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轻度交联PMMA的结构转变及自由体积特性 被引量:3

STRUCTURAL TRANSITIONS AND FREE VOLUME CHARACTERISTICS OF LIGHTLY CROSSLINKED PMMA
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摘要 用正电子湮没技术(PAT)研究了具有两种交联度的轻度交联PMMA试样的结构转变,包括玻璃化转变及次级弛豫过程(β转变),交联度对轻度交联PMMA的β转变无影响,交联度较大试样的Tg较高,用PAT测得的Tg比用动态力学分析(DMA)法得到的Tg低7℃。交联度较高的试样中自由体积孔穴数目较多。讨论了正电子湮没平均寿命(τm)与聚合物总自由体积的关系。此外,还从o-Ps寿命大小计算了轻度交联PMMA中的自由体积孔穴半径,并研究了其随温度变化的规律。 Structural transitions, glass and sub transition, of lightly crosslinked PMMA with two different corsslinking density were studied by positron annihilation technique (PAT). The cross linking density has no influence on T β, T g of the PMMA increases with an increase of cross linking density. T g obtained from danymic mechanical analysis (DMA) is 7 ℃ higher than that measured by PAT. There are much more free volume voids in the PMMA with higher crosslinking density. The relationship between average positron annihilation lifetime ( τ m) and free volume was analyzed. Sizes of free volume voids were calculated from o Ps lifetime and their temperature dependence was also studied.
出处 《高分子材料科学与工程》 EI CAS CSCD 北大核心 1997年第4期73-77,共5页 Polymer Materials Science & Engineering
基金 国家自然科学基金
关键词 PMMA 正电子湮没 结构转变 自由体积 交联度 lightly cross linked PMMA, structural transition, free volume, positron annihilation
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  • 1团体著者,高聚物的结构与性能,1981年

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