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首页> 外文期刊>Nuclear Instruments & Methods in Physics Research. B, Beam Interactions with Materials and Atoms >Volatile evolution from polymer materials induced by irradiation with He~(++) ions and comparative pyrolysis experiments
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Volatile evolution from polymer materials induced by irradiation with He~(++) ions and comparative pyrolysis experiments

机译：He〜（++）离子辐照诱导聚合物材料挥发的过程及比较热解实验

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Irradiation of polymer samples using an accelerated beam of He~(++) ions passed through a 10μm thick window of Havarfoil has been performed. Such an irradiation simulates the effects of large αradiation doses on a vastly reduced time-scale. The experimental set up was designed so that the irradiated materials were contained within a small sample chamber. This chamber was isolated from the main vacuum chamber of the ion beam by means of the Havar foil window. A mass spectrometer linked directly to the sample chamber was used to analyse gaseous products evolved from the materials under irradiation. Samples of a material in which the polymer phase was an ethylenevinylacetate/polyvinylalcohol composite material indicated increased CO_2 and CO evolution upon irradiation. This material, however, evolved a considerable amount of volatiles even without irradiation and so a detailed mechanistic interpretation of the results is not possible. A foamed poly(siloxane) material evolved a number of volatile species upon irradiation and possible chemical degradation mechanisms are commented upon. The sample was extremely resistant to radiation induced degradation as measured by volatile evolution though, so again a detailed mechanistic analysis is not possible. Samples of a polyester based polyurethane evolved CO_2, CO and a number of high mass volatile species. Assignment of chemical structures to the main molecular ions allows deductions about the chemistry underlying radiation induced change to be made. Furthermore, identification of trends in volatile production allows information about potential degradation mechanisms to be deduced. To assess the contribution of sample heating on volatile evolution a series of pyrolysis experiments were performed. These indicate no evolution of volatiles below 100 ℃ and evolution of volatiles possessing masses of greater than 50 amu only at temperature of above 300 ℃.
机译：使用He〜（++）离子的加速束通过Havarfoil的10μm厚的窗口对聚合物样品进行辐照。这样的辐照在大大减少的时间尺度上模拟了大的α辐照剂量的影响。设计了实验装置，以使被辐照的材料被容纳在一个小的样品室中。该室通过哈弗箔窗与离子束的主真空室隔离。直接连接到样品室的质谱仪用于分析在辐照下从材料释放出的气态产物。聚合物相为乙烯乙酸乙烯酯/聚乙烯醇复合材料的材料样品表明，辐照后CO_2和CO逸出量增加。但是，即使没有照射，这种材料也会释放出大量的挥发物，因此无法对结果进行详细的机理解释。泡沫聚（硅氧烷）材料在辐照时会释放出许多挥发性物质，并提出了可能的化学降解机理。但是，通过挥发性演变来测量，样品对辐射诱导的降解具有极强的抵抗力，因此再次进行详细的机械分析是不可能的。聚酯基聚氨酯样品会析出CO_2，CO和许多高质量的挥发性物质。通过将化学结构分配给主要分子离子，可以推断出基于化学原理的辐射诱发的变化。此外，对挥发性生产趋势的识别可以推断出有关潜在降解机理的信息。为了评估样品加热对挥发物释放的贡献，进行了一系列热解实验。这些表明在100℃以下没有挥发物的释放，只有在300℃以上的温度才有质量大于50 amu的挥发物的释放。

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