Study On Blending Modification Of Poly(2,6-dimethyl-1,4-phenylene Oxide)/Polyamide-66 With Triangle-arrayed Triple-screw Extruder

The development of blending technology promotes the polymer industry significantly and the progress and innovation for the continuous mixing equipment has become the foundation of new generations of polymer composites. The triangle-arrayed triple-screw extruder (TTSE) is a novel polymer processing equipment that generates a complicated flow field accompanied with “shear-extensional" alternating flows by three mesh zones and a convergence-divergence central zone. Thus, TTSE is expected to be applied in blending of multi-phase polymer composites which is extremely incompatible because of their difference in polymer polarity and viscosity such as the composite of Poly(2,6-dimethyl-1,4-phenylene oxide)/Polyamide 66 (PPO/PA66). In this dissertation, TTSE is utilized to process PPO/PA66 composites for improvement in mechanical properties and phase morphology.Moreover, a commercial twin screw extruder (TSE) was always used as the reference device to investigate the difference between "shear-extensional"flow and shear flow. We hope that the theoretical and experimental study of TTSE could promote the application of the novel blending equipment in polymer industry. The detail is as follows,1. The flow channel model of the groove zone, mesh zone, and central zone in TTSE was built separately. Moreover, the shear rate and extensional rate of flow field in TTSE was calculated through the theoretical flow channel model while the quantitative evaluation method of TTSE’s mixing capacity was also built up based on the theoretical flow field model.2. For blends processed by TTSE, the particle size was predicted through a new calculation method, which combined the dispersive mixing theory of polymer and the flow field model of TTSE. Furthermore, the reliability of the prediction method was proved through the experimental proof in varying processing conditions. The errors between the prediction and experiment were investigated through rheology analysis.3. The effects of shear-extensional alternating flow on PPO/PA66 blending were evaluated through the comparison between TTSE and TSE. The particle sizes of PPO/PA66 blends processed by TTSE were smaller than that of TSE. Meanwhile, the mechanical properties of PPO/PA66 blends were improved significantly by the extensional effects. Moreover, the toughening mechanism of PPO/PA66/SEBS alloy was explored with the blending experiments in varying PPO contents. The mechanism about the brittle-ductile transition of PPO/PA66/SEBS blends extruded by TTSE occurred at lower PPO content was further revealed.4. The effects of process routes on reactive compatibilization of PPO/PA66/SAG blends was studied through FTIR, morphology, dynamic mechanical, and rhelogical analyses. The side feed method for PA66 was proved to be more efficient than one step blending method in reactive compatibilization of PPO/PA66 composites. The impact strength of samples processed by side feed method is 2 times higher than that of one step method while their tensile strengths and the flexible strengths are similar even with different process routes.5. The relationship between processing parameters of TTSE and properties of PPO/PA66 blends was further investigated through response analysis method (RSM). The screw speeds and proportions of dispersion phase were proved to be the main factors on dispersive mixing. The output of extruder is the key factor for mechanical properties of blends. Finally, the quantitative relationship between processing parameters and properties was utilized to optimize the process conditions for better morphology and mechanical properties.6. PPO/PA66/Organo-montmorillonite (OMMT) nanocomposites were prepared through melt blending in TTSE directly. Because of the polar groups in both molecules of PPO-g-MAH and PA66, the OMMT platelets would selectively located on the surfaces of PPO domains at low OMMT loading.However, some platelets of OMMT would be exfoliated into the PA66 matrix with increasing OMMT loadings. The mechanical properties and thermal stability of nanocomposites were significantly improved with the addition of OMMT. Moreover, TTSE is proved to be more efficient in exfoliating and mixing of OMMT than TSE. The samples processed by TTSE showed smaller particle size and better mechanical properties than that of TSE. Finally, it can be expected that the preparation of PPO/PA66/OMMT nanocomposite would expand the applications of TTSE in polymer industry.