ABSTRACT:The free-volume properties of high-impact polystyrene (HIPS)/polypropylene (PP) and HIPS/highdensity polyethylene (HDPE) blends were investigated by means of positron annihilation lifetime spectroscopy (PALS). The measured results show that the free-volume holes in the semicrystalline polymers, such as PP and HDPE, were not large enough to accommodate the branched chains and the end groups of the macromolecular chains in HIPS to produce favorable interactions between the semicrystalline polymers and the HIPS polymer in these blends; thus immiscible blends were formed. The weak interaction between two dissimilar polymer molecules only took place in the regions between two amorphous phases. In addition, the observed negative deviations of the longest lifetime intensity and the free-volume fraction were attributed to the influence of the interfacial polarization during PALS measurement.

A calculation method is developed for the fluorescence radiation produced in an element by the characteristic X-ray emitted from another element in multi-layer films. The equations, applicable to a thin or a thick layer, are presented to facilitate X-ray analysis on a wide range of systems. An extension of the equations to include multi-layer multi-component films is described.

Radon is readily soluble in water, and radon exposure caused by household water consumption may pose a threat to public health. In this study, the radon concentration in the tap water of residential buildings was measured, and the average value was 543.33 mBq L−1, which was in line with the radon concentration limit recommended by USEPA (11.11 Bq L−1) and EURATOM (100 Bq L−1), and also within the range of the results of radon concentration measurements in tap water in other countries or regions. Through water bath heating at different temperatures, the radon retention curves of multiple groups of samples at different temperatures were fitted and analyzed. The results showed that the radon retention continued to decrease between 25 and 70 °C, remained stable between 70 and 85 °C, and then continued to decline slowly. Combined with the measurement results, the effective doses of α- and β-particles emitted by 222Rn and its progenies to residents respiratory and alimentary tissues and organs were calculated using the computational model provided by ICRP under two typical water scenarios of shower and drinking water, and the results show that radon exposure caused by normal water consumption will not pose a serious threat to public health.

No abstract

Based on a simplified Monte Carlo simulation model of electron scattering and characteristic x-ray excitation of a multicomponent film on a substrate, a calculation method with an iteration approach was developed to transform the x-ray intensity ratios measured by an electron probe microanalyzer into the chemical composition of the thin film on the substrate. The calculation of the characteristic fluorescence is also included in the simulation. The calculation results of compositions for several specimens agree well with measured data. individually: J D 14.0 1 exp 0.1Z C 75.5 Z z/7.5 Z 100 C Z Z 19 J D 9.76 C 58.8Z 1.19 Z 20 J D 13.5Z 21 J D 11.5Z 22 J D [9.0 1 C Z 2/3 C 0.03Z]Z 23 J D 12.4 C 0.027Z Z 24