Measurement and Prediction of Anisotropy in Injection Moulded PP Products
-
K. M. B. Jansen
Abstract
Exact knowledge of anisotropy in thermal and mechanical properties of moulded articles is important since it is directly related to undesired phenomena like warpage. In this study careful measurements of the coefficients of thermal expansion, elastic moduli, Poisson constants and linear compressibilities showed that the anisotropy of these properties was about 10%, for injection moulded polypropylene plates. A simple composite model was proposed which could predict all thermal and mechanical properties mentioned above from data of the amorphous and crystalline phases. The degree of crystallization, skin thickness and average orientation of the fibrillar precursors are the main input parameters. It turned out that although individual values were slightly over or underpredicted, the amount of anisotropy was usually predicted correctly. The only prediction which disagreed with the measurements was that of the coefficient of thermal expansion, which was measured to be larger in flow direction than in width direction.
The changes of shrinkage and shrinkage anisotropy along the flowpath were studied experimentally for different processing conditions. The most remarkable observations were that variations in injection velocity only affected width shrinkage, while melt and mould temperatures specifically acted on length shrinkage. Holding pressure, on the other hand, affected both length and width shrinkage with the same amount.
© 1998, Carl Hanser Verlag, Munich
Artikel in diesem Heft
- Contents
- Contents
- Editorial
- Third in a Series: Pioneers of Polymer Processing Charles Hancock — The First Thermoplastics Processing Innovator
- Internal Mixers
- Finite Element Analysis of Mixing in Partially Filled Twin Blade Internal Mixers
- Screw Extrusion
- Use of Dye Containing Polymeric Microcapsules for Determining Shear Stresses
- Modeling Flow and Fusion of Mixtures/Blends of Polymer Pellets and a Low Viscosity Phase in a Modular Co-rotating Twin Screw Extruder
- Fiber and Film
- Development of High Quality LLDPE and Optimised Processing for Film Blowing
- Molding
- Impregnating Flow of a Rheokinetic Liquid
- Morphology of Injection Molded Polyacetal during Filling
- Crystal Orientation in Injection Moldings of Talc-filled Polyolefins
- Structure and Properties of Injection Moldings of β-Crystal Nucleator-added PP
- Thermal Effects in the Numerical Simulation of the Thermoforming of Multilayered Polymer Sheets
- Measurement and Prediction of Anisotropy in Injection Moulded PP Products
- Rapid Communication
- Gas Penetrations in Symmetrical Tapping Ribs during Gas-Assisted Injection Molding
Artikel in diesem Heft
- Contents
- Contents
- Editorial
- Third in a Series: Pioneers of Polymer Processing Charles Hancock — The First Thermoplastics Processing Innovator
- Internal Mixers
- Finite Element Analysis of Mixing in Partially Filled Twin Blade Internal Mixers
- Screw Extrusion
- Use of Dye Containing Polymeric Microcapsules for Determining Shear Stresses
- Modeling Flow and Fusion of Mixtures/Blends of Polymer Pellets and a Low Viscosity Phase in a Modular Co-rotating Twin Screw Extruder
- Fiber and Film
- Development of High Quality LLDPE and Optimised Processing for Film Blowing
- Molding
- Impregnating Flow of a Rheokinetic Liquid
- Morphology of Injection Molded Polyacetal during Filling
- Crystal Orientation in Injection Moldings of Talc-filled Polyolefins
- Structure and Properties of Injection Moldings of β-Crystal Nucleator-added PP
- Thermal Effects in the Numerical Simulation of the Thermoforming of Multilayered Polymer Sheets
- Measurement and Prediction of Anisotropy in Injection Moulded PP Products
- Rapid Communication
- Gas Penetrations in Symmetrical Tapping Ribs during Gas-Assisted Injection Molding
