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Polymer properties are often engineered in desired directions by additives or by irradiations or by both. However, in space and certain other applications, energetic particles or γ-rays may damage the polymeric parts in undesired directions, needing prior radiation damage studies for necessary precautions. Case studies of three completely different polymer-additive composites follow: (1) shielding  e lectro m agnetic  i nterference (EMI) by different composites of a polymeric binder, (2) electrical, thermal, mechanical (Young’s Modulus, Y) and positron lifetime (PL) characterizations of solid polymer electrolytes (SPEs), and (3) determination of total free volume and hole size by pressure-volume-temperature (P-V-T) and positron lifetime techniques, respectively, in two types of polymers. One type consists of complexes of poly-(ethylene oxide), PEO, with a suitable salt, PEO-salt SPEs. The other type consists of silica-filled and pure varieties of poly(dimethyl siloxane), PDMS. Melting point and glass transition temperature of these polymers have been determined from PL techniques as well as from differential scanning calorimetry (DSC). Electrical contact problem has been addressed by measuring impedance as a function of pressure, p, and then extracting p=0 values of impedance and Young’s Modulus. These illustrative measurements have been carried out for better characterization of the polymers. DSC thermogram showed that radiation induced changes of melting point of PEO-salt samples are in opposite directions for 160 MeV Ne 6  + ion and 1.25 MeV γ-ray irradiations. This interesting feature hints at different mechanisms of radiation damage in two cases.

Modifications of polymers by additives and irradiations and their characterizations