摘要
研究了物理老化对聚苯基单醚喹啉薄膜的结构与力学性能的影响 .用差示扫描量热计 (DSC)及正电子湮没寿命谱 (PALS)方法表征了两种不同物理老化条件试样的凝聚结构以及自由体积的差别 .结果表明 ,物理老化使聚苯基单醚喹啉薄膜玻璃化转变温度移向高温 ,在其末端出现热焓吸收峰 ,分子链堆砌紧密使自由体积减小 ,分子可动性降低 .用动态力学分析 (DMTA)以及静态拉伸性能测试等方法研究了两类试样的力学性能 ,结果表明 ,物理老化后 ,试样的动态储能模量稍有增加 ,力学损耗降低 .而静态拉伸实验的断裂应变降低 ,屈服应力增加 ,断裂能降低 ,试样在宏观上由韧性断裂变为明显的脆性断裂 .
Polyphenylquinoxaline (PPQ\|E) is an aromatic heterocyclic polymer with high performance and water resistance at high temperature.It was synthesized form aromatic tetraamine and aromatic tetraketone by condensation polymerization.The influence of physical aging on structure and mechanical properties of polyphenylquinoxaline has been studied.The free volume and cohensional entanglement structure of samples preapared under two different thermal conditions were measured by positron annihilation life spectroscopy (PALS) and DSC.For samples which underwent physical aging an endothermic peak at the end of the glass transition was observed in a heating process.It means more cohensional entanglement stucture forms during physical aging.The results of PALS show that physical aging may reduce the free volume in samples.A little increase of storage modulus in the temperature range from 100℃ to 300℃ and a decrease of mechanical loss at 250～300℃ result form physical aging.The tensile mechanical tests manifest that physical aging may result in a decrease of fracture strain and energy,an increase of yield stress and a transition from ductile to brittle generate for PPQ\|E samples.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2000年第4期415-419,共5页
Acta Polymerica Sinica
基金
国家科委基础性研究重大关键项目!"高分子凝聚态基本物理问题研究"
高分子物理开放实验室基金资助
关键词
物理老化
力学性能
聚苯基单醚喹恶啉
薄膜
结构
Physical aging,DSC,PALS,Tensile properties,Dynamic mechanical properties,Polyphenylquinoxaline
