The Role of Long Molecules and Nucleating Agents in Shear Induced Crystallization of Isotactic Polypropylenes**
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P. Jerschow
Abstract
Short term shearing at low degrees of supercooling with subsequent monitoring of the crystallization process of iso-tactic polypropylenes leads to highly oriented surface layers and fine grained layers that reach further into the core of the solidified samples. This process is highly dependent on the content of long polymer chains or nucleating agents. The present paper shows a first experimental evidence for these facts together with theoretical considerations. If long polymer chains are present, as it is the case in reactor grades of iPP, shear induced crystallization is more sensitive to shear treatment. As a consequence, the orientation of the surface layers is much higher in these materials. Additionally, the surface layers – both, highly oriented and fine grained – are more distinct and, therefore, allow an easier quantitative determination. If the materials contain nucleating agents, highly oriented layers occur in materials containing long polymer chains as well as in rheology controlled grades. A first theoretical description of the possible role of nucleating agents is given.
© 1997, Carl Hanser Verlag, Munich
Artikel in diesem Heft
- Contents
- Contents
- Editorial
- Editorial
- Screw Extrusion
- Upgrading Recycled HDPE by Rheometer-Controlled Crosslinking
- Blend Morphology of Linear Low Density Polyethylene and Polystyrene in a Non-Intermeshing Twin Screw Extruder
- Mixing
- A Study on the Reactive Compatibilization of a PBT/LCP Blend: Catalyst Effect
- Influence of Processing Temperature on the Morphological and Mechanical Properties of a PC/TLCP Blend
- Fibers
- The Effect of Drawing and Annealing Conditions on the Structure and Properties of Bacterial Poly(3-hydroxybutyrate-co-3 hydroxyvalerate) Fibers
- Numerical Analysis of Cooling Air Systems in Film Blowing
- Moulding
- On the Simulation of Thermoplastic Injection Moulding Process
- Molding
- Rheology of Layered Thermoplastic Matrix Composites during Compression Molding
- Studies of the Trans-Quinacridone Nucleation of Poly-(ethylene-b-propylene)
- The Role of Long Molecules and Nucleating Agents in Shear Induced Crystallization of Isotactic Polypropylenes**
Artikel in diesem Heft
- Contents
- Contents
- Editorial
- Editorial
- Screw Extrusion
- Upgrading Recycled HDPE by Rheometer-Controlled Crosslinking
- Blend Morphology of Linear Low Density Polyethylene and Polystyrene in a Non-Intermeshing Twin Screw Extruder
- Mixing
- A Study on the Reactive Compatibilization of a PBT/LCP Blend: Catalyst Effect
- Influence of Processing Temperature on the Morphological and Mechanical Properties of a PC/TLCP Blend
- Fibers
- The Effect of Drawing and Annealing Conditions on the Structure and Properties of Bacterial Poly(3-hydroxybutyrate-co-3 hydroxyvalerate) Fibers
- Numerical Analysis of Cooling Air Systems in Film Blowing
- Moulding
- On the Simulation of Thermoplastic Injection Moulding Process
- Molding
- Rheology of Layered Thermoplastic Matrix Composites during Compression Molding
- Studies of the Trans-Quinacridone Nucleation of Poly-(ethylene-b-propylene)
- The Role of Long Molecules and Nucleating Agents in Shear Induced Crystallization of Isotactic Polypropylenes**
