| During the course of polymer molding and processing, the condition of processing can affect the morphology of polymer, and the morphology decides the macroscopic performance of the product. We add the vibration field in the course of extrusion molding to control the morphology of polymer and mine the internal potential of polymer sufficiently. Consequently we can endow the desirable performance to the product to adapt more extensive application domain. We designed a kind of rotary valve vibration extrusion equipment according the need of study. The vibration frequency of this equipment is high and adjustable continuously at the 0~93.3Hz. Its oscillation amplitude can be adjusted easily and adjustable continuously at the 0~30mm. The vibration equipment uses hydraulic system. Because of the high hydraulic vibration strength, hydraulic vibration in the course of extrusion molding can make polymer melt be affected by high pressure penetrating vibration field. The influence of the vibration field enhances. The design scheme is initiated. There is no similar equipment in the world. The vibration equipment can control morphology of specimen, and increase their mechanical properties under normal process condition, so it is easy to be applied in practice. We used the rotary valve vibration extrusion equipment to study rheological behavior of polymer melt under vibration extrusion molding. The research about rheological behavior of polymer under the vibration field has been reported . but we have not see the report about adding in median frequency hydraulic vibration field in the course of extrusion molding. The study shows that the extrusion characteristic is improved under the vibration field. Apparent viscosity decreases. With the increase of vibration frequency, the apparent viscosity decreases to the minimum, and then backs up. When it backs up to the definite degree, it keeps invariable basically. After it backs up, the apparent viscosity is still lower than the apparent viscosity in the condition of no vibration. The pressure of extrusion die decreases and the extrusion flow rate increases under the vibration field. The influence of the vibration extrusion to the pressure of extrusion die is larger than to the extrusion flow rate. In the condition of invariable die pressure, the polymer mass flow rate under the vibration field increases obviously. The mould unloading expansion ratio of the extrusion sheet that is extruded under the vibration field decreases. The variety of polymer melt apparent viscosity under the vibration field is relationship with oscillating amplitude, the screw rotational speed of extruder and the die temperature. The bigger the oscillating amplitude is, the stronger the influence of vibration field to polymer melt is. The faster the screw rotational speed is, the feebler the influence of vibration field to polymer melt is. The die temperature has a best temperature interval and in this temperature interval the influence of vibration field to apparent viscosity is strongest. The effect of vibration parameter to polymer apparent viscosity is deferent because of material. As to the four kinds of material studied in this article, the effect degree to apparent viscosity is arrayed from strong to feeble in turn. It is PS,HDPE,PP,LDPE. Using rotary valve vibration extrusion equipment we also studied the change of morphology and properties of sheet under the vibration field. The research about HDPE 6100M vibration extrusion specimen shows that the mechanical properties of HDPE 6100M vibration extrusion specimen increases under the effect of vibration field. The longitudinal yield strength of vibration extrusion specimen is higher than the no vibration specimen. At 150℃the longitudinal yield strength increases 11.5%. The longitudinal yield strength of vibration extrusion specimen extruded at low temperature is higher than the longitudinal yield strength of vibration extrusionspecimen extruded at high temperature. we have not see the report about the transverse properties of the vibration extrusion specimen. We designed a slit die with broad width to produce the specimen that is easy to be tested in the transverse direction. The research shows that the transverse yield strength of vibration extrusion specimen increases too. The improvement degree is less than the improvement of longitudinal yield strength. At 150℃the transverse yield strength of vibration extrusion specimen increases 6.9%. The test result of SEM,DSC and WAXD shows that the crystal grain of HDPE 6100M vibration extrusion specimen is refined and molecular chain orients. It also shows that crystal size in the specimen becomes more homogenous, and crystallinity increases. In conclusion, the vibration field can reinforce the HDPE 6100M specimen. But the reinforcement effect is not distinct. The research about HDPE 6100M/1158 vibration extrusion specimen shows that the influence of vibration field on the HDPE 6100M/1158 specimen properties improves greatly when we add in a little high molecular weight HDPE 1158 in the ordinary molecular weight HDPE. The longitudinal yield strength of vibration extrusion specimen in the deferent technological conditions is higher than the no vibration specimen. Moreover, elongation at rupture increases. When the oscillating amplitude is 1mm, the longitudinal yield strength increases 27.9%, and elongation increases 63.52%. When the oscillating amplitude is 2mm, the longitudinal yield strength increases 12.3%, and elongation increases 53.77%. The transverse yield strength of vibration extrusion specimen increases compared to the no vibration specimen. When the oscillating amplitude is 1mm, the transverse yield strength of vibration extrusion specimen increases 32.5%. However, when the oscillating amplitude is 2mm, the transverse yield strength of vibration extrusion specimen increases 16.5%. The test result of SEM,DSC and WAXD shows that the microcrystalline size decreases,the crystal grain of vibration extrusion specimen is refined and molecular chain orients along the extrusion direction. It also shows that crystallinity increases and crystal size becomes more homogenous. Because of the shear induced crystallization, the improvement effect on the HDPE 6100M/1158specimen of the vibration field is bigger than the effect on the HDPE6100M specimen. The research about PP F401 vibration extrusion specimen shows that the longitudinal yield strength of vibration extrusion specimen at the deferent vibration frequency is higher than the non-vibration specimen. The longitudinal yield strength can increase 9.12% at 160℃. The transverse yield strength can also increase a little. Moreover, the oscillating amplitude can affect the yield strength of vibration extrusion specimen. The longitudinal yield strength of the vibration extrusion specimen produced at different oscillating amplitude is higher than that of non-vibration specimen. The test result of SEM,DSC and WAXD shows that the iPP specimen that is extruded under the vibration field have formed βcrystal ,crystal plates become thin ,the crystal grain of vibration extrusion specimen is refined and crystallinity increases. In the condition of big oscillating amplitude and high vibration frequency, crystallinity of specimen increases distinctly. The research about PP vibration extrusion specimen that is added in βnucleator shows that the longitudinal yield strength and Young's modulus of the specimen both decrease. But the elongations increase. The longitudinal yield strength of the non-vibration specimen is 28.99MPa. The longitudinal yield strength of the specimen which vibration frequency is 9.3Hz is 25.21MPa. It decreases 13%. The transverse yield strength of the vibration specimen is also lower than that of non-vibration specimen. The test result of SEM,DSC and WAXD shows that βcrystal content of the vibration specimen increases distinctly under the vibration field, the crystal grain is refined, molecular chain orientation becomes more distinct, crystal size in the specimen becomes more homogenous and the crystallinity of βcrystal increases greatly.
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