Ultraviolet Radiation Induced Cold Chemi‐Crystallization in Syndiotactic Polypropylene Clay‐Nanocomposites

The effect of ultraviolet radiation on syndiotactic polypropylene (s‐PP) and its nanocomposites with montmorillonite was studied by means of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Nanocomposite materials were manufactured by melt mixing of an organically modified montmorillonite (Cloisite^®20A) with s‐PP matrix. Several compositions of s‐PP and montmorillonite were exposed to UV‐C radiation (254 nm). The effect of chemi‐ or radiation‐induced cold crystallization was confirmed for these nanocomposites by means of both DSC and DMA. Also, shifts in the glass transition temperature were discovered for the different compositions of clay. Finally, Fourier transform infrared spectroscopy (FT‐IR) helped to identify and confirm the changes in the molecular structure of the irradiated s‐PP matrix, providing confirmation of the cold chemi‐crystallization effect.

Keywords:

• chemi‐crystallization
• cold crystallization
• nanocomposites
• nanoclay
• syndiotactic poly(propylene)

Acknowledgements

We are grateful to the Greek Ministry of Development for support via the research grants Program PENED 2001 (PENED136) and EPAN E13.