| The preparation of high performance polymer material is now one of prioritized directions of high polymer scientific field which directly influences high polymer industry development. People hope that the materials are both thermostable and easy to form;both have high toughness and the great rigidity.Obviously, single polymer material is difficult to satisfy these requests simultaneously, thus the polymer modification becomes an important way to develop high performance polymer material. At present poly(ethylene terephthalate)(PET) is one of most important composition material, which is mainly used in synthesizing the polyester fiber, manufacturing thin film and the empty container and so on. Price of PET is low and it has fine resistance, good thermal stability, and great ability to bear the chemicals, the electric insulation as well as higher mechanical strength characteristic. Therefore in 1960s people started to take PET into application development as engineering plastics. When using PET as engineering plastics, its shortcomings are excessively slow crystallization velocity in the commonly used mould temperature(70～110℃), low impact strength, high hygroscopicity, which have limited its widespread application. Therefore people attempt many ways to modify PET to enhance the impact strength.This article mainly uses the radiation method and polymer blending method to study toughening effect of PET and the POE blending. We added different crosslinker into the blend to promote cross-linkage reaction and then we observed the toughening effects after adding crosslinkers.In the second chapter we have studied the gel content of PET blending with five kinds of self-made crosslinker to find which crosslinker is best used as the next step experiment. The experiment data demonstrated that the gel content has achieved 50.41% after PET cross-linked with crosslinker C, and therefore we chose crosslinker C as the PET/POE blending system's crosslinker. In the third chapter we use polyolefine elastomer POE to toughen PET. Along with elastomer POE content's increasing, the impact strength of compound materials'fracture elevates unceasingly and the maximum value arises under the 30kGy radiation dose. When the radiation dose continues to increase, the impact strength starts to decline. We use scanning electron microscope to study the cross section appearance and find out that POE granule as the dispersed phase of PET substrate resin has a quite even distribution in the blend, but we can still observe the trace from the cross section that the POE granule falls off from the PET substrate resin after absorbing impact energy and the surface between POE granule and PET substrate resin is very obvious. The compatibility is not very good.In the fourth chapter we use crosslinker C as the PET/POE blending system's crosslinker to toughen the blend. As nonpolar PET is highly symmetrical in structure, but polar POE is asymmetrical, and therefore adding the multi-functional group monomer (crosslinker) will increase graft reaction on the surface as well as promote PET and POE crosslinking to achieve the toughening effect. The experiment data demonstrated that when the content of crosslinker C is 1% and content of the POE is 15%, the blend has its biggest impact strength value which is 16.4kJ/m2. The blend system's impact strength elevates along with the content of crosslinker reduces. When the content of crosslinker C is 3%, the blend system's impact strength also has a very big enhancement, maximum value is 15.7kJ/m2. From the picture of scanning electron microscope of cross section, we can find out that the fracture is an obvious plastic deformation. Elastomer POE causes shear strength of the substrate becoming higher and higher and makes the blend absorb more energies during the process and so the toughening is obvious. As the impact strength of the blend increasing, the tensile strength and break elongation decline at the same time.
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