Luminescence peculiarities of polyamide-6 α and γ forms

Persistent time-delayed luminescence was observed in bulk polymer Polyamide-6 (nylon 6) samples at room temperature. Using X-ray 2Θ-diagnostics we have separated two crystalline forms of the material which exhibit serious differences in their time-delayed luminescence properties. Whilst for the α-form the afterglow temperature threshold is at the range of 100 °C, the γ-form samples require cooling to about −20 °C for the effect becomes observed by eye. The afterglow relaxation traces are highly reproducible and we extracted the Becquerel law function (compressed hyperbola) for them. The conclusion derived on the origin of the effect is the photoinduced charge recombination process. A theoretical model is presented for the explanation of the experimental results.