Study Of Injection Behavior Of Polymer Melt And Properties And Morphology Of Specimen Under Vibration Injection Molding

A shear vibration equipment and a hydrostatc Pressure vibration equipment aredeveloped according to the characteristics of shear vibration and pressure vibration.The former is used to study the rheology behavior of polymer melt under vibration,and the latter the mechanical properties and morphology The principal concIusionsof this research, Which based on the systematic study of the influence of vibrationparameters on rheology behavior, mechanical properties and morphology, are asfollows.l.Mbration has a great effect on the rheology behavior of polymer melt. Theapparent viscosity of polymer melt decreases rapidly with the increase of vibrationfrequency at the beginning, and then it tends genty There is an optimal frequency,which is about 3.33~6.67 Hz. The apparent viscosity of HDPE, PS, and ABS falls53.2%,60.3% and 26.4% respectively at most. At the same time, amPlitude, melttemperature and pressure can affect the change ofviscosity2. The tensile strengh of specimen produced by vibration injection increases asthe increase of vibration frequency and vibration strength. The maximum incrementof tensile strength of HDPE DGDA6098, HDPE 2200J and PP F401 reaches 4l%,28.7% and 26. 1% respeCtively and such a increment has not been rePorted before.The elongation decreases as the increase of vibration strengtly and it also decreasesas the increase of vibration frequency at the initial stage, but it will pick up as thefrequency reaches a certain range.3.The impact Strength of PP F40l increases as the increase of vibrationfrequency and vibration strength. It will take a leaP, from 0.04KJ/m to 0.1lKJm,under certain process conditions because of emerge of new crystal form. It is notbeen reported before.4.Test methods, include WW,DSC and SEM, prove that cryStaI of HDPEsPecimen is consisted of platelets that is orientated, and that of iliP specimen isconsisted of platelcts or spherulites, and the degree of crystallinity is increasednotably. Crystallites of specimen become smaller under high vibration frequency.5.A change of cryStal structure ofiPP under proper process condition had beenobserved for the first time. WW and DSC prove that At high melt temPerature(230oC), fl form can be obtained additional to Q form. At low melt temperature(l90oC),either fi form or Y form can be induced.6. The vibration equipment can control morphology of specimen, and increasetheir mechanical properties under normal process condition, so it is easy to beaPplied in practice.