热氧老化对阻燃聚酯性能的影响

Effect of thermal oxygen aging on properties of phosphorus flame retardant polyester

阻燃聚酯在加工、储存和应用方面,容易受到水、空气、阳光以及不同环境因素的影响,研究阻燃聚酯材料在自然环境中的热老化特性非常重要。本文研究了阻燃聚酯在70℃、168 h条件下老化前后样品的常规性能与力学性能的变化。通过极限氧指数(LOI)和UL-94垂直燃烧试验研究了老化前后样品阻燃性能的变化。通过激光显微镜、差示扫描量热法(DSC)、热失重分析(TGA)等方法研究了磷系阻燃聚酯在热氧条件下的老化机理。结果表明,热氧老化过程中分子降解占主导地位,导致样品的特性黏度、机械性能下降而结晶度和T c温度升高。热氧老化对阻燃聚酯极限氧指数的影响较小,但由于热氧老化造成的分子链断裂和力学性能下降,阻燃聚酯的UL94性能下降。热氧老化会使阻燃聚酯的热性能和阻燃性能下降,稳定剂的加入可以提升阻燃聚酯的耐热氧老化性。

The long-term thermal oxidation aging behavior of phosphorus flame retardant polyester was studied by comparing with stable samples.Phosphorus flame retardant polyester at 70℃was studied with changes of basic properties and mechanical properties of samples before and after aging at 168 h.The changes of flame retardancy before and after aging were studied by limiting oxygen index(LOI)and UL-94 vertical combustion test.The aging mechanism of phosphorus flame retardant polyester under hot oxygen condition was studied from the aspects of intrinsic viscosity,crystallization behavior and chemical composition by laser microscope,differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA).The results show that molecular degradation is dominant in the process of thermal oxygen aging,resulting in the decline of intrinsic viscosity and mechanical properties,while the crystallinity and T c temperature increase.Thermal oxygen aging has little effect on the limiting oxygen index of flame retardant polyester,but the UL94 properties of flame retardant polyester decrease due to the molecular chain fracture and mechanical properties decline caused by thermal oxygen aging.Thermal oxygen aging will reduce the thermal properties and flame retardant properties of flame retardant polyester,and the addition of stabilizers could improve the resistance of flame retardant polyester to heat and oxygen aging.