高热稳定性低氯聚苯砜树脂合成及表征

结合缩聚方法和封端修饰方法合成苯酚封端的聚苯砜(PPSU)树脂,利用离子色谱方法对PPSU树脂的氯端基含量进行定量测试,并采用毛细管流变仪和高温注塑等方法对比评估了不同氯端基含量PPSU树脂的热稳定性和颜色。结果表明,通过苯酚封端,PPSU树脂的氯端基含量可由3000 mg/kg以上降至700 mg/kg以下,氯端基含量取代比例可达80.6%,同时PPSU树脂的力学性能未发生明显变化,拉伸强度、屈服点伸长率、弯曲强度和缺口冲击强度分别保持在73 MPa,89%,114 MPa和50 kJ/m²左右,并且PPSU树脂的热稳定性得到一定程度提高,颜色等级有所改善。     

聚苯砜树脂聚合脱水工艺对比

对比研究了聚苯砜(PPSU)树脂聚合过程中闭环脱水工艺和传统连续通氮脱水工艺两者的尾气排放量和物料损耗情况,并采用高压毛细管流变测试、力学性能测试、高温注塑等方式,系统地评估了闭环脱水工艺对树脂热稳定性和力学性能的影响,发现闭环脱水工艺的效果较原连续通氮脱水工艺更优异.闭环脱水工艺制备所得到的PPSU树脂热稳定性和力学...     

基于可靠度的组合桥梁设计及维护策略(英文)

Currently,the design practice of highway bridges around the world are moving towards limit states design,a reliability-based design procedure.Canadian Highway Bridge Design Code(CHBDC)is the first design code entirely developed based on limit states design philosophy,including foundations and FRP components.However,reliability of a structure decreases in service due to environmental attacks and material deterioration such as fatigue,corrosion and many other reasons.Therefore,the structure should be inspected periodically,and the reliability of the structure should be evaluated according to its age and field data.If its reliability is reduced to a certain level,a repair should be scheduled as well as some preventive maintenance measures should be implemented to prevent further deterioration.Recently,many research works have been conducted to investigate reliability-deterioration mechanisms for each type of infrastructure and its components,optimize the inspection and maintenance strategy,predict remaining service life,estimate its life cycle cost.This paper is focused on the study of reliability-deterioration mechanisms of slab on steel girder bridges due to fatigue and corrosion of steel girders as well as corrosion of reinforcement in the deck slab.Examples will also be given to illustrate the proposed life cycle management strategy for composite slab on steel girder bridges.     

成盐剂体系对聚醚砜树脂合成与性能的影响

通过缩聚系统研究了成盐剂体系中的K₂CO₃∶Na₂CO₃配比及成盐剂过量比和平均粒径等参数对聚醚砜(PESU)树脂合成过程中成盐反应时间、溶液黏度的影响,并利用高压毛细管流变仪和高温注塑方法对合成的PESU热稳定性和颜色等级进行了测试和对比研究。研究发现,成盐剂最优配方为复合成盐剂体系K₂CO₃∶Na₂CO₃物质的量之比1∶5、成盐剂过量比7%、成盐剂平均粒径31μm。对于研究的PESU聚合体系,采用上述成盐剂配方可实现成盐反应时间的大幅缩短,且聚合所得到的PESU树脂具有较高的热稳定性和较低的黄色指数,从而实现了实际生产过程中PESU树脂合成成本的降低和外观性能的提升。