Free volume in a thin film of epoxy resine coated on a metal base studied by positron annihilation

用正电子湮灭法研究了涂覆在金属基板上薄膜的自由体积。然而，为了研究聚合物的表面，需要脉冲慢正电子束（PSPB）来确定所研究聚合物中的注入时间。在这个项目中，使用了一个桌面大小的小型仪器来使用放射性同位素（RI）产生PSPB。采用射频法，在直径为2cm、长度为5cm的铝管上施加射频场，得到束状脉冲光束。其长度由正电子通过电子管的飞行时间决定。因此，40兆赫的射频被用来束成束束的轮辐波束。宽度为500 - 600ps，足以研究寿命超过1.5 - 2ns的聚合物样品。在样品中注入脉冲束束的装置已经成功地应用于测量聚合物的寿命：聚乙烯、环氧树脂、环氧复合材料、硅金属上的环氧涂层薄膜。制备了注入碳的超高分子量聚乙烯，研究了离子对其表面的影响。表面变形，寿命比样品稍长。在沉积位置的深度附近，Ps的形成强度变得很小，而沉积位置是碳注入层的预期位置。得到了环氧树脂的表面热膨胀系数和体积。在聚乙烯中，正电子离子的形成随深度的增加而增加。采用非破坏性方法对复合材料的表皮层进行了观察。研究了广泛应用于集成电路和电子工业的硅基低钾薄膜。成功地观察到正电子寿命约为50 ns的大空穴

Free volumes in a thin film coated on a metal base plate can be studied by positron annihilation. However, In order to study the surface of polymers, a pulsed slow positron beam (PSPB) is necessary to determine the injection time in the investigated polymer. In this project, a small apparatus desk-top size to generate a PSPB using radio isotopes (RI) has been used. The bunched and pulsing beam was obtained by the RF method, in which RF field is applied on an Al tube with 2cm diameter and 5cm length. The length is determined by the flight time of positrons through the tube. Thus 40 MHz RF is used to bunch the rundum beam to a bunched beam. The width is 500 to 600ps, which is enough to study polymer samples, which have lifetimes longer than 1.5ns to 2 ns.The apparatus to inject a pulsed and bunched beam in samples has been successfully applied to measure lifetimes of polymers : polyethylene, epoxy resin, epoxy composite, epoxy coated films on a Silicon metal. Carbon-implanted ultra-high molecular-weight polyethylene, was prepared and the surface affected by the ions was studied. The surface was distorted and the lifetime became a little longer than the balk sample. Ps formation intensity became small around the depth of the deposited position, where the carbon implanted layer is expected. The heat expansion coefficient of the surface and the bulk of epoxy resin was obtained.The increase in the positronium formation with increasing the depth was observed in polyethylene. The skin layer of the composite materials was observed by a non destructive method. Low K films on Silicon plate, which are extensively used in IC and electric industry has been studied.Large holes with about 50 ns positron lifetime has been successfully observed