Abstract
To understand the processing influence in an intermeshing corotating twin-screw extrusion (ICTSE) on the morphology and impact properties of the uncompatibilized PBT/ABS (70/30) blend, it was submitted to different processing parameters. In this way both morphology and impact properties (resistance and ductile brittle transition temperature (DBTT) would be a function of processing only, because there would be no influence of a compatibilizer. The rotation speed of the screws influenced both impact resistance and Ductile Brittle Transition Temperature (DBTT) of the PBT/ABS blends. Blends prepared with higher rotation speed (240 rpm) did not present toughness at room temperature, whereas the blends prepared at lower speed showed high impact strength at room temperature and DBTT near to 5 °C. The angle between the kneading blocks discs also influenced the impact properties, because blends processed with screw with 90o angle between kneading block disks, for two different feed rates, showed lower DBTT than the blends processed with 45o angle. The morphological analysis by TEM showed that blends processed at low rotation speed of the screws presented a higher dispersion degree than those processed at high rotation speed. Blends processed in screws where the angle between the disks was 90o showed a higher dispersion degree than the blends processed in disks with a 45o angle. These results are in agreement with the impact properties, confirming that high dispersion of the ABS particles improves the impact properties of the blend.
Highlights
Preparation of polymer blends appeared as an alternative to the development of new polymeric systems to achieve different properties from those obtained by existing polymers or copolymers
This study evaluated the effect of extrusion conditions and the use of a compatibilizer in the crystallization of polybutylene terephthalate (PBT)/acrylonitrilebutadiene-styrene copolymer (ABS) blends
Blends prepared with higher rotation speed (240 rpm) did not present toughness at room temperature, whereas the blends prepared at lower speed showed high impact strength at room temperature and Ductile Brittle Transition Temperature (DBTT) near 5 °C
Summary
Preparation of polymer blends appeared as an alternative to the development of new polymeric systems to achieve different properties from those obtained by existing polymers or copolymers. Mixture of polymers allows the combination of properties of the blend's constituent polymers, to achieve one or more desired properties. One of the applications of polymer blends is to promote the toughness of brittle polymers. In this case, the modified polymer is mixed with another with a high deformation capacity, such as elastomers, thermoplastic rubbers or others modified thermoplastics. The main mixing process of polymer blends occurs in the molten state, and the processing in twin screw extruders has been more appropriate for both productivity and mixing quality. During the processing in the twin-screw extruders the polymers are usually subjected to various types of flow (shear, elongational or both) in the screw (kneading blocks) and in the extrusion die
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