Research And Development Of Microlayer Co-extrusion And Mold-clamping Apparatuses And Study On PP/POE Microlayered Products Prepared By Them

Microlayer co-extrusion technology can be used to prepare microlayered polymer parts with alternating multilayered structure. The confined spatial structure and layer interface formed by the special alternating multilayered structure can endow microlayered polymer parts with unique mechanical properties. A novel microlayer co-extrusion apparatus was developed. PP/POE microlayered sheets with different layer number were prepared and their low temperature notched, unnotched, and anisotropic impact strength and toughening mechanism were investigated. Microlayered microcellular foamed PP/POE sheets were prepared. The effects of foaming temperature and layer number on cell structure were analyzed. An electrically-driven extrusion blow molding mold-clamping apparatus was developed to prepare PP/POE microlayered blow molding parts via combining the microlayer co-extrusion apparatus. This dissertation provides new idea and method for broadening the microlayer co-extrusion technology and related microlayered parts preparation.A microlayer co-extrusion apparatus was developed. Its core structure is the layer multipliers assemblied by several layer multiplication elements. By special assembly of the layer multiplication elements, both layer multiplications in radial and circumferential directions can be realized, both sheet and tubular microlayered parts can be produced by this apparatus, which overcomes the drawbacks of existed layer multiplication elements. An electrically-driven mold-clamping apparatus was developed. The mold-clamping apparatus is driven by a single motor to realize mold-opening/closing and mold-moving, and the mold can be adjusted automatically. The size of the mold-clamping apparatus can be reduced by optimization design of the toggle lever mechanism. In comparison with the same specification of hydraulically-driven mold-clamping apparatus, the production consumption of the electrically-driven mold-clamping apparatus can be reduced by about 86.3%.PP/POE microlayered sheets with different layer number were prepared via the developed microlayer co-extrusion apparatus. The notched, unnotched and anisotropic impact strength and toughening mechanism for the microlayered samples were investigated via observing the impact fractured surface morphologies, and using the theory of work of fracture and bending deformation theory. The impact energy for the notched multilayered samples is mainly absorbed by the continuous thin ductile POE layers due to cavitation. Whereas for the unnotched multilayered samples, the continuous thin POE and PP layers both contributed significantly to the total work of fracture due to multiple crazing and distinct plastic deformation in both PP and POE layers, and thus significantly extended crack propagation paths. Microlayered samples possess high ability in energy consumption in ND than that in TD. Because the impact force is transferred by PP and POE layers individually in TD, but the the impact force is transferred synergistically by alternating PP and POE layers in ND.Alternating 16, 32, and 128 layers microlayered microcellular foamed sheets with PP solid layers and POE foamed layers were prepared via a batch process in constant-temperature mode(CTM) and varying-temperature molde(VTM). In the CTM, microlayered microcellular foamed materials with closed-cell, deformed closed-cell, and partly connecting-cell structure were obtained by varying the foaming temperature and layer number. In the VTM, a bi-modal cell structure was achieved with foaming temperatue of 40~60°C for 16 and 32 layer samples. The average cell diameter and density can be flexibly manipulated via varying the foaming temperature and layer number.PP/POE microlayered blow molding parts were prepared via combining the microlayer co-extrusion apparatus and electrically-driven mold-clamping apparatus. Microlayered pipes with 8, 16, and 64 layers were prepared via the microlayer co-extrusion apparatus. Then the pipes were held to the electrically-driven mold-clamping apparatus to prepare PP/POE microlayered bottles. Tensile results showed that the yield strength, elastic modulus, and elongation at break of PP/POE microlayered bottles are slightly lower than those of PP/POE microlayered sheets with same layer number.