FREE VOLUME DURING CURING REACTION OF THERMOSETTING RESIN STUDIED BY POSITRON ANNIHILATION

正电子湮没寿命谱（帕尔斯）已成功应用于固体物理中检测缺陷和杂质。最近，帕尔斯已被应用于聚合物。从放射性同位素如Na注入聚合物的正电子<22>通过与原子和分子的相互作用而失去能量。几百eV的正电子在失去能量后，产生由离子、电子和正电子组成的末端杂散，然后是来自类氢原子正电子素（Ps）的正电子。Ps在聚合物中扩散，直到它被困在分子间空间。Ps在这些空间中衰减，其尺寸可以通过邻位Ps的长寿命（tau_3）来测量。在本研究中，使用帕尔斯研究了双酚A二氰酸酯的聚合，并且观察到比容随着聚合度的增加而增加。还研究了几种环氧树脂的自由体积。结果表明，THPM环氧树脂吸水后，自由体积发生了变化，聚合物结构发生了松弛，在液氮温度下淬火后，由于聚合物链间的应力作用，几个小的分子间形成了大的分子间空间.

Positron annihilation lifetime spectroscopy (PALS) has been applied successfully in solid state physics to detect defects and impurities. Recently, PALS has been applied to polymers. Positrons injected into polymers from radioisotopes such as ^<22>Na lose energy through interaction with atoms and molecules. After loosing the energy, positrons with a few hundred eV make the terminal spurs, which consist of ions, electrons and positrons, and then the positrons from hydrogen like atom, positronium (Ps). Ps diffuses in polymers until it is trapped in intermolecular spaces. Ps decays in these spaces and the size can be measured by the long lifetime (tau_3) of ortho-Ps.In this research, polymerization of bisphenol A dicyanate was examined using PALS and the increase in the specific volume was observed with the increase in the degree of polymerization. Also free volumes of several epoxy resins have been studied. The shift of the size of free volumes was observed when a THPM epoxy resin absorbed water.Also, the relaxation of polymer structures was discussed using PALS.After quenching the novolac epoxy resins to liquid nitrogen temperature, the large intermolecular spaces were observed, which would be formed by combining several small spaces due to the stress among polymer chains.