In this study, polyamide-66/poly(2,6-dimethyl-1,4-phenylene oxide) (PA66/PPO) blends with high viscosity ratio were processed by a self-designed triangle-arrayed triple-screw extruder (TTSE, which simulates extensional flow) and a commercial twin-screw extruder (TSE), respectively. Furthermore, in order to improve the mechanical properties of the immiscible PA66/PPO blends, PPO-grafted maleic anhydride (PPO-g-MA) and styrene-ethylene-butylene-styrene (SEBS) block copolymer were used. The mechanical properties, phase morphology, and rheological properties of both binary PA66/PPO blends and toughened PA66/PPO/ PPO-g-MA blends were comprehensively investigated to compare the above mentioned two processing method. Samples processed with TTSE exhibited better mechanical properties than the TSE-processed blends. The morphologies of the blends were examined by scanning electron microscopy, exhibiting smaller particles sizes and narrower particle size distributions, which were attributed to the significant effects of extensional flow in TTSE. The toughening mechanism of compatibilized blends was investigated through morphology analysis, dynamic mechanical, and rhelogical analysis. Thus, TTSE with an extensional effect was proved to be efficient in the blending of high viscosity ratio polymers.

Improved viscoelastic, thermal, and mechanical properties of in situ microfibrillar polypropylene/polyamide 6,6 composites via direct extrusion using a triple-screw extruder.

Three-dimensional flow field of triangle arrayed triplescrew extruder (TTSE) in different feed rates, screw speeds and screw configurations were simulated by POLYFLOW. Polypropylene processing by TTSE was tested to validate the numerical simulation. The reliability of simulation was tested directly and indirectly by comparing the axial pressure difference and residence time distribution (RTD) separately. The results show that the axial pressure differences from the simulations and experiments were in high agreement. The simulated and experimental RTD curves show the same trend, and so are the simulated and experimental average residence times. These results prove the reliability of simulation and its guidance to the experiment. POLYM. ENG. SCI.,

The nanocomposites consisting of polymer matrix and nanofiller have attracted great attention because of the improved physical properties. In this paper, organomontmorillonite (OMMT) was introduced into poly(2,6-dimethyl-1,4-phenylene oxide) grafted maleic anhydride (PPO-g-MA) compatibilized poly(2,6-dimethyl-1,4-phenylene oxide)/polyamide-66 (PPO/PA66) blends by melt extrusion. The morphology of PPO/PA66 nanocomposites with different amounts of OMMT was investigated using transmission electron microscopy (TEM), wide-angle X-ray diffraction (WAXD), and scanning electron microscopy (SEM). The OMMT platelets exhibited an exfoliated structure in the PA66 matrix and an intercalated structure on the surface of PPO domains at low OMMT loading (2 phr). However, the exfoliated platelets in matrix were found to transform into intercalated stacks by adding 6 phr of OMMT. The mechanical properties and thermal stability were significantly improved with the coexistence of exfoliated and intercalated OMMT at low OMMT loading (2–4 phr). The exfoliated OMMT platelets imposed a confinement effect on the macromolecular chains and thereby increased the storage modulus and complex viscosity of nanocomposites.

The mixing capacity of triangle-arrayed triple-screw extruder (TTSE) was evaluated through the extrusion of polypropylene/ethylene-propylene-diene monomer (PP/EPDM) at varying screw speeds. The micromorphology, mean residence time, melt flow rate (MFR), and mechanical properties of blends were measured for evaluation. Moreover, same experiments were applied on a twin-screw extruder (TSE) for comparison. TTSE shows better mixing performance than TSE in comparison with micromorphology and mean residence time. But the high shear effect and temperature rising in TTSE promote the degradation of PP in blends which make the samples to have worse mechanical properties and higher MFR than those of TSE. K E Y W O R D Sdispersive mixing, mechanical properties, micromorphology, particle size distribution, triple-screw extruder