Changes in thermal properties of isotactic polypropylene with different additives during aging process

Polymer degradation is a change in the properties of a polymer under the influence of one or more environmental factors such as heat, light, humidity or chemicals. These changes may be undesirable, such as changes during use, or desirable, as in biodegradation or deliberately lowering the molecular weight of a polymer. A series of composites of isotactic polypropylene (iPP) has been obtained by the melt intercalation by introducing certain additive into the molten polymer matrix using a twin-screw extruder. The effect of additives (multi-wall carbon nanotubes as nanofiller, montmorillonites, pigments) on the process of isotactic polypropylene degradation, thermal stability, the characteristic temperatures (of melting and crystallization) during the aging process were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). A additives affect the degradation mechanism and consequently change thermal stability of iPP (the most stable are samples with addition of carbon nanotubes). The additives also affect the crystallization of polypropylene and thus the crystallization temperature and crystallinity index of the base material.