构和含氧桥键降冰片烯并酰亚胺环结构的交联成炭阻燃机理。首次提出了交联反应与逆DA反应的竞争关系，探索出解决“提升阻燃效用和抑制熔滴之间的矛盾”这一难题的有效途径。本项目的开展过程中，共发表SCI论文12篇（系统已检录10篇），其中IF≥3的11篇；申请并授权发明专利3项（201410271300.3、201410704537.6和201510111653.1），为制备综合性能优良的无卤阻燃抗熔滴聚酯材料打下理论基础，同时为开发其它阻燃材料提供了一种新的思路。