Studies On The Dynamic Rheological Properties And Morphology Structure Of PP Composites

The dynamic rheological behavior of polypropylene fill the system filled wereinvestigated systematically, the relationship between morphological structure andviscoelastic percolation of composites was also carried out. The dynamic flowrheology testing and fracture morphology analysis polypropylene system filled byfour types of filler (glass fiber, silicon magnesium calcium whisker, talc, calciumcarbonate) were investigated, the relationship between system network structure andviscoelastic percolation was also studied. The mechanical property, crystallization,microscopic structure, and rheological properties of the toughening modification ofrecycled polypropylene were also researched for the composite.The dynamic rheological behavior of polypropylene filled composite systems inthe disordered and oriented state were studied in this work. In the disordered state ofthe glass fiber and whisker filler system, the “pseudo solid-like” behavior obviousedin the filled system when the filler concentration was slightly lower. The orientationfiber obtained though the appropriate one-way pre-shearing, of which the “pseudosolid-like” behavior was less obvious than the disordered state with the same volumeconcentration. The similar phenomenon also existed in the talc system filledcomposite, but it is not significant. But in the calcium carbonate-filled system, weobserved the same result in a slightly lower concentration composite system. Thephase morphology structure of the composite system was also observed. In thedisordered state, the glass fiber and whisker were disordered. The glass fiber andwhisker oriented after the pre-shearing, but the orientation was not obvioused in thetalc filled system. In the calcium carbonate filled system the calcium carbonateaggregated after pre-shearing.The rheological model of the polypropylene fiber filled system was modified, theresulted reveal that the modulus calculation from modified model was more close tothe actual value. Though the calculation of the rheological parameters from therheological model and the correcting one of the system, we could observed that themodulus of the filling system depends on not only the increased network structure offiller, but also the synergy between the filler and the matrix to form more perfectnetwork structure. To describe the rheological parameters of the low concentration offiber filled system better, only the DK model was not sufficient to illustrate the problem. However the calculation results of the correcting model were stillsignificantly less than the actual value of the system in low filler concentration.In the system of SBS thermoplastic elastomer modifing recycled polypropylene,the SBS improved the compatibility of the composite system. SBS as a stressconcentration point to prevent crazing and cracks, which toughen evidently r-PP withthe tensile properties increased slightly. The crystallization behavior of the compositesystem of r-PP/SBS was studied, the resulted reveal that the SBS was theheteronucleation of on r-PP matrix, which can increase the crystallization temperatureof PP in the system. With the increasing SBS content in the r-PP/SBS composites, thenumber of dispersed phase particles increase and the “like gel network” reinforce,resulting in melt viscosity and the storage modulus of the system increases, the meltrheological behavior change from viscous behavior to elastic behavior.