Nylon 6-clay hybrid (NCH) is a molecular composite of nylon 6 and uniformly-dispersed silicate layers of montmorillonite. Gas permeabilities in NCH films were measured to estimate the gas barrier properties. Montmorillonite crystal layers assume planar orientation in NCH. Crystallinity of nylon 6 in NCH was a little larger than that of nylon 6. The gas permeability in NCH decreased with the increase in the montmorillonite content. NCH had a good gas barrier properties compared with nylon 6. The superior gas barrier properties of NCH are ascribed to the increase of tortuosity factor due to the planar orientation of montmorillonite crystal layers.

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The article studied the methods how to shorten the irradiation time by increasing dose rate without changing the effective degradation condition for samples. The samples used was nine kinds of EPDM which have different compounding formula. The different dose of Co-60 γ ray was exposed to samples. The maximum dose was 2MGy.
The reference condition to be compared to short time test is the irradiation of 0.33kG y/h at room temperature. Two methods shown below was studied as the time accelerate irradiation.
1) Irradiation of 4.2kGy/h in 0.5MPa oxygen at room temperature.
2) Irradiation of 5.0kGy/h in air at 70°C.
After irradiation the mechanical properties of samples was measured at room temperature. The changes in 100% modulus suggests that irradiation in 0.5 MPa oxygen increases slightly scission reaction and irradiation at 70°C increases slightly cross-linking, compared with the result of low dose rate irradiation. The deviation of properties obtained in time accelerate methods from that of low dose rate irradiation was studied. The deviation was in ± 0.25 for 100% modulus and was in ± 0.5 for ultimate elongation throughout the all doses, where the value obtained at low dose rate referred to as 1.0. Thus it was found out that two methods mentioned above are available as time accelerate irradiation conditions.

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