Research On The Structure And Properties Of Polyolefin Elastomer Reinforced By In-situ Microfiber

The in situ polyolefin elastomer/poly(trimethylene terephthalate) microfibrillar composites(MFCs) were successfully fabricated by multistage stretching extrusion with the assembly of laminating-multiplying elements(LMEs). The factors influence the morphologies and properties of composites were investigated, including the blend ratio, hot stretching ratio, compatibilizer content and different melt index(MI) of POE.The specific contents are as follows:(1) PTT microfibrils were produced in-situ and the number of microfibrils increased with the addition of PTT phase as revealed from scanning electron microscopy(SEM) studies. After the compression molding, The PTT microfibers were preserved successfully. It was easy to see the incompatibility between POE and PTT when the PTT content was high. When the PTT content was 10%, the tensile strength of the sheets was the highest. Moreover, the flowability of all the specimens obeyed the law of pseudoplastic fluid. The storage modulus G′, the loss modulus G″ values and the complex viscosity η* were increased with the PTT content at constant frequency. And the tanδ values were decreased with the PTT content increased. Shore A hardness of the specimens were increased with the PTT content, including the MFCs and commom blends(CBs).(2) Hot stretching ratio(HSR)is one of the most important factors to influence the microfibrils morphologies and properties of the MFCs. The length-diameter ratio of PTT microfiber increased with increasing in HSR. While many microfibers were broken when the HSR was 16. The mean value of the microfibers diameter was larger than the value when the HSR was 13, and the diameter distribution range was wider, too. The tensile strength and the Shore A hardness were the highest when when the HSR was 13. The G′, G″ values and the η* increased with the increase of the HSR at constant frequency. And the tanδ values were decreased with the HSR increased. The performance was not very good when the the HSR was 16, because many microfibers were broken when the stretching was too high.(3) The influences of the compatibilizer content on the microfibrils morphologies and properties of the MFCs were investigated. POE-g-GMA can be used to improve the compatibility between PTT microfibers and POE. But the length-diameter ratio of PTT microfiber decreased with increasing in the content of POE-g-GMA. The average diameter of PTT fibrils decreased with the increasing POE-g-GMA content, and the diameter distribution of fibrils became narrow, the tensile property and the hardness were improved. When the POE-g-GMA content was 5%, the tensile strength was the highest and when the POE-g-GMA content was 3%, the value of shore A hardness was the highest. The G′, G″ values and the η* were increased with the POE-g-GMA content at constant frequency. And the tanδ values were decreased with the compatilizer content increased. But the G′, G″ values and the η* of the MFCs with 7% POE-g-GMA were lower than the MFCs with 3% and 5% POE-g-GMA.(4) Different MI of POE can be influence the morphologies and properties of the MFCs, too. The models of POE were 8842 and 8200 and the MI of POE(8200) is higher than POE(8842). There were many spindly fibers with small diameter in the 8200 system and the diameter distribution range was wider than the 8842 system when the PTT content was high. The optimal content of PTT for the tensile strength was 10% and 15%, which correspond to the 8842 and 8200 system, respectively. The values were higher 72.3% and 16.9% than the neat POE along the extrusion direction. Moreover, dynamic rheology studies showed that the G′, G″ values and the η* were the highest while the tanδ was the lowest for MFCs prepared at weight ratio 85/15 compared with the neat POE for the 8200 system, and there was a plateau region in the tanδ curve, which indicated the forming of the fiber network. while the PTT content was needed 20% for the 8842 system. Shore A hardness of the MFCs were higher than the CBs’ for two systems, but for the MFCs, the optimum content of PTT was 15% and 20%, which correspond to the 8200 and 8842 system, respectively.