| Based on the flowing properties of polymer melts, a set of special shear equipment including a sheet die used to build controllable shear field and to mould PET sheets was designed and manufactured. The structures and properties of PET blends and GF/PET composites in the shear field were studied. This shear equipment and the sheet die were successively linked to forepart of the single-screw extruder. Samples used for analyzing and testing were cut from PET sheets which have been processed with PET blend pellets successively through plasticizing in single-screw extruder, shearing in the shear equipment and finally forming in the sheet die. Pellets of PET blends and GF/PET used were prepared through double-screw extruder. The influences of the shear field change, phase compatibility and different glass fiber treatment on mechanical properties of the sheets were studied by mechanical tests. The effects of blending components and glass fiber treatment on rheological characters of these materials were investigated by rheology tests. Through DSC, SEM and SALS methods, the crystallizing behavior, microstructure and orientation degree of PET blend sheets were characterized. The interphase structure, crystallizing behavior and glass fiber treatment methods of GF/PET composites were analyzed through DSC, SEM and IR spectroscopy testing. The main results of this study were given as follows:(1) The controllable shear field was built by adjusting the rotating speed of the mandrel in the shear equipment barrel. Through which, the control of shear field strength, plasticization and production output can go on separately. Therefore, the simulated dynamic conditions of the phase morphology study of PET blends and the interphase study of GF/PET composites were obtained. In our study, this shear equipment ran well and the anticipated results were acquired.(2) Through the structure and properties study of PET blends in the shear field, we found that the compatibility and viscosity ratio between the disperse phase and continuous phase can greatly influence the rheological character, disperse phase morphology, crystallizing behavior, orientation degree of PET blends and the response of these characters to shear field change.(3) As to compatible system PBT/PET, the mechanical property of which increased when the blend closed to homogeneous phase on 200rpm. The rheological character of the blend fit for theory calculation very well, and its orientation in the shear field was obvious. PBT can improve the crystallizing ability of PET, thus the blend crystallized sufficiently in moulding process.(4) About to part compatible system PC/PET, the tensile strength of which reached to the highest value when particle size of the disperse phase was smaller and distributed more uniform on 200rpm. As the viscosity ratio of two phases was very large, the rheological character of the blend deviated from theory calculation, and its orientation degree in the shear field was very low.(5) About to incompatible system LDPE/PET, the change of shear field can influence the deformation and fracture of disperse phase, and the tensile strength of this material showed double peaks with the changing of mandrel rotating speed. The rheological character of the blend also deviated from theory calculation, and the viscosity of the blend was lower than both PET and LDPE.(6) Through investigating the interphase structure and properties of GF/PET in the shear field, we discovered that the glass fiber treatment methods could obviously influence the interphase structure and fracture mode, rheological character and crystallizing behavior of GF/PET composites.(7) The silane coupling agents can react with the glass fiber surface, but the interphase debond of GF/PET composites still happened in the shear field, so the increasing extent of composites tensile strength was not prominent.(8) One end of the low molecular PET binder can react with silane coupling agent, and the other end has good compatibility with the matrix. Therefore, the trans-network structure of the i...
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