Study On Morphology And Properties Of Polymer Under Vibration Field

In this thesis, the structure and mechanical property of polymer specimen were studied with a self-made low-frequency vibration injection device. In the work, SEM and WAXD were used to observe and analyze the specimen. With these methods, the effect of vibration parameters on the microstructure and property of polymer specimen was discussed. Based on the results, some conclusions were given as following:1. The specimen's mechanical performance could be enhanced $ignificantly under the appropriate condition as vibration frequency or vibration pressure. Compared to the normal injection specimen, the maximum increment of longitudinal tensile strength of HDPE 2200, HDPE 6098, FRPP and ABS reached 22;5%, 18.1%, 10.2% and 23.0% respectively, and transverse tensile strength 28.2%, 22.6%, 11.9%, 29.7% respectively. The maximum increment of longitudinal impact strength of FRPP and ABS reached 78.0%, 60.0% respectively, and transverse impact strength 79.1%, 56.1% respectively.2. SEM investigation indicated that lamellae structure arranging normal to the longitudinal direction could be found under the condition of relatively hijgh vibration pressure, compared to the spherulite structure corresponding to the Condition of normal injection. The former crystal structure can distribute the tensile stress more even, which can improve the tensile strength of polymer material.3. SEM data showed that low-frequency vibration behavior had effect on thefiber length and fiber distribution of FRPP. WAXD investigation indicated that the change of crystal structure of FRPP form form to form and y form was achieved via melt vibration, and vibration parameter could affect the crystal orientation of FRPP.