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首页> 外文期刊>Journal of Applied Polymer Science >POSITRON ANNIHILATION LIFETIME STUDY OF VAPOR SORPTION IN POLYPROPYLENE AND POLYTETRAFLUOROETHYLENE
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POSITRON ANNIHILATION LIFETIME STUDY OF VAPOR SORPTION IN POLYPROPYLENE AND POLYTETRAFLUOROETHYLENE

机译：聚丙烯和聚四氟乙烯中蒸气吸附的正电子AN没寿命研究

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摘要

Positron annihilation lifetime (PAL) spectra were measured for two different kinds of polymers: polypropylene (PP) and polytetrafluoroethylene (PTFE), during sorption of vapors of the following molecules: n-hexane, cyclohexane, benzene, methyl methacrylate, acrylic acid, and water. The behavior of ortho-positronium (o-Ps) annihilation parameters: lifetime, tau(3), and intensity, I-3, can be explained by considering different sorption mechanisms in rubbery and glassy polymers. The mean size of the intermolecular-space holes and the relative free-volume fraction of PP and PTFE were estimated before and during the sorption process from the o-Ps parameters obtained. Sorption of n-hexane, cyclohexane, and benzene in both polymers affect the o-Ps component in a systematic way, for PP tau(3) and I-3 tend to decrease, while in PTFE, tau(3), stay almost constant and I-3 diminishes. These effects are interpreted in relation to the different states of the polymers studied: rubbery for PP and glassy for PTFE. In case of methyl methacrylate molecules, the behavior of o-Ps parameters was more complicated. For acrylic acid and water, their associated polarity provokes a diminution in I-3, which is explained from the viewpoint of the spur model of positronium formation. Large changes in the mean size and the fraction of free volume, as well as their constant behavior in some cases, were interpreted to be due to positive or negative interactions, respectively, between vapor molecules and PP and PTFE, which could be correlated with the solvent-interaction parameters calculated. (C) 1995 John Wiley and Sons, Inc. [References: 30]
机译：在以下分子的蒸气吸附过程中，对两种不同类型的聚合物（聚丙烯（PP）和聚四氟乙烯（PTFE））的正电子an没寿命（PAL）光谱进行了测量：正己烷，环己烷，苯，甲基丙烯酸甲酯，丙烯酸和水。可以通过考虑橡胶状和玻璃状聚合物中不同的吸附机理来解释邻位正电子（（o-Ps）hil没行为：寿命tau（3）和强度I-3。根据获得的o-Ps参数，估算了吸附过程之前和期间的分子间孔的平均大小以及PP和PTFE的相对自由体积分数。两种聚合物中正己烷，环己烷和苯的吸附都会系统地影响o-Ps组分，对于PP tau（3）和I-3倾向于降低，而在PTFE中，tau（3）则保持几乎恒定I-3减少。这些影响与所研究的聚合物的不同状态有关：PP为橡胶状，PTFE为玻璃状。在甲基丙烯酸甲酯分子的情况下，o-Ps参数的行为更为复杂。对于丙烯酸和水，它们的相关极性导致I-3减小，这是从正电子形成正杂散模型的角度解释的。平均尺寸和自由体积分数的较大变化，以及它们在某些情况下的恒定行为，被认为分别是由于蒸气分子与PP和PTFE之间的正或负相互作用，这可能与计算出溶剂相互作用参数。 （C）1995 John Wiley and Sons，Inc. [参考：30]

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