Crystallization kinetics in the mixtures of poly(vinylidene fluoride) and poly(methyl methacrylate): two-step diffusion mechanism

• Published in: Macromolecules Vol. 24; no. 15; pp. 4446 - 4449
• Main Authors: Saito, Hiromu, Okada, Tetsuo, Hamane, Toshihiko, Inoue, Takashi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.07.1991
• Subjects: Applied sciences; Crystallization; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Crystalline polymer; Spherulites; Vinylidene fluoride polymer; Methyl methacrylate polymer; Amorphous polymer; Kinetics; Experimental study; Isothermal crystallization; Mixture; Molecular weight property relation
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma00015a031

The spherulite growth rate, G, was investigated in mixtures of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) at various crystallization temperatures T sub c . The molecular weight of PMMA, M sub 2 , was changed in a wide range (1.3 < 10 exp --4 M sub 2 < 93). As T sub c increased, a regime transition from II to I was found to occur. At the regime transition temperature, an abrupt drop in G was observed. In regime I, G strongly depended on M sub 2 , while there was a weak dependence in regime II. A systematic regime transition, III - > II - > I, was found to occur as the volume fraction of PMMA, phi sub 2 , increased. The PMMA blend with larger M sub 2 exhibited the regime transition at smaller phi sub 2 . These results were successfully interpreted by the modified Hoffman--Lauritzen theory involving the two-step diffusion mechanism characteristic of the crystallization of a polymer blend, i.e. the mutual-diffusion process for the formation of the first stem at the crystal surface and the self-diffusion process for the attachment of following stems in the chain. Graphs. 12 ref.--AA