Time-resolving small angle X-Ray scattering analysis of melt crystallization of mixtures of regular and irregular isotactic polypropylene samples

POLYMER

卷:215

Article

Auriemma, Finizia¹  de Ballesteros, Odda Ruiz¹  Giusto, Giovangiuseppe²  Di Girolamo, Rocco¹  Malafronte, Anna¹  Scoti, Miriam¹  De Rosa, Claudio¹  Mitchell, Geoffrey R.³ 

[1] Univ Napoli Federico II, Dipartimento Sci Chim, Via Cintia, I-80126 Naples, Italy

[2] CIRA Italian Aerosp Res Ctr, Via Maiorise, IT-81043 Capua, CE, Italy

[3] Ctr Empresarial Marinha Grande, Polytech Leiria, Rua Portugal Zona Ind, P-2430028 Marinha Grande, Portugal

关键词: Tactic polymer blends;    Crystalline polymers;    Phase separation;    Melt strength;   

DOI  :  10.1016/j.polymer.2021.123411

来源: Elsevier

【 摘 要 】

The melting/crystallization properties of blends obtained by mixing two isotactic polypropylene (iPP) samples synthesized using single-site metallocene catalyst systems and containing a high and low concentration of rr triads as stereo-defects, are studied. The changes occurring at lamellar length scale during a heating/cooling cycle at constant scanning rate are followed in situ by performing time-resolved small angle X-ray scattering (SAXS) measurements. Data analysis demonstrates that the evolution of the SAXS intensity with increase/decrease of the temperature is controlled by the separate melting/crystallization of the two components, the differences in the thermal expansion (contraction) coefficient of the amorphous and crystalline phases and the role of thermal fluctuations in electron density. The two components give rise to different populations of intermixed lamellar stacks in the blends which originate from the good miscibility of the low and high stereo-regular samples in the melt.

【 授权许可】

Free