Crystallization and Microstructure Evolution of Microinjection Molded Isotactic Polypropylene with the Assistance of Poly(Ethylene Terephthalate)

Abstract

In this work, a series of isotactic polypropylene/poly(ethylene terephthalate) (iPP/PET) samples were prepared by microinjection molding (μIM) and mini-injection molding (IM). The properties of the samples were investigated in detail by differential scanning calorimetry (DSC), Wide-Angle X-ray Diffraction (WAXD), Polarized light microscope (PLM) and scanning electron microscopy (SEM). Results showed that the difference in thermomechanical history between both processing methods leads to the formation of different microstructures in corresponding iPP/PET moldings. For example, the dispersed spherical PET phase deforms and emerges into continuous in-situ microfibrils due to the intensive shearing flow field and temperature field in μIM. Additionally, the incorporation of PET facilitates both the laminar branching and the reservation of oriented molecular chains, thereby leading to forming a typical hybrid structure (i.e., fan-shaped β-crystals and transcrystalline). Furthermore, more compact and higher degrees of oriented structure can be obtained via increasing the content of PET. Such hybrid structure leads to a remarkable enhancement of mechanical property in terms of μIM samples.

Flexible Polyolefin Elastomer/Paraffin Wax/Alumina/Graphene Nanoplatelets Phase Change Materials with Enhanced Thermal Conductivity and Mechanical Performance for Solar Conversion and Thermal Energy Storage Applications

“…The flowability of composites plays a crucial role in the injection moulding process, which affects the filling properties and microstructural evolution of the products [24,38]. To investigate the effect of adding Al 2 O 3 and GNPs on the flowability of POE/PW composites, the rheological properties of the composites were tested.…”

A Review of Microinjection Moulding of Polymeric Micro Devices

“…The main distinguishments for microinjection moulding lie in the higher temperature for polymer melt and mould, and the higher speed and pressure during moulding. A shear thinning effect would theoretically reduce the polymer viscosity, causing a higher filling length inside the micro cavity [69]. However, the rheological behaviour of flow in micro cavities differs from conventional rheology laws.…”

Impact of Mendong fiber–epoxy composite interface properties on electric field frequency exposure

“…The evolution of the nature of the polymer matrix will affect its composite product. It can be reached through the matrix polymer functionalized by nanoparticles 27 or modification of polymer structure by the orientation of molecular structure using the shearing process in manufacturing processes like injection, extrusion method, and the applied magnetic and electric field, or their combination 28–30 …”

“…It can be reached through the matrix polymer functionalized by nanoparticles 27 or modification of polymer structure by the orientation of molecular structure using the shearing process in manufacturing processes like injection, extrusion method, and the applied magnetic and electric field, or their combination. [28][29][30] The electric field has been applied to modulate the polymer systems morphologies to get anisotropic structures. 30 Both the applied strength and frequency of the electric field affect the structure and properties of the polymer.…”