Many experimental results have shown that the positron annihilation technique is an advanced technique for the test and characterization of the polymer microstructure, such as the free-volume of polymers.

It is observed that the average size of free-volume holes generally remains constant,and the hole concentration and the width of hole radius distribution decrease with the increase in radiation dose.

This paper explained the diffusion of migratory substances from crystalline polyolefins from microcosmic view according to Vrentas-Duda free-volume theory,discussed the effect of temperature,density of polyolefins,molecular structure of migratory substances and swelling on diffusion coeff.

The results indicate that the discrete shear bands are formed around the indent and the local free volume is increased in the bulk metallic glass by deformation.

Positron annihilation lifetime spectroscopy(PALS) was used to investigate the free volume properties of PA6/clay nanocomposites in the temperature range from 10 K to 290 K below their glass transitions.

Effects of toughening agent and temperature on the free volume and mechanical properties were studied by positron annihilation lifetime spectroscopy(PALS) and dynamic mechanical analysis(DMA) for a serious of epoxy resin samples with different toughening agent content(W/W).

Based on complete and censored date, we obtain pointwise consistency of regression fUnction kernel estimates under suitable conditions, the results are distribution free in the sense that they are true for all distributions μ of X.