Shear-induced crystallization of polypropylene: Influence of molecular weight

• Published in: Journal of materials science Vol. 35; no. 24; pp. 6093 - 6103
• Main Authors: Duplay, C, Monasse, B, Haudin, J.-M, Costa, J.-L
• Format: Journal Article
• Language: English
• Published: Heidelberg Kluwer Academic Publishers 01.12.2000; Springer; Springer Nature B.V; Springer Verlag
• Subjects: Applied sciences; chemical structure; Crystallization; Engineering Sciences; Exact sciences and technology; Glass fiber reinforced plastics; glass fibers; Materials; Materials science; Molecular structure; Molecular weight; Organic polymers; Parameters; Physicochemistry of polymers; Polypropylene; polypropylenes; Properties and characterization; Shear flow; Shearing; Isothermal condition; Melt crystallization; Nucleation; Shear flow; Isotactic polymer; Propylene polymer; Kinetics; Experimental study; Crystal morphology; Molecular weight property relation; Crystal growth; Crystallization; Shear stress; Molten materials; Molecular weight; Crystal structure; Glass fibers
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1023/A:1026731917188

Three series of isotactic polypropylene characterized by different molecular weights and the same isotactic index have been studied during crystallization under static and shearing conditions. The shear is induced by the displacement of a glass fiber in the molten polymer. The monoclinic α-phase is here formed under shear with a columnar organization at the surface of the glass fiber, and does not appear under static condition. The growth-rate, constant during the shear-induced crystallization experiment, is compared with the result obtained from static crystallization. An important increase of the growth-rate due to the shear flow is observed. This increase depends on the molecular structure. The average molecular weights ―Mw and ―Mz seem to be the most important molecular parameters, for which an excellent correlation is obtained. The increase of these parameters ―Mw and ―Mz leads to a significant enhancement of the growth-rate, which can be multiplied by a factor of 10 in the present conditions.