Beta-modification of isotactic polypropylene

摘要: Commercial grades of isotactic polypropylene (iPP) crystallize essentially into α-modification (α-iPP) with sporadical occurrence the β-phase (β-iPP). Crystallization in temperature gradient or sheared melt encourages development commercial, non-nucleated iPP [1]. For preparation samples rich β-modification pure β-iPP, introduction selective β-nucleants is most reliable method The known β-nucleating agents are collected Tables 1 and 2, indicating their advantages drawbacks. widespread high active agent a γ-quinacridone red pigment. Some two-component compounds obtained by reactions certain organic acids CaCO3, also possess very activity. Different calcium zinc salts aliphatic aromatic dicarboxylic having thermal stability, belong to β-nucleants, as well β-content — so efficiency influence mechanical conditions crystallization on polymorphic composition - can be characterized k-value determined from wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC) non-recooled polarized light microscopy (PLM) using thin sections It should pointed out that melting curves cooled room do not give correct information about β-content. This statement due βα-recrystallization which takes place during heating sample overlaps process [1, 2]. Unfortunately, was DSC many studies. Therefore, quantitative conclusions these studies treated caution. Studies β-nucleated revealed formation β-iPP has an upper (T(βα) = 140°C) lower limit (T(aβ) 100-110°C) crystal structure, morphology, recrystallization behavior discussed detail later chapter’ spherulitic structure’. section deals preparation, properties application β-iPP.